app: fix automatic window decoration action processing

This commit adapts the use of the automatic window decorations to the
event processing changes introduced in v0.4.0. You must update widget
state before laying it out, not after. Doing so after (as this code used
to do) results in discarding updates.

Fixes: https://todo.sr.ht/~eliasnaur/gio/542
Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>

.builds/apple.yml

@@ -29,7 +29,7 @@ environment:
 tasks:
  - install_go: |
      mkdir -p /home/build/sdk
-     curl -s https://dl.google.com/go/go1.22.2.linux-amd64.tar.gz | tar -C /home/build/sdk -xzf -
+     curl -s https://dl.google.com/go/go1.19.11.linux-amd64.tar.gz | tar -C /home/build/sdk -xzf -
  - prepare_toolchain: |
      mkdir -p $APPLE_TOOLCHAIN_ROOT
      cd $APPLE_TOOLCHAIN_ROOT

.builds/freebsd.yml

@@ -16,7 +16,7 @@ environment:
 tasks:
  - install_go: |
      mkdir -p /home/build/sdk
-     curl https://dl.google.com/go/go1.22.2.freebsd-amd64.tar.gz | tar -C /home/build/sdk -xzf -
+     curl https://dl.google.com/go/go1.19.11.freebsd-amd64.tar.gz | tar -C /home/build/sdk -xzf -
  - test_gio: |
      cd gio
      go test ./...

.builds/linux.yml

@@ -40,7 +40,7 @@ secrets:
 tasks:
  - install_go: |
      mkdir -p /home/build/sdk
-     curl -s https://dl.google.com/go/go1.22.2.linux-amd64.tar.gz | tar -C /home/build/sdk -xzf -
+     curl -s https://dl.google.com/go/go1.19.11.linux-amd64.tar.gz | tar -C /home/build/sdk -xzf -
  - check_gofmt: |
      cd gio
      test -z "$(gofmt -s -l .)"
@@ -80,8 +80,6 @@ tasks:
      unzip -q ndk.zip
      rm ndk.zip
      mv android-ndk-* ndk-bundle
-     # sdkmanager needs lots of file descriptors
-     ulimit -n 10000
      yes|sdkmanager --licenses
      sdkmanager "platforms;android-31" "build-tools;32.0.0"
  - test_android: |

.builds/openbsd.yml

@@ -10,7 +10,7 @@ environment:
 tasks:
  - install_go: |
      mkdir -p /home/build/sdk
-     curl https://dl.google.com/go/go1.22.2.src.tar.gz | tar -C /home/build/sdk -xzf -
+     curl https://dl.google.com/go/go1.19.11.src.tar.gz | tar -C /home/build/sdk -xzf -
      cd /home/build/sdk/go/src
      ./make.bash
  - test_gio: |

app/GioView.java

@@ -65,8 +65,8 @@ public final class GioView extends SurfaceView implements Choreographer.FrameCal
 	private final InputMethodManager imm;
 	private final float scrollXScale;
 	private final float scrollYScale;
-	private final AccessibilityManager accessManager;
 	private int keyboardHint;
+	private AccessibilityManager accessManager;
 
 	private long nhandle;
 

app/app.go

@@ -3,16 +3,9 @@
 package app
 
 import (
-	"image"
 	"os"
 	"path/filepath"
 	"strings"
-	"time"
-
-	"gioui.org/io/input"
-	"gioui.org/layout"
-	"gioui.org/op"
-	"gioui.org/unit"
 )
 
 // extraArgs contains extra arguments to append to
@@ -27,88 +20,23 @@ var extraArgs string
 // On Android ID is the package property of AndroidManifest.xml,
 // on iOS ID is the CFBundleIdentifier of the app Info.plist,
 // on Wayland it is the toplevel app_id,
-// on X11 it is the X11 XClassHint.
+// on X11 it is the X11 XClassHint
 //
-// ID is set by the [gioui.org/cmd/gogio] tool or manually with the -X linker flag. For example,
+// ID is set by the gogio tool or manually with the -X linker flag. For example,
 //
 //	go build -ldflags="-X 'gioui.org/app.ID=org.gioui.example.Kitchen'" .
 //
 // Note that ID is treated as a constant, and that changing it at runtime
-// is not supported. The default value of ID is filepath.Base(os.Args[0]).
+// is not supported. Default value of ID is filepath.Base(os.Args[0]).
 var ID = ""
 
-// A FrameEvent requests a new frame in the form of a list of
-// operations that describes the window content.
-type FrameEvent struct {
-	// Now is the current animation. Use Now instead of time.Now to
-	// synchronize animation and to avoid the time.Now call overhead.
-	Now time.Time
-	// Metric converts device independent dp and sp to device pixels.
-	Metric unit.Metric
-	// Size is the dimensions of the window.
-	Size image.Point
-	// Insets represent the space occupied by system decorations and controls.
-	Insets Insets
-	// Frame completes the FrameEvent by drawing the graphical operations
-	// from ops into the window.
-	Frame func(frame *op.Ops)
-	// Source is the interface between the window and widgets.
-	Source input.Source
-}
-
-// ViewEvent provides handles to the underlying window objects for the
-// current display protocol.
-type ViewEvent interface {
-	implementsViewEvent()
-	ImplementsEvent()
-	// Valid will return true when the ViewEvent does contains valid handles.
-	// If a window receives an invalid ViewEvent, it should deinitialize any
-	// state referring to handles from a previous ViewEvent.
-	Valid() bool
-}
-
-// Insets is the space taken up by
-// system decoration such as translucent
-// system bars and software keyboards.
-type Insets struct {
-	// Values are in pixels.
-	Top, Bottom, Left, Right unit.Dp
-}
-
-// NewContext is shorthand for
-//
-//	layout.Context{
-//	  Ops: ops,
-//	  Now: e.Now,
-//	  Source: e.Source,
-//	  Metric: e.Metric,
-//	  Constraints: layout.Exact(e.Size),
-//	}
-//
-// NewContext calls ops.Reset and adjusts ops for e.Insets.
-func NewContext(ops *op.Ops, e FrameEvent) layout.Context {
-	ops.Reset()
-
-	size := e.Size
-
-	if e.Insets != (Insets{}) {
-		left := e.Metric.Dp(e.Insets.Left)
-		top := e.Metric.Dp(e.Insets.Top)
-		op.Offset(image.Point{
-			X: left,
-			Y: top,
-		}).Add(ops)
-
-		size.X -= left + e.Metric.Dp(e.Insets.Right)
-		size.Y -= top + e.Metric.Dp(e.Insets.Bottom)
+func init() {
+	if extraArgs != "" {
+		args := strings.Split(extraArgs, "|")
+		os.Args = append(os.Args, args...)
 	}
-
-	return layout.Context{
-		Ops:         ops,
-		Now:         e.Now,
-		Source:      e.Source,
-		Metric:      e.Metric,
-		Constraints: layout.Exact(size),
+	if ID == "" {
+		ID = filepath.Base(os.Args[0])
 	}
 }
 
@@ -135,15 +63,3 @@ func DataDir() (string, error) {
 func Main() {
 	osMain()
 }
-
-func (FrameEvent) ImplementsEvent() {}
-
-func init() {
-	if extraArgs != "" {
-		args := strings.Split(extraArgs, "|")
-		os.Args = append(os.Args, args...)
-	}
-	if ID == "" {
-		ID = filepath.Base(os.Args[0])
-	}
-}

app/doc.go

@@ -8,20 +8,21 @@ See https://gioui.org for instructions to set up and run Gio programs.
 
 # Windows
 
-A Window is run by calling its Event method in a loop. The first time a
-method on Window is called, a new GUI window is created and shown. On mobile
-platforms or when Gio is embedded in another project, Window merely connects
-with a previously created GUI window.
+Create a new Window by calling NewWindow. On mobile platforms or when Gio
+is embedded in another project, NewWindow merely connects with a previously
+created window.
 
-The most important event is [FrameEvent] that prompts an update of the window
-contents.
+A Window is run by calling NextEvent in a loop. The most important event is
+FrameEvent that prompts an update of the window contents.
 
 For example:
 
-	w := new(app.Window)
+	import "gioui.org/unit"
+
+	w := app.NewWindow()
 	for {
-		e := w.Event()
-		if e, ok := e.(app.FrameEvent); ok {
+		e := w.NextEvent()
+		if e, ok := e.(system.FrameEvent); ok {
 			ops.Reset()
 			// Add operations to ops.
 			...
@@ -31,7 +32,7 @@ For example:
 	}
 
 A program must keep receiving events from the event channel until
-[DestroyEvent] is received.
+DestroyEvent is received.
 
 # Main
 
@@ -50,12 +51,18 @@ For example, to display a blank but otherwise functional window:
 		go func() {
 			w := app.NewWindow()
 			for {
-				w.Event()
+				w.NextEvent()
 			}
 		}()
 		app.Main()
 	}
 
+# Event queue
+
+A FrameEvent's Queue method returns an event.Queue implementation that distributes
+incoming events to the event handlers declared in the last frame.
+See the gioui.org/io/event package for more information about event handlers.
+
 # Permissions
 
 The packages under gioui.org/app/permission should be imported

app/egl_android.go

@@ -17,8 +17,9 @@ import (
 )
 
 type androidContext struct {
-	win     *window
-	eglSurf egl.NativeWindowType
+	win           *window
+	eglSurf       egl.NativeWindowType
+	width, height int
 	*egl.Context
 }
 
@@ -44,8 +45,9 @@ func (c *androidContext) Refresh() error {
 	if err := c.win.setVisual(c.Context.VisualID()); err != nil {
 		return err
 	}
-	win, _, _ := c.win.nativeWindow()
+	win, width, height := c.win.nativeWindow()
 	c.eglSurf = egl.NativeWindowType(unsafe.Pointer(win))
+	c.width, c.height = width, height
 	return nil
 }
 
@@ -53,7 +55,7 @@ func (c *androidContext) Lock() error {
 	// The Android emulator creates a broken surface if it is not
 	// created on the same thread as the context is made current.
 	if c.eglSurf != nil {
-		if err := c.Context.CreateSurface(c.eglSurf); err != nil {
+		if err := c.Context.CreateSurface(c.eglSurf, c.width, c.height); err != nil {
 			return err
 		}
 		c.eglSurf = nil

app/egl_wayland.go

@@ -69,17 +69,7 @@ func (c *wlContext) Refresh() error {
 	}
 	c.eglWin = eglWin
 	eglSurf := egl.NativeWindowType(uintptr(unsafe.Pointer(eglWin)))
-	if err := c.Context.CreateSurface(eglSurf); err != nil {
-		return err
-	}
-	if err := c.Context.MakeCurrent(); err != nil {
-		return err
-	}
-	defer c.Context.ReleaseCurrent()
-	// We're in charge of the frame callbacks, don't let eglSwapBuffers
-	// wait for callbacks that may never arrive.
-	c.Context.EnableVSync(false)
-	return nil
+	return c.Context.CreateSurface(eglSurf, width, height)
 }
 
 func (c *wlContext) Lock() error {

app/egl_windows.go

@@ -5,6 +5,8 @@
 package app
 
 import (
+	"golang.org/x/sys/windows"
+
 	"gioui.org/internal/egl"
 )
 
@@ -22,18 +24,6 @@ func init() {
 			if err != nil {
 				return nil, err
 			}
-			win, _, _ := w.HWND()
-			eglSurf := egl.NativeWindowType(win)
-			if err := ctx.CreateSurface(eglSurf); err != nil {
-				ctx.Release()
-				return nil, err
-			}
-			if err := ctx.MakeCurrent(); err != nil {
-				ctx.Release()
-				return nil, err
-			}
-			defer ctx.ReleaseCurrent()
-			ctx.EnableVSync(true)
 			return &glContext{win: w, Context: ctx}, nil
 		},
 	})
@@ -47,6 +37,21 @@ func (c *glContext) Release() {
 }
 
 func (c *glContext) Refresh() error {
+	c.Context.ReleaseSurface()
+	var (
+		win           windows.Handle
+		width, height int
+	)
+	win, width, height = c.win.HWND()
+	eglSurf := egl.NativeWindowType(win)
+	if err := c.Context.CreateSurface(eglSurf, width, height); err != nil {
+		return err
+	}
+	if err := c.Context.MakeCurrent(); err != nil {
+		return err
+	}
+	c.Context.EnableVSync(true)
+	c.Context.ReleaseCurrent()
 	return nil
 }
 

app/egl_x11.go

@@ -25,18 +25,6 @@ func init() {
 		if err != nil {
 			return nil, err
 		}
-		win, _, _ := w.window()
-		eglSurf := egl.NativeWindowType(uintptr(win))
-		if err := ctx.CreateSurface(eglSurf); err != nil {
-			ctx.Release()
-			return nil, err
-		}
-		if err := ctx.MakeCurrent(); err != nil {
-			ctx.Release()
-			return nil, err
-		}
-		defer ctx.ReleaseCurrent()
-		ctx.EnableVSync(true)
 		return &x11Context{win: w, Context: ctx}, nil
 	}
 }
@@ -49,6 +37,17 @@ func (c *x11Context) Release() {
 }
 
 func (c *x11Context) Refresh() error {
+	c.Context.ReleaseSurface()
+	win, width, height := c.win.window()
+	eglSurf := egl.NativeWindowType(uintptr(win))
+	if err := c.Context.CreateSurface(eglSurf, width, height); err != nil {
+		return err
+	}
+	if err := c.Context.MakeCurrent(); err != nil {
+		return err
+	}
+	c.Context.EnableVSync(true)
+	c.Context.ReleaseCurrent()
 	return nil
 }
 

app/gl_macos.m

@@ -7,7 +7,7 @@
 #include <OpenGL/OpenGL.h>
 #include "_cgo_export.h"
 
-CALayer *gio_layerFactory(BOOL presentWithTrans) {
+CALayer *gio_layerFactory(void) {
 	@autoreleasepool {
 		return [CALayer layer];
 	}

app/ime.go

@@ -1,118 +0,0 @@
-// SPDX-License-Identifier: Unlicense OR MIT
-package app
-
-import (
-	"unicode"
-	"unicode/utf16"
-
-	"gioui.org/io/input"
-	"gioui.org/io/key"
-)
-
-type editorState struct {
-	input.EditorState
-	compose key.Range
-}
-
-func (e *editorState) Replace(r key.Range, text string) {
-	if r.Start > r.End {
-		r.Start, r.End = r.End, r.Start
-	}
-	runes := []rune(text)
-	newEnd := r.Start + len(runes)
-	adjust := func(pos int) int {
-		switch {
-		case newEnd < pos && pos <= r.End:
-			return newEnd
-		case r.End < pos:
-			diff := newEnd - r.End
-			return pos + diff
-		}
-		return pos
-	}
-	e.Selection.Start = adjust(e.Selection.Start)
-	e.Selection.End = adjust(e.Selection.End)
-	if e.compose.Start != -1 {
-		e.compose.Start = adjust(e.compose.Start)
-		e.compose.End = adjust(e.compose.End)
-	}
-	s := e.Snippet
-	if r.End < s.Start || r.Start > s.End {
-		// Discard snippet if it doesn't overlap with replacement.
-		s = key.Snippet{
-			Range: key.Range{
-				Start: r.Start,
-				End:   r.Start,
-			},
-		}
-	}
-	var newSnippet []rune
-	snippet := []rune(s.Text)
-	// Append first part of existing snippet.
-	if end := r.Start - s.Start; end > 0 {
-		newSnippet = append(newSnippet, snippet[:end]...)
-	}
-	// Append replacement.
-	newSnippet = append(newSnippet, runes...)
-	// Append last part of existing snippet.
-	if start := r.End; start < s.End {
-		newSnippet = append(newSnippet, snippet[start-s.Start:]...)
-	}
-	// Adjust snippet range to include replacement.
-	if r.Start < s.Start {
-		s.Start = r.Start
-	}
-	s.End = s.Start + len(newSnippet)
-	s.Text = string(newSnippet)
-	e.Snippet = s
-}
-
-// UTF16Index converts the given index in runes into an index in utf16 characters.
-func (e *editorState) UTF16Index(runes int) int {
-	if runes == -1 {
-		return -1
-	}
-	if runes < e.Snippet.Start {
-		// Assume runes before sippet are one UTF-16 character each.
-		return runes
-	}
-	chars := e.Snippet.Start
-	runes -= e.Snippet.Start
-	for _, r := range e.Snippet.Text {
-		if runes == 0 {
-			break
-		}
-		runes--
-		chars++
-		if r1, _ := utf16.EncodeRune(r); r1 != unicode.ReplacementChar {
-			chars++
-		}
-	}
-	// Assume runes after snippets are one UTF-16 character each.
-	return chars + runes
-}
-
-// RunesIndex converts the given index in utf16 characters to an index in runes.
-func (e *editorState) RunesIndex(chars int) int {
-	if chars == -1 {
-		return -1
-	}
-	if chars < e.Snippet.Start {
-		// Assume runes before offset are one UTF-16 character each.
-		return chars
-	}
-	runes := e.Snippet.Start
-	chars -= e.Snippet.Start
-	for _, r := range e.Snippet.Text {
-		if chars == 0 {
-			break
-		}
-		chars--
-		runes++
-		if r1, _ := utf16.EncodeRune(r); r1 != unicode.ReplacementChar {
-			chars--
-		}
-	}
-	// Assume runes after snippets are one UTF-16 character each.
-	return runes + chars
-}

app/ime_test.go

@@ -11,8 +11,8 @@ import (
 
 	"gioui.org/font"
 	"gioui.org/font/gofont"
-	"gioui.org/io/input"
 	"gioui.org/io/key"
+	"gioui.org/io/router"
 	"gioui.org/layout"
 	"gioui.org/op"
 	"gioui.org/text"
@@ -31,10 +31,10 @@ func FuzzIME(f *testing.F) {
 	f.Fuzz(func(t *testing.T, cmds []byte) {
 		cache := text.NewShaper(text.WithCollection(gofont.Collection()))
 		e := new(widget.Editor)
+		e.Focus()
 
-		var r input.Router
-		gtx := layout.Context{Ops: new(op.Ops), Source: r.Source()}
-		gtx.Execute(key.FocusCmd{Tag: e})
+		var r router.Router
+		gtx := layout.Context{Ops: new(op.Ops), Queue: &r}
 		// Layout once to register focus.
 		e.Layout(gtx, cache, font.Font{}, unit.Sp(10), op.CallOp{}, op.CallOp{})
 		r.Frame(gtx.Ops)

app/internal/log/log.go

@@ -0,0 +1,7 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+// Package points standard output, standard error and the standard
+// library package log to the platform logger.
+package log
+
+var appID = "gio"

app/internal/log/log_android.go

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: Unlicense OR MIT
 
-package app
+package log
 
 /*
 #cgo LDFLAGS: -llog
@@ -22,7 +22,7 @@ import (
 // 1024 is the truncation limit from android/log.h, plus a \n.
 const logLineLimit = 1024
 
-var logTag = C.CString(ID)
+var logTag = C.CString(appID)
 
 func init() {
 	// Android's logcat already includes timestamps.

app/internal/log/log_ios.go

@@ -3,7 +3,7 @@
 //go:build darwin && ios
 // +build darwin,ios
 
-package app
+package log
 
 /*
 #cgo CFLAGS: -Werror -fmodules -fobjc-arc -x objective-c

app/internal/log/log_windows.go

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: Unlicense OR MIT
 
-package app
+package log
 
 import (
 	"log"

app/internal/windows/windows.go

@@ -266,7 +266,6 @@ const (
 	WM_MOUSEWHEEL           = 0x020A
 	WM_MOUSEHWHEEL          = 0x020E
 	WM_NCACTIVATE           = 0x0086
-	WM_NCLBUTTONDBLCLK      = 0x00A3
 	WM_NCHITTEST            = 0x0084
 	WM_NCCALCSIZE           = 0x0083
 	WM_PAINT                = 0x000F

app/internal/xkb/xkb_unix.go

@@ -238,17 +238,17 @@ func (x *Context) UpdateMask(depressed, latched, locked, depressedGroup, latched
 		C.xkb_layout_index_t(depressedGroup), C.xkb_layout_index_t(latchedGroup), C.xkb_layout_index_t(lockedGroup))
 }
 
-func convertKeysym(s C.xkb_keysym_t) (key.Name, bool) {
+func convertKeysym(s C.xkb_keysym_t) (string, bool) {
 	if 'a' <= s && s <= 'z' {
-		return key.Name(rune(s - 'a' + 'A')), true
+		return string(rune(s - 'a' + 'A')), true
 	}
 	if C.XKB_KEY_KP_0 <= s && s <= C.XKB_KEY_KP_9 {
-		return key.Name(rune(s - C.XKB_KEY_KP_0 + '0')), true
+		return string(rune(s - C.XKB_KEY_KP_0 + '0')), true
 	}
 	if ' ' < s && s <= '~' {
-		return key.Name(rune(s)), true
+		return string(rune(s)), true
 	}
-	var n key.Name
+	var n string
 	switch s {
 	case C.XKB_KEY_Escape:
 		n = key.NameEscape

app/metal_darwin.go

@@ -60,9 +60,8 @@ static void presentDrawable(CFTypeRef queueRef, CFTypeRef drawableRef) {
 		id<MTLDrawable> drawable = (__bridge id<MTLDrawable>)drawableRef;
 		id<MTLCommandQueue> queue = (__bridge id<MTLCommandQueue>)queueRef;
 		id<MTLCommandBuffer> cmdBuffer = [queue commandBuffer];
+		[cmdBuffer presentDrawable:drawable];
 		[cmdBuffer commit];
-		[cmdBuffer waitUntilScheduled];
-		[drawable present];
 	}
 }
 

app/metal_ios.go

@@ -21,10 +21,7 @@ Class gio_layerClass(void) {
 static CFTypeRef getMetalLayer(CFTypeRef viewRef) {
 	@autoreleasepool {
 		UIView *view = (__bridge UIView *)viewRef;
-		CAMetalLayer *l = (CAMetalLayer *)view.layer;
-		l.needsDisplayOnBoundsChange = YES;
-		l.presentsWithTransaction = YES;
-		return CFBridgingRetain(l);
+		return CFBridgingRetain(view.layer);
 	}
 }
 

app/metal_macos.go

@@ -12,13 +12,9 @@ package app
 #import <QuartzCore/CAMetalLayer.h>
 #include <CoreFoundation/CoreFoundation.h>
 
-CALayer *gio_layerFactory(BOOL presentWithTrans) {
+CALayer *gio_layerFactory(void) {
 	@autoreleasepool {
-		CAMetalLayer *l = [CAMetalLayer layer];
-		l.autoresizingMask = kCALayerHeightSizable|kCALayerWidthSizable;
-		l.needsDisplayOnBoundsChange = YES;
-		l.presentsWithTransaction = presentWithTrans;
-		return l;
+		return [CAMetalLayer layer];
 	}
 }
 

app/os.go

@@ -7,9 +7,7 @@ import (
 	"image"
 	"image/color"
 
-	"gioui.org/io/event"
 	"gioui.org/io/key"
-	"gioui.org/op"
 
 	"gioui.org/gpu"
 	"gioui.org/io/pointer"
@@ -45,8 +43,6 @@ type Config struct {
 	CustomRenderer bool
 	// Decorated reports whether window decorations are provided automatically.
 	Decorated bool
-	// Focused reports whether has the keyboard focus.
-	Focused bool
 	// decoHeight is the height of the fallback decoration for platforms such
 	// as Wayland that may need fallback client-side decorations.
 	decoHeight unit.Dp
@@ -135,30 +131,8 @@ func (o Orientation) String() string {
 	return ""
 }
 
-// eventLoop implements the functionality required for drivers where
-// window event loops must run on a separate thread.
-type eventLoop struct {
-	win *callbacks
-	// wakeup is the callback to wake up the event loop.
-	wakeup func()
-	// driverFuncs is a channel of functions to run the next
-	// time the window loop waits for events.
-	driverFuncs chan func()
-	// invalidates is notified when an invalidate is requested by the client.
-	invalidates chan struct{}
-	// immediateInvalidates is an optimistic invalidates that doesn't require a wakeup.
-	immediateInvalidates chan struct{}
-	// events is where the platform backend delivers events bound for the
-	// user program.
-	events   chan event.Event
-	frames   chan *op.Ops
-	frameAck chan struct{}
-	// delivering avoids re-entrant event delivery.
-	delivering bool
-}
-
 type frameEvent struct {
-	FrameEvent
+	system.FrameEvent
 
 	Sync bool
 }
@@ -173,13 +147,9 @@ type context interface {
 	Unlock()
 }
 
-// driver is the interface for the platform implementation
+// Driver is the interface for the platform implementation
 // of a window.
 type driver interface {
-	// Event blocks until an event is available and returns it.
-	Event() event.Event
-	// Invalidate requests a FrameEvent.
-	Invalidate()
 	// SetAnimating sets the animation flag. When the window is animating,
 	// FrameEvents are delivered as fast as the display can handle them.
 	SetAnimating(anim bool)
@@ -190,29 +160,23 @@ type driver interface {
 	// ReadClipboard requests the clipboard content.
 	ReadClipboard()
 	// WriteClipboard requests a clipboard write.
-	WriteClipboard(mime string, s []byte)
+	WriteClipboard(s string)
 	// Configure the window.
 	Configure([]Option)
 	// SetCursor updates the current cursor to name.
 	SetCursor(cursor pointer.Cursor)
 	// Wakeup wakes up the event loop and sends a WakeupEvent.
-	// Wakeup()
+	Wakeup()
 	// Perform actions on the window.
 	Perform(system.Action)
 	// EditorStateChanged notifies the driver that the editor state changed.
 	EditorStateChanged(old, new editorState)
-	// Run a function on the window thread.
-	Run(f func())
-	// Frame receives a frame.
-	Frame(frame *op.Ops)
-	// ProcessEvent processes an event.
-	ProcessEvent(e event.Event)
 }
 
 type windowRendezvous struct {
-	in      chan windowAndConfig
-	out     chan windowAndConfig
-	windows chan struct{}
+	in   chan windowAndConfig
+	out  chan windowAndConfig
+	errs chan error
 }
 
 type windowAndConfig struct {
@@ -222,137 +186,32 @@ type windowAndConfig struct {
 
 func newWindowRendezvous() *windowRendezvous {
 	wr := &windowRendezvous{
-		in:      make(chan windowAndConfig),
-		out:     make(chan windowAndConfig),
-		windows: make(chan struct{}),
+		in:   make(chan windowAndConfig),
+		out:  make(chan windowAndConfig),
+		errs: make(chan error),
 	}
 	go func() {
-		in := wr.in
-		var window windowAndConfig
+		var main windowAndConfig
 		var out chan windowAndConfig
 		for {
 			select {
-			case w := <-in:
-				window = w
+			case w := <-wr.in:
+				var err error
+				if main.window != nil {
+					err = errors.New("multiple windows are not supported")
+				}
+				wr.errs <- err
+				main = w
 				out = wr.out
-			case out <- window:
+			case out <- main:
 			}
 		}
 	}()
 	return wr
 }
 
-func newEventLoop(w *callbacks, wakeup func()) *eventLoop {
-	return &eventLoop{
-		win:                  w,
-		wakeup:               wakeup,
-		events:               make(chan event.Event),
-		invalidates:          make(chan struct{}, 1),
-		immediateInvalidates: make(chan struct{}),
-		frames:               make(chan *op.Ops),
-		frameAck:             make(chan struct{}),
-		driverFuncs:          make(chan func(), 1),
-	}
-}
-
-// Frame receives a frame and waits for its processing. It is called by
-// the client goroutine.
-func (e *eventLoop) Frame(frame *op.Ops) {
-	e.frames <- frame
-	<-e.frameAck
-}
-
-// Event returns the next available event. It is called by the client
-// goroutine.
-func (e *eventLoop) Event() event.Event {
-	for {
-		evt := <-e.events
-		// Receiving a flushEvent indicates to the platform backend that
-		// all previous events have been processed by the user program.
-		if _, ok := evt.(flushEvent); ok {
-			continue
-		}
-		return evt
-	}
-}
-
-// Invalidate requests invalidation of the window. It is called by the client
-// goroutine.
-func (e *eventLoop) Invalidate() {
-	select {
-	case e.immediateInvalidates <- struct{}{}:
-		// The event loop was waiting, no need for a wakeup.
-	case e.invalidates <- struct{}{}:
-		// The event loop is sleeping, wake it up.
-		e.wakeup()
-	default:
-		// A redraw is pending.
-	}
-}
-
-// Run f in the window loop thread. It is called by the client goroutine.
-func (e *eventLoop) Run(f func()) {
-	e.driverFuncs <- f
-	e.wakeup()
-}
-
-// FlushEvents delivers pending events to the client.
-func (e *eventLoop) FlushEvents() {
-	if e.delivering {
-		return
-	}
-	e.delivering = true
-	defer func() { e.delivering = false }()
-	for {
-		evt, ok := e.win.nextEvent()
-		if !ok {
-			break
-		}
-		e.deliverEvent(evt)
-	}
-}
-
-func (e *eventLoop) deliverEvent(evt event.Event) {
-	var frames <-chan *op.Ops
-	for {
-		select {
-		case f := <-e.driverFuncs:
-			f()
-		case frame := <-frames:
-			// The client called FrameEvent.Frame.
-			frames = nil
-			e.win.ProcessFrame(frame, e.frameAck)
-		case e.events <- evt:
-			switch evt.(type) {
-			case flushEvent, DestroyEvent:
-				// DestroyEvents are not flushed.
-				return
-			case FrameEvent:
-				frames = e.frames
-			}
-			evt = theFlushEvent
-		case <-e.invalidates:
-			e.win.Invalidate()
-		case <-e.immediateInvalidates:
-			e.win.Invalidate()
-		}
-	}
-}
-
-func (e *eventLoop) Wakeup() {
-	for {
-		select {
-		case f := <-e.driverFuncs:
-			f()
-		case <-e.invalidates:
-			e.win.Invalidate()
-		case <-e.immediateInvalidates:
-			e.win.Invalidate()
-		default:
-			return
-		}
-	}
-}
+func (wakeupEvent) ImplementsEvent() {}
+func (ConfigEvent) ImplementsEvent() {}
 
 func walkActions(actions system.Action, do func(system.Action)) {
 	for a := system.Action(1); actions != 0; a <<= 1 {
@@ -362,6 +221,3 @@ func walkActions(actions system.Action, do func(system.Action)) {
 		}
 	}
 }
-
-func (wakeupEvent) ImplementsEvent() {}
-func (ConfigEvent) ImplementsEvent() {}

app/os_android.go

@@ -123,36 +123,31 @@ import (
 	"fmt"
 	"image"
 	"image/color"
-	"io"
 	"math"
 	"os"
 	"path/filepath"
 	"runtime"
 	"runtime/cgo"
 	"runtime/debug"
-	"strings"
 	"sync"
 	"time"
 	"unicode/utf16"
 	"unsafe"
 
 	"gioui.org/internal/f32color"
-	"gioui.org/op"
 
 	"gioui.org/f32"
-	"gioui.org/io/event"
-	"gioui.org/io/input"
+	"gioui.org/io/clipboard"
 	"gioui.org/io/key"
 	"gioui.org/io/pointer"
+	"gioui.org/io/router"
 	"gioui.org/io/semantic"
 	"gioui.org/io/system"
-	"gioui.org/io/transfer"
 	"gioui.org/unit"
 )
 
 type window struct {
 	callbacks *callbacks
-	loop      *eventLoop
 
 	view   C.jobject
 	handle cgo.Handle
@@ -161,19 +156,18 @@ type window struct {
 	fontScale float32
 	insets    pixelInsets
 
-	visible   bool
+	stage     system.Stage
 	started   bool
 	animating bool
 
-	win       *C.ANativeWindow
-	config    Config
-	inputHint key.InputHint
+	win    *C.ANativeWindow
+	config Config
 
 	semantic struct {
-		hoverID input.SemanticID
-		rootID  input.SemanticID
-		focusID input.SemanticID
-		diffs   []input.SemanticID
+		hoverID router.SemanticID
+		rootID  router.SemanticID
+		focusID router.SemanticID
+		diffs   []router.SemanticID
 	}
 }
 
@@ -205,9 +199,9 @@ type pixelInsets struct {
 	top, bottom, left, right int
 }
 
-// AndroidViewEvent is sent whenever the Window's underlying Android view
+// ViewEvent is sent whenever the Window's underlying Android view
 // changes.
-type AndroidViewEvent struct {
+type ViewEvent struct {
 	// View is a JNI global reference to the android.view.View
 	// instance backing the Window. The reference is valid until
 	// the next ViewEvent is received.
@@ -491,30 +485,24 @@ func Java_org_gioui_GioView_onCreateView(env *C.JNIEnv, class C.jclass, view C.j
 	})
 	view = C.jni_NewGlobalRef(env, view)
 	wopts := <-mainWindow.out
-	var cnf Config
 	w, ok := windows[wopts.window]
 	if !ok {
 		w = &window{
 			callbacks: wopts.window,
 		}
-		w.loop = newEventLoop(w.callbacks, w.wakeup)
-		w.callbacks.SetDriver(w)
-		cnf.apply(unit.Metric{}, wopts.options)
 		windows[wopts.window] = w
-	} else {
-		cnf = w.config
 	}
-	mainWindow.windows <- struct{}{}
 	if w.view != 0 {
 		w.detach(env)
 	}
 	w.view = view
-	w.visible = false
 	w.handle = cgo.NewHandle(w)
+	w.callbacks.SetDriver(w)
 	w.loadConfig(env, class)
-	w.setConfig(env, cnf)
-	w.SetInputHint(w.inputHint)
-	w.processEvent(AndroidViewEvent{View: uintptr(view)})
+	w.Configure(wopts.options)
+	w.SetInputHint(key.HintAny)
+	w.setStage(system.StagePaused)
+	w.callbacks.Event(ViewEvent{View: uintptr(view)})
 	return C.jlong(w.handle)
 }
 
@@ -528,7 +516,7 @@ func Java_org_gioui_GioView_onDestroyView(env *C.JNIEnv, class C.jclass, handle
 func Java_org_gioui_GioView_onStopView(env *C.JNIEnv, class C.jclass, handle C.jlong) {
 	w := cgo.Handle(handle).Value().(*window)
 	w.started = false
-	w.visible = false
+	w.setStage(system.StagePaused)
 }
 
 //export Java_org_gioui_GioView_onStartView
@@ -544,7 +532,7 @@ func Java_org_gioui_GioView_onStartView(env *C.JNIEnv, class C.jclass, handle C.
 func Java_org_gioui_GioView_onSurfaceDestroyed(env *C.JNIEnv, class C.jclass, handle C.jlong) {
 	w := cgo.Handle(handle).Value().(*window)
 	w.win = nil
-	w.visible = false
+	w.setStage(system.StagePaused)
 }
 
 //export Java_org_gioui_GioView_onSurfaceChanged
@@ -566,7 +554,9 @@ func Java_org_gioui_GioView_onLowMemory(env *C.JNIEnv, class C.jclass) {
 func Java_org_gioui_GioView_onConfigurationChanged(env *C.JNIEnv, class C.jclass, view C.jlong) {
 	w := cgo.Handle(view).Value().(*window)
 	w.loadConfig(env, class)
-	w.draw(env, true)
+	if w.stage >= system.StageInactive {
+		w.draw(env, true)
+	}
 }
 
 //export Java_org_gioui_GioView_onFrameCallback
@@ -575,7 +565,10 @@ func Java_org_gioui_GioView_onFrameCallback(env *C.JNIEnv, class C.jclass, view
 	if !exist {
 		return
 	}
-	if w.visible && w.animating {
+	if w.stage < system.StageInactive {
+		return
+	}
+	if w.animating {
 		w.draw(env, false)
 		callVoidMethod(env, w.view, gioView.postFrameCallback)
 	}
@@ -584,7 +577,7 @@ func Java_org_gioui_GioView_onFrameCallback(env *C.JNIEnv, class C.jclass, view
 //export Java_org_gioui_GioView_onBack
 func Java_org_gioui_GioView_onBack(env *C.JNIEnv, class C.jclass, view C.jlong) C.jboolean {
 	w := cgo.Handle(view).Value().(*window)
-	if w.processEvent(key.Event{Name: key.NameBack}) {
+	if w.callbacks.Event(key.Event{Name: key.NameBack}) {
 		return C.JNI_TRUE
 	}
 	return C.JNI_FALSE
@@ -593,8 +586,7 @@ func Java_org_gioui_GioView_onBack(env *C.JNIEnv, class C.jclass, view C.jlong)
 //export Java_org_gioui_GioView_onFocusChange
 func Java_org_gioui_GioView_onFocusChange(env *C.JNIEnv, class C.jclass, view C.jlong, focus C.jboolean) {
 	w := cgo.Handle(view).Value().(*window)
-	w.config.Focused = focus == C.JNI_TRUE
-	w.processEvent(ConfigEvent{Config: w.config})
+	w.callbacks.Event(key.FocusEvent{Focus: focus == C.JNI_TRUE})
 }
 
 //export Java_org_gioui_GioView_onWindowInsets
@@ -606,7 +598,9 @@ func Java_org_gioui_GioView_onWindowInsets(env *C.JNIEnv, class C.jclass, view C
 		left:   int(left),
 		right:  int(right),
 	}
-	w.draw(env, true)
+	if w.stage >= system.StageInactive {
+		w.draw(env, true)
+	}
 }
 
 //export Java_org_gioui_GioView_initializeAccessibilityNodeInfo
@@ -667,35 +661,7 @@ func Java_org_gioui_GioView_onClearA11yFocus(env *C.JNIEnv, class C.jclass, view
 	}
 }
 
-func (w *window) ProcessEvent(e event.Event) {
-	w.processEvent(e)
-}
-
-func (w *window) processEvent(e event.Event) bool {
-	if !w.callbacks.ProcessEvent(e) {
-		return false
-	}
-	w.loop.FlushEvents()
-	return true
-}
-
-func (w *window) Event() event.Event {
-	return w.loop.Event()
-}
-
-func (w *window) Invalidate() {
-	w.loop.Invalidate()
-}
-
-func (w *window) Run(f func()) {
-	w.loop.Run(f)
-}
-
-func (w *window) Frame(frame *op.Ops) {
-	w.loop.Frame(frame)
-}
-
-func (w *window) initAccessibilityNodeInfo(env *C.JNIEnv, sem input.SemanticNode, off image.Point, info C.jobject) error {
+func (w *window) initAccessibilityNodeInfo(env *C.JNIEnv, sem router.SemanticNode, off image.Point, info C.jobject) error {
 	for _, ch := range sem.Children {
 		err := callVoidMethod(env, info, android.accessibilityNodeInfo.addChild, jvalue(w.view), jvalue(w.virtualIDFor(ch.ID)))
 		if err != nil {
@@ -738,7 +704,7 @@ func (w *window) initAccessibilityNodeInfo(env *C.JNIEnv, sem input.SemanticNode
 			panic(err)
 		}
 	}
-	if d.Gestures&input.ClickGesture != 0 {
+	if d.Gestures&router.ClickGesture != 0 {
 		addAction(ACTION_CLICK)
 	}
 	clsName := android.strings.androidViewView
@@ -783,23 +749,25 @@ func (w *window) initAccessibilityNodeInfo(env *C.JNIEnv, sem input.SemanticNode
 	return nil
 }
 
-func (w *window) virtualIDFor(id input.SemanticID) C.jint {
+func (w *window) virtualIDFor(id router.SemanticID) C.jint {
+	// TODO: Android virtual IDs are 32-bit Java integers, but childID is a int64.
 	if id == w.semantic.rootID {
 		return HOST_VIEW_ID
 	}
 	return C.jint(id)
 }
 
-func (w *window) semIDFor(virtID C.jint) input.SemanticID {
+func (w *window) semIDFor(virtID C.jint) router.SemanticID {
 	if virtID == HOST_VIEW_ID {
 		return w.semantic.rootID
 	}
-	return input.SemanticID(virtID)
+	return router.SemanticID(virtID)
 }
 
 func (w *window) detach(env *C.JNIEnv) {
 	callVoidMethod(env, w.view, gioView.unregister)
-	w.processEvent(AndroidViewEvent{})
+	w.callbacks.Event(ViewEvent{})
+	w.callbacks.SetDriver(nil)
 	w.handle.Delete()
 	C.jni_DeleteGlobalRef(env, w.view)
 	w.view = 0
@@ -810,10 +778,18 @@ func (w *window) setVisible(env *C.JNIEnv) {
 	if width == 0 || height == 0 {
 		return
 	}
-	w.visible = true
+	w.setStage(system.StageRunning)
 	w.draw(env, true)
 }
 
+func (w *window) setStage(stage system.Stage) {
+	if stage == w.stage {
+		return
+	}
+	w.stage = stage
+	w.callbacks.Event(system.StageEvent{stage})
+}
+
 func (w *window) setVisual(visID int) error {
 	if C.ANativeWindow_setBuffersGeometry(w.win, 0, 0, C.int32_t(visID)) != 0 {
 		return errors.New("ANativeWindow_setBuffersGeometry failed")
@@ -850,13 +826,10 @@ func (w *window) SetAnimating(anim bool) {
 }
 
 func (w *window) draw(env *C.JNIEnv, sync bool) {
-	if !w.visible {
-		return
-	}
 	size := image.Pt(int(C.ANativeWindow_getWidth(w.win)), int(C.ANativeWindow_getHeight(w.win)))
 	if size != w.config.Size {
 		w.config.Size = size
-		w.processEvent(ConfigEvent{Config: w.config})
+		w.callbacks.Event(ConfigEvent{Config: w.config})
 	}
 	if size.X == 0 || size.Y == 0 {
 		return
@@ -864,14 +837,14 @@ func (w *window) draw(env *C.JNIEnv, sync bool) {
 	const inchPrDp = 1.0 / 160
 	ppdp := float32(w.dpi) * inchPrDp
 	dppp := unit.Dp(1.0 / ppdp)
-	insets := Insets{
+	insets := system.Insets{
 		Top:    unit.Dp(w.insets.top) * dppp,
 		Bottom: unit.Dp(w.insets.bottom) * dppp,
 		Left:   unit.Dp(w.insets.left) * dppp,
 		Right:  unit.Dp(w.insets.right) * dppp,
 	}
-	w.processEvent(frameEvent{
-		FrameEvent: FrameEvent{
+	w.callbacks.Event(frameEvent{
+		FrameEvent: system.FrameEvent{
 			Now:    time.Now(),
 			Size:   w.config.Size,
 			Insets: insets,
@@ -925,8 +898,8 @@ func runInJVM(jvm *C.JavaVM, f func(env *C.JNIEnv)) {
 	f(env)
 }
 
-func convertKeyCode(code C.jint) (key.Name, bool) {
-	var n key.Name
+func convertKeyCode(code C.jint) (string, bool) {
+	var n string
 	switch code {
 	case C.AKEYCODE_FORWARD_DEL:
 		n = key.NameDeleteForward
@@ -970,7 +943,7 @@ func Java_org_gioui_GioView_onKeyEvent(env *C.JNIEnv, class C.jclass, handle C.j
 		if pressed == C.JNI_TRUE {
 			state = key.Press
 		}
-		w.processEvent(key.Event{Name: n, State: state})
+		w.callbacks.Event(key.Event{Name: n, State: state})
 	}
 	if pressed == C.JNI_TRUE && r != 0 && r != '\n' { // Checking for "\n" to prevent duplication with key.NameEnter (gio#224).
 		w.callbacks.EditorInsert(string(rune(r)))
@@ -1020,7 +993,7 @@ func Java_org_gioui_GioView_onTouchEvent(env *C.JNIEnv, class C.jclass, handle C
 	default:
 		return
 	}
-	w.processEvent(pointer.Event{
+	w.callbacks.Event(pointer.Event{
 		Kind:      kind,
 		Source:    src,
 		Buttons:   btns,
@@ -1172,8 +1145,6 @@ func (w *window) ShowTextInput(show bool) {
 }
 
 func (w *window) SetInputHint(mode key.InputHint) {
-	w.inputHint = mode
-
 	// Constants defined at https://developer.android.com/reference/android/text/InputType.
 	const (
 		TYPE_NULL = 0
@@ -1320,14 +1291,14 @@ func findClass(env *C.JNIEnv, name string) C.jclass {
 func osMain() {
 }
 
-func newWindow(window *callbacks, options []Option) {
+func newWindow(window *callbacks, options []Option) error {
 	mainWindow.in <- windowAndConfig{window, options}
-	<-mainWindow.windows
+	return <-mainWindow.errs
 }
 
-func (w *window) WriteClipboard(mime string, s []byte) {
+func (w *window) WriteClipboard(s string) {
 	runInJVM(javaVM(), func(env *C.JNIEnv) {
-		jstr := javaString(env, string(s))
+		jstr := javaString(env, s)
 		callStaticVoidMethod(env, android.gioCls, android.mwriteClipboard,
 			jvalue(android.appCtx), jvalue(jstr))
 	})
@@ -1341,54 +1312,45 @@ func (w *window) ReadClipboard() {
 			return
 		}
 		content := goString(env, C.jstring(c))
-		w.processEvent(transfer.DataEvent{
-			Type: "application/text",
-			Open: func() io.ReadCloser {
-				return io.NopCloser(strings.NewReader(content))
-			},
-		})
+		w.callbacks.Event(clipboard.Event{Text: content})
 	})
 }
 
 func (w *window) Configure(options []Option) {
-	cnf := w.config
-	cnf.apply(unit.Metric{}, options)
 	runInJVM(javaVM(), func(env *C.JNIEnv) {
-		w.setConfig(env, cnf)
-	})
-}
+		prev := w.config
+		cnf := w.config
+		cnf.apply(unit.Metric{}, options)
+		// Decorations are never disabled.
+		cnf.Decorated = true
 
-func (w *window) setConfig(env *C.JNIEnv, cnf Config) {
-	prev := w.config
-	// Decorations are never disabled.
-	cnf.Decorated = true
-
-	if prev.Orientation != cnf.Orientation {
-		w.config.Orientation = cnf.Orientation
-		setOrientation(env, w.view, cnf.Orientation)
-	}
-	if prev.NavigationColor != cnf.NavigationColor {
-		w.config.NavigationColor = cnf.NavigationColor
-		setNavigationColor(env, w.view, cnf.NavigationColor)
-	}
-	if prev.StatusColor != cnf.StatusColor {
-		w.config.StatusColor = cnf.StatusColor
-		setStatusColor(env, w.view, cnf.StatusColor)
-	}
-	if prev.Mode != cnf.Mode {
-		switch cnf.Mode {
-		case Fullscreen:
-			callVoidMethod(env, w.view, gioView.setFullscreen, C.JNI_TRUE)
-			w.config.Mode = Fullscreen
-		case Windowed:
-			callVoidMethod(env, w.view, gioView.setFullscreen, C.JNI_FALSE)
-			w.config.Mode = Windowed
+		if prev.Orientation != cnf.Orientation {
+			w.config.Orientation = cnf.Orientation
+			setOrientation(env, w.view, cnf.Orientation)
 		}
-	}
-	if cnf.Decorated != prev.Decorated {
-		w.config.Decorated = cnf.Decorated
-	}
-	w.processEvent(ConfigEvent{Config: w.config})
+		if prev.NavigationColor != cnf.NavigationColor {
+			w.config.NavigationColor = cnf.NavigationColor
+			setNavigationColor(env, w.view, cnf.NavigationColor)
+		}
+		if prev.StatusColor != cnf.StatusColor {
+			w.config.StatusColor = cnf.StatusColor
+			setStatusColor(env, w.view, cnf.StatusColor)
+		}
+		if prev.Mode != cnf.Mode {
+			switch cnf.Mode {
+			case Fullscreen:
+				callVoidMethod(env, w.view, gioView.setFullscreen, C.JNI_TRUE)
+				w.config.Mode = Fullscreen
+			case Windowed:
+				callVoidMethod(env, w.view, gioView.setFullscreen, C.JNI_FALSE)
+				w.config.Mode = Windowed
+			}
+		}
+		if cnf.Decorated != prev.Decorated {
+			w.config.Decorated = cnf.Decorated
+		}
+		w.callbacks.Event(ConfigEvent{Config: w.config})
+	})
 }
 
 func (w *window) Perform(system.Action) {}
@@ -1399,10 +1361,9 @@ func (w *window) SetCursor(cursor pointer.Cursor) {
 	})
 }
 
-func (w *window) wakeup() {
+func (w *window) Wakeup() {
 	runOnMain(func(env *C.JNIEnv) {
-		w.loop.Wakeup()
-		w.loop.FlushEvents()
+		w.callbacks.Event(wakeupEvent{})
 	})
 }
 
@@ -1493,8 +1454,4 @@ func Java_org_gioui_Gio_scheduleMainFuncs(env *C.JNIEnv, cls C.jclass) {
 	}
 }
 
-func (AndroidViewEvent) implementsViewEvent() {}
-func (AndroidViewEvent) ImplementsEvent()     {}
-func (a AndroidViewEvent) Valid() bool {
-	return a != (AndroidViewEvent{})
-}
+func (_ ViewEvent) ImplementsEvent() {}

app/os_darwin.go

@@ -75,13 +75,9 @@ var displayLinks sync.Map
 
 var mainFuncs = make(chan func(), 1)
 
-func isMainThread() bool {
-	return bool(C.isMainThread())
-}
-
 // runOnMain runs the function on the main thread.
 func runOnMain(f func()) {
-	if isMainThread() {
+	if C.isMainThread() {
 		f()
 		return
 	}
@@ -264,9 +260,8 @@ func windowSetCursor(from, to pointer.Cursor) pointer.Cursor {
 	return to
 }
 
-func (w *window) wakeup() {
+func (w *window) Wakeup() {
 	runOnMain(func() {
-		w.loop.Wakeup()
-		w.loop.FlushEvents()
+		w.w.Event(wakeupEvent{})
 	})
 }

app/os_ios.go

@@ -12,9 +12,6 @@ package app
 #include <UIKit/UIKit.h>
 #include <stdint.h>
 
-__attribute__ ((visibility ("hidden"))) int gio_applicationMain(int argc, char *argv[]);
-__attribute__ ((visibility ("hidden"))) void gio_viewSetHandle(CFTypeRef viewRef, uintptr_t handle);
-
 struct drawParams {
 	CGFloat dpi, sdpi;
 	CGFloat width, height;
@@ -22,7 +19,6 @@ struct drawParams {
 };
 
 static void writeClipboard(unichar *chars, NSUInteger length) {
-#if !TARGET_OS_TV
 	@autoreleasepool {
 		NSString *s = [NSString string];
 		if (length > 0) {
@@ -31,18 +27,13 @@ static void writeClipboard(unichar *chars, NSUInteger length) {
 		UIPasteboard *p = UIPasteboard.generalPasteboard;
 		p.string = s;
 	}
-#endif
 }
 
 static CFTypeRef readClipboard(void) {
-#if !TARGET_OS_TV
 	@autoreleasepool {
 		UIPasteboard *p = UIPasteboard.generalPasteboard;
 		return (__bridge_retained CFTypeRef)p.string;
 	}
-#else
-	return nil;
-#endif
 }
 
 static void showTextInput(CFTypeRef viewRef) {
@@ -81,27 +72,21 @@ import "C"
 
 import (
 	"image"
-	"io"
-	"os"
 	"runtime"
-	"runtime/cgo"
 	"runtime/debug"
-	"strings"
 	"time"
 	"unicode/utf16"
 	"unsafe"
 
 	"gioui.org/f32"
-	"gioui.org/io/event"
+	"gioui.org/io/clipboard"
 	"gioui.org/io/key"
 	"gioui.org/io/pointer"
 	"gioui.org/io/system"
-	"gioui.org/io/transfer"
-	"gioui.org/op"
 	"gioui.org/unit"
 )
 
-type UIKitViewEvent struct {
+type ViewEvent struct {
 	// ViewController is a CFTypeRef for the UIViewController backing a Window.
 	ViewController uintptr
 }
@@ -110,17 +95,18 @@ type window struct {
 	view        C.CFTypeRef
 	w           *callbacks
 	displayLink *displayLink
-	loop        *eventLoop
 
-	hidden bool
-	cursor pointer.Cursor
-	config Config
+	visible bool
+	cursor  pointer.Cursor
+	config  Config
 
 	pointerMap []C.CFTypeRef
 }
 
 var mainWindow = newWindowRendezvous()
 
+var views = make(map[C.CFTypeRef]*window)
+
 func init() {
 	// Darwin requires UI operations happen on the main thread only.
 	runtime.LockOSThread()
@@ -128,59 +114,55 @@ func init() {
 
 //export onCreate
 func onCreate(view, controller C.CFTypeRef) {
-	wopts := <-mainWindow.out
 	w := &window{
 		view: view,
-		w:    wopts.window,
 	}
-	w.loop = newEventLoop(w.w, w.wakeup)
-	w.w.SetDriver(w)
-	mainWindow.windows <- struct{}{}
 	dl, err := newDisplayLink(func() {
 		w.draw(false)
 	})
 	if err != nil {
-		w.w.ProcessEvent(DestroyEvent{Err: err})
-		return
+		panic(err)
 	}
 	w.displayLink = dl
-	C.gio_viewSetHandle(view, C.uintptr_t(cgo.NewHandle(w)))
+	wopts := <-mainWindow.out
+	w.w = wopts.window
+	w.w.SetDriver(w)
+	views[view] = w
 	w.Configure(wopts.options)
-	w.ProcessEvent(UIKitViewEvent{ViewController: uintptr(controller)})
-}
-
-func viewFor(h C.uintptr_t) *window {
-	return cgo.Handle(h).Value().(*window)
+	w.w.Event(system.StageEvent{Stage: system.StagePaused})
+	w.w.Event(ViewEvent{ViewController: uintptr(controller)})
 }
 
 //export gio_onDraw
-func gio_onDraw(h C.uintptr_t) {
-	w := viewFor(h)
+func gio_onDraw(view C.CFTypeRef) {
+	w := views[view]
 	w.draw(true)
 }
 
 func (w *window) draw(sync bool) {
-	if w.hidden {
-		return
-	}
 	params := C.viewDrawParams(w.view)
 	if params.width == 0 || params.height == 0 {
 		return
 	}
+	wasVisible := w.visible
+	w.visible = true
+	if !wasVisible {
+		w.w.Event(system.StageEvent{Stage: system.StageRunning})
+	}
 	const inchPrDp = 1.0 / 163
 	m := unit.Metric{
 		PxPerDp: float32(params.dpi) * inchPrDp,
 		PxPerSp: float32(params.sdpi) * inchPrDp,
 	}
 	dppp := unit.Dp(1. / m.PxPerDp)
-	w.ProcessEvent(frameEvent{
-		FrameEvent: FrameEvent{
+	w.w.Event(frameEvent{
+		FrameEvent: system.FrameEvent{
 			Now: time.Now(),
 			Size: image.Point{
 				X: int(params.width + .5),
 				Y: int(params.height + .5),
 			},
-			Insets: Insets{
+			Insets: system.Insets{
 				Top:    unit.Dp(params.top) * dppp,
 				Bottom: unit.Dp(params.bottom) * dppp,
 				Left:   unit.Dp(params.left) * dppp,
@@ -193,34 +175,26 @@ func (w *window) draw(sync bool) {
 }
 
 //export onStop
-func onStop(h C.uintptr_t) {
-	w := viewFor(h)
-	w.hidden = true
-}
-
-//export onStart
-func onStart(h C.uintptr_t) {
-	w := viewFor(h)
-	w.hidden = false
-	w.draw(true)
+func onStop(view C.CFTypeRef) {
+	w := views[view]
+	w.visible = false
+	w.w.Event(system.StageEvent{Stage: system.StagePaused})
 }
 
 //export onDestroy
-func onDestroy(h C.uintptr_t) {
-	w := viewFor(h)
-	w.ProcessEvent(UIKitViewEvent{})
-	w.ProcessEvent(DestroyEvent{})
+func onDestroy(view C.CFTypeRef) {
+	w := views[view]
+	delete(views, view)
+	w.w.Event(ViewEvent{})
+	w.w.Event(system.DestroyEvent{})
 	w.displayLink.Close()
-	w.displayLink = nil
-	cgo.Handle(h).Delete()
 	w.view = 0
 }
 
 //export onFocus
-func onFocus(h C.uintptr_t, focus int) {
-	w := viewFor(h)
-	w.config.Focused = focus != 0
-	w.ProcessEvent(ConfigEvent{Config: w.config})
+func onFocus(view C.CFTypeRef, focus int) {
+	w := views[view]
+	w.w.Event(key.FocusEvent{Focus: focus != 0})
 }
 
 //export onLowMemory
@@ -230,38 +204,38 @@ func onLowMemory() {
 }
 
 //export onUpArrow
-func onUpArrow(h C.uintptr_t) {
-	viewFor(h).onKeyCommand(key.NameUpArrow)
+func onUpArrow(view C.CFTypeRef) {
+	views[view].onKeyCommand(key.NameUpArrow)
 }
 
 //export onDownArrow
-func onDownArrow(h C.uintptr_t) {
-	viewFor(h).onKeyCommand(key.NameDownArrow)
+func onDownArrow(view C.CFTypeRef) {
+	views[view].onKeyCommand(key.NameDownArrow)
 }
 
 //export onLeftArrow
-func onLeftArrow(h C.uintptr_t) {
-	viewFor(h).onKeyCommand(key.NameLeftArrow)
+func onLeftArrow(view C.CFTypeRef) {
+	views[view].onKeyCommand(key.NameLeftArrow)
 }
 
 //export onRightArrow
-func onRightArrow(h C.uintptr_t) {
-	viewFor(h).onKeyCommand(key.NameRightArrow)
+func onRightArrow(view C.CFTypeRef) {
+	views[view].onKeyCommand(key.NameRightArrow)
 }
 
 //export onDeleteBackward
-func onDeleteBackward(h C.uintptr_t) {
-	viewFor(h).onKeyCommand(key.NameDeleteBackward)
+func onDeleteBackward(view C.CFTypeRef) {
+	views[view].onKeyCommand(key.NameDeleteBackward)
 }
 
 //export onText
-func onText(h C.uintptr_t, str C.CFTypeRef) {
-	w := viewFor(h)
+func onText(view, str C.CFTypeRef) {
+	w := views[view]
 	w.w.EditorInsert(nsstringToString(str))
 }
 
 //export onTouch
-func onTouch(h C.uintptr_t, last C.int, touchRef C.CFTypeRef, phase C.NSInteger, x, y C.CGFloat, ti C.double) {
+func onTouch(last C.int, view, touchRef C.CFTypeRef, phase C.NSInteger, x, y C.CGFloat, ti C.double) {
 	var kind pointer.Kind
 	switch phase {
 	case C.UITouchPhaseBegan:
@@ -275,10 +249,10 @@ func onTouch(h C.uintptr_t, last C.int, touchRef C.CFTypeRef, phase C.NSInteger,
 	default:
 		return
 	}
-	w := viewFor(h)
+	w := views[view]
 	t := time.Duration(float64(ti) * float64(time.Second))
 	p := f32.Point{X: float32(x), Y: float32(y)}
-	w.ProcessEvent(pointer.Event{
+	w.w.Event(pointer.Event{
 		Kind:      kind,
 		Source:    pointer.Touch,
 		PointerID: w.lookupTouch(last != 0, touchRef),
@@ -291,16 +265,11 @@ func (w *window) ReadClipboard() {
 	cstr := C.readClipboard()
 	defer C.CFRelease(cstr)
 	content := nsstringToString(cstr)
-	w.ProcessEvent(transfer.DataEvent{
-		Type: "application/text",
-		Open: func() io.ReadCloser {
-			return io.NopCloser(strings.NewReader(content))
-		},
-	})
+	w.w.Event(clipboard.Event{Text: content})
 }
 
-func (w *window) WriteClipboard(mime string, s []byte) {
-	u16 := utf16.Encode([]rune(string(s)))
+func (w *window) WriteClipboard(s string) {
+	u16 := utf16.Encode([]rune(s))
 	var chars *C.unichar
 	if len(u16) > 0 {
 		chars = (*C.unichar)(unsafe.Pointer(&u16[0]))
@@ -311,7 +280,7 @@ func (w *window) WriteClipboard(mime string, s []byte) {
 func (w *window) Configure([]Option) {
 	// Decorations are never disabled.
 	w.config.Decorated = true
-	w.ProcessEvent(ConfigEvent{Config: w.config})
+	w.w.Event(ConfigEvent{Config: w.config})
 }
 
 func (w *window) EditorStateChanged(old, new editorState) {}
@@ -319,6 +288,10 @@ func (w *window) EditorStateChanged(old, new editorState) {}
 func (w *window) Perform(system.Action) {}
 
 func (w *window) SetAnimating(anim bool) {
+	v := w.view
+	if v == 0 {
+		return
+	}
 	if anim {
 		w.displayLink.Start()
 	} else {
@@ -330,8 +303,8 @@ func (w *window) SetCursor(cursor pointer.Cursor) {
 	w.cursor = windowSetCursor(w.cursor, cursor)
 }
 
-func (w *window) onKeyCommand(name key.Name) {
-	w.ProcessEvent(key.Event{
+func (w *window) onKeyCommand(name string) {
+	w.w.Event(key.Event{
 		Name: name,
 	})
 }
@@ -370,77 +343,17 @@ func (w *window) ShowTextInput(show bool) {
 
 func (w *window) SetInputHint(_ key.InputHint) {}
 
-func (w *window) ProcessEvent(e event.Event) {
-	w.w.ProcessEvent(e)
-	w.loop.FlushEvents()
-}
-
-func (w *window) Event() event.Event {
-	return w.loop.Event()
-}
-
-func (w *window) Invalidate() {
-	w.loop.Invalidate()
-}
-
-func (w *window) Run(f func()) {
-	w.loop.Run(f)
-}
-
-func (w *window) Frame(frame *op.Ops) {
-	w.loop.Frame(frame)
-}
-
-func newWindow(win *callbacks, options []Option) {
+func newWindow(win *callbacks, options []Option) error {
 	mainWindow.in <- windowAndConfig{win, options}
-	<-mainWindow.windows
+	return <-mainWindow.errs
 }
 
-var mainMode = mainModeUndefined
-
-const (
-	mainModeUndefined = iota
-	mainModeExe
-	mainModeLibrary
-)
-
 func osMain() {
-	if !isMainThread() {
-		panic("app.Main must be run on the main goroutine")
-	}
-	switch mainMode {
-	case mainModeUndefined:
-		mainMode = mainModeExe
-		var argv []*C.char
-		for _, arg := range os.Args {
-			a := C.CString(arg)
-			defer C.free(unsafe.Pointer(a))
-			argv = append(argv, a)
-		}
-		C.gio_applicationMain(C.int(len(argv)), unsafe.SliceData(argv))
-	case mainModeExe:
-		panic("app.Main may be called only once")
-	case mainModeLibrary:
-		// Do nothing, we're embedded as a library.
-	}
 }
 
 //export gio_runMain
 func gio_runMain() {
-	if !isMainThread() {
-		panic("app.Main must be run on the main goroutine")
-	}
-	switch mainMode {
-	case mainModeUndefined:
-		mainMode = mainModeLibrary
-		runMain()
-	case mainModeExe:
-		// Do nothing, main has already been called.
-	}
+	runMain()
 }
 
-func (UIKitViewEvent) implementsViewEvent() {}
-func (UIKitViewEvent) ImplementsEvent()     {}
-func (u UIKitViewEvent) Valid() bool {
-	return u != (UIKitViewEvent{})
-}
+func (_ ViewEvent) ImplementsEvent() {}

app/os_ios.m

@@ -11,7 +11,6 @@
 __attribute__ ((visibility ("hidden"))) Class gio_layerClass(void);
 
 @interface GioView: UIView <UIKeyInput>
-@property uintptr_t handle;
 @end
 
 @implementation GioViewController
@@ -26,13 +25,12 @@ CGFloat _keyboardHeight;
 	self.view.layoutMargins = UIEdgeInsetsMake(0, 0, 0, 0);
 	UIView *drawView = [[GioView alloc] initWithFrame:zeroFrame];
 	[self.view addSubview: drawView];
-#if !TARGET_OS_TV
+#ifndef TARGET_OS_TV
 	drawView.multipleTouchEnabled = YES;
 #endif
 	drawView.preservesSuperviewLayoutMargins = YES;
 	drawView.layoutMargins = UIEdgeInsetsMake(0, 0, 0, 0);
 	onCreate((__bridge CFTypeRef)drawView, (__bridge CFTypeRef)self);
-#if !TARGET_OS_TV
 	[[NSNotificationCenter defaultCenter] addObserver:self
 											 selector:@selector(keyboardWillChange:)
 												 name:UIKeyboardWillShowNotification
@@ -45,7 +43,6 @@ CGFloat _keyboardHeight;
 											 selector:@selector(keyboardWillHide:)
 												 name:UIKeyboardWillHideNotification
 											   object:nil];
-#endif
 	[[NSNotificationCenter defaultCenter] addObserver: self
 											 selector: @selector(applicationDidEnterBackground:)
 												 name: UIApplicationDidEnterBackgroundNotification
@@ -57,33 +54,33 @@ CGFloat _keyboardHeight;
 }
 
 - (void)applicationWillEnterForeground:(UIApplication *)application {
-	GioView *view = (GioView *)self.view.subviews[0];
-	if (view != nil) {
-		onStart(view.handle);
+	UIView *drawView = self.view.subviews[0];
+	if (drawView != nil) {
+		gio_onDraw((__bridge CFTypeRef)drawView);
 	}
 }
 
 - (void)applicationDidEnterBackground:(UIApplication *)application {
-	GioView *view = (GioView *)self.view.subviews[0];
-	if (view != nil) {
-		onStop(view.handle);
+	UIView *drawView = self.view.subviews[0];
+	if (drawView != nil) {
+		onStop((__bridge CFTypeRef)drawView);
 	}
 }
 
 - (void)viewDidDisappear:(BOOL)animated {
 	[super viewDidDisappear:animated];
-	GioView *view = (GioView *)self.view.subviews[0];
-	onDestroy(view.handle);
+	CFTypeRef viewRef = (__bridge CFTypeRef)self.view.subviews[0];
+	onDestroy(viewRef);
 }
 
 - (void)viewDidLayoutSubviews {
 	[super viewDidLayoutSubviews];
-	GioView *view = (GioView *)self.view.subviews[0];
+	UIView *view = self.view.subviews[0];
 	CGRect frame = self.view.bounds;
 	// Adjust view bounds to make room for the keyboard.
 	frame.size.height -= _keyboardHeight;
 	view.frame = frame;
-	gio_onDraw(view.handle);
+	gio_onDraw((__bridge CFTypeRef)view);
 }
 
 - (void)didReceiveMemoryWarning {
@@ -91,7 +88,6 @@ CGFloat _keyboardHeight;
 	[super didReceiveMemoryWarning];
 }
 
-#if !TARGET_OS_TV
 - (void)keyboardWillChange:(NSNotification *)note {
 	NSDictionary *userInfo = note.userInfo;
 	CGRect f = [userInfo[UIKeyboardFrameEndUserInfoKey] CGRectValue];
@@ -103,13 +99,13 @@ CGFloat _keyboardHeight;
 	_keyboardHeight = 0.0;
 	[self.view setNeedsLayout];
 }
-#endif
 @end
 
-static void handleTouches(int last, GioView *view, NSSet<UITouch *> *touches, UIEvent *event) {
+static void handleTouches(int last, UIView *view, NSSet<UITouch *> *touches, UIEvent *event) {
 	CGFloat scale = view.contentScaleFactor;
 	NSUInteger i = 0;
 	NSUInteger n = [touches count];
+	CFTypeRef viewRef = (__bridge CFTypeRef)view;
 	for (UITouch *touch in touches) {
 		CFTypeRef touchRef = (__bridge CFTypeRef)touch;
 		i++;
@@ -120,7 +116,7 @@ static void handleTouches(int last, GioView *view, NSSet<UITouch *> *touches, UI
 			CGPoint loc = [coalescedTouch locationInView:view];
 			j++;
 			int lastTouch = last && i == n && j == m;
-			onTouch(view.handle, lastTouch, touchRef, touch.phase, loc.x*scale, loc.y*scale, [coalescedTouch timestamp]);
+			onTouch(lastTouch, viewRef, touchRef, touch.phase, loc.x*scale, loc.y*scale, [coalescedTouch timestamp]);
 		}
 	}
 }
@@ -155,13 +151,13 @@ NSArray<UIKeyCommand *> *_keyCommands;
 
 - (void)onWindowDidBecomeKey:(NSNotification *)note {
 	if (self.isFirstResponder) {
-		onFocus(self.handle, YES);
+		onFocus((__bridge CFTypeRef)self, YES);
 	}
 }
 
 - (void)onWindowDidResignKey:(NSNotification *)note {
 	if (self.isFirstResponder) {
-		onFocus(self.handle, NO);
+		onFocus((__bridge CFTypeRef)self, NO);
 	}
 }
 
@@ -182,7 +178,7 @@ NSArray<UIKeyCommand *> *_keyCommands;
 }
 
 - (void)insertText:(NSString *)text {
-	onText(self.handle, (__bridge CFTypeRef)text);
+	onText((__bridge CFTypeRef)self, (__bridge CFTypeRef)text);
 }
 
 - (BOOL)canBecomeFirstResponder {
@@ -194,23 +190,23 @@ NSArray<UIKeyCommand *> *_keyCommands;
 }
 
 - (void)deleteBackward {
-	onDeleteBackward(self.handle);
+	onDeleteBackward((__bridge CFTypeRef)self);
 }
 
 - (void)onUpArrow {
-	onUpArrow(self.handle);
+	onUpArrow((__bridge CFTypeRef)self);
 }
 
 - (void)onDownArrow {
-	onDownArrow(self.handle);
+	onDownArrow((__bridge CFTypeRef)self);
 }
 
 - (void)onLeftArrow {
-	onLeftArrow(self.handle);
+	onLeftArrow((__bridge CFTypeRef)self);
 }
 
 - (void)onRightArrow {
-	onRightArrow(self.handle);
+	onRightArrow((__bridge CFTypeRef)self);
 }
 
 - (NSArray<UIKeyCommand *> *)keyCommands {
@@ -275,28 +271,3 @@ void gio_showCursor() {
 void gio_setCursor(NSUInteger curID) {
 	// Not supported.
 }
-
-void gio_viewSetHandle(CFTypeRef viewRef, uintptr_t handle) {
-	GioView *v = (__bridge GioView *)viewRef;
-	v.handle = handle;
-}
-
-@interface _gioAppDelegate : UIResponder <UIApplicationDelegate>
-@property (strong, nonatomic) UIWindow *window;
-@end
-
-@implementation _gioAppDelegate
-- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
-	self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
-	GioViewController *controller = [[GioViewController alloc] initWithNibName:nil bundle:nil];
-	self.window.rootViewController = controller;
-	[self.window makeKeyAndVisible];
-	return YES;
-}
-@end
-
-int gio_applicationMain(int argc, char *argv[]) {
-	@autoreleasepool {
-		return UIApplicationMain(argc, argv, nil, NSStringFromClass([_gioAppDelegate class]));
-	}
-}

app/os_js.go

@@ -6,7 +6,6 @@ import (
 	"fmt"
 	"image"
 	"image/color"
-	"io"
 	"strings"
 	"syscall/js"
 	"time"
@@ -14,18 +13,16 @@ import (
 	"unicode/utf8"
 
 	"gioui.org/internal/f32color"
-	"gioui.org/op"
 
 	"gioui.org/f32"
-	"gioui.org/io/event"
+	"gioui.org/io/clipboard"
 	"gioui.org/io/key"
 	"gioui.org/io/pointer"
 	"gioui.org/io/system"
-	"gioui.org/io/transfer"
 	"gioui.org/unit"
 )
 
-type JSViewEvent struct {
+type ViewEvent struct {
 	Element js.Value
 }
 
@@ -56,6 +53,9 @@ type window struct {
 	composing             bool
 	requestFocus          bool
 
+	chanAnimation chan struct{}
+	chanRedraw    chan struct{}
+
 	config    Config
 	inset     f32.Point
 	scale     float32
@@ -68,7 +68,7 @@ type window struct {
 	contextStatus contextStatus
 }
 
-func newWindow(win *callbacks, options []Option) {
+func newWindow(win *callbacks, options []Option) error {
 	doc := js.Global().Get("document")
 	cont := getContainer(doc)
 	cnv := createCanvas(doc)
@@ -83,9 +83,7 @@ func newWindow(win *callbacks, options []Option) {
 		head:      doc.Get("head"),
 		clipboard: js.Global().Get("navigator").Get("clipboard"),
 		wakeups:   make(chan struct{}, 1),
-		w:         win,
 	}
-	w.w.SetDriver(w)
 	w.requestAnimationFrame = w.window.Get("requestAnimationFrame")
 	w.browserHistory = w.window.Get("history")
 	w.visualViewport = w.window.Get("visualViewport")
@@ -95,28 +93,42 @@ func newWindow(win *callbacks, options []Option) {
 	if screen := w.window.Get("screen"); screen.Truthy() {
 		w.screenOrientation = screen.Get("orientation")
 	}
+	w.chanAnimation = make(chan struct{}, 1)
+	w.chanRedraw = make(chan struct{}, 1)
 	w.redraw = w.funcOf(func(this js.Value, args []js.Value) interface{} {
-		w.draw(false)
+		w.chanAnimation <- struct{}{}
 		return nil
 	})
 	w.clipboardCallback = w.funcOf(func(this js.Value, args []js.Value) interface{} {
 		content := args[0].String()
-		w.processEvent(transfer.DataEvent{
-			Type: "application/text",
-			Open: func() io.ReadCloser {
-				return io.NopCloser(strings.NewReader(content))
-			},
-		})
+		go win.Event(clipboard.Event{Text: content})
 		return nil
 	})
 	w.addEventListeners()
 	w.addHistory()
+	w.w = win
 
-	w.Configure(options)
-	w.blur()
-	w.processEvent(JSViewEvent{Element: cont})
-	w.resize()
-	w.draw(true)
+	go func() {
+		defer w.cleanup()
+		w.w.SetDriver(w)
+		w.Configure(options)
+		w.blur()
+		w.w.Event(ViewEvent{Element: cont})
+		w.w.Event(system.StageEvent{Stage: system.StageRunning})
+		w.resize()
+		w.draw(true)
+		for {
+			select {
+			case <-w.wakeups:
+				w.w.Event(wakeupEvent{})
+			case <-w.chanAnimation:
+				w.animCallback()
+			case <-w.chanRedraw:
+				w.draw(true)
+			}
+		}
+	}()
+	return nil
 }
 
 func getContainer(doc js.Value) js.Value {
@@ -176,12 +188,12 @@ func (w *window) addEventListeners() {
 		w.cnv.Set("width", 0)
 		w.cnv.Set("height", 0)
 		w.resize()
-		w.draw(true)
+		w.requestRedraw()
 		return nil
 	})
 	w.addEventListener(w.visualViewport, "resize", func(this js.Value, args []js.Value) interface{} {
 		w.resize()
-		w.draw(true)
+		w.requestRedraw()
 		return nil
 	})
 	w.addEventListener(w.window, "contextmenu", func(this js.Value, args []js.Value) interface{} {
@@ -189,11 +201,22 @@ func (w *window) addEventListeners() {
 		return nil
 	})
 	w.addEventListener(w.window, "popstate", func(this js.Value, args []js.Value) interface{} {
-		if w.processEvent(key.Event{Name: key.NameBack}) {
+		if w.w.Event(key.Event{Name: key.NameBack}) {
 			return w.browserHistory.Call("forward")
 		}
 		return w.browserHistory.Call("back")
 	})
+	w.addEventListener(w.document, "visibilitychange", func(this js.Value, args []js.Value) interface{} {
+		ev := system.StageEvent{}
+		switch w.document.Get("visibilityState").String() {
+		case "hidden", "prerender", "unloaded":
+			ev.Stage = system.StagePaused
+		default:
+			ev.Stage = system.StageRunning
+		}
+		w.w.Event(ev)
+		return nil
+	})
 	w.addEventListener(w.cnv, "mousemove", func(this js.Value, args []js.Value) interface{} {
 		w.pointerEvent(pointer.Move, 0, 0, args[0])
 		return nil
@@ -251,20 +274,18 @@ func (w *window) addEventListeners() {
 			w.touches[i] = js.Null()
 		}
 		w.touches = w.touches[:0]
-		w.processEvent(pointer.Event{
+		w.w.Event(pointer.Event{
 			Kind:   pointer.Cancel,
 			Source: pointer.Touch,
 		})
 		return nil
 	})
 	w.addEventListener(w.tarea, "focus", func(this js.Value, args []js.Value) interface{} {
-		w.config.Focused = true
-		w.processEvent(ConfigEvent{Config: w.config})
+		w.w.Event(key.FocusEvent{Focus: true})
 		return nil
 	})
 	w.addEventListener(w.tarea, "blur", func(this js.Value, args []js.Value) interface{} {
-		w.config.Focused = false
-		w.processEvent(ConfigEvent{Config: w.config})
+		w.w.Event(key.FocusEvent{Focus: false})
 		w.blur()
 		return nil
 	})
@@ -353,50 +374,10 @@ func (w *window) keyEvent(e js.Value, ks key.State) {
 			Modifiers: modifiersFor(e),
 			State:     ks,
 		}
-		w.processEvent(cmd)
+		w.w.Event(cmd)
 	}
 }
 
-func (w *window) ProcessEvent(e event.Event) {
-	w.processEvent(e)
-}
-
-func (w *window) processEvent(e event.Event) bool {
-	if !w.w.ProcessEvent(e) {
-		return false
-	}
-	select {
-	case w.wakeups <- struct{}{}:
-	default:
-	}
-	return true
-}
-
-func (w *window) Event() event.Event {
-	for {
-		evt, ok := w.w.nextEvent()
-		if ok {
-			if _, destroy := evt.(DestroyEvent); destroy {
-				w.cleanup()
-			}
-			return evt
-		}
-		<-w.wakeups
-	}
-}
-
-func (w *window) Invalidate() {
-	w.w.Invalidate()
-}
-
-func (w *window) Run(f func()) {
-	f()
-}
-
-func (w *window) Frame(frame *op.Ops) {
-	w.w.ProcessFrame(frame, nil)
-}
-
 // modifiersFor returns the modifier set for a DOM MouseEvent or
 // KeyEvent.
 func modifiersFor(e js.Value) key.Modifiers {
@@ -444,7 +425,7 @@ func (w *window) touchEvent(kind pointer.Kind, e js.Value) {
 			X: float32(x) * scale,
 			Y: float32(y) * scale,
 		}
-		w.processEvent(pointer.Event{
+		w.w.Event(pointer.Event{
 			Kind:      kind,
 			Source:    pointer.Touch,
 			Position:  pos,
@@ -494,7 +475,7 @@ func (w *window) pointerEvent(kind pointer.Kind, dx, dy float32, e js.Value) {
 	if jbtns&4 != 0 {
 		btns |= pointer.ButtonTertiary
 	}
-	w.processEvent(pointer.Event{
+	w.w.Event(pointer.Event{
 		Kind:      kind,
 		Source:    pointer.Mouse,
 		Buttons:   btns,
@@ -521,6 +502,17 @@ func (w *window) funcOf(f func(this js.Value, args []js.Value) interface{}) js.F
 	return jsf
 }
 
+func (w *window) animCallback() {
+	anim := w.animating
+	w.animRequested = anim
+	if anim {
+		w.requestAnimationFrame.Invoke(w.redraw)
+	}
+	if anim {
+		w.draw(false)
+	}
+}
+
 func (w *window) EditorStateChanged(old, new editorState) {}
 
 func (w *window) SetAnimating(anim bool) {
@@ -541,14 +533,14 @@ func (w *window) ReadClipboard() {
 	w.clipboard.Call("readText", w.clipboard).Call("then", w.clipboardCallback)
 }
 
-func (w *window) WriteClipboard(mime string, s []byte) {
+func (w *window) WriteClipboard(s string) {
 	if w.clipboard.IsUndefined() {
 		return
 	}
 	if w.clipboard.Get("writeText").IsUndefined() {
 		return
 	}
-	w.clipboard.Call("writeText", string(s))
+	w.clipboard.Call("writeText", s)
 }
 
 func (w *window) Configure(options []Option) {
@@ -576,7 +568,7 @@ func (w *window) Configure(options []Option) {
 	if cnf.Decorated != prev.Decorated {
 		w.config.Decorated = cnf.Decorated
 	}
-	w.processEvent(ConfigEvent{Config: w.config})
+	w.w.Event(ConfigEvent{Config: w.config})
 }
 
 func (w *window) Perform(system.Action) {}
@@ -615,14 +607,23 @@ func (w *window) SetCursor(cursor pointer.Cursor) {
 	style.Set("cursor", webCursor[cursor])
 }
 
+func (w *window) Wakeup() {
+	select {
+	case w.wakeups <- struct{}{}:
+	default:
+	}
+}
+
 func (w *window) ShowTextInput(show bool) {
 	// Run in a goroutine to avoid a deadlock if the
 	// focus change result in an event.
-	if show {
-		w.focus()
-	} else {
-		w.blur()
-	}
+	go func() {
+		if show {
+			w.focus()
+		} else {
+			w.blur()
+		}
+	}()
 }
 
 func (w *window) SetInputHint(mode key.InputHint) {
@@ -639,7 +640,7 @@ func (w *window) resize() {
 	}
 	if size != w.config.Size {
 		w.config.Size = size
-		w.processEvent(ConfigEvent{Config: w.config})
+		w.w.Event(ConfigEvent{Config: w.config})
 	}
 
 	if vx, vy := w.visualViewport.Get("width"), w.visualViewport.Get("height"); !vx.IsUndefined() && !vy.IsUndefined() {
@@ -659,20 +660,13 @@ func (w *window) draw(sync bool) {
 	if w.contextStatus == contextStatusLost {
 		return
 	}
-	anim := w.animating
-	w.animRequested = anim
-	if anim {
-		w.requestAnimationFrame.Invoke(w.redraw)
-	} else if !sync {
-		return
-	}
 	size, insets, metric := w.getConfig()
 	if metric == (unit.Metric{}) || size.X == 0 || size.Y == 0 {
 		return
 	}
 
-	w.processEvent(frameEvent{
-		FrameEvent: FrameEvent{
+	w.w.Event(frameEvent{
+		FrameEvent: system.FrameEvent{
 			Now:    time.Now(),
 			Size:   size,
 			Insets: insets,
@@ -682,10 +676,10 @@ func (w *window) draw(sync bool) {
 	})
 }
 
-func (w *window) getConfig() (image.Point, Insets, unit.Metric) {
+func (w *window) getConfig() (image.Point, system.Insets, unit.Metric) {
 	invscale := unit.Dp(1. / w.scale)
 	return image.Pt(w.config.Size.X, w.config.Size.Y),
-		Insets{
+		system.Insets{
 			Bottom: unit.Dp(w.inset.Y) * invscale,
 			Right:  unit.Dp(w.inset.X) * invscale,
 		}, unit.Metric{
@@ -741,12 +735,19 @@ func (w *window) navigationColor(c color.NRGBA) {
 	theme.Set("content", fmt.Sprintf("#%06X", []uint8{rgba.R, rgba.G, rgba.B}))
 }
 
+func (w *window) requestRedraw() {
+	select {
+	case w.chanRedraw <- struct{}{}:
+	default:
+	}
+}
+
 func osMain() {
 	select {}
 }
 
-func translateKey(k string) (key.Name, bool) {
-	var n key.Name
+func translateKey(k string) (string, bool) {
+	var n string
 
 	switch k {
 	case "ArrowUp":
@@ -813,15 +814,11 @@ func translateKey(k string) (key.Name, bool) {
 		r, s := utf8.DecodeRuneInString(k)
 		// If there is exactly one printable character, return that.
 		if s == len(k) && unicode.IsPrint(r) {
-			return key.Name(strings.ToUpper(k)), true
+			return strings.ToUpper(k), true
 		}
 		return "", false
 	}
 	return n, true
 }
 
-func (JSViewEvent) implementsViewEvent() {}
-func (JSViewEvent) ImplementsEvent()     {}
-func (j JSViewEvent) Valid() bool {
-	return !(j.Element.IsNull() || j.Element.IsUndefined())
-}
+func (_ ViewEvent) ImplementsEvent() {}

app/os_macos.go

@@ -8,21 +8,16 @@ package app
 import (
 	"errors"
 	"image"
-	"io"
 	"runtime"
-	"runtime/cgo"
-	"strings"
 	"time"
 	"unicode"
 	"unicode/utf8"
 
 	"gioui.org/internal/f32"
-	"gioui.org/io/event"
+	"gioui.org/io/clipboard"
 	"gioui.org/io/key"
 	"gioui.org/io/pointer"
 	"gioui.org/io/system"
-	"gioui.org/io/transfer"
-	"gioui.org/op"
 	"gioui.org/unit"
 
 	_ "gioui.org/internal/cocoainit"
@@ -40,9 +35,8 @@ import (
 #define MOUSE_SCROLL 4
 
 __attribute__ ((visibility ("hidden"))) void gio_main(void);
-__attribute__ ((visibility ("hidden"))) CFTypeRef gio_createView(int presentWithTrans);
+__attribute__ ((visibility ("hidden"))) CFTypeRef gio_createView(void);
 __attribute__ ((visibility ("hidden"))) CFTypeRef gio_createWindow(CFTypeRef viewRef, CGFloat width, CGFloat height, CGFloat minWidth, CGFloat minHeight, CGFloat maxWidth, CGFloat maxHeight);
-__attribute__ ((visibility ("hidden"))) void gio_viewSetHandle(CFTypeRef viewRef, uintptr_t handle);
 
 static void writeClipboard(CFTypeRef str) {
 	@autoreleasepool {
@@ -62,212 +56,148 @@ static CFTypeRef readClipboard(void) {
 }
 
 static CGFloat viewHeight(CFTypeRef viewRef) {
-	@autoreleasepool {
-		NSView *view = (__bridge NSView *)viewRef;
-		return [view bounds].size.height;
-	}
+	NSView *view = (__bridge NSView *)viewRef;
+	return [view bounds].size.height;
 }
 
 static CGFloat viewWidth(CFTypeRef viewRef) {
-	@autoreleasepool {
-		NSView *view = (__bridge NSView *)viewRef;
-		return [view bounds].size.width;
-	}
+	NSView *view = (__bridge NSView *)viewRef;
+	return [view bounds].size.width;
 }
 
 static CGFloat getScreenBackingScale(void) {
-	@autoreleasepool {
-		return [NSScreen.mainScreen backingScaleFactor];
-	}
+	return [NSScreen.mainScreen backingScaleFactor];
 }
 
 static CGFloat getViewBackingScale(CFTypeRef viewRef) {
-	@autoreleasepool {
-		NSView *view = (__bridge NSView *)viewRef;
-		return [view.window backingScaleFactor];
-	}
+	NSView *view = (__bridge NSView *)viewRef;
+	return [view.window backingScaleFactor];
 }
 
 static void setNeedsDisplay(CFTypeRef viewRef) {
-	@autoreleasepool {
-		NSView *view = (__bridge NSView *)viewRef;
-		[view setNeedsDisplay:YES];
-	}
+	NSView *view = (__bridge NSView *)viewRef;
+	[view setNeedsDisplay:YES];
 }
 
 static NSPoint cascadeTopLeftFromPoint(CFTypeRef windowRef, NSPoint topLeft) {
-	@autoreleasepool {
-		NSWindow *window = (__bridge NSWindow *)windowRef;
-		return [window cascadeTopLeftFromPoint:topLeft];
-	}
+	NSWindow *window = (__bridge NSWindow *)windowRef;
+	return [window cascadeTopLeftFromPoint:topLeft];
 }
 
 static void makeKeyAndOrderFront(CFTypeRef windowRef) {
-	@autoreleasepool {
-		NSWindow *window = (__bridge NSWindow *)windowRef;
-		[window makeKeyAndOrderFront:nil];
-	}
+	NSWindow *window = (__bridge NSWindow *)windowRef;
+	[window makeKeyAndOrderFront:nil];
 }
 
 static void toggleFullScreen(CFTypeRef windowRef) {
-	@autoreleasepool {
-		NSWindow *window = (__bridge NSWindow *)windowRef;
-		[window toggleFullScreen:nil];
-	}
+	NSWindow *window = (__bridge NSWindow *)windowRef;
+	[window toggleFullScreen:nil];
 }
 
 static NSWindowStyleMask getWindowStyleMask(CFTypeRef windowRef) {
-	@autoreleasepool {
-		NSWindow *window = (__bridge NSWindow *)windowRef;
-		return [window styleMask];
-	}
+	NSWindow *window = (__bridge NSWindow *)windowRef;
+	return [window styleMask];
 }
 
 static void setWindowStyleMask(CFTypeRef windowRef, NSWindowStyleMask mask) {
-	@autoreleasepool {
-		NSWindow *window = (__bridge NSWindow *)windowRef;
-		window.styleMask = mask;
-	}
+	NSWindow *window = (__bridge NSWindow *)windowRef;
+	window.styleMask = mask;
 }
 
 static void setWindowTitleVisibility(CFTypeRef windowRef, NSWindowTitleVisibility state) {
-	@autoreleasepool {
-		NSWindow *window = (__bridge NSWindow *)windowRef;
-		window.titleVisibility = state;
-	}
+	NSWindow *window = (__bridge NSWindow *)windowRef;
+	window.titleVisibility = state;
 }
 
 static void setWindowTitlebarAppearsTransparent(CFTypeRef windowRef, int transparent) {
-	@autoreleasepool {
-		NSWindow *window = (__bridge NSWindow *)windowRef;
-		window.titlebarAppearsTransparent = (BOOL)transparent;
-	}
+	NSWindow *window = (__bridge NSWindow *)windowRef;
+	window.titlebarAppearsTransparent = (BOOL)transparent;
 }
 
 static void setWindowStandardButtonHidden(CFTypeRef windowRef, NSWindowButton btn, int hide) {
-	@autoreleasepool {
-		NSWindow *window = (__bridge NSWindow *)windowRef;
-		[window standardWindowButton:btn].hidden = (BOOL)hide;
-	}
+	NSWindow *window = (__bridge NSWindow *)windowRef;
+	[window standardWindowButton:btn].hidden = (BOOL)hide;
 }
 
 static void performWindowDragWithEvent(CFTypeRef windowRef, CFTypeRef evt) {
-	@autoreleasepool {
-		NSWindow *window = (__bridge NSWindow *)windowRef;
-		[window performWindowDragWithEvent:(__bridge NSEvent*)evt];
-	}
+	NSWindow *window = (__bridge NSWindow *)windowRef;
+	[window performWindowDragWithEvent:(__bridge NSEvent*)evt];
 }
 
 static void closeWindow(CFTypeRef windowRef) {
-	@autoreleasepool {
-		NSWindow* window = (__bridge NSWindow *)windowRef;
-		[window performClose:nil];
-	}
+	NSWindow* window = (__bridge NSWindow *)windowRef;
+	[window performClose:nil];
 }
 
 static void setSize(CFTypeRef windowRef, CGFloat width, CGFloat height) {
-	@autoreleasepool {
-		NSWindow* window = (__bridge NSWindow *)windowRef;
-		NSSize size = NSMakeSize(width, height);
-		[window setContentSize:size];
-	}
+	NSWindow* window = (__bridge NSWindow *)windowRef;
+	NSSize size = NSMakeSize(width, height);
+	[window setContentSize:size];
 }
 
 static void setMinSize(CFTypeRef windowRef, CGFloat width, CGFloat height) {
-	@autoreleasepool {
-		NSWindow* window = (__bridge NSWindow *)windowRef;
-		window.contentMinSize = NSMakeSize(width, height);
-	}
+	NSWindow* window = (__bridge NSWindow *)windowRef;
+	window.contentMinSize = NSMakeSize(width, height);
 }
 
 static void setMaxSize(CFTypeRef windowRef, CGFloat width, CGFloat height) {
-	@autoreleasepool {
-		NSWindow* window = (__bridge NSWindow *)windowRef;
-		window.contentMaxSize = NSMakeSize(width, height);
-	}
+	NSWindow* window = (__bridge NSWindow *)windowRef;
+	window.contentMaxSize = NSMakeSize(width, height);
 }
 
 static void setScreenFrame(CFTypeRef windowRef, CGFloat x, CGFloat y, CGFloat w, CGFloat h) {
-	@autoreleasepool {
-		NSWindow* window = (__bridge NSWindow *)windowRef;
-		NSRect r = NSMakeRect(x, y, w, h);
-		[window setFrame:r display:YES];
-	}
-}
-
-static void resetLayerFrame(CFTypeRef viewRef) {
-	@autoreleasepool {
-		NSView* view = (__bridge NSView *)viewRef;
-		NSRect r = view.frame;
-		view.layer.frame = r;
-	}
+	NSWindow* window = (__bridge NSWindow *)windowRef;
+	NSRect r = NSMakeRect(x, y, w, h);
+	[window setFrame:r display:YES];
 }
 
 static void hideWindow(CFTypeRef windowRef) {
-	@autoreleasepool {
-		NSWindow* window = (__bridge NSWindow *)windowRef;
-		[window miniaturize:window];
-	}
+	NSWindow* window = (__bridge NSWindow *)windowRef;
+	[window miniaturize:window];
 }
 
 static void unhideWindow(CFTypeRef windowRef) {
-	@autoreleasepool {
-		NSWindow* window = (__bridge NSWindow *)windowRef;
-		[window deminiaturize:window];
-	}
+	NSWindow* window = (__bridge NSWindow *)windowRef;
+	[window deminiaturize:window];
 }
 
 static NSRect getScreenFrame(CFTypeRef windowRef) {
-	@autoreleasepool {
-		NSWindow* window = (__bridge NSWindow *)windowRef;
-		return [[window screen] frame];
-	}
+	NSWindow* window = (__bridge NSWindow *)windowRef;
+	return [[window screen] frame];
 }
 
 static void setTitle(CFTypeRef windowRef, CFTypeRef titleRef) {
-	@autoreleasepool {
-		NSWindow *window = (__bridge NSWindow *)windowRef;
-		window.title = (__bridge NSString *)titleRef;
-	}
+	NSWindow *window = (__bridge NSWindow *)windowRef;
+	window.title = (__bridge NSString *)titleRef;
 }
 
 static int isWindowZoomed(CFTypeRef windowRef) {
-	@autoreleasepool {
-		NSWindow *window = (__bridge NSWindow *)windowRef;
-		return window.zoomed ? 1 : 0;
-	}
+	NSWindow *window = (__bridge NSWindow *)windowRef;
+	return window.zoomed ? 1 : 0;
 }
 
 static void zoomWindow(CFTypeRef windowRef) {
-	@autoreleasepool {
-		NSWindow *window = (__bridge NSWindow *)windowRef;
-		[window zoom:nil];
-	}
+	NSWindow *window = (__bridge NSWindow *)windowRef;
+	[window zoom:nil];
 }
 
 static CFTypeRef layerForView(CFTypeRef viewRef) {
-	@autoreleasepool {
-		NSView *view = (__bridge NSView *)viewRef;
-		return (__bridge CFTypeRef)view.layer;
-	}
+	NSView *view = (__bridge NSView *)viewRef;
+	return (__bridge CFTypeRef)view.layer;
 }
 
 static CFTypeRef windowForView(CFTypeRef viewRef) {
-	@autoreleasepool {
-		NSView *view = (__bridge NSView *)viewRef;
-		return (__bridge CFTypeRef)view.window;
-	}
+	NSView *view = (__bridge NSView *)viewRef;
+	return (__bridge CFTypeRef)view.window;
 }
 
 static void raiseWindow(CFTypeRef windowRef) {
-	@autoreleasepool {
-		NSRunningApplication *currentApp = [NSRunningApplication currentApplication];
-		if (![currentApp isActive]) {
-			[currentApp activateWithOptions:(NSApplicationActivateAllWindows | NSApplicationActivateIgnoringOtherApps)];
-		}
-		NSWindow* window = (__bridge NSWindow *)windowRef;
-		[window makeKeyAndOrderFront:nil];
+	NSRunningApplication *currentApp = [NSRunningApplication currentApplication];
+	if (![currentApp isActive]) {
+		[currentApp activateWithOptions:(NSApplicationActivateAllWindows | NSApplicationActivateIgnoringOtherApps)];
 	}
+	NSWindow* window = (__bridge NSWindow *)windowRef;
+	[window makeKeyAndOrderFront:nil];
 }
 
 static CFTypeRef createInputContext(CFTypeRef clientRef) {
@@ -279,23 +209,23 @@ static CFTypeRef createInputContext(CFTypeRef clientRef) {
 }
 
 static void discardMarkedText(CFTypeRef viewRef) {
-	@autoreleasepool {
+    @autoreleasepool {
 		id<NSTextInputClient> view = (__bridge id<NSTextInputClient>)viewRef;
 		NSTextInputContext *ctx = [NSTextInputContext currentInputContext];
 		if (view == [ctx client]) {
 			[ctx discardMarkedText];
 		}
-	}
+    }
 }
 
 static void invalidateCharacterCoordinates(CFTypeRef viewRef) {
-	@autoreleasepool {
+    @autoreleasepool {
 		id<NSTextInputClient> view = (__bridge id<NSTextInputClient>)viewRef;
 		NSTextInputContext *ctx = [NSTextInputContext currentInputContext];
 		if (view == [ctx client]) {
 			[ctx invalidateCharacterCoordinates];
 		}
-	}
+    }
 }
 */
 import "C"
@@ -305,9 +235,9 @@ func init() {
 	runtime.LockOSThread()
 }
 
-// AppKitViewEvent notifies the client of changes to the window AppKit handles.
-// The handles are retained until another AppKitViewEvent is sent.
-type AppKitViewEvent struct {
+// ViewEvent notified the client of changes to the window AppKit handles.
+// The handles are retained until another ViewEvent is sent.
+type ViewEvent struct {
 	// View is a CFTypeRef for the NSView for the window.
 	View uintptr
 	// Layer is a CFTypeRef of the CALayer of View.
@@ -317,20 +247,21 @@ type AppKitViewEvent struct {
 type window struct {
 	view        C.CFTypeRef
 	w           *callbacks
-	anim        bool
-	visible     bool
+	stage       system.Stage
 	displayLink *displayLink
 	// redraw is a single entry channel for making sure only one
 	// display link redraw request is in flight.
 	redraw      chan struct{}
 	cursor      pointer.Cursor
 	pointerBtns pointer.Buttons
-	loop        *eventLoop
 
 	scale  float32
 	config Config
 }
 
+// viewMap is the mapping from Cocoa NSViews to Go windows.
+var viewMap = make(map[C.CFTypeRef]*window)
+
 // launched is closed when applicationDidFinishLaunching is called.
 var launched = make(chan struct{})
 
@@ -338,8 +269,30 @@ var launched = make(chan struct{})
 // cascadeTopLeftFromPoint.
 var nextTopLeft C.NSPoint
 
-func windowFor(h C.uintptr_t) *window {
-	return cgo.Handle(h).Value().(*window)
+// mustView is like lookupView, except that it panics
+// if the view isn't mapped.
+func mustView(view C.CFTypeRef) *window {
+	w, ok := lookupView(view)
+	if !ok {
+		panic("no window for view")
+	}
+	return w
+}
+
+func lookupView(view C.CFTypeRef) (*window, bool) {
+	w, exists := viewMap[view]
+	if !exists {
+		return nil, false
+	}
+	return w, true
+}
+
+func deleteView(view C.CFTypeRef) {
+	delete(viewMap, view)
+}
+
+func insertView(view C.CFTypeRef, w *window) {
+	viewMap[view] = w
 }
 
 func (w *window) contextView() C.CFTypeRef {
@@ -352,16 +305,11 @@ func (w *window) ReadClipboard() {
 		defer C.CFRelease(cstr)
 	}
 	content := nsstringToString(cstr)
-	w.ProcessEvent(transfer.DataEvent{
-		Type: "application/text",
-		Open: func() io.ReadCloser {
-			return io.NopCloser(strings.NewReader(content))
-		},
-	})
+	w.w.Event(clipboard.Event{Text: content})
 }
 
-func (w *window) WriteClipboard(mime string, s []byte) {
-	cstr := stringToNSString(string(s))
+func (w *window) WriteClipboard(s string) {
+	cstr := stringToNSString(s)
 	defer C.CFRelease(cstr)
 	C.writeClipboard(cstr)
 }
@@ -464,11 +412,8 @@ func (w *window) Configure(options []Option) {
 		C.setWindowStandardButtonHidden(window, C.NSWindowCloseButton, barTrans)
 		C.setWindowStandardButtonHidden(window, C.NSWindowMiniaturizeButton, barTrans)
 		C.setWindowStandardButtonHidden(window, C.NSWindowZoomButton, barTrans)
-		// When toggling the titlebar, the layer doesn't update its frame
-		// until the next resize. Force it.
-		C.resetLayerFrame(w.view)
 	}
-	w.ProcessEvent(ConfigEvent{Config: w.config})
+	w.w.Event(ConfigEvent{Config: w.config})
 }
 
 func (w *window) setTitle(prev, cnf Config) {
@@ -519,8 +464,7 @@ func (w *window) ShowTextInput(show bool) {}
 func (w *window) SetInputHint(_ key.InputHint) {}
 
 func (w *window) SetAnimating(anim bool) {
-	w.anim = anim
-	if w.anim && w.visible {
+	if anim {
 		w.displayLink.Start()
 	} else {
 		w.displayLink.Stop()
@@ -537,18 +481,26 @@ func (w *window) runOnMain(f func()) {
 	})
 }
 
+func (w *window) setStage(stage system.Stage) {
+	if stage == w.stage {
+		return
+	}
+	w.stage = stage
+	w.w.Event(system.StageEvent{Stage: stage})
+}
+
 //export gio_onKeys
-func gio_onKeys(h C.uintptr_t, cstr C.CFTypeRef, ti C.double, mods C.NSUInteger, keyDown C.bool) {
+func gio_onKeys(view, cstr C.CFTypeRef, ti C.double, mods C.NSUInteger, keyDown C.bool) {
 	str := nsstringToString(cstr)
 	kmods := convertMods(mods)
 	ks := key.Release
 	if keyDown {
 		ks = key.Press
 	}
-	w := windowFor(h)
+	w := mustView(view)
 	for _, k := range str {
 		if n, ok := convertKey(k); ok {
-			w.ProcessEvent(key.Event{
+			w.w.Event(key.Event{
 				Name:      n,
 				Modifiers: kmods,
 				State:     ks,
@@ -558,15 +510,15 @@ func gio_onKeys(h C.uintptr_t, cstr C.CFTypeRef, ti C.double, mods C.NSUInteger,
 }
 
 //export gio_onText
-func gio_onText(h C.uintptr_t, cstr C.CFTypeRef) {
+func gio_onText(view, cstr C.CFTypeRef) {
 	str := nsstringToString(cstr)
-	w := windowFor(h)
+	w := mustView(view)
 	w.w.EditorInsert(str)
 }
 
 //export gio_onMouse
-func gio_onMouse(h C.uintptr_t, evt C.CFTypeRef, cdir C.int, cbtn C.NSInteger, x, y, dx, dy C.CGFloat, ti C.double, mods C.NSUInteger) {
-	w := windowFor(h)
+func gio_onMouse(view, evt C.CFTypeRef, cdir C.int, cbtn C.NSInteger, x, y, dx, dy C.CGFloat, ti C.double, mods C.NSUInteger) {
+	w := mustView(view)
 	t := time.Duration(float64(ti)*float64(time.Second) + .5)
 	xf, yf := float32(x)*w.scale, float32(y)*w.scale
 	dxf, dyf := float32(dx)*w.scale, float32(dy)*w.scale
@@ -603,7 +555,7 @@ func gio_onMouse(h C.uintptr_t, evt C.CFTypeRef, cdir C.int, cbtn C.NSInteger, x
 	default:
 		panic("invalid direction")
 	}
-	w.ProcessEvent(pointer.Event{
+	w.w.Event(pointer.Event{
 		Kind:      typ,
 		Source:    pointer.Mouse,
 		Time:      t,
@@ -615,29 +567,35 @@ func gio_onMouse(h C.uintptr_t, evt C.CFTypeRef, cdir C.int, cbtn C.NSInteger, x
 }
 
 //export gio_onDraw
-func gio_onDraw(h C.uintptr_t) {
-	w := windowFor(h)
+func gio_onDraw(view C.CFTypeRef) {
+	w := mustView(view)
 	w.draw()
 }
 
 //export gio_onFocus
-func gio_onFocus(h C.uintptr_t, focus C.int) {
-	w := windowFor(h)
+func gio_onFocus(view C.CFTypeRef, focus C.int) {
+	w := mustView(view)
+	w.w.Event(key.FocusEvent{Focus: focus == 1})
+	if w.stage >= system.StageInactive {
+		if focus == 0 {
+			w.setStage(system.StageInactive)
+		} else {
+			w.setStage(system.StageRunning)
+		}
+	}
 	w.SetCursor(w.cursor)
-	w.config.Focused = focus == 1
-	w.ProcessEvent(ConfigEvent{Config: w.config})
 }
 
 //export gio_onChangeScreen
-func gio_onChangeScreen(h C.uintptr_t, did uint64) {
-	w := windowFor(h)
+func gio_onChangeScreen(view C.CFTypeRef, did uint64) {
+	w := mustView(view)
 	w.displayLink.SetDisplayID(did)
 	C.setNeedsDisplay(w.view)
 }
 
 //export gio_hasMarkedText
-func gio_hasMarkedText(h C.uintptr_t) C.int {
-	w := windowFor(h)
+func gio_hasMarkedText(view C.CFTypeRef) C.int {
+	w := mustView(view)
 	state := w.w.EditorState()
 	if state.compose.Start != -1 {
 		return 1
@@ -646,8 +604,8 @@ func gio_hasMarkedText(h C.uintptr_t) C.int {
 }
 
 //export gio_markedRange
-func gio_markedRange(h C.uintptr_t) C.NSRange {
-	w := windowFor(h)
+func gio_markedRange(view C.CFTypeRef) C.NSRange {
+	w := mustView(view)
 	state := w.w.EditorState()
 	rng := state.compose
 	start, end := rng.Start, rng.End
@@ -662,8 +620,8 @@ func gio_markedRange(h C.uintptr_t) C.NSRange {
 }
 
 //export gio_selectedRange
-func gio_selectedRange(h C.uintptr_t) C.NSRange {
-	w := windowFor(h)
+func gio_selectedRange(view C.CFTypeRef) C.NSRange {
+	w := mustView(view)
 	state := w.w.EditorState()
 	rng := state.Selection
 	start, end := rng.Start, rng.End
@@ -678,14 +636,14 @@ func gio_selectedRange(h C.uintptr_t) C.NSRange {
 }
 
 //export gio_unmarkText
-func gio_unmarkText(h C.uintptr_t) {
-	w := windowFor(h)
+func gio_unmarkText(view C.CFTypeRef) {
+	w := mustView(view)
 	w.w.SetComposingRegion(key.Range{Start: -1, End: -1})
 }
 
 //export gio_setMarkedText
-func gio_setMarkedText(h C.uintptr_t, cstr C.CFTypeRef, selRange C.NSRange, replaceRange C.NSRange) {
-	w := windowFor(h)
+func gio_setMarkedText(view, cstr C.CFTypeRef, selRange C.NSRange, replaceRange C.NSRange) {
+	w := mustView(view)
 	str := nsstringToString(cstr)
 	state := w.w.EditorState()
 	rng := state.compose
@@ -724,8 +682,8 @@ func gio_setMarkedText(h C.uintptr_t, cstr C.CFTypeRef, selRange C.NSRange, repl
 }
 
 //export gio_substringForProposedRange
-func gio_substringForProposedRange(h C.uintptr_t, crng C.NSRange, actual C.NSRangePointer) C.CFTypeRef {
-	w := windowFor(h)
+func gio_substringForProposedRange(view C.CFTypeRef, crng C.NSRange, actual C.NSRangePointer) C.CFTypeRef {
+	w := mustView(view)
 	state := w.w.EditorState()
 	start, end := state.Snippet.Start, state.Snippet.End
 	if start > end {
@@ -745,8 +703,8 @@ func gio_substringForProposedRange(h C.uintptr_t, crng C.NSRange, actual C.NSRan
 }
 
 //export gio_insertText
-func gio_insertText(h C.uintptr_t, cstr C.CFTypeRef, crng C.NSRange) {
-	w := windowFor(h)
+func gio_insertText(view, cstr C.CFTypeRef, crng C.NSRange) {
+	w := mustView(view)
 	state := w.w.EditorState()
 	rng := state.compose
 	if rng.Start == -1 {
@@ -770,13 +728,13 @@ func gio_insertText(h C.uintptr_t, cstr C.CFTypeRef, crng C.NSRange) {
 }
 
 //export gio_characterIndexForPoint
-func gio_characterIndexForPoint(h C.uintptr_t, p C.NSPoint) C.NSUInteger {
+func gio_characterIndexForPoint(view C.CFTypeRef, p C.NSPoint) C.NSUInteger {
 	return C.NSNotFound
 }
 
 //export gio_firstRectForCharacterRange
-func gio_firstRectForCharacterRange(h C.uintptr_t, crng C.NSRange, actual C.NSRangePointer) C.NSRect {
-	w := windowFor(h)
+func gio_firstRectForCharacterRange(view C.CFTypeRef, crng C.NSRange, actual C.NSRangePointer) C.NSRect {
+	w := mustView(view)
 	state := w.w.EditorState()
 	sel := state.Selection
 	u16start := state.UTF16Index(sel.Start)
@@ -803,10 +761,6 @@ func (w *window) draw() {
 	case <-w.redraw:
 	default:
 	}
-	w.visible = true
-	if w.anim {
-		w.SetAnimating(w.anim)
-	}
 	w.scale = float32(C.getViewBackingScale(w.view))
 	wf, hf := float32(C.viewWidth(w.view)), float32(C.viewHeight(w.view))
 	sz := image.Point{
@@ -815,14 +769,15 @@ func (w *window) draw() {
 	}
 	if sz != w.config.Size {
 		w.config.Size = sz
-		w.ProcessEvent(ConfigEvent{Config: w.config})
+		w.w.Event(ConfigEvent{Config: w.config})
 	}
 	if sz.X == 0 || sz.Y == 0 {
 		return
 	}
 	cfg := configFor(w.scale)
-	w.ProcessEvent(frameEvent{
-		FrameEvent: FrameEvent{
+	w.setStage(system.StageRunning)
+	w.w.Event(frameEvent{
+		FrameEvent: system.FrameEvent{
 			Now:    time.Now(),
 			Size:   w.config.Size,
 			Metric: cfg,
@@ -831,27 +786,6 @@ func (w *window) draw() {
 	})
 }
 
-func (w *window) ProcessEvent(e event.Event) {
-	w.w.ProcessEvent(e)
-	w.loop.FlushEvents()
-}
-
-func (w *window) Event() event.Event {
-	return w.loop.Event()
-}
-
-func (w *window) Invalidate() {
-	w.loop.Invalidate()
-}
-
-func (w *window) Run(f func()) {
-	w.loop.Run(f)
-}
-
-func (w *window) Frame(frame *op.Ops) {
-	w.loop.Frame(frame)
-}
-
 func configFor(scale float32) unit.Metric {
 	return unit.Metric{
 		PxPerDp: scale,
@@ -859,54 +793,56 @@ func configFor(scale float32) unit.Metric {
 	}
 }
 
-//export gio_onAttached
-func gio_onAttached(h C.uintptr_t, attached C.int) {
-	w := windowFor(h)
-	if attached != 0 {
-		layer := C.layerForView(w.view)
-		w.ProcessEvent(AppKitViewEvent{View: uintptr(w.view), Layer: uintptr(layer)})
-	} else {
-		w.ProcessEvent(AppKitViewEvent{})
-		w.visible = false
-		w.SetAnimating(w.anim)
-	}
-}
-
-//export gio_onDestroy
-func gio_onDestroy(h C.uintptr_t) {
-	w := windowFor(h)
-	w.ProcessEvent(DestroyEvent{})
+//export gio_onClose
+func gio_onClose(view C.CFTypeRef) {
+	w := mustView(view)
+	w.w.Event(ViewEvent{})
+	w.w.Event(system.DestroyEvent{})
 	w.displayLink.Close()
 	w.displayLink = nil
-	cgo.Handle(h).Delete()
+	deleteView(view)
+	C.CFRelease(w.view)
 	w.view = 0
 }
 
 //export gio_onHide
-func gio_onHide(h C.uintptr_t) {
-	w := windowFor(h)
-	w.visible = false
-	w.SetAnimating(w.anim)
+func gio_onHide(view C.CFTypeRef) {
+	w := mustView(view)
+	w.setStage(system.StagePaused)
 }
 
 //export gio_onShow
-func gio_onShow(h C.uintptr_t) {
-	w := windowFor(h)
-	w.draw()
+func gio_onShow(view C.CFTypeRef) {
+	w := mustView(view)
+	w.setStage(system.StageRunning)
 }
 
 //export gio_onFullscreen
-func gio_onFullscreen(h C.uintptr_t) {
-	w := windowFor(h)
+func gio_onFullscreen(view C.CFTypeRef) {
+	w := mustView(view)
 	w.config.Mode = Fullscreen
-	w.ProcessEvent(ConfigEvent{Config: w.config})
+	w.w.Event(ConfigEvent{Config: w.config})
 }
 
 //export gio_onWindowed
-func gio_onWindowed(h C.uintptr_t) {
-	w := windowFor(h)
+func gio_onWindowed(view C.CFTypeRef) {
+	w := mustView(view)
 	w.config.Mode = Windowed
-	w.ProcessEvent(ConfigEvent{Config: w.config})
+	w.w.Event(ConfigEvent{Config: w.config})
+}
+
+//export gio_onAppHide
+func gio_onAppHide() {
+	for _, w := range viewMap {
+		w.setStage(system.StagePaused)
+	}
+}
+
+//export gio_onAppShow
+func gio_onAppShow() {
+	for _, w := range viewMap {
+		w.setStage(system.StageRunning)
+	}
 }
 
 //export gio_onFinishLaunching
@@ -914,27 +850,20 @@ func gio_onFinishLaunching() {
 	close(launched)
 }
 
-func newWindow(win *callbacks, options []Option) {
+func newWindow(win *callbacks, options []Option) error {
 	<-launched
-	res := make(chan struct{})
+	errch := make(chan error)
 	runOnMain(func() {
-		w := &window{
-			redraw: make(chan struct{}, 1),
-			w:      win,
-		}
-		w.loop = newEventLoop(w.w, w.wakeup)
-		win.SetDriver(w)
-		res <- struct{}{}
-		var cnf Config
-		cnf.apply(unit.Metric{}, options)
-		if err := w.init(cnf.CustomRenderer); err != nil {
-			w.ProcessEvent(DestroyEvent{Err: err})
+		w, err := newOSWindow()
+		if err != nil {
+			errch <- err
 			return
 		}
+		errch <- nil
+		w.w = win
 		window := C.gio_createWindow(w.view, 0, 0, 0, 0, 0, 0)
-		// Release our reference now that the NSWindow has it.
-		C.CFRelease(w.view)
 		w.updateWindowMode()
+		win.SetDriver(w)
 		w.Configure(options)
 		if nextTopLeft.x == 0 && nextTopLeft.y == 0 {
 			// cascadeTopLeftFromPoint treats (0, 0) as a no-op,
@@ -944,21 +873,23 @@ func newWindow(win *callbacks, options []Option) {
 		nextTopLeft = C.cascadeTopLeftFromPoint(window, nextTopLeft)
 		// makeKeyAndOrderFront assumes ownership of our window reference.
 		C.makeKeyAndOrderFront(window)
+		layer := C.layerForView(w.view)
+		w.w.Event(ViewEvent{View: uintptr(w.view), Layer: uintptr(layer)})
 	})
-	<-res
+	return <-errch
 }
 
-func (w *window) init(customRenderer bool) error {
-	presentWithTrans := 1
-	if customRenderer {
-		presentWithTrans = 0
-	}
-	view := C.gio_createView(C.int(presentWithTrans))
+func newOSWindow() (*window, error) {
+	view := C.gio_createView()
 	if view == 0 {
-		return errors.New("newOSWindow: failed to create view")
+		return nil, errors.New("newOSWindows: failed to create view")
 	}
 	scale := float32(C.getViewBackingScale(view))
-	w.scale = scale
+	w := &window{
+		view:   view,
+		scale:  scale,
+		redraw: make(chan struct{}, 1),
+	}
 	dl, err := newDisplayLink(func() {
 		select {
 		case w.redraw <- struct{}{}:
@@ -966,30 +897,24 @@ func (w *window) init(customRenderer bool) error {
 			return
 		}
 		w.runOnMain(func() {
-			if w.visible {
-				C.setNeedsDisplay(w.view)
-			}
+			C.setNeedsDisplay(w.view)
 		})
 	})
 	w.displayLink = dl
 	if err != nil {
 		C.CFRelease(view)
-		return err
+		return nil, err
 	}
-	C.gio_viewSetHandle(view, C.uintptr_t(cgo.NewHandle(w)))
-	w.view = view
-	return nil
+	insertView(view, w)
+	return w, nil
 }
 
 func osMain() {
-	if !isMainThread() {
-		panic("app.Main must run on the main goroutine")
-	}
 	C.gio_main()
 }
 
-func convertKey(k rune) (key.Name, bool) {
-	var n key.Name
+func convertKey(k rune) (string, bool) {
+	var n string
 	switch k {
 	case 0x1b:
 		n = key.NameEscape
@@ -1050,7 +975,7 @@ func convertKey(k rune) (key.Name, bool) {
 		if !unicode.IsPrint(k) {
 			return "", false
 		}
-		n = key.Name(k)
+		n = string(k)
 	}
 	return n, true
 }
@@ -1072,8 +997,4 @@ func convertMods(mods C.NSUInteger) key.Modifiers {
 	return kmods
 }
 
-func (AppKitViewEvent) implementsViewEvent() {}
-func (AppKitViewEvent) ImplementsEvent()     {}
-func (a AppKitViewEvent) Valid() bool {
-	return a != (AppKitViewEvent{})
-}
+func (_ ViewEvent) ImplementsEvent() {}

app/os_macos.m

@@ -6,7 +6,7 @@
 
 #include "_cgo_export.h"
 
-__attribute__ ((visibility ("hidden"))) CALayer *gio_layerFactory(BOOL presentWithTrans);
+__attribute__ ((visibility ("hidden"))) CALayer *gio_layerFactory(void);
 
 @interface GioAppDelegate : NSObject<NSApplicationDelegate>
 @end
@@ -14,55 +14,40 @@ __attribute__ ((visibility ("hidden"))) CALayer *gio_layerFactory(BOOL presentWi
 @interface GioWindowDelegate : NSObject<NSWindowDelegate>
 @end
 
-@interface GioView : NSView <CALayerDelegate,NSTextInputClient>
-@property uintptr_t handle;
-@property BOOL presentWithTrans;
-@end
-
 @implementation GioWindowDelegate
 - (void)windowWillMiniaturize:(NSNotification *)notification {
 	NSWindow *window = (NSWindow *)[notification object];
-  GioView *view = (GioView *)window.contentView;
-	gio_onHide(view.handle);
+	gio_onHide((__bridge CFTypeRef)window.contentView);
 }
 - (void)windowDidDeminiaturize:(NSNotification *)notification {
 	NSWindow *window = (NSWindow *)[notification object];
-  GioView *view = (GioView *)window.contentView;
-	gio_onShow(view.handle);
+	gio_onShow((__bridge CFTypeRef)window.contentView);
 }
 - (void)windowWillEnterFullScreen:(NSNotification *)notification {
 	NSWindow *window = (NSWindow *)[notification object];
-  GioView *view = (GioView *)window.contentView;
-	gio_onFullscreen(view.handle);
+	gio_onFullscreen((__bridge CFTypeRef)window.contentView);
 }
 - (void)windowWillExitFullScreen:(NSNotification *)notification {
 	NSWindow *window = (NSWindow *)[notification object];
-  GioView *view = (GioView *)window.contentView;
-	gio_onWindowed(view.handle);
+	gio_onWindowed((__bridge CFTypeRef)window.contentView);
 }
 - (void)windowDidChangeScreen:(NSNotification *)notification {
 	NSWindow *window = (NSWindow *)[notification object];
 	CGDirectDisplayID dispID = [[[window screen] deviceDescription][@"NSScreenNumber"] unsignedIntValue];
-  GioView *view = (GioView *)window.contentView;
-	gio_onChangeScreen(view.handle, dispID);
+	CFTypeRef view = (__bridge CFTypeRef)window.contentView;
+	gio_onChangeScreen(view, dispID);
 }
 - (void)windowDidBecomeKey:(NSNotification *)notification {
 	NSWindow *window = (NSWindow *)[notification object];
-	GioView *view = (GioView *)window.contentView;
-	if ([window firstResponder] == view) {
-		gio_onFocus(view.handle, 1);
-	}
+	gio_onFocus((__bridge CFTypeRef)window.contentView, 1);
 }
 - (void)windowDidResignKey:(NSNotification *)notification {
 	NSWindow *window = (NSWindow *)[notification object];
-	GioView *view = (GioView *)window.contentView;
-	if ([window firstResponder] == view) {
-		gio_onFocus(view.handle, 0);
-	}
+	gio_onFocus((__bridge CFTypeRef)window.contentView, 0);
 }
 @end
 
-static void handleMouse(GioView *view, NSEvent *event, int typ, CGFloat dx, CGFloat dy) {
+static void handleMouse(NSView *view, NSEvent *event, int typ, CGFloat dx, CGFloat dy) {
 	NSPoint p = [view convertPoint:[event locationInWindow] fromView:nil];
 	if (!event.hasPreciseScrollingDeltas) {
 		// dx and dy are in rows and columns.
@@ -71,9 +56,12 @@ static void handleMouse(GioView *view, NSEvent *event, int typ, CGFloat dx, CGFl
 	}
 	// Origin is in the lower left corner. Convert to upper left.
 	CGFloat height = view.bounds.size.height;
-	gio_onMouse(view.handle, (__bridge CFTypeRef)event, typ, event.buttonNumber, p.x, height - p.y, dx, dy, [event timestamp], [event modifierFlags]);
+	gio_onMouse((__bridge CFTypeRef)view, (__bridge CFTypeRef)event, typ, event.buttonNumber, p.x, height - p.y, dx, dy, [event timestamp], [event modifierFlags]);
 }
 
+@interface GioView : NSView <CALayerDelegate,NSTextInputClient>
+@end
+
 @implementation GioView
 - (void)setFrameSize:(NSSize)newSize {
 	[super setFrameSize:newSize];
@@ -82,19 +70,21 @@ static void handleMouse(GioView *view, NSEvent *event, int typ, CGFloat dx, CGFl
 // drawRect is called when OpenGL is used, displayLayer otherwise.
 // Don't know why.
 - (void)drawRect:(NSRect)r {
-	gio_onDraw(self.handle);
+	gio_onDraw((__bridge CFTypeRef)self);
 }
 - (void)displayLayer:(CALayer *)layer {
 	layer.contentsScale = self.window.backingScaleFactor;
-	gio_onDraw(self.handle);
+	gio_onDraw((__bridge CFTypeRef)self);
 }
 - (CALayer *)makeBackingLayer {
-	CALayer *layer = gio_layerFactory(self.presentWithTrans);
+	CALayer *layer = gio_layerFactory();
 	layer.delegate = self;
 	return layer;
 }
 - (void)viewDidMoveToWindow {
-	gio_onAttached(self.handle, self.window != nil ? 1 : 0);
+	if (self.window == nil) {
+		gio_onClose((__bridge CFTypeRef)self);
+	}
 }
 - (void)mouseDown:(NSEvent *)event {
 	handleMouse(self, event, MOUSE_DOWN, 0, 0);
@@ -134,14 +124,14 @@ static void handleMouse(GioView *view, NSEvent *event, int typ, CGFloat dx, CGFl
 - (void)keyDown:(NSEvent *)event {
 	[self interpretKeyEvents:[NSArray arrayWithObject:event]];
 	NSString *keys = [event charactersIgnoringModifiers];
-	gio_onKeys(self.handle, (__bridge CFTypeRef)keys, [event timestamp], [event modifierFlags], true);
+	gio_onKeys((__bridge CFTypeRef)self, (__bridge CFTypeRef)keys, [event timestamp], [event modifierFlags], true);
 }
 - (void)keyUp:(NSEvent *)event {
 	NSString *keys = [event charactersIgnoringModifiers];
-	gio_onKeys(self.handle, (__bridge CFTypeRef)keys, [event timestamp], [event modifierFlags], false);
+	gio_onKeys((__bridge CFTypeRef)self, (__bridge CFTypeRef)keys, [event timestamp], [event modifierFlags], false);
 }
 - (void)insertText:(id)string {
-	gio_onText(self.handle, (__bridge CFTypeRef)string);
+	gio_onText((__bridge CFTypeRef)self, (__bridge CFTypeRef)string);
 }
 - (void)doCommandBySelector:(SEL)sel {
 	// Don't pass commands up the responder chain.
@@ -149,17 +139,17 @@ static void handleMouse(GioView *view, NSEvent *event, int typ, CGFloat dx, CGFl
 }
 
 - (BOOL)hasMarkedText {
-	int res = gio_hasMarkedText(self.handle);
+	int res = gio_hasMarkedText((__bridge CFTypeRef)self);
 	return res ? YES : NO;
 }
 - (NSRange)markedRange {
-	return gio_markedRange(self.handle);
+	return gio_markedRange((__bridge CFTypeRef)self);
 }
 - (NSRange)selectedRange {
-	return gio_selectedRange(self.handle);
+	return gio_selectedRange((__bridge CFTypeRef)self);
 }
 - (void)unmarkText {
-	gio_unmarkText(self.handle);
+	gio_unmarkText((__bridge CFTypeRef)self);
 }
 - (void)setMarkedText:(id)string
         selectedRange:(NSRange)selRange
@@ -171,14 +161,14 @@ static void handleMouse(GioView *view, NSEvent *event, int typ, CGFloat dx, CGFl
 	} else {
 		str = string;
 	}
-	gio_setMarkedText(self.handle, (__bridge CFTypeRef)str, selRange, replaceRange);
+	gio_setMarkedText((__bridge CFTypeRef)self, (__bridge CFTypeRef)str, selRange, replaceRange);
 }
 - (NSArray<NSAttributedStringKey> *)validAttributesForMarkedText {
 	return nil;
 }
 - (NSAttributedString *)attributedSubstringForProposedRange:(NSRange)range
                                                 actualRange:(NSRangePointer)actualRange {
-	NSString *str = CFBridgingRelease(gio_substringForProposedRange(self.handle, range, actualRange));
+	NSString *str = CFBridgingRelease(gio_substringForProposedRange((__bridge CFTypeRef)self, range, actualRange));
 	return [[NSAttributedString alloc] initWithString:str attributes:nil];
 }
 - (void)insertText:(id)string
@@ -190,34 +180,17 @@ static void handleMouse(GioView *view, NSEvent *event, int typ, CGFloat dx, CGFl
 	} else {
 		str = string;
 	}
-	gio_insertText(self.handle, (__bridge CFTypeRef)str, replaceRange);
+	gio_insertText((__bridge CFTypeRef)self, (__bridge CFTypeRef)str, replaceRange);
 }
 - (NSUInteger)characterIndexForPoint:(NSPoint)p {
-	return gio_characterIndexForPoint(self.handle, p);
+	return gio_characterIndexForPoint((__bridge CFTypeRef)self, p);
 }
 - (NSRect)firstRectForCharacterRange:(NSRange)rng
                          actualRange:(NSRangePointer)actual {
-    NSRect r = gio_firstRectForCharacterRange(self.handle, rng, actual);
+    NSRect r = gio_firstRectForCharacterRange((__bridge CFTypeRef)self, rng, actual);
     r = [self convertRect:r toView:nil];
     return [[self window] convertRectToScreen:r];
 }
-- (void)applicationWillUnhide:(NSNotification *)notification {
-	gio_onShow(self.handle);
-}
-- (void)applicationDidHide:(NSNotification *)notification {
-	gio_onHide(self.handle);
-}
-- (void)dealloc {
-	gio_onDestroy(self.handle);
-}
-- (BOOL) becomeFirstResponder {
-	gio_onFocus(self.handle, 1);
-	return [super becomeFirstResponder];
- }
-- (BOOL) resignFirstResponder {
-	gio_onFocus(self.handle, 0);
-	return [super resignFirstResponder];
-}
 @end
 
 // Delegates are weakly referenced from their peers. Nothing
@@ -267,7 +240,7 @@ void gio_showCursor() {
 
 // some cursors are not public, this tries to use a private cursor
 // and uses fallback when the use of private cursor fails.
-static void trySetPrivateCursor(SEL cursorName, NSCursor* fallback) {
+void gio_trySetPrivateCursor(SEL cursorName, NSCursor* fallback) {
 	if ([NSCursor respondsToSelector:cursorName]) {
 		id object = [NSCursor performSelector:cursorName];
 		if ([object isKindOfClass:[NSCursor class]]) {
@@ -299,7 +272,7 @@ void gio_setCursor(NSUInteger curID) {
 				break;
 			case 6: // pointer.CursorAllScroll
 				// For some reason, using _moveCursor fails on Monterey.
-				// trySetPrivateCursor(@selector(_moveCursor), NSCursor.arrowCursor);
+				// gio_trySetPrivateCursor(@selector(_moveCursor), NSCursor.arrowCursor);
 				[NSCursor.arrowCursor set];
 				break;
 			case 7: // pointer.CursorColResize
@@ -309,31 +282,33 @@ void gio_setCursor(NSUInteger curID) {
 				[NSCursor.resizeUpDownCursor set];
 				break;
 			case 9: // pointer.CursorGrab
-				[NSCursor.openHandCursor set];
+				// [NSCursor.openHandCursor set];
+				gio_trySetPrivateCursor(@selector(openHandCursor), NSCursor.arrowCursor);
 				break;
 			case 10: // pointer.CursorGrabbing
-				[NSCursor.closedHandCursor set];
+				// [NSCursor.closedHandCursor set];
+				gio_trySetPrivateCursor(@selector(closedHandCursor), NSCursor.arrowCursor);
 				break;
 			case 11: // pointer.CursorNotAllowed
 				[NSCursor.operationNotAllowedCursor set];
 				break;
 			case 12: // pointer.CursorWait
-				trySetPrivateCursor(@selector(busyButClickableCursor), NSCursor.arrowCursor);
+				gio_trySetPrivateCursor(@selector(busyButClickableCursor), NSCursor.arrowCursor);
 				break;
 			case 13: // pointer.CursorProgress
-				trySetPrivateCursor(@selector(busyButClickableCursor), NSCursor.arrowCursor);
+				gio_trySetPrivateCursor(@selector(busyButClickableCursor), NSCursor.arrowCursor);
 				break;
 			case 14: // pointer.CursorNorthWestResize
-				trySetPrivateCursor(@selector(_windowResizeNorthWestCursor), NSCursor.resizeUpDownCursor);
+				gio_trySetPrivateCursor(@selector(_windowResizeNorthWestCursor), NSCursor.resizeUpDownCursor);
 				break;
 			case 15: // pointer.CursorNorthEastResize
-				trySetPrivateCursor(@selector(_windowResizeNorthEastCursor), NSCursor.resizeUpDownCursor);
+				gio_trySetPrivateCursor(@selector(_windowResizeNorthEastCursor), NSCursor.resizeUpDownCursor);
 				break;
 			case 16: // pointer.CursorSouthWestResize
-				trySetPrivateCursor(@selector(_windowResizeSouthWestCursor), NSCursor.resizeUpDownCursor);
+				gio_trySetPrivateCursor(@selector(_windowResizeSouthWestCursor), NSCursor.resizeUpDownCursor);
 				break;
 			case 17: // pointer.CursorSouthEastResize
-				trySetPrivateCursor(@selector(_windowResizeSouthEastCursor), NSCursor.resizeUpDownCursor);
+				gio_trySetPrivateCursor(@selector(_windowResizeSouthEastCursor), NSCursor.resizeUpDownCursor);
 				break;
 			case 18: // pointer.CursorNorthSouthResize
 				[NSCursor.resizeUpDownCursor set];
@@ -354,10 +329,10 @@ void gio_setCursor(NSUInteger curID) {
 				[NSCursor.resizeDownCursor set];
 				break;
 			case 24: // pointer.CursorNorthEastSouthWestResize
-				trySetPrivateCursor(@selector(_windowResizeNorthEastSouthWestCursor), NSCursor.resizeUpDownCursor);
+				gio_trySetPrivateCursor(@selector(_windowResizeNorthEastSouthWestCursor), NSCursor.resizeUpDownCursor);
 				break;
 			case 25: // pointer.CursorNorthWestSouthEastResize
-				trySetPrivateCursor(@selector(_windowResizeNorthWestSouthEastCursor), NSCursor.resizeUpDownCursor);
+				gio_trySetPrivateCursor(@selector(_windowResizeNorthWestSouthEastCursor), NSCursor.resizeUpDownCursor);
 				break;
 			default:
 				[NSCursor.arrowCursor set];
@@ -393,39 +368,28 @@ CFTypeRef gio_createWindow(CFTypeRef viewRef, CGFloat width, CGFloat height, CGF
 	}
 }
 
-CFTypeRef gio_createView(int presentWithTrans) {
+CFTypeRef gio_createView(void) {
 	@autoreleasepool {
 		NSRect frame = NSMakeRect(0, 0, 0, 0);
 		GioView* view = [[GioView alloc] initWithFrame:frame];
-		view.presentWithTrans = presentWithTrans ? YES : NO;
 		view.wantsLayer = YES;
 		view.layerContentsRedrawPolicy = NSViewLayerContentsRedrawDuringViewResize;
-
-		[[NSNotificationCenter defaultCenter] addObserver:view
-												 selector:@selector(applicationWillUnhide:)
-													 name:NSApplicationWillUnhideNotification
-												   object:nil];
-		[[NSNotificationCenter defaultCenter] addObserver:view
-												 selector:@selector(applicationDidHide:)
-													 name:NSApplicationDidHideNotification
-												   object:nil];
 		return CFBridgingRetain(view);
 	}
 }
 
-void gio_viewSetHandle(CFTypeRef viewRef, uintptr_t handle) {
-	@autoreleasepool {
-		GioView *v = (__bridge GioView *)viewRef;
-		v.handle = handle;
-	}
-}
-
 @implementation GioAppDelegate
 - (void)applicationDidFinishLaunching:(NSNotification *)aNotification {
 	[NSApp setActivationPolicy:NSApplicationActivationPolicyRegular];
 	[NSApp activateIgnoringOtherApps:YES];
 	gio_onFinishLaunching();
 }
+- (void)applicationDidHide:(NSNotification *)aNotification {
+	gio_onAppHide();
+}
+- (void)applicationWillUnhide:(NSNotification *)notification {
+	gio_onAppShow();
+}
 @end
 
 void gio_main() {

app/os_unix.go

@@ -12,6 +12,13 @@ import (
 	"gioui.org/io/pointer"
 )
 
+// ViewEvent provides handles to the underlying window objects for the
+// current display protocol.
+type ViewEvent interface {
+	implementsViewEvent()
+	ImplementsEvent()
+}
+
 type X11ViewEvent struct {
 	// Display is a pointer to the X11 Display created by XOpenDisplay.
 	Display unsafe.Pointer
@@ -21,9 +28,6 @@ type X11ViewEvent struct {
 
 func (X11ViewEvent) implementsViewEvent() {}
 func (X11ViewEvent) ImplementsEvent()     {}
-func (x X11ViewEvent) Valid() bool {
-	return x != (X11ViewEvent{})
-}
 
 type WaylandViewEvent struct {
 	// Display is the *wl_display returned by wl_display_connect.
@@ -34,9 +38,6 @@ type WaylandViewEvent struct {
 
 func (WaylandViewEvent) implementsViewEvent() {}
 func (WaylandViewEvent) ImplementsEvent()     {}
-func (w WaylandViewEvent) Valid() bool {
-	return w != (WaylandViewEvent{})
-}
 
 func osMain() {
 	select {}
@@ -48,7 +49,7 @@ type windowDriver func(*callbacks, []Option) error
 // let each driver initialize these variables with their own version of createWindow.
 var wlDriver, x11Driver windowDriver
 
-func newWindow(window *callbacks, options []Option) {
+func newWindow(window *callbacks, options []Option) error {
 	var errFirst error
 	for _, d := range []windowDriver{wlDriver, x11Driver} {
 		if d == nil {
@@ -56,16 +57,16 @@ func newWindow(window *callbacks, options []Option) {
 		}
 		err := d(window, options)
 		if err == nil {
-			return
+			return nil
 		}
 		if errFirst == nil {
 			errFirst = err
 		}
 	}
-	if errFirst == nil {
-		errFirst = errors.New("app: no window driver available")
+	if errFirst != nil {
+		return errFirst
 	}
-	window.ProcessEvent(DestroyEvent{Err: errFirst})
+	return errors.New("app: no window driver available")
 }
 
 // xCursor contains mapping from pointer.Cursor to XCursor.

app/os_wayland.go

@@ -15,7 +15,6 @@ import (
 	"math"
 	"os"
 	"os/exec"
-	"runtime"
 	"strconv"
 	"sync"
 	"time"
@@ -26,12 +25,10 @@ import (
 	"gioui.org/app/internal/xkb"
 	"gioui.org/f32"
 	"gioui.org/internal/fling"
-	"gioui.org/io/event"
+	"gioui.org/io/clipboard"
 	"gioui.org/io/key"
 	"gioui.org/io/pointer"
 	"gioui.org/io/system"
-	"gioui.org/io/transfer"
-	"gioui.org/op"
 	"gioui.org/unit"
 )
 
@@ -100,9 +97,7 @@ type wlDisplay struct {
 		read, write int
 	}
 
-	repeat        repeatState
-	poller        poller
-	readClipClose chan struct{}
+	repeat repeatState
 }
 
 type wlSeat struct {
@@ -142,7 +137,7 @@ type repeatState struct {
 	delay time.Duration
 
 	key   uint32
-	win   *window
+	win   *callbacks
 	stopC chan struct{}
 
 	start time.Duration
@@ -199,10 +194,12 @@ type window struct {
 		dir            f32.Point
 	}
 
-	configured        bool
+	stage             system.Stage
+	dead              bool
 	lastFrameCallback *C.struct_wl_callback
 
 	animating bool
+	redraw    bool
 	// The most recent configure serial waiting to be ack'ed.
 	serial C.uint32_t
 	scale  int
@@ -212,11 +209,9 @@ type window struct {
 	wsize        image.Point // window config size before going fullscreen or maximized
 	inCompositor bool        // window is moving or being resized
 
-	clipReads chan transfer.DataEvent
+	clipReads chan clipboard.Event
 
 	wakeups chan struct{}
-
-	closing bool
 }
 
 type poller struct {
@@ -265,17 +260,25 @@ func newWLWindow(callbacks *callbacks, options []Option) error {
 		return err
 	}
 	w.w = callbacks
-	w.w.SetDriver(w)
+	go func() {
+		defer d.destroy()
+		defer w.destroy()
 
-	// Finish and commit setup from createNativeWindow.
-	w.Configure(options)
-	w.draw(true)
-	C.wl_surface_commit(w.surf)
+		w.w.SetDriver(w)
 
-	w.ProcessEvent(WaylandViewEvent{
-		Display: unsafe.Pointer(w.display()),
-		Surface: unsafe.Pointer(w.surf),
-	})
+		// Finish and commit setup from createNativeWindow.
+		w.Configure(options)
+		C.wl_surface_commit(w.surf)
+
+		w.w.Event(WaylandViewEvent{
+			Display: unsafe.Pointer(w.display()),
+			Surface: unsafe.Pointer(w.surf),
+		})
+
+		err := w.loop()
+		w.w.Event(WaylandViewEvent{})
+		w.w.Event(system.DestroyEvent{Err: err})
+	}()
 	return nil
 }
 
@@ -351,7 +354,7 @@ func (d *wlDisplay) createNativeWindow(options []Option) (*window, error) {
 		ppdp:      ppdp,
 		ppsp:      ppdp,
 		wakeups:   make(chan struct{}, 1),
-		clipReads: make(chan transfer.DataEvent, 1),
+		clipReads: make(chan clipboard.Event, 1),
 	}
 	w.surf = C.wl_compositor_create_surface(d.compositor)
 	if w.surf == nil {
@@ -546,15 +549,15 @@ func gio_onSeatName(data unsafe.Pointer, seat *C.struct_wl_seat, name *C.char) {
 func gio_onXdgSurfaceConfigure(data unsafe.Pointer, wmSurf *C.struct_xdg_surface, serial C.uint32_t) {
 	w := callbackLoad(data).(*window)
 	w.serial = serial
+	w.redraw = true
 	C.xdg_surface_ack_configure(wmSurf, serial)
-	w.configured = true
-	w.draw(true)
+	w.setStage(system.StageRunning)
 }
 
 //export gio_onToplevelClose
 func gio_onToplevelClose(data unsafe.Pointer, topLvl *C.struct_xdg_toplevel) {
 	w := callbackLoad(data).(*window)
-	w.closing = true
+	w.dead = true
 }
 
 //export gio_onToplevelConfigure
@@ -583,8 +586,8 @@ func gio_onToplevelDecorationConfigure(data unsafe.Pointer, deco *C.struct_zxdg_
 		} else {
 			w.size.Y += int(w.config.decoHeight)
 		}
-		w.ProcessEvent(ConfigEvent{Config: w.config})
-		w.draw(true)
+		w.w.Event(ConfigEvent{Config: w.config})
+		w.redraw = true
 	}
 }
 
@@ -642,7 +645,7 @@ func gio_onSurfaceEnter(data unsafe.Pointer, surf *C.struct_wl_surface, output *
 	if w.config.Mode == Minimized {
 		// Minimized window got brought back up: it is no longer so.
 		w.config.Mode = Windowed
-		w.ProcessEvent(ConfigEvent{Config: w.config})
+		w.w.Event(ConfigEvent{Config: w.config})
 	}
 }
 
@@ -787,7 +790,7 @@ func gio_onTouchDown(data unsafe.Pointer, touch *C.struct_wl_touch, serial, t C.
 		X: fromFixed(x) * float32(w.scale),
 		Y: fromFixed(y) * float32(w.scale),
 	}
-	w.ProcessEvent(pointer.Event{
+	w.w.Event(pointer.Event{
 		Kind:      pointer.Press,
 		Source:    pointer.Touch,
 		Position:  w.lastTouch,
@@ -803,7 +806,7 @@ func gio_onTouchUp(data unsafe.Pointer, touch *C.struct_wl_touch, serial, t C.ui
 	s.serial = serial
 	w := s.touchFoci[id]
 	delete(s.touchFoci, id)
-	w.ProcessEvent(pointer.Event{
+	w.w.Event(pointer.Event{
 		Kind:      pointer.Release,
 		Source:    pointer.Touch,
 		Position:  w.lastTouch,
@@ -821,7 +824,7 @@ func gio_onTouchMotion(data unsafe.Pointer, touch *C.struct_wl_touch, t C.uint32
 		X: fromFixed(x) * float32(w.scale),
 		Y: fromFixed(y) * float32(w.scale),
 	}
-	w.ProcessEvent(pointer.Event{
+	w.w.Event(pointer.Event{
 		Kind:      pointer.Move,
 		Position:  w.lastTouch,
 		Source:    pointer.Touch,
@@ -840,7 +843,7 @@ func gio_onTouchCancel(data unsafe.Pointer, touch *C.struct_wl_touch) {
 	s := callbackLoad(data).(*wlSeat)
 	for id, w := range s.touchFoci {
 		delete(s.touchFoci, id)
-		w.ProcessEvent(pointer.Event{
+		w.w.Event(pointer.Event{
 			Kind:   pointer.Cancel,
 			Source: pointer.Touch,
 		})
@@ -866,7 +869,7 @@ func gio_onPointerLeave(data unsafe.Pointer, p *C.struct_wl_pointer, serial C.ui
 	s.serial = serial
 	if w.inCompositor {
 		w.inCompositor = false
-		w.ProcessEvent(pointer.Event{Kind: pointer.Cancel})
+		w.w.Event(pointer.Event{Kind: pointer.Cancel})
 	}
 }
 
@@ -927,7 +930,7 @@ func gio_onPointerButton(data unsafe.Pointer, p *C.struct_wl_pointer, serial, t,
 	}
 	w.flushScroll()
 	w.resetFling()
-	w.ProcessEvent(pointer.Event{
+	w.w.Event(pointer.Event{
 		Kind:      kind,
 		Source:    pointer.Mouse,
 		Buttons:   w.pointerBtns,
@@ -1015,34 +1018,23 @@ func gio_onPointerAxisDiscrete(data unsafe.Pointer, p *C.struct_wl_pointer, axis
 }
 
 func (w *window) ReadClipboard() {
-	if w.disp.readClipClose != nil {
-		return
-	}
-	w.disp.readClipClose = make(chan struct{})
 	r, err := w.disp.readClipboard()
+	// Send empty responses on unavailable clipboards or errors.
 	if r == nil || err != nil {
+		w.w.Event(clipboard.Event{})
 		return
 	}
 	// Don't let slow clipboard transfers block event loop.
 	go func() {
 		defer r.Close()
 		data, _ := io.ReadAll(r)
-		e := transfer.DataEvent{
-			Type: "application/text",
-			Open: func() io.ReadCloser {
-				return io.NopCloser(bytes.NewReader(data))
-			},
-		}
-		select {
-		case w.clipReads <- e:
-			w.disp.wakeup()
-		case <-w.disp.readClipClose:
-		}
+		w.clipReads <- clipboard.Event{Text: string(data)}
+		w.Wakeup()
 	}()
 }
 
-func (w *window) WriteClipboard(mime string, s []byte) {
-	w.disp.writeClipboard(s)
+func (w *window) WriteClipboard(s string) {
+	w.disp.writeClipboard([]byte(s))
 }
 
 func (w *window) Configure(options []Option) {
@@ -1100,7 +1092,8 @@ func (w *window) Configure(options []Option) {
 		w.config.MaxSize = cnf.MaxSize
 		w.setWindowConstraints()
 	}
-	w.ProcessEvent(ConfigEvent{Config: w.config})
+	w.w.Event(ConfigEvent{Config: w.config})
+	w.redraw = true
 }
 
 func (w *window) setWindowConstraints() {
@@ -1137,7 +1130,7 @@ func (w *window) Perform(actions system.Action) {
 	walkActions(actions, func(action system.Action) {
 		switch action {
 		case system.ActionClose:
-			w.closing = true
+			w.dead = true
 		}
 	})
 }
@@ -1220,8 +1213,7 @@ func gio_onKeyboardEnter(data unsafe.Pointer, keyboard *C.struct_wl_keyboard, se
 	w := callbackLoad(unsafe.Pointer(surf)).(*window)
 	s.keyboardFocus = w
 	s.disp.repeat.Stop(0)
-	w.config.Focused = true
-	w.ProcessEvent(ConfigEvent{Config: w.config})
+	w.w.Event(key.FocusEvent{Focus: true})
 }
 
 //export gio_onKeyboardLeave
@@ -1230,8 +1222,7 @@ func gio_onKeyboardLeave(data unsafe.Pointer, keyboard *C.struct_wl_keyboard, se
 	s.serial = serial
 	s.disp.repeat.Stop(0)
 	w := s.keyboardFocus
-	w.config.Focused = false
-	w.ProcessEvent(ConfigEvent{Config: w.config})
+	w.w.Event(key.FocusEvent{Focus: false})
 }
 
 //export gio_onKeyboardKey
@@ -1249,7 +1240,7 @@ func gio_onKeyboardKey(data unsafe.Pointer, keyboard *C.struct_wl_keyboard, seri
 			// There's no support for IME yet.
 			w.w.EditorInsert(ee.Text)
 		} else {
-			w.ProcessEvent(e)
+			w.w.Event(e)
 		}
 	}
 	if state != C.WL_KEYBOARD_KEY_STATE_PRESSED {
@@ -1284,7 +1275,7 @@ func (r *repeatState) Start(w *window, keyCode uint32, t time.Duration) {
 	r.now = 0
 	r.stopC = stopC
 	r.key = keyCode
-	r.win = w
+	r.win = w.w
 	rate, delay := r.rate, r.delay
 	go func() {
 		timer := time.NewTimer(delay)
@@ -1342,9 +1333,9 @@ func (r *repeatState) Repeat(d *wlDisplay) {
 		for _, e := range d.xkb.DispatchKey(r.key, key.Press) {
 			if ee, ok := e.(key.EditEvent); ok {
 				// There's no support for IME yet.
-				r.win.w.EditorInsert(ee.Text)
+				r.win.EditorInsert(ee.Text)
 			} else {
-				r.win.ProcessEvent(e)
+				r.win.Event(e)
 			}
 		}
 		r.last += delay
@@ -1357,68 +1348,28 @@ func gio_onFrameDone(data unsafe.Pointer, callback *C.struct_wl_callback, t C.ui
 	w := callbackLoad(data).(*window)
 	if w.lastFrameCallback == callback {
 		w.lastFrameCallback = nil
-		w.draw(false)
 	}
 }
 
-func (w *window) close(err error) {
-	w.ProcessEvent(WaylandViewEvent{})
-	w.ProcessEvent(DestroyEvent{Err: err})
-	w.destroy()
-	w.disp.destroy()
-	w.disp = nil
-}
-
-func (w *window) dispatch() {
-	if w.disp == nil {
-		<-w.wakeups
-		w.w.Invalidate()
-		return
-	}
-	if err := w.disp.dispatch(); err != nil || w.closing {
-		w.close(err)
-		return
-	}
-	select {
-	case e := <-w.clipReads:
-		w.disp.readClipClose = nil
-		w.ProcessEvent(e)
-	case <-w.wakeups:
-		w.w.Invalidate()
-	default:
-	}
-}
-
-func (w *window) ProcessEvent(e event.Event) {
-	w.w.ProcessEvent(e)
-}
-
-func (w *window) Event() event.Event {
+func (w *window) loop() error {
+	var p poller
 	for {
-		evt, ok := w.w.nextEvent()
-		if !ok {
-			w.dispatch()
-			continue
+		if err := w.disp.dispatch(&p); err != nil {
+			return err
 		}
-		return evt
+		select {
+		case e := <-w.clipReads:
+			w.w.Event(e)
+		case <-w.wakeups:
+			w.w.Event(wakeupEvent{})
+		default:
+		}
+		if w.dead {
+			break
+		}
+		w.draw()
 	}
-}
-
-func (w *window) Invalidate() {
-	select {
-	case w.wakeups <- struct{}{}:
-	default:
-		return
-	}
-	w.disp.wakeup()
-}
-
-func (w *window) Run(f func()) {
-	f()
-}
-
-func (w *window) Frame(frame *op.Ops) {
-	w.w.ProcessFrame(frame, nil)
+	return nil
 }
 
 // bindDataDevice initializes the dataDev field if and only if both
@@ -1434,21 +1385,13 @@ func (d *wlDisplay) bindDataDevice() {
 	}
 }
 
-func (d *wlDisplay) dispatch() error {
-	// wl_display_prepare_read records the current thread for
-	// use in wl_display_read_events or wl_display_cancel_events.
-	runtime.LockOSThread()
-	defer runtime.UnlockOSThread()
-
+func (d *wlDisplay) dispatch(p *poller) error {
 	dispfd := C.wl_display_get_fd(d.disp)
 	// Poll for events and notifications.
-	pollfds := append(d.poller.pollfds[:0],
+	pollfds := append(p.pollfds[:0],
 		syscall.PollFd{Fd: int32(dispfd), Events: syscall.POLLIN | syscall.POLLERR},
 		syscall.PollFd{Fd: int32(d.notify.read), Events: syscall.POLLIN | syscall.POLLERR},
 	)
-	for C.wl_display_prepare_read(d.disp) != 0 {
-		C.wl_display_dispatch_pending(d.disp)
-	}
 	dispFd := &pollfds[0]
 	if ret, err := C.wl_display_flush(d.disp); ret < 0 {
 		if err != syscall.EAGAIN {
@@ -1459,25 +1402,11 @@ func (d *wlDisplay) dispatch() error {
 		dispFd.Events |= syscall.POLLOUT
 	}
 	if _, err := syscall.Poll(pollfds, -1); err != nil && err != syscall.EINTR {
-		C.wl_display_cancel_read(d.disp)
 		return fmt.Errorf("wayland: poll failed: %v", err)
 	}
-	if dispFd.Revents&(syscall.POLLERR|syscall.POLLHUP) != 0 {
-		C.wl_display_cancel_read(d.disp)
-		return errors.New("wayland: display file descriptor gone")
-	}
-	// Handle events.
-	if dispFd.Revents&syscall.POLLIN != 0 {
-		if ret, err := C.wl_display_read_events(d.disp); ret < 0 {
-			return fmt.Errorf("wayland: wl_display_read_events failed: %v", err)
-		}
-		C.wl_display_dispatch_pending(d.disp)
-	} else {
-		C.wl_display_cancel_read(d.disp)
-	}
 	// Clear notifications.
 	for {
-		_, err := syscall.Read(d.notify.read, d.poller.buf[:])
+		_, err := syscall.Read(d.notify.read, p.buf[:])
 		if err == syscall.EAGAIN {
 			break
 		}
@@ -1485,15 +1414,29 @@ func (d *wlDisplay) dispatch() error {
 			return fmt.Errorf("wayland: read from notify pipe failed: %v", err)
 		}
 	}
+	// Handle events
+	switch {
+	case dispFd.Revents&syscall.POLLIN != 0:
+		if ret, err := C.wl_display_dispatch(d.disp); ret < 0 {
+			return fmt.Errorf("wayland: wl_display_dispatch failed: %v", err)
+		}
+	case dispFd.Revents&(syscall.POLLERR|syscall.POLLHUP) != 0:
+		return errors.New("wayland: display file descriptor gone")
+	}
 	d.repeat.Repeat(d)
 	return nil
 }
 
+func (w *window) Wakeup() {
+	select {
+	case w.wakeups <- struct{}{}:
+	default:
+	}
+	w.disp.wakeup()
+}
+
 func (w *window) SetAnimating(anim bool) {
 	w.animating = anim
-	if anim {
-		w.draw(false)
-	}
 }
 
 // Wakeup wakes up the event loop through the notification pipe.
@@ -1505,10 +1448,6 @@ func (d *wlDisplay) wakeup() {
 }
 
 func (w *window) destroy() {
-	if w.lastFrameCallback != nil {
-		C.wl_callback_destroy(w.lastFrameCallback)
-		w.lastFrameCallback = nil
-	}
 	if w.cursor.surf != nil {
 		C.wl_surface_destroy(w.cursor.surf)
 	}
@@ -1633,15 +1572,7 @@ func (w *window) flushScroll() {
 	if total == (f32.Point{}) {
 		return
 	}
-	if w.scroll.steps == (image.Point{}) {
-		w.fling.xExtrapolation.SampleDelta(w.scroll.time, -w.scroll.dist.X)
-		w.fling.yExtrapolation.SampleDelta(w.scroll.time, -w.scroll.dist.Y)
-	}
-	// Zero scroll distance prior to calling ProcessEvent, otherwise we may recursively
-	// re-process the scroll distance.
-	w.scroll.dist = f32.Point{}
-	w.scroll.steps = image.Point{}
-	w.ProcessEvent(pointer.Event{
+	w.w.Event(pointer.Event{
 		Kind:      pointer.Scroll,
 		Source:    pointer.Mouse,
 		Buttons:   w.pointerBtns,
@@ -1650,6 +1581,12 @@ func (w *window) flushScroll() {
 		Time:      w.scroll.time,
 		Modifiers: w.disp.xkb.Modifiers(),
 	})
+	if w.scroll.steps == (image.Point{}) {
+		w.fling.xExtrapolation.SampleDelta(w.scroll.time, -w.scroll.dist.X)
+		w.fling.yExtrapolation.SampleDelta(w.scroll.time, -w.scroll.dist.Y)
+	}
+	w.scroll.dist = f32.Point{}
+	w.scroll.steps = image.Point{}
 }
 
 func (w *window) onPointerMotion(x, y C.wl_fixed_t, t C.uint32_t) {
@@ -1658,7 +1595,7 @@ func (w *window) onPointerMotion(x, y C.wl_fixed_t, t C.uint32_t) {
 		X: fromFixed(x) * float32(w.scale),
 		Y: fromFixed(y) * float32(w.scale),
 	}
-	w.ProcessEvent(pointer.Event{
+	w.w.Event(pointer.Event{
 		Kind:      pointer.Move,
 		Position:  w.lastPos,
 		Buttons:   w.pointerBtns,
@@ -1679,8 +1616,7 @@ func (w *window) systemGesture() (*C.struct_wl_cursor, C.uint32_t) {
 	if w.config.Mode != Windowed || w.config.Decorated {
 		return nil, 0
 	}
-	_, cfg := w.getConfig()
-	border := cfg.Dp(3)
+	border := w.w.w.metric.Dp(3)
 	x, y, size := int(w.lastPos.X), int(w.lastPos.Y), w.config.Size
 	north := y <= border
 	south := y >= size.Y-border
@@ -1734,10 +1670,13 @@ func (w *window) updateOutputs() {
 	if found && scale != w.scale {
 		w.scale = scale
 		C.wl_surface_set_buffer_scale(w.surf, C.int32_t(w.scale))
-		w.draw(true)
+		w.redraw = true
 	}
-	if found {
-		w.draw(true)
+	if !found {
+		w.setStage(system.StagePaused)
+	} else {
+		w.setStage(system.StageRunning)
+		w.redraw = true
 	}
 }
 
@@ -1749,10 +1688,7 @@ func (w *window) getConfig() (image.Point, unit.Metric) {
 	}
 }
 
-func (w *window) draw(sync bool) {
-	if !w.configured {
-		return
-	}
+func (w *window) draw() {
 	w.flushScroll()
 	size, cfg := w.getConfig()
 	if cfg == (unit.Metric{}) {
@@ -1760,9 +1696,11 @@ func (w *window) draw(sync bool) {
 	}
 	if size != w.config.Size {
 		w.config.Size = size
-		w.ProcessEvent(ConfigEvent{Config: w.config})
+		w.w.Event(ConfigEvent{Config: w.config})
 	}
 	anim := w.animating || w.fling.anim.Active()
+	sync := w.redraw
+	w.redraw = false
 	// Draw animation only when not waiting for frame callback.
 	redrawAnim := anim && w.lastFrameCallback == nil
 	if !redrawAnim && !sync {
@@ -1773,8 +1711,8 @@ func (w *window) draw(sync bool) {
 		// Use the surface as listener data for gio_onFrameDone.
 		C.wl_callback_add_listener(w.lastFrameCallback, &C.gio_callback_listener, unsafe.Pointer(w.surf))
 	}
-	w.ProcessEvent(frameEvent{
-		FrameEvent: FrameEvent{
+	w.w.Event(frameEvent{
+		FrameEvent: system.FrameEvent{
 			Now:    time.Now(),
 			Size:   w.config.Size,
 			Metric: cfg,
@@ -1783,6 +1721,14 @@ func (w *window) draw(sync bool) {
 	})
 }
 
+func (w *window) setStage(s system.Stage) {
+	if s == w.stage {
+		return
+	}
+	w.stage = s
+	w.w.Event(system.StageEvent{Stage: s})
+}
+
 func (w *window) display() *C.struct_wl_display {
 	return w.disp.disp
 }
@@ -1874,10 +1820,6 @@ func newWLDisplay() (*wlDisplay, error) {
 }
 
 func (d *wlDisplay) destroy() {
-	if d.readClipClose != nil {
-		close(d.readClipClose)
-		d.readClipClose = nil
-	}
 	if d.notify.write != 0 {
 		syscall.Close(d.notify.write)
 		d.notify.write = 0
@@ -1919,7 +1861,6 @@ func (d *wlDisplay) destroy() {
 	if d.disp != nil {
 		C.wl_display_disconnect(d.disp)
 		callbackDelete(unsafe.Pointer(d.disp))
-		d.disp = nil
 	}
 }
 

app/os_windows.go

@@ -6,7 +6,6 @@ import (
 	"errors"
 	"fmt"
 	"image"
-	"io"
 	"runtime"
 	"sort"
 	"strings"
@@ -19,19 +18,17 @@ import (
 	syscall "golang.org/x/sys/windows"
 
 	"gioui.org/app/internal/windows"
-	"gioui.org/op"
 	"gioui.org/unit"
 	gowindows "golang.org/x/sys/windows"
 
 	"gioui.org/f32"
-	"gioui.org/io/event"
+	"gioui.org/io/clipboard"
 	"gioui.org/io/key"
 	"gioui.org/io/pointer"
 	"gioui.org/io/system"
-	"gioui.org/io/transfer"
 )
 
-type Win32ViewEvent struct {
+type ViewEvent struct {
 	HWND uintptr
 }
 
@@ -39,6 +36,7 @@ type window struct {
 	hwnd        syscall.Handle
 	hdc         syscall.Handle
 	w           *callbacks
+	stage       system.Stage
 	pointerBtns pointer.Buttons
 
 	// cursorIn tracks whether the cursor was inside the window according
@@ -50,10 +48,10 @@ type window struct {
 	placement *windows.WindowPlacement
 
 	animating bool
+	focused   bool
 
 	borderSize image.Point
 	config     Config
-	loop       *eventLoop
 }
 
 const _WM_WAKEUP = windows.WM_USER + iota
@@ -86,38 +84,36 @@ func osMain() {
 	select {}
 }
 
-func newWindow(win *callbacks, options []Option) {
-	done := make(chan struct{})
+func newWindow(window *callbacks, options []Option) error {
+	cerr := make(chan error)
 	go func() {
 		// GetMessage and PeekMessage can filter on a window HWND, but
 		// then thread-specific messages such as WM_QUIT are ignored.
 		// Instead lock the thread so window messages arrive through
 		// unfiltered GetMessage calls.
 		runtime.LockOSThread()
-
-		w := &window{
-			w: win,
-		}
-		w.loop = newEventLoop(w.w, w.wakeup)
-		w.w.SetDriver(w)
-		err := w.init()
-		done <- struct{}{}
+		w, err := createNativeWindow()
 		if err != nil {
-			w.ProcessEvent(DestroyEvent{Err: err})
+			cerr <- err
 			return
 		}
+		cerr <- nil
 		winMap.Store(w.hwnd, w)
 		defer winMap.Delete(w.hwnd)
-		w.ProcessEvent(Win32ViewEvent{HWND: uintptr(w.hwnd)})
+		w.w = window
+		w.w.SetDriver(w)
+		w.w.Event(ViewEvent{HWND: uintptr(w.hwnd)})
 		w.Configure(options)
 		windows.SetForegroundWindow(w.hwnd)
 		windows.SetFocus(w.hwnd)
 		// Since the window class for the cursor is null,
 		// set it here to show the cursor.
 		w.SetCursor(pointer.CursorDefault)
-		w.runLoop()
+		if err := w.loop(); err != nil {
+			panic(err)
+		}
 	}()
-	<-done
+	return <-cerr
 }
 
 // initResources initializes the resources global.
@@ -152,13 +148,13 @@ func initResources() error {
 
 const dwExStyle = windows.WS_EX_APPWINDOW | windows.WS_EX_WINDOWEDGE
 
-func (w *window) init() error {
+func createNativeWindow() (*window, error) {
 	var resErr error
 	resources.once.Do(func() {
 		resErr = initResources()
 	})
 	if resErr != nil {
-		return resErr
+		return nil, resErr
 	}
 	const dwStyle = windows.WS_OVERLAPPEDWINDOW
 
@@ -174,15 +170,16 @@ func (w *window) init() error {
 		resources.handle,
 		0)
 	if err != nil {
-		return err
+		return nil, err
+	}
+	w := &window{
+		hwnd: hwnd,
 	}
 	w.hdc, err = windows.GetDC(hwnd)
 	if err != nil {
-		windows.DestroyWindow(hwnd)
-		return err
+		return nil, err
 	}
-	w.hwnd = hwnd
-	return nil
+	return w, nil
 }
 
 // update() handles changes done by the user, and updates the configuration.
@@ -199,7 +196,7 @@ func (w *window) update() {
 		windows.GetSystemMetrics(windows.SM_CXSIZEFRAME),
 		windows.GetSystemMetrics(windows.SM_CYSIZEFRAME),
 	)
-	w.ProcessEvent(ConfigEvent{Config: w.config})
+	w.w.Event(ConfigEvent{Config: w.config})
 }
 
 func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr {
@@ -240,7 +237,7 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 				e.State = key.Release
 			}
 
-			w.ProcessEvent(e)
+			w.w.Event(e)
 
 			if (wParam == windows.VK_F10) && (msg == windows.WM_SYSKEYDOWN || msg == windows.WM_SYSKEYUP) {
 				// Reserve F10 for ourselves, and don't let it open the system menu. Other Windows programs
@@ -261,15 +258,23 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 	case windows.WM_MBUTTONUP:
 		w.pointerButton(pointer.ButtonTertiary, false, lParam, getModifiers())
 	case windows.WM_CANCELMODE:
-		w.ProcessEvent(pointer.Event{
+		w.w.Event(pointer.Event{
 			Kind: pointer.Cancel,
 		})
 	case windows.WM_SETFOCUS:
-		w.config.Focused = true
-		w.ProcessEvent(ConfigEvent{Config: w.config})
+		w.focused = true
+		w.w.Event(key.FocusEvent{Focus: true})
 	case windows.WM_KILLFOCUS:
-		w.config.Focused = false
-		w.ProcessEvent(ConfigEvent{Config: w.config})
+		w.focused = false
+		w.w.Event(key.FocusEvent{Focus: false})
+	case windows.WM_NCACTIVATE:
+		if w.stage >= system.StageInactive {
+			if wParam == windows.TRUE {
+				w.setStage(system.StageRunning)
+			} else {
+				w.setStage(system.StageInactive)
+			}
+		}
 	case windows.WM_NCHITTEST:
 		if w.config.Decorated {
 			// Let the system handle it.
@@ -282,7 +287,7 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 	case windows.WM_MOUSEMOVE:
 		x, y := coordsFromlParam(lParam)
 		p := f32.Point{X: float32(x), Y: float32(y)}
-		w.ProcessEvent(pointer.Event{
+		w.w.Event(pointer.Event{
 			Kind:      pointer.Move,
 			Source:    pointer.Mouse,
 			Position:  p,
@@ -295,8 +300,8 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 	case windows.WM_MOUSEHWHEEL:
 		w.scrollEvent(wParam, lParam, true, getModifiers())
 	case windows.WM_DESTROY:
-		w.ProcessEvent(Win32ViewEvent{})
-		w.ProcessEvent(DestroyEvent{})
+		w.w.Event(ViewEvent{})
+		w.w.Event(system.DestroyEvent{})
 		if w.hdc != 0 {
 			windows.ReleaseDC(w.hdc)
 			w.hdc = 0
@@ -322,16 +327,10 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 		// Adjust window position to avoid the extra padding in maximized
 		// state. See https://devblogs.microsoft.com/oldnewthing/20150304-00/?p=44543.
 		// Note that trying to do the adjustment in WM_GETMINMAXINFO is ignored by Windows.
-		szp := (*windows.NCCalcSizeParams)(unsafe.Pointer(lParam))
+		szp := (*windows.NCCalcSizeParams)(unsafe.Pointer(uintptr(lParam)))
 		mi := windows.GetMonitorInfo(w.hwnd)
 		szp.Rgrc[0] = mi.WorkArea
 		return 0
-	case windows.WM_NCLBUTTONDBLCLK:
-		if !w.config.Decorated {
-			// Override Windows behaviour when we
-			// draw decorations.
-			return 0
-		}
 	case windows.WM_PAINT:
 		w.draw(true)
 	case windows.WM_SIZE:
@@ -339,15 +338,18 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 		switch wParam {
 		case windows.SIZE_MINIMIZED:
 			w.config.Mode = Minimized
+			w.setStage(system.StagePaused)
 		case windows.SIZE_MAXIMIZED:
 			w.config.Mode = Maximized
+			w.setStage(system.StageRunning)
 		case windows.SIZE_RESTORED:
 			if w.config.Mode != Fullscreen {
 				w.config.Mode = Windowed
 			}
+			w.setStage(system.StageRunning)
 		}
 	case windows.WM_GETMINMAXINFO:
-		mm := (*windows.MinMaxInfo)(unsafe.Pointer(lParam))
+		mm := (*windows.MinMaxInfo)(unsafe.Pointer(uintptr(lParam)))
 		var bw, bh int32
 		if w.config.Decorated {
 			r := windows.GetWindowRect(w.hwnd)
@@ -375,8 +377,7 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 			return windows.TRUE
 		}
 	case _WM_WAKEUP:
-		w.loop.Wakeup()
-		w.loop.FlushEvents()
+		w.w.Event(wakeupEvent{})
 	case windows.WM_IME_STARTCOMPOSITION:
 		imc := windows.ImmGetContext(w.hwnd)
 		if imc == 0 {
@@ -496,7 +497,7 @@ func (w *window) hitTest(x, y int) uintptr {
 }
 
 func (w *window) pointerButton(btn pointer.Buttons, press bool, lParam uintptr, kmods key.Modifiers) {
-	if !w.config.Focused {
+	if !w.focused {
 		windows.SetFocus(w.hwnd)
 	}
 
@@ -516,7 +517,7 @@ func (w *window) pointerButton(btn pointer.Buttons, press bool, lParam uintptr,
 	}
 	x, y := coordsFromlParam(lParam)
 	p := f32.Point{X: float32(x), Y: float32(y)}
-	w.ProcessEvent(pointer.Event{
+	w.w.Event(pointer.Event{
 		Kind:      kind,
 		Source:    pointer.Mouse,
 		Position:  p,
@@ -551,7 +552,7 @@ func (w *window) scrollEvent(wParam, lParam uintptr, horizontal bool, kmods key.
 			sp.Y = -dist
 		}
 	}
-	w.ProcessEvent(pointer.Event{
+	w.w.Event(pointer.Event{
 		Kind:      pointer.Scroll,
 		Source:    pointer.Mouse,
 		Position:  p,
@@ -563,7 +564,7 @@ func (w *window) scrollEvent(wParam, lParam uintptr, horizontal bool, kmods key.
 }
 
 // Adapted from https://blogs.msdn.microsoft.com/oldnewthing/20060126-00/?p=32513/
-func (w *window) runLoop() {
+func (w *window) loop() error {
 	msg := new(windows.Msg)
 loop:
 	for {
@@ -574,7 +575,7 @@ loop:
 		}
 		switch ret := windows.GetMessage(msg, 0, 0, 0); ret {
 		case -1:
-			panic(errors.New("GetMessage failed"))
+			return errors.New("GetMessage failed")
 		case 0:
 			// WM_QUIT received.
 			break loop
@@ -582,6 +583,7 @@ loop:
 		windows.TranslateMessage(msg)
 		windows.DispatchMessage(msg)
 	}
+	return nil
 }
 
 func (w *window) EditorStateChanged(old, new editorState) {
@@ -599,41 +601,27 @@ func (w *window) SetAnimating(anim bool) {
 	w.animating = anim
 }
 
-func (w *window) ProcessEvent(e event.Event) {
-	w.w.ProcessEvent(e)
-	w.loop.FlushEvents()
-}
-
-func (w *window) Event() event.Event {
-	return w.loop.Event()
-}
-
-func (w *window) Invalidate() {
-	w.loop.Invalidate()
-}
-
-func (w *window) Run(f func()) {
-	w.loop.Run(f)
-}
-
-func (w *window) Frame(frame *op.Ops) {
-	w.loop.Frame(frame)
-}
-
-func (w *window) wakeup() {
+func (w *window) Wakeup() {
 	if err := windows.PostMessage(w.hwnd, _WM_WAKEUP, 0, 0); err != nil {
 		panic(err)
 	}
 }
 
+func (w *window) setStage(s system.Stage) {
+	if s != w.stage {
+		w.stage = s
+		w.w.Event(system.StageEvent{Stage: s})
+	}
+}
+
 func (w *window) draw(sync bool) {
 	if w.config.Size.X == 0 || w.config.Size.Y == 0 {
 		return
 	}
 	dpi := windows.GetWindowDPI(w.hwnd)
 	cfg := configForDPI(dpi)
-	w.ProcessEvent(frameEvent{
-		FrameEvent: FrameEvent{
+	w.w.Event(frameEvent{
+		FrameEvent: system.FrameEvent{
 			Now:    time.Now(),
 			Size:   w.config.Size,
 			Metric: cfg,
@@ -679,12 +667,7 @@ func (w *window) readClipboard() error {
 	}
 	defer windows.GlobalUnlock(mem)
 	content := gowindows.UTF16PtrToString((*uint16)(unsafe.Pointer(ptr)))
-	w.ProcessEvent(transfer.DataEvent{
-		Type: "application/text",
-		Open: func() io.ReadCloser {
-			return io.NopCloser(strings.NewReader(content))
-		},
-	})
+	w.w.Event(clipboard.Event{Text: content})
 	return nil
 }
 
@@ -752,8 +735,8 @@ func (w *window) Configure(options []Option) {
 	w.update()
 }
 
-func (w *window) WriteClipboard(mime string, s []byte) {
-	w.writeClipboard(string(s))
+func (w *window) WriteClipboard(s string) {
+	w.writeClipboard(s)
 }
 
 func (w *window) writeClipboard(s string) error {
@@ -881,11 +864,11 @@ func (w *window) raise() {
 		windows.SWP_NOMOVE|windows.SWP_NOSIZE|windows.SWP_SHOWWINDOW)
 }
 
-func convertKeyCode(code uintptr) (key.Name, bool) {
+func convertKeyCode(code uintptr) (string, bool) {
 	if '0' <= code && code <= '9' || 'A' <= code && code <= 'Z' {
-		return key.Name(rune(code)), true
+		return string(rune(code)), true
 	}
-	var r key.Name
+	var r string
 
 	switch code {
 	case windows.VK_ESCAPE:
@@ -985,8 +968,4 @@ func configForDPI(dpi int) unit.Metric {
 	}
 }
 
-func (Win32ViewEvent) implementsViewEvent() {}
-func (Win32ViewEvent) ImplementsEvent()     {}
-func (w Win32ViewEvent) Valid() bool {
-	return w != (Win32ViewEvent{})
-}
+func (_ ViewEvent) ImplementsEvent() {}

app/os_x11.go

@@ -30,20 +30,16 @@ import (
 	"errors"
 	"fmt"
 	"image"
-	"io"
 	"strconv"
-	"strings"
 	"sync"
 	"time"
 	"unsafe"
 
 	"gioui.org/f32"
-	"gioui.org/io/event"
+	"gioui.org/io/clipboard"
 	"gioui.org/io/key"
 	"gioui.org/io/pointer"
 	"gioui.org/io/system"
-	"gioui.org/io/transfer"
-	"gioui.org/op"
 	"gioui.org/unit"
 
 	syscall "golang.org/x/sys/unix"
@@ -95,10 +91,12 @@ type x11Window struct {
 		// _NET_WM_STATE_MAXIMIZED_VERT
 		wmStateMaximizedVert C.Atom
 	}
+	stage  system.Stage
 	metric unit.Metric
 	notify struct {
 		read, write int
 	}
+	dead bool
 
 	animating bool
 
@@ -111,8 +109,6 @@ type x11Window struct {
 	config Config
 
 	wakeups chan struct{}
-	handler x11EventHandler
-	buf     [100]byte
 }
 
 var (
@@ -155,8 +151,8 @@ func (w *x11Window) ReadClipboard() {
 	C.XConvertSelection(w.x, w.atoms.clipboard, w.atoms.utf8string, w.atoms.clipboardContent, w.xw, C.CurrentTime)
 }
 
-func (w *x11Window) WriteClipboard(mime string, s []byte) {
-	w.clipboard.content = s
+func (w *x11Window) WriteClipboard(s string) {
+	w.clipboard.content = []byte(s)
 	C.XSetSelectionOwner(w.x, w.atoms.clipboard, w.xw, C.CurrentTime)
 	C.XSetSelectionOwner(w.x, w.atoms.primary, w.xw, C.CurrentTime)
 }
@@ -236,7 +232,7 @@ func (w *x11Window) Configure(options []Option) {
 	if cnf.Decorated != prev.Decorated {
 		w.config.Decorated = cnf.Decorated
 	}
-	w.ProcessEvent(ConfigEvent{Config: w.config})
+	w.w.Event(ConfigEvent{Config: w.config})
 }
 
 func (w *x11Window) setTitle(prev, cnf Config) {
@@ -379,36 +375,7 @@ func (w *x11Window) sendWMStateEvent(action C.long, atom1, atom2 C.ulong) {
 
 var x11OneByte = make([]byte, 1)
 
-func (w *x11Window) ProcessEvent(e event.Event) {
-	w.w.ProcessEvent(e)
-}
-
-func (w *x11Window) shutdown(err error) {
-	w.ProcessEvent(X11ViewEvent{})
-	w.ProcessEvent(DestroyEvent{Err: err})
-	w.destroy()
-}
-
-func (w *x11Window) Event() event.Event {
-	for {
-		evt, ok := w.w.nextEvent()
-		if !ok {
-			w.dispatch()
-			continue
-		}
-		return evt
-	}
-}
-
-func (w *x11Window) Run(f func()) {
-	f()
-}
-
-func (w *x11Window) Frame(frame *op.Ops) {
-	w.w.ProcessFrame(frame, nil)
-}
-
-func (w *x11Window) Invalidate() {
+func (w *x11Window) Wakeup() {
 	select {
 	case w.wakeups <- struct{}{}:
 	default:
@@ -426,20 +393,16 @@ func (w *x11Window) window() (C.Window, int, int) {
 	return w.xw, w.config.Size.X, w.config.Size.Y
 }
 
-func (w *x11Window) dispatch() {
-	if w.x == nil {
-		// Only Invalidate can wake us up.
-		<-w.wakeups
-		w.w.Invalidate()
+func (w *x11Window) setStage(s system.Stage) {
+	if s == w.stage {
 		return
 	}
+	w.stage = s
+	w.w.Event(system.StageEvent{Stage: s})
+}
 
-	select {
-	case <-w.wakeups:
-		w.w.Invalidate()
-	default:
-	}
-
+func (w *x11Window) loop() {
+	h := x11EventHandler{w: w, xev: new(C.XEvent), text: make([]byte, 4)}
 	xfd := C.XConnectionNumber(w.x)
 
 	// Poll for events and notifications.
@@ -449,54 +412,60 @@ func (w *x11Window) dispatch() {
 	}
 	xEvents := &pollfds[0].Revents
 	// Plenty of room for a backlog of notifications.
+	buf := make([]byte, 100)
 
-	var syn, anim bool
-	// Check for pending draw events before checking animation or blocking.
-	// This fixes an issue on Xephyr where on startup XPending() > 0 but
-	// poll will still block. This also prevents no-op calls to poll.
-	syn = w.handler.handleEvents()
-	if w.x == nil {
-		// handleEvents received a close request and destroyed the window.
-		return
-	}
-	if !syn {
-		anim = w.animating
-		if !anim {
-			// Clear poll events.
-			*xEvents = 0
-			// Wait for X event or gio notification.
-			if _, err := syscall.Poll(pollfds, -1); err != nil && err != syscall.EINTR {
-				panic(fmt.Errorf("x11 loop: poll failed: %w", err))
-			}
-			switch {
-			case *xEvents&syscall.POLLIN != 0:
-				syn = w.handler.handleEvents()
-				if w.x == nil {
-					return
+loop:
+	for !w.dead {
+		var syn, anim bool
+		// Check for pending draw events before checking animation or blocking.
+		// This fixes an issue on Xephyr where on startup XPending() > 0 but
+		// poll will still block. This also prevents no-op calls to poll.
+		if syn = h.handleEvents(); !syn {
+			anim = w.animating
+			if !anim {
+				// Clear poll events.
+				*xEvents = 0
+				// Wait for X event or gio notification.
+				if _, err := syscall.Poll(pollfds, -1); err != nil && err != syscall.EINTR {
+					panic(fmt.Errorf("x11 loop: poll failed: %w", err))
+				}
+				switch {
+				case *xEvents&syscall.POLLIN != 0:
+					syn = h.handleEvents()
+					if w.dead {
+						break loop
+					}
+				case *xEvents&(syscall.POLLERR|syscall.POLLHUP) != 0:
+					break loop
 				}
-			case *xEvents&(syscall.POLLERR|syscall.POLLHUP) != 0:
 			}
 		}
-	}
-	// Clear notifications.
-	for {
-		_, err := syscall.Read(w.notify.read, w.buf[:])
-		if err == syscall.EAGAIN {
-			break
+		// Clear notifications.
+		for {
+			_, err := syscall.Read(w.notify.read, buf)
+			if err == syscall.EAGAIN {
+				break
+			}
+			if err != nil {
+				panic(fmt.Errorf("x11 loop: read from notify pipe failed: %w", err))
+			}
 		}
-		if err != nil {
-			panic(fmt.Errorf("x11 loop: read from notify pipe failed: %w", err))
+		select {
+		case <-w.wakeups:
+			w.w.Event(wakeupEvent{})
+		default:
+		}
+
+		if (anim || syn) && w.config.Size.X != 0 && w.config.Size.Y != 0 {
+			w.w.Event(frameEvent{
+				FrameEvent: system.FrameEvent{
+					Now:    time.Now(),
+					Size:   w.config.Size,
+					Metric: w.metric,
+				},
+				Sync: syn,
+			})
 		}
-	}
-	if (anim || syn) && w.config.Size.X != 0 && w.config.Size.Y != 0 {
-		w.ProcessEvent(frameEvent{
-			FrameEvent: FrameEvent{
-				Now:    time.Now(),
-				Size:   w.config.Size,
-				Metric: w.metric,
-			},
-			Sync: syn,
-		})
 	}
 }
 
@@ -515,7 +484,6 @@ func (w *x11Window) destroy() {
 	}
 	C.XDestroyWindow(w.x, w.xw)
 	C.XCloseDisplay(w.x)
-	w.x = nil
 }
 
 // atom is a wrapper around XInternAtom. Callers should cache the result
@@ -573,7 +541,7 @@ func (h *x11EventHandler) handleEvents() bool {
 					// There's no support for IME yet.
 					w.w.EditorInsert(ee.Text)
 				} else {
-					w.ProcessEvent(e)
+					w.w.Event(e)
 				}
 			}
 		case C.ButtonPress, C.ButtonRelease:
@@ -635,10 +603,10 @@ func (h *x11EventHandler) handleEvents() bool {
 				w.pointerBtns &^= btn
 			}
 			ev.Buttons = w.pointerBtns
-			w.ProcessEvent(ev)
+			w.w.Event(ev)
 		case C.MotionNotify:
 			mevt := (*C.XMotionEvent)(unsafe.Pointer(xev))
-			w.ProcessEvent(pointer.Event{
+			w.w.Event(pointer.Event{
 				Kind:    pointer.Move,
 				Source:  pointer.Mouse,
 				Buttons: w.pointerBtns,
@@ -653,16 +621,14 @@ func (h *x11EventHandler) handleEvents() bool {
 			// redraw only on the last expose event
 			redraw = (*C.XExposeEvent)(unsafe.Pointer(xev)).count == 0
 		case C.FocusIn:
-			w.config.Focused = true
-			w.ProcessEvent(ConfigEvent{Config: w.config})
+			w.w.Event(key.FocusEvent{Focus: true})
 		case C.FocusOut:
-			w.config.Focused = false
-			w.ProcessEvent(ConfigEvent{Config: w.config})
+			w.w.Event(key.FocusEvent{Focus: false})
 		case C.ConfigureNotify: // window configuration change
 			cevt := (*C.XConfigureEvent)(unsafe.Pointer(xev))
 			if sz := image.Pt(int(cevt.width), int(cevt.height)); sz != w.config.Size {
 				w.config.Size = sz
-				w.ProcessEvent(ConfigEvent{Config: w.config})
+				w.w.Event(ConfigEvent{Config: w.config})
 			}
 			// redraw will be done by a later expose event
 		case C.SelectionNotify:
@@ -684,12 +650,7 @@ func (h *x11EventHandler) handleEvents() bool {
 				break
 			}
 			str := C.GoStringN((*C.char)(unsafe.Pointer(text.value)), C.int(text.nitems))
-			w.ProcessEvent(transfer.DataEvent{
-				Type: "application/text",
-				Open: func() io.ReadCloser {
-					return io.NopCloser(strings.NewReader(str))
-				},
-			})
+			w.w.Event(clipboard.Event{Text: str})
 		case C.SelectionRequest:
 			cevt := (*C.XSelectionRequestEvent)(unsafe.Pointer(xev))
 			if (cevt.selection != w.atoms.clipboard && cevt.selection != w.atoms.primary) || cevt.property == C.None {
@@ -743,7 +704,7 @@ func (h *x11EventHandler) handleEvents() bool {
 			cevt := (*C.XClientMessageEvent)(unsafe.Pointer(xev))
 			switch *(*C.long)(unsafe.Pointer(&cevt.data)) {
 			case C.long(w.atoms.evDelWindow):
-				w.shutdown(nil)
+				w.dead = true
 				return false
 			}
 		}
@@ -825,10 +786,8 @@ func newX11Window(gioWin *callbacks, options []Option) error {
 		wakeups:      make(chan struct{}, 1),
 		config:       Config{Size: cnf.Size},
 	}
-	w.handler = x11EventHandler{w: w, xev: new(C.XEvent), text: make([]byte, 4)}
 	w.notify.read = pipe[0]
 	w.notify.write = pipe[1]
-	w.w.SetDriver(w)
 
 	if err := w.updateXkbKeymap(); err != nil {
 		w.destroy()
@@ -864,10 +823,19 @@ func newX11Window(gioWin *callbacks, options []Option) error {
 	// extensions
 	C.XSetWMProtocols(dpy, win, &w.atoms.evDelWindow, 1)
 
-	// make the window visible on the screen
-	C.XMapWindow(dpy, win)
-	w.Configure(options)
-	w.ProcessEvent(X11ViewEvent{Display: unsafe.Pointer(dpy), Window: uintptr(win)})
+	go func() {
+		w.w.SetDriver(w)
+
+		// make the window visible on the screen
+		C.XMapWindow(dpy, win)
+		w.Configure(options)
+		w.w.Event(X11ViewEvent{Display: unsafe.Pointer(dpy), Window: uintptr(win)})
+		w.setStage(system.StageRunning)
+		w.loop()
+		w.w.Event(X11ViewEvent{})
+		w.w.Event(system.DestroyEvent{Err: nil})
+		w.destroy()
+	}()
 	return nil
 }
 

app/system.go

@@ -1,13 +0,0 @@
-// SPDX-License-Identifier: Unlicense OR MIT
-
-package app
-
-// DestroyEvent is the last event sent through
-// a window event channel.
-type DestroyEvent struct {
-	// Err is nil for normal window closures. If a
-	// window is prematurely closed, Err is the cause.
-	Err error
-}
-
-func (DestroyEvent) ImplementsEvent() {}

flake.lock

@@ -9,11 +9,11 @@
         ]
       },
       "locked": {
-        "lastModified": 1701721028,
-        "narHash": "sha256-2z4YrdHPLoMZNWR1MPOjNZMqPg057i1eZXaYI6RTahQ=",
+        "lastModified": 1659298920,
+        "narHash": "sha256-LgRMge8BZUG15EN43iDJOlnEMX1dvRprB7SaoNqgibU=",
         "owner": "tadfisher",
         "repo": "android-nixpkgs",
-        "rev": "c923f9ec0f4dd0d7dc725dc5b73fbf03658e50dd",
+        "rev": "d4f20a3cd4ce961bb23b48447457f6810d69ae5e",
         "type": "github"
       },
       "original": {
@@ -24,18 +24,21 @@
     },
     "devshell": {
       "inputs": {
-        "nixpkgs": [
+        "flake-utils": [
           "android",
           "nixpkgs"
         ],
-        "systems": "systems"
+        "nixpkgs": [
+          "android",
+          "nixpkgs"
+        ]
       },
       "locked": {
-        "lastModified": 1701697687,
-        "narHash": "sha256-dLLE5wQBVv+pIb4bWmKFSw2DvLVyuEk0F7ng6hpZPSU=",
+        "lastModified": 1658746384,
+        "narHash": "sha256-CCJcoMOcXyZFrV1ag4XMTpAPjLWb4Anbv+ktXFI1ry0=",
         "owner": "numtide",
         "repo": "devshell",
-        "rev": "c3bd77911391eb1638af6ce773de86da57ee6df5",
+        "rev": "0ffc7937bb5e8141af03d462b468bd071eb18e1b",
         "type": "github"
       },
       "original": {
@@ -45,15 +48,12 @@
       }
     },
     "flake-utils": {
-      "inputs": {
-        "systems": "systems_2"
-      },
       "locked": {
-        "lastModified": 1701680307,
-        "narHash": "sha256-kAuep2h5ajznlPMD9rnQyffWG8EM/C73lejGofXvdM8=",
+        "lastModified": 1656928814,
+        "narHash": "sha256-RIFfgBuKz6Hp89yRr7+NR5tzIAbn52h8vT6vXkYjZoM=",
         "owner": "numtide",
         "repo": "flake-utils",
-        "rev": "4022d587cbbfd70fe950c1e2083a02621806a725",
+        "rev": "7e2a3b3dfd9af950a856d66b0a7d01e3c18aa249",
         "type": "github"
       },
       "original": {
@@ -64,16 +64,15 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1701282334,
-        "narHash": "sha256-MxCVrXY6v4QmfTwIysjjaX0XUhqBbxTWWB4HXtDYsdk=",
+        "lastModified": 1659305579,
+        "narHash": "sha256-SFeQTmh7hc9Y2fSkooHaoS8mDfPa04sfmUCtQ8MA6Pg=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "057f9aecfb71c4437d2b27d3323df7f93c010b7e",
+        "rev": "5857574d45925585baffde730369414319228a84",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "23.11",
         "repo": "nixpkgs",
         "type": "github"
       }
@@ -83,36 +82,6 @@
         "android": "android",
         "nixpkgs": "nixpkgs"
       }
-    },
-    "systems": {
-      "locked": {
-        "lastModified": 1681028828,
-        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
-        "owner": "nix-systems",
-        "repo": "default",
-        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
-        "type": "github"
-      },
-      "original": {
-        "owner": "nix-systems",
-        "repo": "default",
-        "type": "github"
-      }
-    },
-    "systems_2": {
-      "locked": {
-        "lastModified": 1681028828,
-        "narHash": "sha256-Vy1rq5AaRuLzOxct8nz4T6wlgyUR7zLU309k9mBC768=",
-        "owner": "nix-systems",
-        "repo": "default",
-        "rev": "da67096a3b9bf56a91d16901293e51ba5b49a27e",
-        "type": "github"
-      },
-      "original": {
-        "owner": "nix-systems",
-        "repo": "default",
-        "type": "github"
-      }
     }
   },
   "root": "root",

flake.nix

@@ -3,7 +3,7 @@
   description = "Gio build environment";
 
   inputs = {
-    nixpkgs.url = "github:NixOS/nixpkgs/23.11";
+    nixpkgs.url = "github:NixOS/nixpkgs";
     android.url = "github:tadfisher/android-nixpkgs";
     android.inputs.nixpkgs.follows = "nixpkgs";
   };
@@ -33,10 +33,10 @@
             default = with pkgs; mkShell
               ({
                 ANDROID_SDK_ROOT = "${android-sdk}/share/android-sdk";
-                JAVA_HOME = jdk17.home;
+                JAVA_HOME = jdk8.home;
                 packages = [
                   android-sdk
-                  jdk17
+                  jdk8
                   clang
                 ] ++ (if stdenv.isLinux then [
                   vulkan-headers
@@ -46,7 +46,7 @@
                   xorg.libXcursor
                   xorg.libXfixes
                   libGL
-                  pkg-config
+                  pkgconfig
                 ] else if stdenv.isDarwin then [
                   darwin.apple_sdk_11_0.frameworks.Foundation
                   darwin.apple_sdk_11_0.frameworks.Metal

gesture/gesture.go

@@ -18,7 +18,6 @@ import (
 	"gioui.org/f32"
 	"gioui.org/internal/fling"
 	"gioui.org/io/event"
-	"gioui.org/io/input"
 	"gioui.org/io/key"
 	"gioui.org/io/pointer"
 	"gioui.org/op"
@@ -38,19 +37,15 @@ type Hover struct {
 
 // Add the gesture to detect hovering over the current pointer area.
 func (h *Hover) Add(ops *op.Ops) {
-	event.Op(ops, h)
+	pointer.InputOp{
+		Tag:   h,
+		Kinds: pointer.Enter | pointer.Leave,
+	}.Add(ops)
 }
 
 // Update state and report whether a pointer is inside the area.
-func (h *Hover) Update(q input.Source) bool {
-	for {
-		ev, ok := q.Event(pointer.Filter{
-			Target: h,
-			Kinds:  pointer.Enter | pointer.Leave | pointer.Cancel,
-		})
-		if !ok {
-			break
-		}
+func (h *Hover) Update(q event.Queue) bool {
+	for _, ev := range q.Events(h) {
 		e, ok := ev.(pointer.Event)
 		if !ok {
 			continue
@@ -112,6 +107,7 @@ type Drag struct {
 	pressed  bool
 	pid      pointer.ID
 	start    f32.Point
+	grab     bool
 }
 
 // Scroll detects scroll gestures and reduces them to
@@ -119,9 +115,11 @@ type Drag struct {
 // movements as well as drag and fling touch gestures.
 type Scroll struct {
 	dragging  bool
+	axis      Axis
 	estimator fling.Extrapolation
 	flinger   fling.Animation
 	pid       pointer.ID
+	grab      bool
 	last      int
 	// Leftover scroll.
 	scroll float32
@@ -163,7 +161,10 @@ const touchSlop = unit.Dp(3)
 
 // Add the handler to the operation list to receive click events.
 func (c *Click) Add(ops *op.Ops) {
-	event.Op(ops, c)
+	pointer.InputOp{
+		Tag:   c,
+		Kinds: pointer.Press | pointer.Release | pointer.Enter | pointer.Leave,
+	}.Add(ops)
 }
 
 // Hovered returns whether a pointer is inside the area.
@@ -176,16 +177,10 @@ func (c *Click) Pressed() bool {
 	return c.pressed
 }
 
-// Update state and return the next click events, if any.
-func (c *Click) Update(q input.Source) (ClickEvent, bool) {
-	for {
-		evt, ok := q.Event(pointer.Filter{
-			Target: c,
-			Kinds:  pointer.Press | pointer.Release | pointer.Enter | pointer.Leave | pointer.Cancel,
-		})
-		if !ok {
-			break
-		}
+// Update state and return the click events.
+func (c *Click) Update(q event.Queue) []ClickEvent {
+	var events []ClickEvent
+	for _, evt := range q.Events(c) {
 		e, ok := evt.(pointer.Event)
 		if !ok {
 			continue
@@ -197,15 +192,9 @@ func (c *Click) Update(q input.Source) (ClickEvent, bool) {
 			}
 			c.pressed = false
 			if !c.entered || c.hovered {
-				return ClickEvent{
-					Kind:      KindClick,
-					Position:  e.Position.Round(),
-					Source:    e.Source,
-					Modifiers: e.Modifiers,
-					NumClicks: c.clicks,
-				}, true
+				events = append(events, ClickEvent{Kind: KindClick, Position: e.Position.Round(), Source: e.Source, Modifiers: e.Modifiers, NumClicks: c.clicks})
 			} else {
-				return ClickEvent{Kind: KindCancel}, true
+				events = append(events, ClickEvent{Kind: KindCancel})
 			}
 		case pointer.Cancel:
 			wasPressed := c.pressed
@@ -213,7 +202,7 @@ func (c *Click) Update(q input.Source) (ClickEvent, bool) {
 			c.hovered = false
 			c.entered = false
 			if wasPressed {
-				return ClickEvent{Kind: KindCancel}, true
+				events = append(events, ClickEvent{Kind: KindCancel})
 			}
 		case pointer.Press:
 			if c.pressed {
@@ -235,7 +224,7 @@ func (c *Click) Update(q input.Source) (ClickEvent, bool) {
 				c.clicks = 1
 			}
 			c.clickedAt = e.Time
-			return ClickEvent{Kind: KindPress, Position: e.Position.Round(), Source: e.Source, Modifiers: e.Modifiers, NumClicks: c.clicks}, true
+			events = append(events, ClickEvent{Kind: KindPress, Position: e.Position.Round(), Source: e.Source, Modifiers: e.Modifiers, NumClicks: c.clicks})
 		case pointer.Leave:
 			if !c.pressed {
 				c.pid = e.PointerID
@@ -253,16 +242,25 @@ func (c *Click) Update(q input.Source) (ClickEvent, bool) {
 			}
 		}
 	}
-	return ClickEvent{}, false
+	return events
 }
 
 func (ClickEvent) ImplementsEvent() {}
 
 // Add the handler to the operation list to receive scroll events.
 // The bounds variable refers to the scrolling boundaries
-// as defined in [pointer.Filter].
-func (s *Scroll) Add(ops *op.Ops) {
-	event.Op(ops, s)
+// as defined in io/pointer.InputOp.
+func (s *Scroll) Add(ops *op.Ops, bounds image.Rectangle) {
+	oph := pointer.InputOp{
+		Tag:          s,
+		Grab:         s.grab,
+		Kinds:        pointer.Press | pointer.Drag | pointer.Release | pointer.Scroll,
+		ScrollBounds: bounds,
+	}
+	oph.Add(ops)
+	if s.flinger.Active() {
+		op.InvalidateOp{}.Add(ops)
+	}
 }
 
 // Stop any remaining fling movement.
@@ -271,19 +269,13 @@ func (s *Scroll) Stop() {
 }
 
 // Update state and report the scroll distance along axis.
-func (s *Scroll) Update(cfg unit.Metric, q input.Source, t time.Time, axis Axis, scrollx, scrolly pointer.ScrollRange) int {
-	total := 0
-	f := pointer.Filter{
-		Target:  s,
-		Kinds:   pointer.Press | pointer.Drag | pointer.Release | pointer.Scroll | pointer.Cancel,
-		ScrollX: scrollx,
-		ScrollY: scrolly,
+func (s *Scroll) Update(cfg unit.Metric, q event.Queue, t time.Time, axis Axis) int {
+	if s.axis != axis {
+		s.axis = axis
+		return 0
 	}
-	for {
-		evt, ok := q.Event(f)
-		if !ok {
-			break
-		}
+	total := 0
+	for _, evt := range q.Events(s) {
 		e, ok := evt.(pointer.Event)
 		if !ok {
 			continue
@@ -300,7 +292,7 @@ func (s *Scroll) Update(cfg unit.Metric, q input.Source, t time.Time, axis Axis,
 			}
 			s.Stop()
 			s.estimator = fling.Extrapolation{}
-			v := s.val(axis, e.Position)
+			v := s.val(e.Position)
 			s.last = int(math.Round(float64(v)))
 			s.estimator.Sample(e.Time, v)
 			s.dragging = true
@@ -316,8 +308,9 @@ func (s *Scroll) Update(cfg unit.Metric, q input.Source, t time.Time, axis Axis,
 			fallthrough
 		case pointer.Cancel:
 			s.dragging = false
+			s.grab = false
 		case pointer.Scroll:
-			switch axis {
+			switch s.axis {
 			case Horizontal:
 				s.scroll += e.Scroll.X
 			case Vertical:
@@ -330,14 +323,14 @@ func (s *Scroll) Update(cfg unit.Metric, q input.Source, t time.Time, axis Axis,
 			if !s.dragging || s.pid != e.PointerID {
 				continue
 			}
-			val := s.val(axis, e.Position)
+			val := s.val(e.Position)
 			s.estimator.Sample(e.Time, val)
 			v := int(math.Round(float64(val)))
 			dist := s.last - v
 			if e.Priority < pointer.Grabbed {
 				slop := cfg.Dp(touchSlop)
 				if dist := dist; dist >= slop || -slop >= dist {
-					q.Execute(pointer.GrabCmd{Tag: s, ID: e.PointerID})
+					s.grab = true
 				}
 			} else {
 				s.last = v
@@ -346,14 +339,11 @@ func (s *Scroll) Update(cfg unit.Metric, q input.Source, t time.Time, axis Axis,
 		}
 	}
 	total += s.flinger.Tick(t)
-	if s.flinger.Active() {
-		q.Execute(op.InvalidateCmd{})
-	}
 	return total
 }
 
-func (s *Scroll) val(axis Axis, p f32.Point) float32 {
-	if axis == Horizontal {
+func (s *Scroll) val(p f32.Point) float32 {
+	if s.axis == Horizontal {
 		return p.X
 	} else {
 		return p.Y
@@ -374,20 +364,18 @@ func (s *Scroll) State() ScrollState {
 
 // Add the handler to the operation list to receive drag events.
 func (d *Drag) Add(ops *op.Ops) {
-	event.Op(ops, d)
+	pointer.InputOp{
+		Tag:   d,
+		Grab:  d.grab,
+		Kinds: pointer.Press | pointer.Drag | pointer.Release,
+	}.Add(ops)
 }
 
-// Update state and return the next drag event, if any.
-func (d *Drag) Update(cfg unit.Metric, q input.Source, axis Axis) (pointer.Event, bool) {
-	for {
-		ev, ok := q.Event(pointer.Filter{
-			Target: d,
-			Kinds:  pointer.Press | pointer.Drag | pointer.Release | pointer.Cancel,
-		})
-		if !ok {
-			break
-		}
-		e, ok := ev.(pointer.Event)
+// Update state and return the drag events.
+func (d *Drag) Update(cfg unit.Metric, q event.Queue, axis Axis) []pointer.Event {
+	var events []pointer.Event
+	for _, e := range q.Events(d) {
+		e, ok := e.(pointer.Event)
 		if !ok {
 			continue
 		}
@@ -420,7 +408,7 @@ func (d *Drag) Update(cfg unit.Metric, q input.Source, axis Axis) (pointer.Event
 				diff := e.Position.Sub(d.start)
 				slop := cfg.Dp(touchSlop)
 				if diff.X*diff.X+diff.Y*diff.Y > float32(slop*slop) {
-					q.Execute(pointer.GrabCmd{Tag: d, ID: e.PointerID})
+					d.grab = true
 				}
 			}
 		case pointer.Release, pointer.Cancel:
@@ -429,12 +417,13 @@ func (d *Drag) Update(cfg unit.Metric, q input.Source, axis Axis) (pointer.Event
 				continue
 			}
 			d.dragging = false
+			d.grab = false
 		}
 
-		return e, true
+		events = append(events, e)
 	}
 
-	return pointer.Event{}, false
+	return events
 }
 
 // Dragging reports whether it is currently in use.

gesture/gesture_test.go

@@ -9,8 +9,8 @@ import (
 
 	"gioui.org/f32"
 	"gioui.org/io/event"
-	"gioui.org/io/input"
 	"gioui.org/io/pointer"
+	"gioui.org/io/router"
 	"gioui.org/op"
 	"gioui.org/op/clip"
 )
@@ -22,21 +22,20 @@ func TestHover(t *testing.T) {
 	stack := clip.Rect(rect).Push(ops)
 	h.Add(ops)
 	stack.Pop()
-	r := new(input.Router)
-	h.Update(r.Source())
+	r := new(router.Router)
 	r.Frame(ops)
 
 	r.Queue(
 		pointer.Event{Kind: pointer.Move, Position: f32.Pt(30, 30)},
 	)
-	if !h.Update(r.Source()) {
+	if !h.Update(r) {
 		t.Fatal("expected hovered")
 	}
 
 	r.Queue(
 		pointer.Event{Kind: pointer.Move, Position: f32.Pt(50, 50)},
 	)
-	if h.Update(r.Source()) {
+	if h.Update(r) {
 		t.Fatal("expected not hovered")
 	}
 }
@@ -72,21 +71,12 @@ func TestMouseClicks(t *testing.T) {
 			var ops op.Ops
 			click.Add(&ops)
 
-			var r input.Router
-			click.Update(r.Source())
+			var r router.Router
 			r.Frame(&ops)
 			r.Queue(tc.events...)
 
-			var clicks []ClickEvent
-			for {
-				ev, ok := click.Update(r.Source())
-				if !ok {
-					break
-				}
-				if ev.Kind == KindClick {
-					clicks = append(clicks, ev)
-				}
-			}
+			events := click.Update(&r)
+			clicks := filterMouseClicks(events)
 			if got, want := len(clicks), len(tc.clicks); got != want {
 				t.Fatalf("got %d mouse clicks, expected %d", got, want)
 			}
@@ -116,3 +106,13 @@ func mouseClickEvents(times ...time.Duration) []event.Event {
 	}
 	return events
 }
+
+func filterMouseClicks(events []ClickEvent) []ClickEvent {
+	var clicks []ClickEvent
+	for _, ev := range events {
+		if ev.Kind == KindClick {
+			clicks = append(clicks, ev)
+		}
+	}
+	return clicks
+}

go.mod

@@ -1,16 +1,16 @@
 module gioui.org
 
-go 1.21
+go 1.19
 
 require (
 	eliasnaur.com/font v0.0.0-20230308162249-dd43949cb42d
 	gioui.org/cpu v0.0.0-20210817075930-8d6a761490d2
 	gioui.org/shader v1.0.8
-	github.com/go-text/typesetting v0.1.1
+	github.com/go-text/typesetting v0.0.0-20230803102845-24e03d8b5372
 	golang.org/x/exp v0.0.0-20221012211006-4de253d81b95
 	golang.org/x/exp/shiny v0.0.0-20220827204233-334a2380cb91
 	golang.org/x/image v0.5.0
-	golang.org/x/sys v0.5.0
+	golang.org/x/sys v0.0.0-20220825204002-c680a09ffe64
 )
 
-require golang.org/x/text v0.9.0
+require golang.org/x/text v0.7.0

go.sum

@@ -5,10 +5,9 @@ gioui.org/cpu v0.0.0-20210817075930-8d6a761490d2 h1:AGDDxsJE1RpcXTAxPG2B4jrwVUJG
 gioui.org/cpu v0.0.0-20210817075930-8d6a761490d2/go.mod h1:A8M0Cn5o+vY5LTMlnRoK3O5kG+rH0kWfJjeKd9QpBmQ=
 gioui.org/shader v1.0.8 h1:6ks0o/A+b0ne7RzEqRZK5f4Gboz2CfG+mVliciy6+qA=
 gioui.org/shader v1.0.8/go.mod h1:mWdiME581d/kV7/iEhLmUgUK5iZ09XR5XpduXzbePVM=
-github.com/go-text/typesetting v0.1.1 h1:bGAesCuo85nXnEN5LmFMVGAGpGkCPtHrZLi//qD7EJo=
-github.com/go-text/typesetting v0.1.1/go.mod h1:d22AnmeKq/on0HNv73UFriMKc4Ez6EqZAofLhAzpSzI=
-github.com/go-text/typesetting-utils v0.0.0-20231211103740-d9332ae51f04 h1:zBx+p/W2aQYtNuyZNcTfinWvXBQwYtDfme051PR/lAY=
-github.com/go-text/typesetting-utils v0.0.0-20231211103740-d9332ae51f04/go.mod h1:DDxDdQEnB70R8owOx3LVpEFvpMK9eeH1o2r0yZhFI9o=
+github.com/go-text/typesetting v0.0.0-20230803102845-24e03d8b5372 h1:FQivqchis6bE2/9uF70M2gmmLpe82esEm2QadL0TEJo=
+github.com/go-text/typesetting v0.0.0-20230803102845-24e03d8b5372/go.mod h1:evDBbvNR/KaVFZ2ZlDSOWWXIUKq0wCOEtzLxRM8SG3k=
+github.com/go-text/typesetting-utils v0.0.0-20230616150549-2a7df14b6a22 h1:LBQTFxP2MfsyEDqSKmUBZaDuDHN1vpqDyOZjcqS7MYI=
 github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20210921155107-089bfa567519/go.mod h1:GvvjBRRGRdwPK5ydBHafDWAxML/pGHZbMvKqRZ5+Abc=
@@ -29,16 +28,15 @@ golang.org/x/sys v0.0.0-20201119102817-f84b799fce68/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20210615035016-665e8c7367d1/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220520151302-bc2c85ada10a/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.0.0-20220722155257-8c9f86f7a55f/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.5.0 h1:MUK/U/4lj1t1oPg0HfuXDN/Z1wv31ZJ/YcPiGccS4DU=
-golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.0.0-20220825204002-c680a09ffe64 h1:UiNENfZ8gDvpiWw7IpOMQ27spWmThO1RwwdQVbJahJM=
+golang.org/x/sys v0.0.0-20220825204002-c680a09ffe64/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
 golang.org/x/term v0.0.0-20210927222741-03fcf44c2211/go.mod h1:jbD1KX2456YbFQfuXm/mYQcufACuNUgVhRMnK/tPxf8=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
 golang.org/x/text v0.3.7/go.mod h1:u+2+/6zg+i71rQMx5EYifcz6MCKuco9NR6JIITiCfzQ=
+golang.org/x/text v0.7.0 h1:4BRB4x83lYWy72KwLD/qYDuTu7q9PjSagHvijDw7cLo=
 golang.org/x/text v0.7.0/go.mod h1:mrYo+phRRbMaCq/xk9113O4dZlRixOauAjOtrjsXDZ8=
-golang.org/x/text v0.9.0 h1:2sjJmO8cDvYveuX97RDLsxlyUxLl+GHoLxBiRdHllBE=
-golang.org/x/text v0.9.0/go.mod h1:e1OnstbJyHTd6l/uOt8jFFHp6TRDWZR/bV3emEE/zU8=
 golang.org/x/tools v0.0.0-20180917221912-90fa682c2a6e/go.mod h1:n7NCudcB/nEzxVGmLbDWY5pfWTLqBcC2KZ6jyYvM4mQ=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.1.12/go.mod h1:hNGJHUnrk76NpqgfD5Aqm5Crs+Hm0VOH/i9J2+nxYbc=

gpu/caches.go

@@ -8,13 +8,8 @@ import (
 	"gioui.org/internal/f32"
 )
 
-type textureCacheKey struct {
-	filter byte
-	handle any
-}
-
-type textureCache struct {
-	res map[textureCacheKey]resourceCacheValue
+type resourceCache struct {
+	res map[interface{}]resourceCacheValue
 }
 
 type resourceCacheValue struct {
@@ -42,13 +37,13 @@ type opCacheValue struct {
 	keep bool
 }
 
-func newTextureCache() *textureCache {
-	return &textureCache{
-		res: make(map[textureCacheKey]resourceCacheValue),
+func newResourceCache() *resourceCache {
+	return &resourceCache{
+		res: make(map[interface{}]resourceCacheValue),
 	}
 }
 
-func (r *textureCache) get(key textureCacheKey) (resource, bool) {
+func (r *resourceCache) get(key interface{}) (resource, bool) {
 	v, exists := r.res[key]
 	if !exists {
 		return nil, false
@@ -60,17 +55,17 @@ func (r *textureCache) get(key textureCacheKey) (resource, bool) {
 	return v.resource, exists
 }
 
-func (r *textureCache) put(key textureCacheKey, val resource) {
+func (r *resourceCache) put(key interface{}, val resource) {
 	v, exists := r.res[key]
 	if exists && v.used {
-		panic(fmt.Errorf("key exists, %v", key))
+		panic(fmt.Errorf("key exists, %p", key))
 	}
 	v.used = true
 	v.resource = val
 	r.res[key] = v
 }
 
-func (r *textureCache) frame() {
+func (r *resourceCache) frame() {
 	for k, v := range r.res {
 		if v.used {
 			v.used = false
@@ -82,7 +77,7 @@ func (r *textureCache) frame() {
 	}
 }
 
-func (r *textureCache) release() {
+func (r *resourceCache) release() {
 	for _, v := range r.res {
 		v.resource.release()
 	}

gpu/caches_test.go

@@ -0,0 +1,24 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package gpu
+
+import "testing"
+
+func BenchmarkResourceCache(b *testing.B) {
+	offset := 0
+	const N = 100
+
+	cache := newResourceCache()
+	for i := 0; i < b.N; i++ {
+		// half are the same and half updated
+		for k := 0; k < N; k++ {
+			cache.put(offset+k, nullResource{})
+		}
+		cache.frame()
+		offset += N / 2
+	}
+}
+
+type nullResource struct{}
+
+func (nullResource) release() {}

gpu/compute.go

@@ -93,6 +93,7 @@ type compute struct {
 		}
 	}
 	timers struct {
+		profile string
 		t       *timers
 		compact *timer
 		render  *timer
@@ -175,6 +176,7 @@ type materialUniforms struct {
 
 type collector struct {
 	hasher     maphash.Hash
+	profile    bool
 	reader     ops.Reader
 	states     []f32.Affine2D
 	clear      bool
@@ -595,7 +597,7 @@ func (g *compute) frame(target RenderTarget) error {
 	defer g.ctx.EndFrame()
 
 	t := &g.timers
-	if false && t.t == nil && g.ctx.Caps().Features.Has(driver.FeatureTimers) {
+	if g.collector.profile && t.t == nil && g.ctx.Caps().Features.Has(driver.FeatureTimers) {
 		t.t = newTimers(g.ctx)
 		t.compact = t.t.newTimer()
 		t.render = t.t.newTimer()
@@ -629,13 +631,13 @@ func (g *compute) frame(target RenderTarget) error {
 		return err
 	}
 	t.compact.end()
-	if false && t.t.ready() {
+	if g.collector.profile && t.t.ready() {
 		com, ren, blit := t.compact.Elapsed, t.render.Elapsed, t.blit.Elapsed
 		ft := com + ren + blit
 		q := 100 * time.Microsecond
 		ft = ft.Round(q)
 		com, ren, blit = com.Round(q), ren.Round(q), blit.Round(q)
-		// t.profile = fmt.Sprintf("ft:%7s com: %7s ren:%7s blit:%7s", ft, com, ren, blit)
+		t.profile = fmt.Sprintf("ft:%7s com: %7s ren:%7s blit:%7s", ft, com, ren, blit)
 	}
 	return nil
 }
@@ -659,6 +661,10 @@ func (g *compute) dumpAtlases() {
 	}
 }
 
+func (g *compute) Profile() string {
+	return g.timers.profile
+}
+
 func (g *compute) compactAllocs() error {
 	const (
 		maxAllocAge = 3
@@ -1650,6 +1656,7 @@ func (e *encoder) line(start, end f32.Point) {
 
 func (c *collector) reset() {
 	c.prevFrame, c.frame = c.frame, c.prevFrame
+	c.profile = false
 	c.clipStates = c.clipStates[:0]
 	c.transStack = c.transStack[:0]
 	c.frame.reset()
@@ -1729,6 +1736,8 @@ func (c *collector) collect(root *op.Ops, viewport image.Point, texOps *[]textur
 	c.addClip(&state, fview, fview, nil, ops.Key{}, 0, 0, false)
 	for encOp, ok := r.Decode(); ok; encOp, ok = r.Decode() {
 		switch ops.OpType(encOp.Data[0]) {
+		case ops.TypeProfile:
+			c.profile = true
 		case ops.TypeTransform:
 			dop, push := ops.DecodeTransform(encOp.Data)
 			if push {

gpu/gpu.go

@@ -44,10 +44,14 @@ type GPU interface {
 	Clear(color color.NRGBA)
 	// Frame draws the graphics operations from op into a viewport of target.
 	Frame(frame *op.Ops, target RenderTarget, viewport image.Point) error
+	// Profile returns the last available profiling information. Profiling
+	// information is requested when Frame sees an io/profile.Op, and the result
+	// is available through Profile at some later time.
+	Profile() string
 }
 
 type gpu struct {
-	cache *textureCache
+	cache *resourceCache
 
 	profile                                string
 	timers                                 *timers
@@ -69,6 +73,7 @@ type renderer struct {
 }
 
 type drawOps struct {
+	profile      bool
 	reader       ops.Reader
 	states       []f32.Affine2D
 	transStack   []f32.Affine2D
@@ -261,7 +266,7 @@ type texture struct {
 type blitter struct {
 	ctx                    driver.Device
 	viewport               image.Point
-	pipelines              [2][3]*pipeline
+	pipelines              [3]*pipeline
 	colUniforms            *blitColUniforms
 	texUniforms            *blitTexUniforms
 	linearGradientUniforms *blitLinearGradientUniforms
@@ -354,7 +359,7 @@ func NewWithDevice(d driver.Device) (GPU, error) {
 
 func newGPU(ctx driver.Device) (*gpu, error) {
 	g := &gpu{
-		cache: newTextureCache(),
+		cache: newResourceCache(),
 	}
 	g.drawOps.pathCache = newOpCache()
 	if err := g.init(ctx); err != nil {
@@ -394,7 +399,7 @@ func (g *gpu) collect(viewport image.Point, frameOps *op.Ops) {
 	g.renderer.pather.viewport = viewport
 	g.drawOps.reset(viewport)
 	g.drawOps.collect(frameOps, viewport)
-	if false && g.timers == nil && g.ctx.Caps().Features.Has(driver.FeatureTimers) {
+	if g.drawOps.profile && g.timers == nil && g.ctx.Caps().Features.Has(driver.FeatureTimers) {
 		g.frameStart = time.Now()
 		g.timers = newTimers(g.ctx)
 		g.stencilTimer = g.timers.newTimer()
@@ -420,9 +425,9 @@ func (g *gpu) frame(target RenderTarget) error {
 	g.stencilTimer.end()
 	g.coverTimer.begin()
 	g.renderer.uploadImages(g.cache, g.drawOps.imageOps)
-	g.renderer.prepareDrawOps(g.drawOps.imageOps)
+	g.renderer.prepareDrawOps(g.cache, g.drawOps.imageOps)
 	g.drawOps.layers = g.renderer.packLayers(g.drawOps.layers)
-	g.renderer.drawLayers(g.drawOps.layers, g.drawOps.imageOps)
+	g.renderer.drawLayers(g.cache, g.drawOps.layers, g.drawOps.imageOps)
 	d := driver.LoadDesc{
 		ClearColor: g.drawOps.clearColor,
 	}
@@ -432,14 +437,14 @@ func (g *gpu) frame(target RenderTarget) error {
 	}
 	g.ctx.BeginRenderPass(defFBO, d)
 	g.ctx.Viewport(0, 0, viewport.X, viewport.Y)
-	g.renderer.drawOps(false, image.Point{}, g.renderer.blitter.viewport, g.drawOps.imageOps)
+	g.renderer.drawOps(g.cache, false, image.Point{}, g.renderer.blitter.viewport, g.drawOps.imageOps)
 	g.coverTimer.end()
 	g.ctx.EndRenderPass()
 	g.cleanupTimer.begin()
 	g.cache.frame()
 	g.drawOps.pathCache.frame()
 	g.cleanupTimer.end()
-	if false && g.timers.ready() {
+	if g.drawOps.profile && g.timers.ready() {
 		st, covt, cleant := g.stencilTimer.Elapsed, g.coverTimer.Elapsed, g.cleanupTimer.Elapsed
 		ft := st + covt + cleant
 		q := 100 * time.Microsecond
@@ -455,8 +460,12 @@ func (g *gpu) Profile() string {
 	return g.profile
 }
 
-func (r *renderer) texHandle(cache *textureCache, data imageOpData) driver.Texture {
-	key := textureCacheKey{
+func (r *renderer) texHandle(cache *resourceCache, data imageOpData) driver.Texture {
+	type cachekey struct {
+		filter byte
+		handle any
+	}
+	key := cachekey{
 		filter: data.filter,
 		handle: data.handle,
 	}
@@ -560,24 +569,12 @@ func newBlitter(ctx driver.Device) *blitter {
 func (b *blitter) release() {
 	b.quadVerts.Release()
 	for _, p := range b.pipelines {
-		for _, p := range p {
-			p.Release()
-		}
+		p.Release()
 	}
 }
 
-func createColorPrograms(b driver.Device, vsSrc shader.Sources, fsSrc [3]shader.Sources, uniforms [3]interface{}) (pipelines [2][3]*pipeline, err error) {
-	defer func() {
-		if err != nil {
-			for _, p := range pipelines {
-				for _, p := range p {
-					if p != nil {
-						p.Release()
-					}
-				}
-			}
-		}
-	}()
+func createColorPrograms(b driver.Device, vsSrc shader.Sources, fsSrc [3]shader.Sources, uniforms [3]interface{}) ([3]*pipeline, error) {
+	var pipelines [3]*pipeline
 	blend := driver.BlendDesc{
 		Enable:    true,
 		SrcFactor: driver.BlendFactorOne,
@@ -595,76 +592,86 @@ func createColorPrograms(b driver.Device, vsSrc shader.Sources, fsSrc [3]shader.
 		return pipelines, err
 	}
 	defer vsh.Release()
-	for i, format := range []driver.TextureFormat{driver.TextureFormatOutput, driver.TextureFormatSRGBA} {
-		{
-			fsh, err := b.NewFragmentShader(fsSrc[materialTexture])
-			if err != nil {
-				return pipelines, err
-			}
-			defer fsh.Release()
-			pipe, err := b.NewPipeline(driver.PipelineDesc{
-				VertexShader:   vsh,
-				FragmentShader: fsh,
-				BlendDesc:      blend,
-				VertexLayout:   layout,
-				PixelFormat:    format,
-				Topology:       driver.TopologyTriangleStrip,
-			})
-			if err != nil {
-				return pipelines, err
-			}
-			var vertBuffer *uniformBuffer
-			if u := uniforms[materialTexture]; u != nil {
-				vertBuffer = newUniformBuffer(b, u)
-			}
-			pipelines[i][materialTexture] = &pipeline{pipe, vertBuffer}
+	{
+		fsh, err := b.NewFragmentShader(fsSrc[materialTexture])
+		if err != nil {
+			return pipelines, err
 		}
-		{
-			var vertBuffer *uniformBuffer
-			fsh, err := b.NewFragmentShader(fsSrc[materialColor])
-			if err != nil {
-				return pipelines, err
-			}
-			defer fsh.Release()
-			pipe, err := b.NewPipeline(driver.PipelineDesc{
-				VertexShader:   vsh,
-				FragmentShader: fsh,
-				BlendDesc:      blend,
-				VertexLayout:   layout,
-				PixelFormat:    format,
-				Topology:       driver.TopologyTriangleStrip,
-			})
-			if err != nil {
-				return pipelines, err
-			}
-			if u := uniforms[materialColor]; u != nil {
-				vertBuffer = newUniformBuffer(b, u)
-			}
-			pipelines[i][materialColor] = &pipeline{pipe, vertBuffer}
+		defer fsh.Release()
+		pipe, err := b.NewPipeline(driver.PipelineDesc{
+			VertexShader:   vsh,
+			FragmentShader: fsh,
+			BlendDesc:      blend,
+			VertexLayout:   layout,
+			PixelFormat:    driver.TextureFormatOutput,
+			Topology:       driver.TopologyTriangleStrip,
+		})
+		if err != nil {
+			return pipelines, err
 		}
-		{
-			var vertBuffer *uniformBuffer
-			fsh, err := b.NewFragmentShader(fsSrc[materialLinearGradient])
-			if err != nil {
-				return pipelines, err
-			}
-			defer fsh.Release()
-			pipe, err := b.NewPipeline(driver.PipelineDesc{
-				VertexShader:   vsh,
-				FragmentShader: fsh,
-				BlendDesc:      blend,
-				VertexLayout:   layout,
-				PixelFormat:    format,
-				Topology:       driver.TopologyTriangleStrip,
-			})
-			if err != nil {
-				return pipelines, err
-			}
-			if u := uniforms[materialLinearGradient]; u != nil {
-				vertBuffer = newUniformBuffer(b, u)
-			}
-			pipelines[i][materialLinearGradient] = &pipeline{pipe, vertBuffer}
+		var vertBuffer *uniformBuffer
+		if u := uniforms[materialTexture]; u != nil {
+			vertBuffer = newUniformBuffer(b, u)
 		}
+		pipelines[materialTexture] = &pipeline{pipe, vertBuffer}
+	}
+	{
+		var vertBuffer *uniformBuffer
+		fsh, err := b.NewFragmentShader(fsSrc[materialColor])
+		if err != nil {
+			pipelines[materialTexture].Release()
+			return pipelines, err
+		}
+		defer fsh.Release()
+		pipe, err := b.NewPipeline(driver.PipelineDesc{
+			VertexShader:   vsh,
+			FragmentShader: fsh,
+			BlendDesc:      blend,
+			VertexLayout:   layout,
+			PixelFormat:    driver.TextureFormatOutput,
+			Topology:       driver.TopologyTriangleStrip,
+		})
+		if err != nil {
+			pipelines[materialTexture].Release()
+			return pipelines, err
+		}
+		if u := uniforms[materialColor]; u != nil {
+			vertBuffer = newUniformBuffer(b, u)
+		}
+		pipelines[materialColor] = &pipeline{pipe, vertBuffer}
+	}
+	{
+		var vertBuffer *uniformBuffer
+		fsh, err := b.NewFragmentShader(fsSrc[materialLinearGradient])
+		if err != nil {
+			pipelines[materialTexture].Release()
+			pipelines[materialColor].Release()
+			return pipelines, err
+		}
+		defer fsh.Release()
+		pipe, err := b.NewPipeline(driver.PipelineDesc{
+			VertexShader:   vsh,
+			FragmentShader: fsh,
+			BlendDesc:      blend,
+			VertexLayout:   layout,
+			PixelFormat:    driver.TextureFormatOutput,
+			Topology:       driver.TopologyTriangleStrip,
+		})
+		if err != nil {
+			pipelines[materialTexture].Release()
+			pipelines[materialColor].Release()
+			return pipelines, err
+		}
+		if u := uniforms[materialLinearGradient]; u != nil {
+			vertBuffer = newUniformBuffer(b, u)
+		}
+		pipelines[materialLinearGradient] = &pipeline{pipe, vertBuffer}
+	}
+	if err != nil {
+		for _, p := range pipelines {
+			p.Release()
+		}
+		return pipelines, err
 	}
 	return pipelines, nil
 }
@@ -846,7 +853,7 @@ func (r *renderer) packLayers(layers []opacityLayer) []opacityLayer {
 	return layers
 }
 
-func (r *renderer) drawLayers(layers []opacityLayer, ops []imageOp) {
+func (r *renderer) drawLayers(cache *resourceCache, layers []opacityLayer, ops []imageOp) {
 	if len(r.layers.sizes) == 0 {
 		return
 	}
@@ -867,9 +874,9 @@ func (r *renderer) drawLayers(layers []opacityLayer, ops []imageOp) {
 			Min: l.place.Pos,
 			Max: l.place.Pos.Add(l.clip.Size()),
 		}
-		r.ctx.Viewport(v.Min.X, v.Min.Y, v.Dx(), v.Dy())
+		r.ctx.Viewport(v.Min.X, v.Min.Y, v.Max.X, v.Max.Y)
 		f := r.layerFBOs.fbos[fbo]
-		r.drawOps(true, l.clip.Min.Mul(-1), l.clip.Size(), ops[l.opStart:l.opEnd])
+		r.drawOps(cache, true, l.clip.Min.Mul(-1), l.clip.Size(), ops[l.opStart:l.opEnd])
 		sr := f32.FRect(v)
 		uvScale, uvOffset := texSpaceTransform(sr, f.size)
 		uvTrans := f32.Affine2D{}.Scale(f32.Point{}, uvScale).Offset(uvOffset)
@@ -892,6 +899,7 @@ func (r *renderer) drawLayers(layers []opacityLayer, ops []imageOp) {
 }
 
 func (d *drawOps) reset(viewport image.Point) {
+	d.profile = false
 	d.viewport = viewport
 	d.imageOps = d.imageOps[:0]
 	d.pathOps = d.pathOps[:0]
@@ -932,7 +940,7 @@ func (d *drawOps) newPathOp() *pathOp {
 	return &d.pathOpCache[len(d.pathOpCache)-1]
 }
 
-func (d *drawOps) addClipPath(state *drawState, aux []byte, auxKey opKey, bounds f32.Rectangle, off f32.Point) {
+func (d *drawOps) addClipPath(state *drawState, aux []byte, auxKey opKey, bounds f32.Rectangle, off f32.Point, push bool) {
 	npath := d.newPathOp()
 	*npath = pathOp{
 		parent:    state.cpath,
@@ -985,6 +993,8 @@ func (d *drawOps) collectOps(r *ops.Reader, viewport f32.Rectangle) {
 loop:
 	for encOp, ok := r.Decode(); ok; encOp, ok = r.Decode() {
 		switch ops.OpType(encOp.Data[0]) {
+		case ops.TypeProfile:
+			d.profile = true
 		case ops.TypeTransform:
 			dop, push := ops.DecodeTransform(encOp.Data)
 			if push {
@@ -1057,7 +1067,7 @@ loop:
 				quads.aux, bounds, _ = d.boundsForTransformedRect(bounds, trans)
 				quads.key = opKey{Key: encOp.Key}
 			}
-			d.addClipPath(&state, quads.aux, quads.key, bounds, off)
+			d.addClipPath(&state, quads.aux, quads.key, bounds, off, true)
 			quads = quadsOp{}
 		case ops.TypePopClip:
 			state.cpath = state.cpath.parent
@@ -1102,7 +1112,7 @@ loop:
 				// this transformed rectangle.
 				k := opKey{Key: encOp.Key}
 				k.SetTransform(t) // TODO: This call has no effect.
-				d.addClipPath(&state, clipData, k, bnd, off)
+				d.addClipPath(&state, clipData, k, bnd, off, false)
 			}
 
 			bounds := cl.Round()
@@ -1201,7 +1211,7 @@ func (d *drawState) materialFor(rect f32.Rectangle, off f32.Point, partTrans f32
 	return m
 }
 
-func (r *renderer) uploadImages(cache *textureCache, ops []imageOp) {
+func (r *renderer) uploadImages(cache *resourceCache, ops []imageOp) {
 	for i := range ops {
 		img := &ops[i]
 		m := img.material
@@ -1211,7 +1221,7 @@ func (r *renderer) uploadImages(cache *textureCache, ops []imageOp) {
 	}
 }
 
-func (r *renderer) prepareDrawOps(ops []imageOp) {
+func (r *renderer) prepareDrawOps(cache *resourceCache, ops []imageOp) {
 	for _, img := range ops {
 		m := img.material
 		switch m.material {
@@ -1232,7 +1242,7 @@ func (r *renderer) prepareDrawOps(ops []imageOp) {
 	}
 }
 
-func (r *renderer) drawOps(isFBO bool, opOff, viewport image.Point, ops []imageOp) {
+func (r *renderer) drawOps(cache *resourceCache, isFBO bool, opOff image.Point, viewport image.Point, ops []imageOp) {
 	var coverTex driver.Texture
 	for i := 0; i < len(ops); i++ {
 		img := ops[i]
@@ -1246,13 +1256,9 @@ func (r *renderer) drawOps(isFBO bool, opOff, viewport image.Point, ops []imageO
 
 		scale, off := clipSpaceTransform(drc, viewport)
 		var fbo FBO
-		fboIdx := 0
-		if isFBO {
-			fboIdx = 1
-		}
 		switch img.clipType {
 		case clipTypeNone:
-			p := r.blitter.pipelines[fboIdx][m.material]
+			p := r.blitter.pipelines[m.material]
 			r.ctx.BindPipeline(p.pipeline)
 			r.ctx.BindVertexBuffer(r.blitter.quadVerts, 0)
 			r.blitter.blit(m.material, isFBO, m.color, m.color1, m.color2, scale, off, m.opacity, m.uvTrans)
@@ -1271,7 +1277,7 @@ func (r *renderer) drawOps(isFBO bool, opOff, viewport image.Point, ops []imageO
 			Max: img.place.Pos.Add(drc.Size()),
 		}
 		coverScale, coverOff := texSpaceTransform(f32.FRect(uv), fbo.size)
-		p := r.pather.coverer.pipelines[fboIdx][m.material]
+		p := r.pather.coverer.pipelines[m.material]
 		r.ctx.BindPipeline(p.pipeline)
 		r.ctx.BindVertexBuffer(r.blitter.quadVerts, 0)
 		r.pather.cover(m.material, isFBO, m.color, m.color1, m.color2, scale, off, m.uvTrans, coverScale, coverOff)
@@ -1279,11 +1285,7 @@ func (r *renderer) drawOps(isFBO bool, opOff, viewport image.Point, ops []imageO
 }
 
 func (b *blitter) blit(mat materialType, fbo bool, col f32color.RGBA, col1, col2 f32color.RGBA, scale, off f32.Point, opacity float32, uvTrans f32.Affine2D) {
-	fboIdx := 0
-	if fbo {
-		fboIdx = 1
-	}
-	p := b.pipelines[fboIdx][mat]
+	p := b.pipelines[mat]
 	b.ctx.BindPipeline(p.pipeline)
 	var uniforms *blitUniforms
 	switch mat {

gpu/internal/rendertest/render_test.go

@@ -483,14 +483,14 @@ func TestGapsInPath(t *testing.T) {
 func TestOpacity(t *testing.T) {
 	run(t, func(ops *op.Ops) {
 		opc1 := paint.PushOpacity(ops, .3)
-		// Fill screen to exercise the glClear optimization.
+		// Fill screen to exercize the glClear optimization.
 		paint.FillShape(ops, color.NRGBA{R: 255, A: 255}, clip.Rect{Max: image.Pt(1024, 1024)}.Op())
 		opc2 := paint.PushOpacity(ops, .6)
 		paint.FillShape(ops, color.NRGBA{G: 255, A: 255}, clip.Rect{Min: image.Pt(20, 10), Max: image.Pt(64, 128)}.Op())
 		opc2.Pop()
 		opc1.Pop()
 		opc3 := paint.PushOpacity(ops, .6)
-		paint.FillShape(ops, color.NRGBA{B: 255, A: 255}, clip.Ellipse(image.Rectangle{Min: image.Pt(20+20, 10), Max: image.Pt(50+64, 128)}).Op(ops))
+		paint.FillShape(ops, color.NRGBA{G: 255, A: 255}, clip.Rect{Min: image.Pt(50+20, 10), Max: image.Pt(50+64, 128)}.Op())
 		opc3.Pop()
 	}, func(r result) {
 	})

gpu/path.go

@@ -30,7 +30,7 @@ type pather struct {
 
 type coverer struct {
 	ctx                    driver.Device
-	pipelines              [2][3]*pipeline
+	pipelines              [3]*pipeline
 	texUniforms            *coverTexUniforms
 	colUniforms            *coverColUniforms
 	linearGradientUniforms *coverLinearGradientUniforms
@@ -309,9 +309,7 @@ func (p *pather) release() {
 
 func (c *coverer) release() {
 	for _, p := range c.pipelines {
-		for _, p := range p {
-			p.Release()
-		}
+		p.Release()
 	}
 }
 
@@ -407,11 +405,7 @@ func (c *coverer) cover(mat materialType, isFBO bool, col f32color.RGBA, col1, c
 	}
 	uniforms.transform = [4]float32{scale.X, scale.Y, off.X, off.Y}
 	uniforms.uvCoverTransform = [4]float32{coverScale.X, coverScale.Y, coverOff.X, coverOff.Y}
-	fboIdx := 0
-	if isFBO {
-		fboIdx = 1
-	}
-	c.pipelines[fboIdx][mat].UploadUniforms(c.ctx)
+	c.pipelines[mat].UploadUniforms(c.ctx)
 	c.ctx.DrawArrays(0, 4)
 }
 

internal/egl/egl.go

@@ -15,9 +15,10 @@ import (
 )
 
 type Context struct {
-	disp    _EGLDisplay
-	eglCtx  *eglContext
-	eglSurf _EGLSurface
+	disp          _EGLDisplay
+	eglCtx        *eglContext
+	eglSurf       _EGLSurface
+	width, height int
 }
 
 type eglContext struct {
@@ -120,9 +121,11 @@ func (c *Context) VisualID() int {
 	return c.eglCtx.visualID
 }
 
-func (c *Context) CreateSurface(win NativeWindowType) error {
+func (c *Context) CreateSurface(win NativeWindowType, width, height int) error {
 	eglSurf, err := createSurface(c.disp, c.eglCtx, win)
 	c.eglSurf = eglSurf
+	c.width = width
+	c.height = height
 	return err
 }
 

internal/gl/gl_unix.go

@@ -665,7 +665,7 @@ func (f *Functions) load(forceES bool) error {
 	case runtime.GOOS == "android":
 		libNames = []string{"libGLESv2.so", "libGLESv3.so"}
 	default:
-		libNames = []string{"libGLESv2.so.2", "libGLESv2.so.3.0"}
+		libNames = []string{"libGLESv2.so.2"}
 	}
 	for _, lib := range libNames {
 		if h := dlopen(lib); h != nil {

internal/gl/gl_windows.go

@@ -361,9 +361,6 @@ func (c *Functions) GetProgrami(p Program, pname Enum) int {
 }
 func (c *Functions) GetProgramInfoLog(p Program) string {
 	n := c.GetProgrami(p, INFO_LOG_LENGTH)
-	if n == 0 {
-		return ""
-	}
 	buf := make([]byte, n)
 	syscall.Syscall6(_glGetProgramInfoLog.Addr(), 4, uintptr(p.V), uintptr(len(buf)), 0, uintptr(unsafe.Pointer(&buf[0])), 0, 0)
 	return string(buf)

internal/ops/ops.go

@@ -55,19 +55,28 @@ const (
 	TypePopTransform
 	TypePushOpacity
 	TypePopOpacity
+	TypeInvalidate
 	TypeImage
 	TypePaint
 	TypeColor
 	TypeLinearGradient
 	TypePass
 	TypePopPass
-	TypeInput
-	TypeKeyInputHint
+	TypePointerInput
+	TypeClipboardRead
+	TypeClipboardWrite
+	TypeSource
+	TypeTarget
+	TypeOffer
+	TypeKeyInput
+	TypeKeyFocus
+	TypeKeySoftKeyboard
 	TypeSave
 	TypeLoad
 	TypeAux
 	TypeClip
 	TypePopClip
+	TypeProfile
 	TypeCursor
 	TypePath
 	TypeStroke
@@ -76,6 +85,8 @@ const (
 	TypeSemanticClass
 	TypeSemanticSelected
 	TypeSemanticEnabled
+	TypeSnippet
+	TypeSelection
 	TypeActionInput
 )
 
@@ -137,13 +148,21 @@ const (
 	TypeLinearGradientLen   = 1 + 8*2 + 4*2
 	TypePassLen             = 1
 	TypePopPassLen          = 1
-	TypeInputLen            = 1
-	TypeKeyInputHintLen     = 1 + 1
+	TypePointerInputLen     = 1 + 1 + 1*2 + 2*4 + 2*4
+	TypeClipboardReadLen    = 1
+	TypeClipboardWriteLen   = 1
+	TypeSourceLen           = 1
+	TypeTargetLen           = 1
+	TypeOfferLen            = 1
+	TypeKeyInputLen         = 1 + 1
+	TypeKeyFocusLen         = 1 + 1
+	TypeKeySoftKeyboardLen  = 1 + 1
 	TypeSaveLen             = 1 + 4
 	TypeLoadLen             = 1 + 4
 	TypeAuxLen              = 1
 	TypeClipLen             = 1 + 4*4 + 1 + 1
 	TypePopClipLen          = 1
+	TypeProfileLen          = 1
 	TypeCursorLen           = 2
 	TypePathLen             = 8 + 1
 	TypeStrokeLen           = 1 + 4
@@ -152,6 +171,8 @@ const (
 	TypeSemanticClassLen    = 2
 	TypeSemanticSelectedLen = 2
 	TypeSemanticEnabledLen  = 2
+	TypeSnippetLen          = 1 + 4 + 4
+	TypeSelectionLen        = 1 + 2*4 + 2*4 + 4 + 4
 	TypeActionInputLen      = 1 + 1
 )
 
@@ -404,19 +425,28 @@ var opProps = [0x100]opProp{
 	TypePopTransform:     {Size: TypePopTransformLen, NumRefs: 0},
 	TypePushOpacity:      {Size: TypePushOpacityLen, NumRefs: 0},
 	TypePopOpacity:       {Size: TypePopOpacityLen, NumRefs: 0},
+	TypeInvalidate:       {Size: TypeRedrawLen, NumRefs: 0},
 	TypeImage:            {Size: TypeImageLen, NumRefs: 2},
 	TypePaint:            {Size: TypePaintLen, NumRefs: 0},
 	TypeColor:            {Size: TypeColorLen, NumRefs: 0},
 	TypeLinearGradient:   {Size: TypeLinearGradientLen, NumRefs: 0},
 	TypePass:             {Size: TypePassLen, NumRefs: 0},
 	TypePopPass:          {Size: TypePopPassLen, NumRefs: 0},
-	TypeInput:            {Size: TypeInputLen, NumRefs: 1},
-	TypeKeyInputHint:     {Size: TypeKeyInputHintLen, NumRefs: 1},
+	TypePointerInput:     {Size: TypePointerInputLen, NumRefs: 1},
+	TypeClipboardRead:    {Size: TypeClipboardReadLen, NumRefs: 1},
+	TypeClipboardWrite:   {Size: TypeClipboardWriteLen, NumRefs: 1},
+	TypeSource:           {Size: TypeSourceLen, NumRefs: 2},
+	TypeTarget:           {Size: TypeTargetLen, NumRefs: 2},
+	TypeOffer:            {Size: TypeOfferLen, NumRefs: 3},
+	TypeKeyInput:         {Size: TypeKeyInputLen, NumRefs: 2},
+	TypeKeyFocus:         {Size: TypeKeyFocusLen, NumRefs: 1},
+	TypeKeySoftKeyboard:  {Size: TypeKeySoftKeyboardLen, NumRefs: 0},
 	TypeSave:             {Size: TypeSaveLen, NumRefs: 0},
 	TypeLoad:             {Size: TypeLoadLen, NumRefs: 0},
 	TypeAux:              {Size: TypeAuxLen, NumRefs: 0},
 	TypeClip:             {Size: TypeClipLen, NumRefs: 0},
 	TypePopClip:          {Size: TypePopClipLen, NumRefs: 0},
+	TypeProfile:          {Size: TypeProfileLen, NumRefs: 1},
 	TypeCursor:           {Size: TypeCursorLen, NumRefs: 0},
 	TypePath:             {Size: TypePathLen, NumRefs: 0},
 	TypeStroke:           {Size: TypeStrokeLen, NumRefs: 0},
@@ -425,6 +455,8 @@ var opProps = [0x100]opProp{
 	TypeSemanticClass:    {Size: TypeSemanticClassLen, NumRefs: 0},
 	TypeSemanticSelected: {Size: TypeSemanticSelectedLen, NumRefs: 0},
 	TypeSemanticEnabled:  {Size: TypeSemanticEnabledLen, NumRefs: 0},
+	TypeSnippet:          {Size: TypeSnippetLen, NumRefs: 2},
+	TypeSelection:        {Size: TypeSelectionLen, NumRefs: 1},
 	TypeActionInput:      {Size: TypeActionInputLen, NumRefs: 0},
 }
 
@@ -457,6 +489,8 @@ func (t OpType) String() string {
 		return "PushOpacity"
 	case TypePopOpacity:
 		return "PopOpacity"
+	case TypeInvalidate:
+		return "Invalidate"
 	case TypeImage:
 		return "Image"
 	case TypePaint:
@@ -469,10 +503,24 @@ func (t OpType) String() string {
 		return "Pass"
 	case TypePopPass:
 		return "PopPass"
-	case TypeInput:
-		return "Input"
-	case TypeKeyInputHint:
-		return "KeyInputHint"
+	case TypePointerInput:
+		return "PointerInput"
+	case TypeClipboardRead:
+		return "ClipboardRead"
+	case TypeClipboardWrite:
+		return "ClipboardWrite"
+	case TypeSource:
+		return "Source"
+	case TypeTarget:
+		return "Target"
+	case TypeOffer:
+		return "Offer"
+	case TypeKeyInput:
+		return "KeyInput"
+	case TypeKeyFocus:
+		return "KeyFocus"
+	case TypeKeySoftKeyboard:
+		return "KeySoftKeyboard"
 	case TypeSave:
 		return "Save"
 	case TypeLoad:
@@ -483,6 +531,8 @@ func (t OpType) String() string {
 		return "Clip"
 	case TypePopClip:
 		return "PopClip"
+	case TypeProfile:
+		return "Profile"
 	case TypeCursor:
 		return "Cursor"
 	case TypePath:

internal/stroke/stroke.go

@@ -327,9 +327,6 @@ func strokePathNorm(p0, p1, p2 f32.Point, t, d float32) f32.Point {
 func rot90CW(p f32.Point) f32.Point { return f32.Pt(+p.Y, -p.X) }
 
 func normPt(p f32.Point, l float32) f32.Point {
-	if (p.X == 0 && p.Y == l) || (p.Y == 0 && p.X == l) {
-		return f32.Point{X: p.X, Y: p.Y}
-	}
 	d := math.Hypot(float64(p.X), float64(p.Y))
 	l64 := float64(l)
 	if math.Abs(d-l64) < 1e-10 {

io/clipboard/clipboard.go

@@ -3,22 +3,35 @@
 package clipboard
 
 import (
-	"io"
-
+	"gioui.org/internal/ops"
 	"gioui.org/io/event"
+	"gioui.org/op"
 )
 
-// WriteCmd copies Text to the clipboard.
-type WriteCmd struct {
-	Type string
-	Data io.ReadCloser
+// Event is generated when the clipboard content is requested.
+type Event struct {
+	Text string
 }
 
-// ReadCmd requests the text of the clipboard, delivered to
-// the handler through an [io/transfer.DataEvent].
-type ReadCmd struct {
+// ReadOp requests the text of the clipboard, delivered to
+// the current handler through an Event.
+type ReadOp struct {
 	Tag event.Tag
 }
 
-func (WriteCmd) ImplementsCommand() {}
-func (ReadCmd) ImplementsCommand()  {}
+// WriteOp copies Text to the clipboard.
+type WriteOp struct {
+	Text string
+}
+
+func (h ReadOp) Add(o *op.Ops) {
+	data := ops.Write1(&o.Internal, ops.TypeClipboardReadLen, h.Tag)
+	data[0] = byte(ops.TypeClipboardRead)
+}
+
+func (h WriteOp) Add(o *op.Ops) {
+	data := ops.Write1String(&o.Internal, ops.TypeClipboardWriteLen, h.Text)
+	data[0] = byte(ops.TypeClipboardWrite)
+}
+
+func (Event) ImplementsEvent() {}

io/event/event.go

@@ -1,12 +1,41 @@
 // SPDX-License-Identifier: Unlicense OR MIT
 
-// Package event contains types for event handling.
+/*
+Package event contains the types for event handling.
+
+The Queue interface is the protocol for receiving external events.
+
+For example:
+
+	var queue event.Queue = ...
+
+	for _, e := range queue.Events(h) {
+		switch e.(type) {
+			...
+		}
+	}
+
+In general, handlers must be declared before events become
+available. Other packages such as pointer and key provide
+the means for declaring handlers for specific event types.
+
+The following example declares a handler ready for key input:
+
+	import gioui.org/io/key
+
+	ops := new(op.Ops)
+	var h *Handler = ...
+	key.InputOp{Tag: h, Filter: ...}.Add(ops)
+*/
 package event
 
-import (
-	"gioui.org/internal/ops"
-	"gioui.org/op"
-)
+// Queue maps an event handler key to the events
+// available to the handler.
+type Queue interface {
+	// Events returns the available events for an
+	// event handler tag.
+	Events(t Tag) []Event
+}
 
 // Tag is the stable identifier for an event handler.
 // For a handler h, the tag is typically &h.
@@ -16,18 +45,3 @@ type Tag interface{}
 type Event interface {
 	ImplementsEvent()
 }
-
-// Filter represents a filter for [Event] types.
-type Filter interface {
-	ImplementsFilter()
-}
-
-// Op declares a tag for input routing at the current transformation
-// and clip area hierarchy. It panics if tag is nil.
-func Op(o *op.Ops, tag Tag) {
-	if tag == nil {
-		panic("Tag must be non-nil")
-	}
-	data := ops.Write1(&o.Internal, ops.TypeInputLen, tag)
-	data[0] = byte(ops.TypeInput)
-}

io/input/clipboard.go

@@ -1,72 +0,0 @@
-// SPDX-License-Identifier: Unlicense OR MIT
-
-package input
-
-import (
-	"io"
-
-	"gioui.org/io/clipboard"
-	"gioui.org/io/event"
-)
-
-// clipboardState contains the state for clipboard event routing.
-type clipboardState struct {
-	receivers []event.Tag
-}
-
-type clipboardQueue struct {
-	// request avoid read clipboard every frame while waiting.
-	requested bool
-	mime      string
-	text      []byte
-}
-
-// WriteClipboard returns the most recent data to be copied
-// to the clipboard, if any.
-func (q *clipboardQueue) WriteClipboard() (mime string, content []byte, ok bool) {
-	if q.text == nil {
-		return "", nil, false
-	}
-	content = q.text
-	q.text = nil
-	return q.mime, content, true
-}
-
-// ClipboardRequested reports if any new handler is waiting
-// to read the clipboard.
-func (q *clipboardQueue) ClipboardRequested(state clipboardState) bool {
-	req := len(state.receivers) > 0 && q.requested
-	q.requested = false
-	return req
-}
-
-func (q *clipboardQueue) Push(state clipboardState, e event.Event) (clipboardState, []taggedEvent) {
-	var evts []taggedEvent
-	for _, r := range state.receivers {
-		evts = append(evts, taggedEvent{tag: r, event: e})
-	}
-	state.receivers = nil
-	return state, evts
-}
-
-func (q *clipboardQueue) ProcessWriteClipboard(req clipboard.WriteCmd) {
-	defer req.Data.Close()
-	content, err := io.ReadAll(req.Data)
-	if err != nil {
-		return
-	}
-	q.mime = req.Type
-	q.text = content
-}
-
-func (q *clipboardQueue) ProcessReadClipboard(state clipboardState, tag event.Tag) clipboardState {
-	for _, k := range state.receivers {
-		if k == tag {
-			return state
-		}
-	}
-	n := len(state.receivers)
-	state.receivers = append(state.receivers[:n:n], tag)
-	q.requested = true
-	return state
-}

io/input/clipboard_test.go

@@ -1,125 +0,0 @@
-// SPDX-License-Identifier: Unlicense OR MIT
-
-package input
-
-import (
-	"io"
-	"strings"
-	"testing"
-
-	"gioui.org/io/clipboard"
-	"gioui.org/io/transfer"
-	"gioui.org/op"
-)
-
-func TestClipboardDuplicateEvent(t *testing.T) {
-	ops, r, handlers := new(op.Ops), new(Router), make([]int, 2)
-
-	// Both must receive the event once.
-	r.Source().Execute(clipboard.ReadCmd{Tag: &handlers[0]})
-	r.Source().Execute(clipboard.ReadCmd{Tag: &handlers[1]})
-
-	event := transfer.DataEvent{
-		Type: "application/text",
-		Open: func() io.ReadCloser {
-			return io.NopCloser(strings.NewReader("Test"))
-		},
-	}
-	r.Queue(event)
-	for i := range handlers {
-		f := transfer.TargetFilter{Target: &handlers[i], Type: "application/text"}
-		assertEventTypeSequence(t, events(r, -1, f), transfer.DataEvent{})
-	}
-	assertClipboardReadCmd(t, r, 0)
-
-	r.Source().Execute(clipboard.ReadCmd{Tag: &handlers[0]})
-
-	r.Frame(ops)
-	// No ClipboardEvent sent
-	assertClipboardReadCmd(t, r, 1)
-	for i := range handlers {
-		f := transfer.TargetFilter{Target: &handlers[i]}
-		assertEventTypeSequence(t, events(r, -1, f))
-	}
-}
-
-func TestQueueProcessReadClipboard(t *testing.T) {
-	ops, r, handler := new(op.Ops), new(Router), make([]int, 2)
-
-	// Request read
-	r.Source().Execute(clipboard.ReadCmd{Tag: &handler[0]})
-
-	assertClipboardReadCmd(t, r, 1)
-	ops.Reset()
-
-	for i := 0; i < 3; i++ {
-		// No ReadCmd
-		// One receiver must still wait for response
-
-		r.Frame(ops)
-		assertClipboardReadDuplicated(t, r, 1)
-	}
-
-	// Send the clipboard event
-	event := transfer.DataEvent{
-		Type: "application/text",
-		Open: func() io.ReadCloser {
-			return io.NopCloser(strings.NewReader("Text 2"))
-		},
-	}
-	r.Queue(event)
-	assertEventTypeSequence(t, events(r, -1, transfer.TargetFilter{Target: &handler[0], Type: "application/text"}), transfer.DataEvent{})
-	assertClipboardReadCmd(t, r, 0)
-}
-
-func TestQueueProcessWriteClipboard(t *testing.T) {
-	r := new(Router)
-
-	const mime = "application/text"
-	r.Source().Execute(clipboard.WriteCmd{Type: mime, Data: io.NopCloser(strings.NewReader("Write 1"))})
-
-	assertClipboardWriteCmd(t, r, mime, "Write 1")
-	assertClipboardWriteCmd(t, r, "", "")
-
-	r.Source().Execute(clipboard.WriteCmd{Type: mime, Data: io.NopCloser(strings.NewReader("Write 2"))})
-
-	assertClipboardReadCmd(t, r, 0)
-	assertClipboardWriteCmd(t, r, mime, "Write 2")
-}
-
-func assertClipboardReadCmd(t *testing.T, router *Router, expected int) {
-	t.Helper()
-	if got := len(router.state().receivers); got != expected {
-		t.Errorf("unexpected %d receivers, got %d", expected, got)
-	}
-	if router.ClipboardRequested() != (expected > 0) {
-		t.Error("missing requests")
-	}
-}
-
-func assertClipboardReadDuplicated(t *testing.T, router *Router, expected int) {
-	t.Helper()
-	if len(router.state().receivers) != expected {
-		t.Error("receivers removed")
-	}
-	if router.ClipboardRequested() != false {
-		t.Error("duplicated requests")
-	}
-}
-
-func assertClipboardWriteCmd(t *testing.T, router *Router, mimeExp, expected string) {
-	t.Helper()
-	if (router.cqueue.text != nil) != (expected != "") {
-		t.Error("text not defined")
-	}
-	mime, text, ok := router.cqueue.WriteClipboard()
-	if ok != (expected != "") {
-		t.Error("duplicated requests")
-	}
-	if string(mime) != mimeExp {
-		t.Errorf("got MIME type %s, expected %s", mime, mimeExp)
-	}
-	if string(text) != expected {
-		t.Errorf("got text %s, expected %s", text, expected)
-	}
-}

io/input/doc.go

@@ -1,15 +0,0 @@
-// SPDX-License-Identifier: Unlicense OR MIT
-
-/*
-Package input implements input routing and tracking of interface
-state for a window.
-
-The [Source] is the interface between the window and the widgets
-of a user interface and is exposed by [gioui.org/app.FrameEvent]
-received from windows.
-
-The [Router] is used by [gioui.org/app.Window] to track window state and route
-events from the platform to event handlers. It is otherwise only
-useful for using Gio with external window implementations.
-*/
-package input

io/input/key.go

@@ -1,364 +0,0 @@
-// SPDX-License-Identifier: Unlicense OR MIT
-
-package input
-
-import (
-	"image"
-	"sort"
-
-	"gioui.org/f32"
-	"gioui.org/io/event"
-	"gioui.org/io/key"
-)
-
-// EditorState represents the state of an editor needed by input handlers.
-type EditorState struct {
-	Selection struct {
-		Transform f32.Affine2D
-		key.Range
-		key.Caret
-	}
-	Snippet key.Snippet
-}
-
-type TextInputState uint8
-
-type keyQueue struct {
-	order    []event.Tag
-	dirOrder []dirFocusEntry
-	hint     key.InputHint
-}
-
-// keyState is the input state related to key events.
-type keyState struct {
-	focus   event.Tag
-	state   TextInputState
-	content EditorState
-}
-
-type keyHandler struct {
-	// visible will be true if the InputOp is present
-	// in the current frame.
-	visible bool
-	// reset tracks whether the handler has seen a
-	// focus reset.
-	reset        bool
-	hint         key.InputHint
-	orderPlusOne int
-	dirOrder     int
-	trans        f32.Affine2D
-}
-
-type keyFilter []key.Filter
-
-type dirFocusEntry struct {
-	tag    event.Tag
-	row    int
-	area   int
-	bounds image.Rectangle
-}
-
-const (
-	TextInputKeep TextInputState = iota
-	TextInputClose
-	TextInputOpen
-)
-
-func (k *keyHandler) inputHint(hint key.InputHint) {
-	k.hint = hint
-}
-
-// InputState returns the input state and returns a state
-// reset to [TextInputKeep].
-func (s keyState) InputState() (keyState, TextInputState) {
-	state := s.state
-	s.state = TextInputKeep
-	return s, state
-}
-
-// InputHint returns the input hint from the focused handler and whether it was
-// changed since the last call.
-func (q *keyQueue) InputHint(handlers map[event.Tag]*handler, state keyState) (key.InputHint, bool) {
-	focused, ok := handlers[state.focus]
-	if !ok {
-		return q.hint, false
-	}
-	old := q.hint
-	q.hint = focused.key.hint
-	return q.hint, old != q.hint
-}
-
-func (k *keyHandler) Reset() {
-	k.visible = false
-	k.orderPlusOne = 0
-	k.hint = key.HintAny
-}
-
-func (q *keyQueue) Reset() {
-	q.order = q.order[:0]
-	q.dirOrder = q.dirOrder[:0]
-}
-
-func (k *keyHandler) ResetEvent() (event.Event, bool) {
-	if k.reset {
-		return nil, false
-	}
-	k.reset = true
-	return key.FocusEvent{Focus: false}, true
-}
-
-func (q *keyQueue) Frame(handlers map[event.Tag]*handler, state keyState) keyState {
-	if state.focus != nil {
-		if h, ok := handlers[state.focus]; !ok || !h.filter.focusable || !h.key.visible {
-			// Remove focus from the handler that is no longer focusable.
-			state.focus = nil
-			state.state = TextInputClose
-		}
-	}
-	q.updateFocusLayout(handlers)
-	return state
-}
-
-// updateFocusLayout partitions input handlers handlers into rows
-// for directional focus moves.
-//
-// The approach is greedy: pick the topmost handler and create a row
-// containing it. Then, extend the handler bounds to a horizontal beam
-// and add to the row every handler whose center intersect it. Repeat
-// until no handlers remain.
-func (q *keyQueue) updateFocusLayout(handlers map[event.Tag]*handler) {
-	order := q.dirOrder
-	// Sort by ascending y position.
-	sort.SliceStable(order, func(i, j int) bool {
-		return order[i].bounds.Min.Y < order[j].bounds.Min.Y
-	})
-	row := 0
-	for len(order) > 0 {
-		h := &order[0]
-		h.row = row
-		bottom := h.bounds.Max.Y
-		end := 1
-		for ; end < len(order); end++ {
-			h := &order[end]
-			center := (h.bounds.Min.Y + h.bounds.Max.Y) / 2
-			if center > bottom {
-				break
-			}
-			h.row = row
-		}
-		// Sort row by ascending x position.
-		sort.SliceStable(order[:end], func(i, j int) bool {
-			return order[i].bounds.Min.X < order[j].bounds.Min.X
-		})
-		order = order[end:]
-		row++
-	}
-	for i, o := range q.dirOrder {
-		handlers[o.tag].key.dirOrder = i
-	}
-}
-
-// MoveFocus attempts to move the focus in the direction of dir.
-func (q *keyQueue) MoveFocus(handlers map[event.Tag]*handler, state keyState, dir key.FocusDirection) (keyState, []taggedEvent) {
-	if len(q.dirOrder) == 0 {
-		return state, nil
-	}
-	order := 0
-	if state.focus != nil {
-		order = handlers[state.focus].key.dirOrder
-	}
-	focus := q.dirOrder[order]
-	switch dir {
-	case key.FocusForward, key.FocusBackward:
-		if len(q.order) == 0 {
-			break
-		}
-		order := 0
-		if dir == key.FocusBackward {
-			order = -1
-		}
-		if state.focus != nil {
-			order = handlers[state.focus].key.orderPlusOne - 1
-			if dir == key.FocusForward {
-				order++
-			} else {
-				order--
-			}
-		}
-		order = (order + len(q.order)) % len(q.order)
-		return q.Focus(handlers, state, q.order[order])
-	case key.FocusRight, key.FocusLeft:
-		next := order
-		if state.focus != nil {
-			next = order + 1
-			if dir == key.FocusLeft {
-				next = order - 1
-			}
-		}
-		if 0 <= next && next < len(q.dirOrder) {
-			newFocus := q.dirOrder[next]
-			if newFocus.row == focus.row {
-				return q.Focus(handlers, state, newFocus.tag)
-			}
-		}
-	case key.FocusUp, key.FocusDown:
-		delta := +1
-		if dir == key.FocusUp {
-			delta = -1
-		}
-		nextRow := 0
-		if state.focus != nil {
-			nextRow = focus.row + delta
-		}
-		var closest event.Tag
-		dist := int(1e6)
-		center := (focus.bounds.Min.X + focus.bounds.Max.X) / 2
-	loop:
-		for 0 <= order && order < len(q.dirOrder) {
-			next := q.dirOrder[order]
-			switch next.row {
-			case nextRow:
-				nextCenter := (next.bounds.Min.X + next.bounds.Max.X) / 2
-				d := center - nextCenter
-				if d < 0 {
-					d = -d
-				}
-				if d > dist {
-					break loop
-				}
-				dist = d
-				closest = next.tag
-			case nextRow + delta:
-				break loop
-			}
-			order += delta
-		}
-		if closest != nil {
-			return q.Focus(handlers, state, closest)
-		}
-	}
-	return state, nil
-}
-
-func (q *keyQueue) BoundsFor(k *keyHandler) image.Rectangle {
-	order := k.dirOrder
-	return q.dirOrder[order].bounds
-}
-
-func (q *keyQueue) AreaFor(k *keyHandler) int {
-	order := k.dirOrder
-	return q.dirOrder[order].area
-}
-
-func (k *keyFilter) Matches(focus event.Tag, e key.Event, system bool) bool {
-	for _, f := range *k {
-		if keyFilterMatch(focus, f, e, system) {
-			return true
-		}
-	}
-	return false
-}
-
-func keyFilterMatch(focus event.Tag, f key.Filter, e key.Event, system bool) bool {
-	if f.Focus != nil && f.Focus != focus {
-		return false
-	}
-	if (f.Name != "" || system) && f.Name != e.Name {
-		return false
-	}
-	if e.Modifiers&f.Required != f.Required {
-		return false
-	}
-	if e.Modifiers&^(f.Required|f.Optional) != 0 {
-		return false
-	}
-	return true
-}
-
-func (q *keyQueue) Focus(handlers map[event.Tag]*handler, state keyState, focus event.Tag) (keyState, []taggedEvent) {
-	if focus == state.focus {
-		return state, nil
-	}
-	state.content = EditorState{}
-	var evts []taggedEvent
-	if state.focus != nil {
-		evts = append(evts, taggedEvent{tag: state.focus, event: key.FocusEvent{Focus: false}})
-	}
-	state.focus = focus
-	if state.focus != nil {
-		evts = append(evts, taggedEvent{tag: state.focus, event: key.FocusEvent{Focus: true}})
-	}
-	if state.focus == nil || state.state == TextInputKeep {
-		state.state = TextInputClose
-	}
-	return state, evts
-}
-
-func (s keyState) softKeyboard(show bool) keyState {
-	if show {
-		s.state = TextInputOpen
-	} else {
-		s.state = TextInputClose
-	}
-	return s
-}
-
-func (k *keyFilter) Add(f key.Filter) {
-	for _, f2 := range *k {
-		if f == f2 {
-			return
-		}
-	}
-	*k = append(*k, f)
-}
-
-func (k *keyFilter) Merge(k2 keyFilter) {
-	*k = append(*k, k2...)
-}
-
-func (q *keyQueue) inputOp(tag event.Tag, state *keyHandler, t f32.Affine2D, area int, bounds image.Rectangle) {
-	state.visible = true
-	if state.orderPlusOne == 0 {
-		state.orderPlusOne = len(q.order) + 1
-		q.order = append(q.order, tag)
-		q.dirOrder = append(q.dirOrder, dirFocusEntry{tag: tag, area: area, bounds: bounds})
-	}
-	state.trans = t
-}
-
-func (q *keyQueue) setSelection(state keyState, req key.SelectionCmd) keyState {
-	if req.Tag != state.focus {
-		return state
-	}
-	state.content.Selection.Range = req.Range
-	state.content.Selection.Caret = req.Caret
-	return state
-}
-
-func (q *keyQueue) editorState(handlers map[event.Tag]*handler, state keyState) EditorState {
-	s := state.content
-	if f := state.focus; f != nil {
-		s.Selection.Transform = handlers[f].key.trans
-	}
-	return s
-}
-
-func (q *keyQueue) setSnippet(state keyState, req key.SnippetCmd) keyState {
-	if req.Tag == state.focus {
-		state.content.Snippet = req.Snippet
-	}
-	return state
-}
-
-func (t TextInputState) String() string {
-	switch t {
-	case TextInputKeep:
-		return "Keep"
-	case TextInputClose:
-		return "Close"
-	case TextInputOpen:
-		return "Open"
-	default:
-		panic("unexpected value")
-	}
-}

io/input/key_test.go

@@ -1,332 +0,0 @@
-// SPDX-License-Identifier: Unlicense OR MIT
-
-package input
-
-import (
-	"image"
-	"testing"
-
-	"gioui.org/f32"
-	"gioui.org/io/event"
-	"gioui.org/io/key"
-	"gioui.org/io/pointer"
-	"gioui.org/op"
-	"gioui.org/op/clip"
-)
-
-func TestAllMatchKeyFilter(t *testing.T) {
-	r := new(Router)
-	r.Event(key.Filter{})
-	ke := key.Event{Name: "A"}
-	r.Queue(ke)
-	// Catch-all gets all non-system events.
-	assertEventSequence(t, events(r, -1, key.Filter{}), ke)
-
-	r = new(Router)
-	r.Event(key.Filter{Name: "A"})
-	r.Queue(SystemEvent{ke})
-	if _, handled := r.WakeupTime(); !handled {
-		t.Errorf("system event was unexpectedly ignored")
-	}
-	// Only specific filters match system events.
-	assertEventSequence(t, events(r, -1, key.Filter{Name: "A"}), ke)
-}
-
-func TestInputHint(t *testing.T) {
-	r := new(Router)
-	if hint, changed := r.TextInputHint(); hint != key.HintAny || changed {
-		t.Fatal("unexpected hint")
-	}
-	ops := new(op.Ops)
-	h := new(int)
-	key.InputHintOp{Tag: h, Hint: key.HintEmail}.Add(ops)
-	r.Frame(ops)
-	if hint, changed := r.TextInputHint(); hint != key.HintAny || changed {
-		t.Fatal("unexpected hint")
-	}
-	r.Source().Execute(key.FocusCmd{Tag: h})
-	if hint, changed := r.TextInputHint(); hint != key.HintEmail || !changed {
-		t.Fatal("unexpected hint")
-	}
-}
-
-func TestDeferred(t *testing.T) {
-	r := new(Router)
-	h := new(int)
-	f := []event.Filter{
-		key.FocusFilter{Target: h},
-		key.Filter{Name: "A"},
-	}
-	// Provoke deferring by exhausting events for h.
-	events(r, -1, f...)
-	r.Source().Execute(key.FocusCmd{Tag: h})
-	ke := key.Event{Name: "A"}
-	r.Queue(ke)
-	// All events are deferred at this point.
-	assertEventSequence(t, events(r, -1, f...))
-	r.Frame(new(op.Ops))
-	// But delivered after a frame.
-	assertEventSequence(t, events(r, -1, f...), key.FocusEvent{Focus: true}, ke)
-}
-
-func TestInputWakeup(t *testing.T) {
-	handler := new(int)
-	var ops op.Ops
-	// InputOps shouldn't trigger redraws.
-	event.Op(&ops, handler)
-
-	var r Router
-	// Reset events shouldn't either.
-	evts := events(&r, -1, key.FocusFilter{Target: new(int)}, key.Filter{Name: "A"})
-	assertEventSequence(t, evts, key.FocusEvent{Focus: false})
-	r.Frame(&ops)
-	if _, wake := r.WakeupTime(); wake {
-		t.Errorf("InputOp or the resetting FocusEvent triggered a wakeup")
-	}
-	// And neither does events that don't match anything.
-	r.Queue(key.SnippetEvent{})
-	if _, handled := r.WakeupTime(); handled {
-		t.Errorf("a not-matching event triggered a wakeup")
-	}
-	// However, events that does match should trigger wakeup.
-	r.Queue(key.Event{Name: "A"})
-	if _, handled := r.WakeupTime(); !handled {
-		t.Errorf("a key.Event didn't trigger redraw")
-	}
-}
-
-func TestKeyMultiples(t *testing.T) {
-	handlers := make([]int, 3)
-	r := new(Router)
-	r.Source().Execute(key.SoftKeyboardCmd{Show: true})
-	for i := range handlers {
-		assertEventSequence(t, events(r, 1, key.FocusFilter{Target: &handlers[i]}), key.FocusEvent{Focus: false})
-	}
-	r.Source().Execute(key.FocusCmd{Tag: &handlers[2]})
-	assertEventSequence(t, events(r, -1, key.FocusFilter{Target: &handlers[2]}), key.FocusEvent{Focus: true})
-	assertFocus(t, r, &handlers[2])
-
-	assertKeyboard(t, r, TextInputOpen)
-}
-
-func TestKeySoftKeyboardNoFocus(t *testing.T) {
-	r := new(Router)
-
-	// It's possible to open the keyboard
-	// without any active focus:
-	r.Source().Execute(key.SoftKeyboardCmd{Show: true})
-
-	assertFocus(t, r, nil)
-	assertKeyboard(t, r, TextInputOpen)
-}
-
-func TestKeyRemoveFocus(t *testing.T) {
-	handlers := make([]int, 2)
-	r := new(Router)
-
-	filters := func(h event.Tag) []event.Filter {
-		return []event.Filter{
-			key.FocusFilter{Target: h},
-			key.Filter{Focus: h, Name: key.NameTab, Required: key.ModShortcut},
-		}
-	}
-	var all []event.Filter
-	for i := range handlers {
-		all = append(all, filters(&handlers[i])...)
-	}
-	assertEventSequence(t, events(r, len(handlers), all...), key.FocusEvent{}, key.FocusEvent{})
-	r.Source().Execute(key.FocusCmd{Tag: &handlers[0]})
-	r.Source().Execute(key.SoftKeyboardCmd{Show: true})
-
-	evt := key.Event{Name: key.NameTab, Modifiers: key.ModShortcut, State: key.Press}
-	r.Queue(evt)
-
-	assertEventSequence(t, events(r, 2, filters(&handlers[0])...), key.FocusEvent{Focus: true}, evt)
-	assertFocus(t, r, &handlers[0])
-	assertKeyboard(t, r, TextInputOpen)
-
-	// Frame removes focus from tags that don't filter for focus events nor mentioned in an InputOp.
-	r.Source().Execute(key.FocusCmd{Tag: new(int)})
-	r.Frame(new(op.Ops))
-
-	assertEventSequence(t, events(r, -1, filters(&handlers[1])...))
-	assertFocus(t, r, nil)
-	assertKeyboard(t, r, TextInputClose)
-
-	// Set focus to InputOp which already
-	// exists in the previous frame:
-	r.Source().Execute(key.FocusCmd{Tag: &handlers[0]})
-	assertFocus(t, r, &handlers[0])
-}
-
-func TestKeyFocusedInvisible(t *testing.T) {
-	handlers := make([]int, 2)
-	ops := new(op.Ops)
-	r := new(Router)
-
-	for i := range handlers {
-		assertEventSequence(t, events(r, 1, key.FocusFilter{Target: &handlers[i]}), key.FocusEvent{Focus: false})
-	}
-
-	// Set new InputOp with focus:
-	r.Source().Execute(key.FocusCmd{Tag: &handlers[0]})
-	r.Source().Execute(key.SoftKeyboardCmd{Show: true})
-
-	assertEventSequence(t, events(r, 1, key.FocusFilter{Target: &handlers[0]}), key.FocusEvent{Focus: true})
-	assertFocus(t, r, &handlers[0])
-	assertKeyboard(t, r, TextInputOpen)
-
-	// Frame will clear the focus because the handler is not visible.
-	r.Frame(ops)
-
-	for i := range handlers {
-		assertEventSequence(t, events(r, -1, key.FocusFilter{Target: &handlers[i]}))
-	}
-	assertFocus(t, r, nil)
-	assertKeyboard(t, r, TextInputClose)
-
-	r.Frame(ops)
-	r.Frame(ops)
-
-	ops.Reset()
-
-	// Respawn the first element:
-	// It must receive one `Event{Focus: false}`.
-	event.Op(ops, &handlers[0])
-
-	assertEventSequence(t, events(r, -1, key.FocusFilter{Target: &handlers[0]}), key.FocusEvent{Focus: false})
-}
-
-func TestNoOps(t *testing.T) {
-	r := new(Router)
-	r.Frame(nil)
-}
-
-func TestDirectionalFocus(t *testing.T) {
-	ops := new(op.Ops)
-	r := new(Router)
-	handlers := []image.Rectangle{
-		image.Rect(10, 10, 50, 50),
-		image.Rect(50, 20, 100, 80),
-		image.Rect(20, 26, 60, 80),
-		image.Rect(10, 60, 50, 100),
-	}
-
-	for i, bounds := range handlers {
-		cl := clip.Rect(bounds).Push(ops)
-		event.Op(ops, &handlers[i])
-		cl.Pop()
-		events(r, -1, key.FocusFilter{Target: &handlers[i]})
-	}
-	r.Frame(ops)
-
-	r.MoveFocus(key.FocusLeft)
-	assertFocus(t, r, &handlers[0])
-	r.MoveFocus(key.FocusLeft)
-	assertFocus(t, r, &handlers[0])
-	r.MoveFocus(key.FocusRight)
-	assertFocus(t, r, &handlers[1])
-	r.MoveFocus(key.FocusRight)
-	assertFocus(t, r, &handlers[1])
-	r.MoveFocus(key.FocusDown)
-	assertFocus(t, r, &handlers[2])
-	r.MoveFocus(key.FocusDown)
-	assertFocus(t, r, &handlers[2])
-	r.MoveFocus(key.FocusLeft)
-	assertFocus(t, r, &handlers[3])
-	r.MoveFocus(key.FocusUp)
-	assertFocus(t, r, &handlers[0])
-
-	r.MoveFocus(key.FocusForward)
-	assertFocus(t, r, &handlers[1])
-	r.MoveFocus(key.FocusBackward)
-	assertFocus(t, r, &handlers[0])
-}
-
-func TestFocusScroll(t *testing.T) {
-	ops := new(op.Ops)
-	r := new(Router)
-	h := new(int)
-
-	filters := []event.Filter{
-		key.FocusFilter{Target: h},
-		pointer.Filter{
-			Target:  h,
-			Kinds:   pointer.Scroll,
-			ScrollX: pointer.ScrollRange{Min: -100, Max: +100},
-			ScrollY: pointer.ScrollRange{Min: -100, Max: +100},
-		},
-	}
-	events(r, -1, filters...)
-	parent := clip.Rect(image.Rect(1, 1, 14, 39)).Push(ops)
-	cl := clip.Rect(image.Rect(10, -20, 20, 30)).Push(ops)
-	event.Op(ops, h)
-	// Test that h is scrolled even if behind another handler.
-	event.Op(ops, new(int))
-	cl.Pop()
-	parent.Pop()
-	r.Frame(ops)
-
-	r.MoveFocus(key.FocusLeft)
-	r.RevealFocus(image.Rect(0, 0, 15, 40))
-	evts := events(r, -1, filters...)
-	assertScrollEvent(t, evts[len(evts)-1], f32.Pt(6, -9))
-}
-
-func TestFocusClick(t *testing.T) {
-	ops := new(op.Ops)
-	r := new(Router)
-	h := new(int)
-
-	filters := []event.Filter{
-		key.FocusFilter{Target: h},
-		pointer.Filter{
-			Target: h,
-			Kinds:  pointer.Press | pointer.Release | pointer.Cancel,
-		},
-	}
-	assertEventPointerTypeSequence(t, events(r, -1, filters...), pointer.Cancel)
-	cl := clip.Rect(image.Rect(0, 0, 10, 10)).Push(ops)
-	event.Op(ops, h)
-	cl.Pop()
-	r.Frame(ops)
-
-	r.MoveFocus(key.FocusLeft)
-	r.ClickFocus()
-
-	assertEventPointerTypeSequence(t, events(r, -1, filters...), pointer.Press, pointer.Release)
-}
-
-func TestNoFocus(t *testing.T) {
-	r := new(Router)
-	r.MoveFocus(key.FocusForward)
-}
-
-func TestKeyRouting(t *testing.T) {
-	r := new(Router)
-	h := new(int)
-	A, B := key.Event{Name: "A"}, key.Event{Name: "B"}
-	// Register filters.
-	events(r, -1, key.Filter{Name: "A"}, key.Filter{Name: "B"})
-	r.Frame(new(op.Ops))
-	r.Queue(A, B)
-	// The handler is not focused, so only B is delivered.
-	assertEventSequence(t, events(r, -1, key.Filter{Focus: h, Name: "A"}, key.Filter{Name: "B"}), B)
-	r.Source().Execute(key.FocusCmd{Tag: h})
-	// A is delivered to the focused handler.
-	assertEventSequence(t, events(r, -1, key.Filter{Focus: h, Name: "A"}, key.Filter{Name: "B"}), A)
-}
-
-func assertFocus(t *testing.T, router *Router, expected event.Tag) {
-	t.Helper()
-	if !router.Source().Focused(expected) {
-		t.Errorf("expected %v to be focused", expected)
-	}
-}
-
-func assertKeyboard(t *testing.T, router *Router, expected TextInputState) {
-	t.Helper()
-	if got := router.state().state; got != expected {
-		t.Errorf("expected %v keyboard, got %v", expected, got)
-	}
-}

io/input/router.go

@@ -1,881 +0,0 @@
-// SPDX-License-Identifier: Unlicense OR MIT
-
-package input
-
-import (
-	"image"
-	"io"
-	"strings"
-	"time"
-
-	"gioui.org/f32"
-	f32internal "gioui.org/internal/f32"
-	"gioui.org/internal/ops"
-	"gioui.org/io/clipboard"
-	"gioui.org/io/event"
-	"gioui.org/io/key"
-	"gioui.org/io/pointer"
-	"gioui.org/io/semantic"
-	"gioui.org/io/system"
-	"gioui.org/io/transfer"
-	"gioui.org/op"
-)
-
-// Router tracks the [io/event.Tag] identifiers of user interface widgets
-// and routes events to them. [Source] is its interface exposed to widgets.
-type Router struct {
-	savedTrans []f32.Affine2D
-	transStack []f32.Affine2D
-	handlers   map[event.Tag]*handler
-	pointer    struct {
-		queue     pointerQueue
-		collector pointerCollector
-	}
-	key struct {
-		queue keyQueue
-		// The following fields have the same purpose as the fields in
-		// type handler, but for key.Events.
-		filter        keyFilter
-		nextFilter    keyFilter
-		scratchFilter keyFilter
-	}
-	cqueue clipboardQueue
-	// states is the list of pending state changes resulting from
-	// incoming events. The first element, if present, contains the state
-	// and events for the current frame.
-	changes []stateChange
-	reader  ops.Reader
-	// InvalidateCmd summary.
-	wakeup     bool
-	wakeupTime time.Time
-	// Changes queued for next call to Frame.
-	commands []Command
-	// transfers is the pending transfer.DataEvent.Open functions.
-	transfers []io.ReadCloser
-	// deferring is set if command execution and event delivery is deferred
-	// to the next frame.
-	deferring bool
-	// scratchFilters is for garbage-free construction of ephemeral filters.
-	scratchFilters []taggedFilter
-}
-
-// Source implements the interface between a Router and user interface widgets.
-// The value Source is disabled.
-type Source struct {
-	r *Router
-}
-
-// Command represents a request such as moving the focus, or initiating a clipboard read.
-// Commands are queued by calling [Source.Queue].
-type Command interface {
-	ImplementsCommand()
-}
-
-// SemanticNode represents a node in the tree describing the components
-// contained in a frame.
-type SemanticNode struct {
-	ID       SemanticID
-	ParentID SemanticID
-	Children []SemanticNode
-	Desc     SemanticDesc
-
-	areaIdx int
-}
-
-// SemanticDesc provides a semantic description of a UI component.
-type SemanticDesc struct {
-	Class       semantic.ClassOp
-	Description string
-	Label       string
-	Selected    bool
-	Disabled    bool
-	Gestures    SemanticGestures
-	Bounds      image.Rectangle
-}
-
-// SemanticGestures is a bit-set of supported gestures.
-type SemanticGestures int
-
-const (
-	ClickGesture SemanticGestures = 1 << iota
-	ScrollGesture
-)
-
-// SemanticID uniquely identifies a SemanticDescription.
-//
-// By convention, the zero value denotes the non-existent ID.
-type SemanticID uint
-
-// SystemEvent is a marker for events that have platform specific
-// side-effects. SystemEvents are never matched by catch-all filters.
-type SystemEvent struct {
-	Event event.Event
-}
-
-// handler contains the per-handler state tracked by a [Router].
-type handler struct {
-	// active tracks whether the handler was active in the current
-	// frame. Router deletes state belonging to inactive handlers during Frame.
-	active  bool
-	pointer pointerHandler
-	key     keyHandler
-	// filter the handler has asked for through event handling
-	// in the previous frame. It is used for routing events in the
-	// current frame.
-	filter filter
-	// prevFilter is the filter being built in the current frame.
-	nextFilter filter
-	// processedFilter is the filters that have exhausted available events.
-	processedFilter filter
-}
-
-// filter is the union of a set of [io/event.Filters].
-type filter struct {
-	pointer   pointerFilter
-	focusable bool
-}
-
-// taggedFilter is a filter for a particular tag.
-type taggedFilter struct {
-	tag    event.Tag
-	filter filter
-}
-
-// stateChange represents the new state and outgoing events
-// resulting from an incoming event.
-type stateChange struct {
-	// event, if set, is the trigger for the change.
-	event  event.Event
-	state  inputState
-	events []taggedEvent
-}
-
-// inputState represent a immutable snapshot of the state required
-// to route events.
-type inputState struct {
-	clipboardState
-	keyState
-	pointerState
-}
-
-// taggedEvent represents an event and its target handler.
-type taggedEvent struct {
-	event event.Event
-	tag   event.Tag
-}
-
-// Source returns a Source backed by this Router.
-func (q *Router) Source() Source {
-	return Source{r: q}
-}
-
-// Execute a command.
-func (s Source) Execute(c Command) {
-	if !s.Enabled() {
-		return
-	}
-	s.r.execute(c)
-}
-
-// Enabled reports whether the source is enabled. Only enabled
-// Sources deliver events and respond to commands.
-func (s Source) Enabled() bool {
-	return s.r != nil
-}
-
-// Focused reports whether tag is focused, according to the most recent
-// [key.FocusEvent] delivered.
-func (s Source) Focused(tag event.Tag) bool {
-	if !s.Enabled() {
-		return false
-	}
-	return s.r.state().keyState.focus == tag
-}
-
-// Event returns the next event that matches at least one of filters.
-func (s Source) Event(filters ...event.Filter) (event.Event, bool) {
-	if !s.Enabled() {
-		return nil, false
-	}
-	return s.r.Event(filters...)
-}
-
-func (q *Router) Event(filters ...event.Filter) (event.Event, bool) {
-	// Merge filters into scratch filters.
-	q.scratchFilters = q.scratchFilters[:0]
-	q.key.scratchFilter = q.key.scratchFilter[:0]
-	for _, f := range filters {
-		var t event.Tag
-		switch f := f.(type) {
-		case key.Filter:
-			q.key.scratchFilter = append(q.key.scratchFilter, f)
-			continue
-		case transfer.SourceFilter:
-			t = f.Target
-		case transfer.TargetFilter:
-			t = f.Target
-		case key.FocusFilter:
-			t = f.Target
-		case pointer.Filter:
-			t = f.Target
-		}
-		if t == nil {
-			continue
-		}
-		var filter *filter
-		for i := range q.scratchFilters {
-			s := &q.scratchFilters[i]
-			if s.tag == t {
-				filter = &s.filter
-				break
-			}
-		}
-		if filter == nil {
-			n := len(q.scratchFilters)
-			if n < cap(q.scratchFilters) {
-				// Re-use previously allocated filter.
-				q.scratchFilters = q.scratchFilters[:n+1]
-				tf := &q.scratchFilters[n]
-				tf.tag = t
-				filter = &tf.filter
-				filter.Reset()
-			} else {
-				q.scratchFilters = append(q.scratchFilters, taggedFilter{tag: t})
-				filter = &q.scratchFilters[n].filter
-			}
-		}
-		filter.Add(f)
-	}
-	for _, tf := range q.scratchFilters {
-		h := q.stateFor(tf.tag)
-		h.filter.Merge(tf.filter)
-		h.nextFilter.Merge(tf.filter)
-	}
-	q.key.filter = append(q.key.filter, q.key.scratchFilter...)
-	q.key.nextFilter = append(q.key.nextFilter, q.key.scratchFilter...)
-	// Deliver reset event, if any.
-	for _, f := range filters {
-		switch f := f.(type) {
-		case key.FocusFilter:
-			if f.Target == nil {
-				break
-			}
-			h := q.stateFor(f.Target)
-			if reset, ok := h.key.ResetEvent(); ok {
-				return reset, true
-			}
-		case pointer.Filter:
-			if f.Target == nil {
-				break
-			}
-			h := q.stateFor(f.Target)
-			if reset, ok := h.pointer.ResetEvent(); ok && h.filter.pointer.Matches(reset) {
-				return reset, true
-			}
-		}
-	}
-	for i := range q.changes {
-		if q.deferring && i > 0 {
-			break
-		}
-		change := &q.changes[i]
-		for j, evt := range change.events {
-			match := false
-			switch e := evt.event.(type) {
-			case key.Event:
-				match = q.key.scratchFilter.Matches(change.state.keyState.focus, e, false)
-			default:
-				for _, tf := range q.scratchFilters {
-					if evt.tag == tf.tag && tf.filter.Matches(evt.event) {
-						match = true
-						break
-					}
-				}
-			}
-			if match {
-				change.events = append(change.events[:j], change.events[j+1:]...)
-				// Fast forward state to last matched.
-				q.collapseState(i)
-				return evt.event, true
-			}
-		}
-	}
-	for _, tf := range q.scratchFilters {
-		h := q.stateFor(tf.tag)
-		h.processedFilter.Merge(tf.filter)
-	}
-	return nil, false
-}
-
-// collapseState in the interval [1;idx] into q.changes[0].
-func (q *Router) collapseState(idx int) {
-	if idx == 0 {
-		return
-	}
-	first := &q.changes[0]
-	first.state = q.changes[idx].state
-	for _, ch := range q.changes[1 : idx+1] {
-		first.events = append(first.events, ch.events...)
-	}
-	q.changes = append(q.changes[:1], q.changes[idx+1:]...)
-}
-
-// Frame completes the current frame and starts a new with the
-// handlers from the frame argument. Remaining events are discarded,
-// unless they were deferred by a command.
-func (q *Router) Frame(frame *op.Ops) {
-	var remaining []event.Event
-	if n := len(q.changes); n > 0 {
-		if q.deferring {
-			// Collect events for replay.
-			for _, ch := range q.changes[1:] {
-				remaining = append(remaining, ch.event)
-			}
-			q.changes = append(q.changes[:0], stateChange{state: q.changes[0].state})
-		} else {
-			// Collapse state.
-			state := q.changes[n-1].state
-			q.changes = append(q.changes[:0], stateChange{state: state})
-		}
-	}
-	for _, rc := range q.transfers {
-		if rc != nil {
-			rc.Close()
-		}
-	}
-	q.transfers = nil
-	q.deferring = false
-	for _, h := range q.handlers {
-		h.filter, h.nextFilter = h.nextFilter, h.filter
-		h.nextFilter.Reset()
-		h.processedFilter.Reset()
-		h.pointer.Reset()
-		h.key.Reset()
-	}
-	q.key.filter, q.key.nextFilter = q.key.nextFilter, q.key.filter
-	q.key.nextFilter = q.key.nextFilter[:0]
-	var ops *ops.Ops
-	if frame != nil {
-		ops = &frame.Internal
-	}
-	q.reader.Reset(ops)
-	q.collect()
-	for k, h := range q.handlers {
-		if !h.active {
-			delete(q.handlers, k)
-		} else {
-			h.active = false
-		}
-	}
-	q.executeCommands()
-	q.Queue(remaining...)
-	st := q.lastState()
-	pst, evts := q.pointer.queue.Frame(q.handlers, st.pointerState)
-	st.pointerState = pst
-	st.keyState = q.key.queue.Frame(q.handlers, q.lastState().keyState)
-	q.changeState(nil, st, evts)
-
-	// Collapse state and events.
-	q.collapseState(len(q.changes) - 1)
-}
-
-// Queue events to be routed.
-func (q *Router) Queue(events ...event.Event) {
-	for _, e := range events {
-		se, system := e.(SystemEvent)
-		if system {
-			e = se.Event
-		}
-		q.processEvent(e, system)
-	}
-}
-
-func (f *filter) Add(flt event.Filter) {
-	switch flt := flt.(type) {
-	case key.FocusFilter:
-		f.focusable = true
-	case pointer.Filter:
-		f.pointer.Add(flt)
-	case transfer.SourceFilter, transfer.TargetFilter:
-		f.pointer.Add(flt)
-	}
-}
-
-// Merge f2 into f.
-func (f *filter) Merge(f2 filter) {
-	f.focusable = f.focusable || f2.focusable
-	f.pointer.Merge(f2.pointer)
-}
-
-func (f *filter) Matches(e event.Event) bool {
-	switch e.(type) {
-	case key.FocusEvent, key.SnippetEvent, key.EditEvent, key.SelectionEvent:
-		return f.focusable
-	default:
-		return f.pointer.Matches(e)
-	}
-}
-
-func (f *filter) Reset() {
-	*f = filter{
-		pointer: pointerFilter{
-			sourceMimes: f.pointer.sourceMimes[:0],
-			targetMimes: f.pointer.targetMimes[:0],
-		},
-	}
-}
-
-func (q *Router) processEvent(e event.Event, system bool) {
-	state := q.lastState()
-	switch e := e.(type) {
-	case pointer.Event:
-		pstate, evts := q.pointer.queue.Push(q.handlers, state.pointerState, e)
-		state.pointerState = pstate
-		q.changeState(e, state, evts)
-	case key.Event:
-		var evts []taggedEvent
-		if q.key.filter.Matches(state.keyState.focus, e, system) {
-			evts = append(evts, taggedEvent{event: e})
-		}
-		q.changeState(e, state, evts)
-	case key.SnippetEvent:
-		// Expand existing, overlapping snippet.
-		if r := state.content.Snippet.Range; rangeOverlaps(r, key.Range(e)) {
-			if e.Start > r.Start {
-				e.Start = r.Start
-			}
-			if e.End < r.End {
-				e.End = r.End
-			}
-		}
-		var evts []taggedEvent
-		if f := state.focus; f != nil {
-			evts = append(evts, taggedEvent{tag: f, event: e})
-		}
-		q.changeState(e, state, evts)
-	case key.EditEvent, key.FocusEvent, key.SelectionEvent:
-		var evts []taggedEvent
-		if f := state.focus; f != nil {
-			evts = append(evts, taggedEvent{tag: f, event: e})
-		}
-		q.changeState(e, state, evts)
-	case transfer.DataEvent:
-		cstate, evts := q.cqueue.Push(state.clipboardState, e)
-		state.clipboardState = cstate
-		q.changeState(e, state, evts)
-	default:
-		panic("unknown event type")
-	}
-}
-
-func (q *Router) execute(c Command) {
-	// The command can be executed immediately if event delivery is not frozen, and
-	// no event receiver has completed their event handling.
-	if !q.deferring {
-		ch := q.executeCommand(c)
-		immediate := true
-		for _, e := range ch.events {
-			h, ok := q.handlers[e.tag]
-			immediate = immediate && (!ok || !h.processedFilter.Matches(e.event))
-		}
-		if immediate {
-			// Hold on to the remaining events for state replay.
-			var evts []event.Event
-			for _, ch := range q.changes {
-				if ch.event != nil {
-					evts = append(evts, ch.event)
-				}
-			}
-			if len(q.changes) > 1 {
-				q.changes = q.changes[:1]
-			}
-			q.changeState(nil, ch.state, ch.events)
-			q.Queue(evts...)
-			return
-		}
-	}
-	q.deferring = true
-	q.commands = append(q.commands, c)
-}
-
-func (q *Router) state() inputState {
-	if len(q.changes) > 0 {
-		return q.changes[0].state
-	}
-	return inputState{}
-}
-
-func (q *Router) lastState() inputState {
-	if n := len(q.changes); n > 0 {
-		return q.changes[n-1].state
-	}
-	return inputState{}
-}
-
-func (q *Router) executeCommands() {
-	for _, c := range q.commands {
-		ch := q.executeCommand(c)
-		q.changeState(nil, ch.state, ch.events)
-	}
-	q.commands = nil
-}
-
-// executeCommand the command and return the resulting state change along with the
-// tag the state change depended on, if any.
-func (q *Router) executeCommand(c Command) stateChange {
-	state := q.state()
-	var evts []taggedEvent
-	switch req := c.(type) {
-	case key.SelectionCmd:
-		state.keyState = q.key.queue.setSelection(state.keyState, req)
-	case key.FocusCmd:
-		state.keyState, evts = q.key.queue.Focus(q.handlers, state.keyState, req.Tag)
-	case key.SoftKeyboardCmd:
-		state.keyState = state.keyState.softKeyboard(req.Show)
-	case key.SnippetCmd:
-		state.keyState = q.key.queue.setSnippet(state.keyState, req)
-	case transfer.OfferCmd:
-		state.pointerState, evts = q.pointer.queue.offerData(q.handlers, state.pointerState, req)
-	case clipboard.WriteCmd:
-		q.cqueue.ProcessWriteClipboard(req)
-	case clipboard.ReadCmd:
-		state.clipboardState = q.cqueue.ProcessReadClipboard(state.clipboardState, req.Tag)
-	case pointer.GrabCmd:
-		state.pointerState, evts = q.pointer.queue.grab(state.pointerState, req)
-	case op.InvalidateCmd:
-		if !q.wakeup || req.At.Before(q.wakeupTime) {
-			q.wakeup = true
-			q.wakeupTime = req.At
-		}
-	}
-	return stateChange{state: state, events: evts}
-}
-
-func (q *Router) changeState(e event.Event, state inputState, evts []taggedEvent) {
-	// Wrap pointer.DataEvent.Open functions to detect them not being called.
-	for i := range evts {
-		e := &evts[i]
-		if de, ok := e.event.(transfer.DataEvent); ok {
-			transferIdx := len(q.transfers)
-			data := de.Open()
-			q.transfers = append(q.transfers, data)
-			de.Open = func() io.ReadCloser {
-				q.transfers[transferIdx] = nil
-				return data
-			}
-			e.event = de
-		}
-	}
-	// Initialize the first change to contain the current state
-	// and events that are bound for the current frame.
-	if len(q.changes) == 0 {
-		q.changes = append(q.changes, stateChange{})
-	}
-	if e != nil && len(evts) > 0 {
-		// An event triggered events bound for user receivers. Add a state change to be
-		// able to redo the change in case of a command execution.
-		q.changes = append(q.changes, stateChange{event: e, state: state, events: evts})
-	} else {
-		// Otherwise, merge with previous change.
-		prev := &q.changes[len(q.changes)-1]
-		prev.state = state
-		prev.events = append(prev.events, evts...)
-	}
-}
-
-func rangeOverlaps(r1, r2 key.Range) bool {
-	r1 = rangeNorm(r1)
-	r2 = rangeNorm(r2)
-	return r1.Start <= r2.Start && r2.Start < r1.End ||
-		r1.Start <= r2.End && r2.End < r1.End
-}
-
-func rangeNorm(r key.Range) key.Range {
-	if r.End < r.Start {
-		r.End, r.Start = r.Start, r.End
-	}
-	return r
-}
-
-func (q *Router) MoveFocus(dir key.FocusDirection) {
-	state := q.lastState()
-	kstate, evts := q.key.queue.MoveFocus(q.handlers, state.keyState, dir)
-	state.keyState = kstate
-	q.changeState(nil, state, evts)
-}
-
-// RevealFocus scrolls the current focus (if any) into viewport
-// if there are scrollable parent handlers.
-func (q *Router) RevealFocus(viewport image.Rectangle) {
-	state := q.lastState()
-	focus := state.focus
-	if focus == nil {
-		return
-	}
-	kh := &q.handlers[focus].key
-	bounds := q.key.queue.BoundsFor(kh)
-	area := q.key.queue.AreaFor(kh)
-	viewport = q.pointer.queue.ClipFor(area, viewport)
-
-	topleft := bounds.Min.Sub(viewport.Min)
-	topleft = max(topleft, bounds.Max.Sub(viewport.Max))
-	topleft = min(image.Pt(0, 0), topleft)
-	bottomright := bounds.Max.Sub(viewport.Max)
-	bottomright = min(bottomright, bounds.Min.Sub(viewport.Min))
-	bottomright = max(image.Pt(0, 0), bottomright)
-	s := topleft
-	if s.X == 0 {
-		s.X = bottomright.X
-	}
-	if s.Y == 0 {
-		s.Y = bottomright.Y
-	}
-	q.ScrollFocus(s)
-}
-
-// ScrollFocus scrolls the focused widget, if any, by dist.
-func (q *Router) ScrollFocus(dist image.Point) {
-	state := q.lastState()
-	focus := state.focus
-	if focus == nil {
-		return
-	}
-	kh := &q.handlers[focus].key
-	area := q.key.queue.AreaFor(kh)
-	q.changeState(nil, q.lastState(), q.pointer.queue.Deliver(q.handlers, area, pointer.Event{
-		Kind:   pointer.Scroll,
-		Source: pointer.Touch,
-		Scroll: f32internal.FPt(dist),
-	}))
-}
-
-func max(p1, p2 image.Point) image.Point {
-	m := p1
-	if p2.X > m.X {
-		m.X = p2.X
-	}
-	if p2.Y > m.Y {
-		m.Y = p2.Y
-	}
-	return m
-}
-
-func min(p1, p2 image.Point) image.Point {
-	m := p1
-	if p2.X < m.X {
-		m.X = p2.X
-	}
-	if p2.Y < m.Y {
-		m.Y = p2.Y
-	}
-	return m
-}
-
-func (q *Router) ActionAt(p f32.Point) (system.Action, bool) {
-	return q.pointer.queue.ActionAt(p)
-}
-
-func (q *Router) ClickFocus() {
-	focus := q.lastState().focus
-	if focus == nil {
-		return
-	}
-	kh := &q.handlers[focus].key
-	bounds := q.key.queue.BoundsFor(kh)
-	center := bounds.Max.Add(bounds.Min).Div(2)
-	e := pointer.Event{
-		Position: f32.Pt(float32(center.X), float32(center.Y)),
-		Source:   pointer.Touch,
-	}
-	area := q.key.queue.AreaFor(kh)
-	e.Kind = pointer.Press
-	state := q.lastState()
-	q.changeState(nil, state, q.pointer.queue.Deliver(q.handlers, area, e))
-	e.Kind = pointer.Release
-	q.changeState(nil, state, q.pointer.queue.Deliver(q.handlers, area, e))
-}
-
-// TextInputState returns the input state from the most recent
-// call to Frame.
-func (q *Router) TextInputState() TextInputState {
-	state := q.state()
-	kstate, s := state.InputState()
-	state.keyState = kstate
-	q.changeState(nil, state, nil)
-	return s
-}
-
-// TextInputHint returns the input mode from the most recent key.InputOp.
-func (q *Router) TextInputHint() (key.InputHint, bool) {
-	return q.key.queue.InputHint(q.handlers, q.state().keyState)
-}
-
-// WriteClipboard returns the most recent content to be copied
-// to the clipboard, if any.
-func (q *Router) WriteClipboard() (mime string, content []byte, ok bool) {
-	return q.cqueue.WriteClipboard()
-}
-
-// ClipboardRequested reports if any new handler is waiting
-// to read the clipboard.
-func (q *Router) ClipboardRequested() bool {
-	return q.cqueue.ClipboardRequested(q.lastState().clipboardState)
-}
-
-// Cursor returns the last cursor set.
-func (q *Router) Cursor() pointer.Cursor {
-	return q.state().cursor
-}
-
-// SemanticAt returns the first semantic description under pos, if any.
-func (q *Router) SemanticAt(pos f32.Point) (SemanticID, bool) {
-	return q.pointer.queue.SemanticAt(pos)
-}
-
-// AppendSemantics appends the semantic tree to nodes, and returns the result.
-// The root node is the first added.
-func (q *Router) AppendSemantics(nodes []SemanticNode) []SemanticNode {
-	q.pointer.collector.q = &q.pointer.queue
-	q.pointer.collector.ensureRoot()
-	return q.pointer.queue.AppendSemantics(nodes)
-}
-
-// EditorState returns the editor state for the focused handler, or the
-// zero value if there is none.
-func (q *Router) EditorState() EditorState {
-	return q.key.queue.editorState(q.handlers, q.state().keyState)
-}
-
-func (q *Router) stateFor(tag event.Tag) *handler {
-	if tag == nil {
-		panic("internal error: nil tag")
-	}
-	s, ok := q.handlers[tag]
-	if !ok {
-		s = new(handler)
-		if q.handlers == nil {
-			q.handlers = make(map[event.Tag]*handler)
-		}
-		q.handlers[tag] = s
-	}
-	s.active = true
-	return s
-}
-
-func (q *Router) collect() {
-	q.transStack = q.transStack[:0]
-	pc := &q.pointer.collector
-	pc.q = &q.pointer.queue
-	pc.Reset()
-	kq := &q.key.queue
-	q.key.queue.Reset()
-	var t f32.Affine2D
-	for encOp, ok := q.reader.Decode(); ok; encOp, ok = q.reader.Decode() {
-		switch ops.OpType(encOp.Data[0]) {
-		case ops.TypeSave:
-			id := ops.DecodeSave(encOp.Data)
-			if extra := id - len(q.savedTrans) + 1; extra > 0 {
-				q.savedTrans = append(q.savedTrans, make([]f32.Affine2D, extra)...)
-			}
-			q.savedTrans[id] = t
-		case ops.TypeLoad:
-			id := ops.DecodeLoad(encOp.Data)
-			t = q.savedTrans[id]
-			pc.resetState()
-			pc.setTrans(t)
-
-		case ops.TypeClip:
-			var op ops.ClipOp
-			op.Decode(encOp.Data)
-			pc.clip(op)
-		case ops.TypePopClip:
-			pc.popArea()
-		case ops.TypeTransform:
-			t2, push := ops.DecodeTransform(encOp.Data)
-			if push {
-				q.transStack = append(q.transStack, t)
-			}
-			t = t.Mul(t2)
-			pc.setTrans(t)
-		case ops.TypePopTransform:
-			n := len(q.transStack)
-			t = q.transStack[n-1]
-			q.transStack = q.transStack[:n-1]
-			pc.setTrans(t)
-
-		case ops.TypeInput:
-			tag := encOp.Refs[0].(event.Tag)
-			s := q.stateFor(tag)
-			pc.inputOp(tag, &s.pointer)
-			a := pc.currentArea()
-			b := pc.currentAreaBounds()
-			if s.filter.focusable {
-				kq.inputOp(tag, &s.key, t, a, b)
-			}
-
-		// Pointer ops.
-		case ops.TypePass:
-			pc.pass()
-		case ops.TypePopPass:
-			pc.popPass()
-		case ops.TypeCursor:
-			name := pointer.Cursor(encOp.Data[1])
-			pc.cursor(name)
-		case ops.TypeActionInput:
-			act := system.Action(encOp.Data[1])
-			pc.actionInputOp(act)
-		case ops.TypeKeyInputHint:
-			op := key.InputHintOp{
-				Tag:  encOp.Refs[0].(event.Tag),
-				Hint: key.InputHint(encOp.Data[1]),
-			}
-			s := q.stateFor(op.Tag)
-			s.key.inputHint(op.Hint)
-
-		// Semantic ops.
-		case ops.TypeSemanticLabel:
-			lbl := *encOp.Refs[0].(*string)
-			pc.semanticLabel(lbl)
-		case ops.TypeSemanticDesc:
-			desc := *encOp.Refs[0].(*string)
-			pc.semanticDesc(desc)
-		case ops.TypeSemanticClass:
-			class := semantic.ClassOp(encOp.Data[1])
-			pc.semanticClass(class)
-		case ops.TypeSemanticSelected:
-			if encOp.Data[1] != 0 {
-				pc.semanticSelected(true)
-			} else {
-				pc.semanticSelected(false)
-			}
-		case ops.TypeSemanticEnabled:
-			if encOp.Data[1] != 0 {
-				pc.semanticEnabled(true)
-			} else {
-				pc.semanticEnabled(false)
-			}
-		}
-	}
-}
-
-// WakeupTime returns the most recent time for doing another frame,
-// as determined from the last call to Frame.
-func (q *Router) WakeupTime() (time.Time, bool) {
-	t, w := q.wakeupTime, q.wakeup
-	q.wakeup = false
-	// Pending events always trigger wakeups.
-	if len(q.changes) > 1 || len(q.changes) == 1 && len(q.changes[0].events) > 0 {
-		t, w = time.Time{}, true
-	}
-	return t, w
-}
-
-func (s SemanticGestures) String() string {
-	var gestures []string
-	if s&ClickGesture != 0 {
-		gestures = append(gestures, "Click")
-	}
-	return strings.Join(gestures, ",")
-}
-
-func (SystemEvent) ImplementsEvent() {}

io/input/router_test.go

@@ -1,34 +0,0 @@
-// SPDX-License-Identifier: Unlicense OR MIT
-
-package input
-
-import (
-	"testing"
-
-	"gioui.org/io/pointer"
-	"gioui.org/op"
-)
-
-func TestNoFilterAllocs(t *testing.T) {
-	b := testing.Benchmark(func(b *testing.B) {
-		var r Router
-		s := r.Source()
-		b.ReportAllocs()
-		b.ResetTimer()
-		for i := 0; i < b.N; i++ {
-			s.Event(pointer.Filter{})
-		}
-	})
-	if allocs := b.AllocsPerOp(); allocs != 0 {
-		t.Fatalf("expected 0 AllocsPerOp, got %d", allocs)
-	}
-}
-
-func TestRouterWakeup(t *testing.T) {
-	r := new(Router)
-	r.Source().Execute(op.InvalidateCmd{})
-	r.Frame(new(op.Ops))
-	if _, wake := r.WakeupTime(); !wake {
-		t.Errorf("InvalidateCmd did not trigger a redraw")
-	}
-}

io/key/key.go

@@ -1,9 +1,18 @@
 // SPDX-License-Identifier: Unlicense OR MIT
 
-// Package key implements key and text events and operations.
+/*
+Package key implements key and text events and operations.
+
+The InputOp operations is used for declaring key input handlers. Use
+an implementation of the Queue interface from package ui to receive
+events.
+*/
 package key
 
 import (
+	"encoding/binary"
+	"fmt"
+	"math"
 	"strings"
 
 	"gioui.org/f32"
@@ -12,40 +21,59 @@ import (
 	"gioui.org/op"
 )
 
-// Filter matches any [Event] that matches the parameters.
-type Filter struct {
-	// Focus is the tag that must be focused for the filter to match. It has no effect
-	// if it is nil.
-	Focus event.Tag
-	// Required is the set of modifiers that must be included in events matched.
-	Required Modifiers
-	// Optional is the set of modifiers that may be included in events matched.
-	Optional Modifiers
-	// Name of the key to be matched. As a special case, the empty
-	// Name matches every key not matched by any other filter.
-	Name Name
-}
-
-// InputHintOp describes the type of text expected by a tag.
-type InputHintOp struct {
-	Tag  event.Tag
+// InputOp declares a handler ready for key events.
+// Key events are in general only delivered to the
+// focused key handler.
+type InputOp struct {
+	Tag event.Tag
+	// Hint describes the type of text expected by Tag.
 	Hint InputHint
+	// Keys is the set of keys Tag can handle. That is, Tag will only
+	// receive an Event if its key and modifiers are accepted by Keys.Contains.
+	// As a special case, the topmost (first added) InputOp handler receives all
+	// unhandled events.
+	Keys Set
 }
 
-// SoftKeyboardCmd shows or hides the on-screen keyboard, if available.
-type SoftKeyboardCmd struct {
+// Set is an expression that describes a set of key combinations, in the form
+// "<modifiers>-<keyset>|...".  Modifiers are separated by dashes, optional
+// modifiers are enclosed by parentheses.  A key set is either a literal key
+// name or a list of key names separated by commas and enclosed in brackets.
+//
+// The "Short" modifier matches the shortcut modifier (ModShortcut) and
+// "ShortAlt" matches the alternative modifier (ModShortcutAlt).
+//
+// Examples:
+//
+//   - A|B matches the A and B keys
+//   - [A,B] also matches the A and B keys
+//   - Shift-A matches A key if shift is pressed, and no other modifier.
+//   - Shift-(Ctrl)-A matches A if shift is pressed, and optionally ctrl.
+type Set string
+
+// SoftKeyboardOp shows or hide the on-screen keyboard, if available.
+// It replaces any previous SoftKeyboardOp.
+type SoftKeyboardOp struct {
 	Show bool
 }
 
-// SelectionCmd updates the selection for an input handler.
-type SelectionCmd struct {
+// FocusOp sets or clears the keyboard focus. It replaces any previous
+// FocusOp in the same frame.
+type FocusOp struct {
+	// Tag is the new focus. The focus is cleared if Tag is nil, or if Tag
+	// has no InputOp in the same frame.
+	Tag event.Tag
+}
+
+// SelectionOp updates the selection for an input handler.
+type SelectionOp struct {
 	Tag event.Tag
 	Range
 	Caret
 }
 
-// SnippetCmd updates the content snippet for an input handler.
-type SnippetCmd struct {
+// SnippetOp updates the content snippet for an input handler.
+type SnippetOp struct {
 	Tag event.Tag
 	Snippet
 }
@@ -90,8 +118,11 @@ type FocusEvent struct {
 // An Event is generated when a key is pressed. For text input
 // use EditEvent.
 type Event struct {
-	// Name of the key.
-	Name Name
+	// Name of the key. For letters, the upper case form is used, via
+	// unicode.ToUpper. The shift modifier is taken into account, all other
+	// modifiers are ignored. For example, the "shift-1" and "ctrl-shift-1"
+	// combinations both give the Name "!" with the US keyboard layout.
+	Name string
 	// Modifiers is the set of active modifiers when the key was pressed.
 	Modifiers Modifiers
 	// State is the state of the key when the event was fired.
@@ -105,13 +136,6 @@ type EditEvent struct {
 	Text  string
 }
 
-// FocusFilter matches any [FocusEvent], [EditEvent], [SnippetEvent],
-// or [SelectionEvent] with the specified target.
-type FocusFilter struct {
-	// Target is a tag specified in a previous event.Op.
-	Target event.Tag
-}
-
 // InputHint changes the on-screen-keyboard type. That hints the
 // type of data that might be entered by the user.
 type InputHint uint8
@@ -165,60 +189,41 @@ const (
 	ModSuper
 )
 
-// Name is the identifier for a keyboard key.
-//
-// For letters, the upper case form is used, via unicode.ToUpper.
-// The shift modifier is taken into account, all other
-// modifiers are ignored. For example, the "shift-1" and "ctrl-shift-1"
-// combinations both give the Name "!" with the US keyboard layout.
-type Name string
-
 const (
 	// Names for special keys.
-	NameLeftArrow      Name = "←"
-	NameRightArrow     Name = "→"
-	NameUpArrow        Name = "↑"
-	NameDownArrow      Name = "↓"
-	NameReturn         Name = "⏎"
-	NameEnter          Name = "⌤"
-	NameEscape         Name = "⎋"
-	NameHome           Name = "⇱"
-	NameEnd            Name = "⇲"
-	NameDeleteBackward Name = "⌫"
-	NameDeleteForward  Name = "⌦"
-	NamePageUp         Name = "⇞"
-	NamePageDown       Name = "⇟"
-	NameTab            Name = "Tab"
-	NameSpace          Name = "Space"
-	NameCtrl           Name = "Ctrl"
-	NameShift          Name = "Shift"
-	NameAlt            Name = "Alt"
-	NameSuper          Name = "Super"
-	NameCommand        Name = "⌘"
-	NameF1             Name = "F1"
-	NameF2             Name = "F2"
-	NameF3             Name = "F3"
-	NameF4             Name = "F4"
-	NameF5             Name = "F5"
-	NameF6             Name = "F6"
-	NameF7             Name = "F7"
-	NameF8             Name = "F8"
-	NameF9             Name = "F9"
-	NameF10            Name = "F10"
-	NameF11            Name = "F11"
-	NameF12            Name = "F12"
-	NameBack           Name = "Back"
-)
-
-type FocusDirection int
-
-const (
-	FocusRight FocusDirection = iota
-	FocusLeft
-	FocusUp
-	FocusDown
-	FocusForward
-	FocusBackward
+	NameLeftArrow      = "←"
+	NameRightArrow     = "→"
+	NameUpArrow        = "↑"
+	NameDownArrow      = "↓"
+	NameReturn         = "⏎"
+	NameEnter          = "⌤"
+	NameEscape         = "⎋"
+	NameHome           = "⇱"
+	NameEnd            = "⇲"
+	NameDeleteBackward = "⌫"
+	NameDeleteForward  = "⌦"
+	NamePageUp         = "⇞"
+	NamePageDown       = "⇟"
+	NameTab            = "Tab"
+	NameSpace          = "Space"
+	NameCtrl           = "Ctrl"
+	NameShift          = "Shift"
+	NameAlt            = "Alt"
+	NameSuper          = "Super"
+	NameCommand        = "⌘"
+	NameF1             = "F1"
+	NameF2             = "F2"
+	NameF3             = "F3"
+	NameF4             = "F4"
+	NameF5             = "F5"
+	NameF6             = "F6"
+	NameF7             = "F7"
+	NameF8             = "F8"
+	NameF9             = "F9"
+	NameF10            = "F10"
+	NameF11            = "F11"
+	NameF12            = "F12"
+	NameBack           = "Back"
 )
 
 // Contain reports whether m contains all modifiers
@@ -227,52 +232,161 @@ func (m Modifiers) Contain(m2 Modifiers) bool {
 	return m&m2 == m2
 }
 
-// FocusCmd requests to set or clear the keyboard focus.
-type FocusCmd struct {
-	// Tag is the new focus. The focus is cleared if Tag is nil, or if Tag
-	// has no [event.Op] references.
-	Tag event.Tag
+func (k Set) Contains(name string, mods Modifiers) bool {
+	ks := string(k)
+	for len(ks) > 0 {
+		// Cut next key expression.
+		chord, rest, _ := cut(ks, "|")
+		ks = rest
+		// Separate key set and modifier set.
+		var modSet, keySet string
+		sep := strings.LastIndex(chord, "-")
+		if sep != -1 {
+			modSet, keySet = chord[:sep], chord[sep+1:]
+		} else {
+			modSet, keySet = "", chord
+		}
+		if !keySetContains(keySet, name) {
+			continue
+		}
+		if modSetContains(modSet, mods) {
+			return true
+		}
+	}
+	return false
 }
 
-func (h InputHintOp) Add(o *op.Ops) {
+func keySetContains(keySet, name string) bool {
+	// Check for single key match.
+	if keySet == name {
+		return true
+	}
+	// Check for set match.
+	if len(keySet) < 2 || keySet[0] != '[' || keySet[len(keySet)-1] != ']' {
+		return false
+	}
+	keySet = keySet[1 : len(keySet)-1]
+	for len(keySet) > 0 {
+		key, rest, _ := cut(keySet, ",")
+		keySet = rest
+		if key == name {
+			return true
+		}
+	}
+	return false
+}
+
+func modSetContains(modSet string, mods Modifiers) bool {
+	var smods Modifiers
+	for len(modSet) > 0 {
+		mod, rest, _ := cut(modSet, "-")
+		modSet = rest
+		if len(mod) >= 2 && mod[0] == '(' && mod[len(mod)-1] == ')' {
+			mods &^= modFor(mod[1 : len(mod)-1])
+		} else {
+			smods |= modFor(mod)
+		}
+	}
+	return mods == smods
+}
+
+// cut is a copy of the standard library strings.Cut.
+// TODO: remove when Go 1.18 is our minimum.
+func cut(s, sep string) (before, after string, found bool) {
+	if i := strings.Index(s, sep); i >= 0 {
+		return s[:i], s[i+len(sep):], true
+	}
+	return s, "", false
+}
+
+func modFor(name string) Modifiers {
+	switch name {
+	case NameCtrl:
+		return ModCtrl
+	case NameShift:
+		return ModShift
+	case NameAlt:
+		return ModAlt
+	case NameSuper:
+		return ModSuper
+	case NameCommand:
+		return ModCommand
+	case "Short":
+		return ModShortcut
+	case "ShortAlt":
+		return ModShortcutAlt
+	}
+	return 0
+}
+
+func (h InputOp) Add(o *op.Ops) {
 	if h.Tag == nil {
 		panic("Tag must be non-nil")
 	}
-	data := ops.Write1(&o.Internal, ops.TypeKeyInputHintLen, h.Tag)
-	data[0] = byte(ops.TypeKeyInputHint)
+	data := ops.Write2String(&o.Internal, ops.TypeKeyInputLen, h.Tag, string(h.Keys))
+	data[0] = byte(ops.TypeKeyInput)
 	data[1] = byte(h.Hint)
 }
 
+func (h SoftKeyboardOp) Add(o *op.Ops) {
+	data := ops.Write(&o.Internal, ops.TypeKeySoftKeyboardLen)
+	data[0] = byte(ops.TypeKeySoftKeyboard)
+	if h.Show {
+		data[1] = 1
+	}
+}
+
+func (h FocusOp) Add(o *op.Ops) {
+	data := ops.Write1(&o.Internal, ops.TypeKeyFocusLen, h.Tag)
+	data[0] = byte(ops.TypeKeyFocus)
+}
+
+func (s SnippetOp) Add(o *op.Ops) {
+	data := ops.Write2String(&o.Internal, ops.TypeSnippetLen, s.Tag, s.Text)
+	data[0] = byte(ops.TypeSnippet)
+	bo := binary.LittleEndian
+	bo.PutUint32(data[1:], uint32(s.Range.Start))
+	bo.PutUint32(data[5:], uint32(s.Range.End))
+}
+
+func (s SelectionOp) Add(o *op.Ops) {
+	data := ops.Write1(&o.Internal, ops.TypeSelectionLen, s.Tag)
+	data[0] = byte(ops.TypeSelection)
+	bo := binary.LittleEndian
+	bo.PutUint32(data[1:], uint32(s.Start))
+	bo.PutUint32(data[5:], uint32(s.End))
+	bo.PutUint32(data[9:], math.Float32bits(s.Pos.X))
+	bo.PutUint32(data[13:], math.Float32bits(s.Pos.Y))
+	bo.PutUint32(data[17:], math.Float32bits(s.Ascent))
+	bo.PutUint32(data[21:], math.Float32bits(s.Descent))
+}
+
 func (EditEvent) ImplementsEvent()      {}
 func (Event) ImplementsEvent()          {}
 func (FocusEvent) ImplementsEvent()     {}
 func (SnippetEvent) ImplementsEvent()   {}
 func (SelectionEvent) ImplementsEvent() {}
 
-func (FocusCmd) ImplementsCommand()        {}
-func (SoftKeyboardCmd) ImplementsCommand() {}
-func (SelectionCmd) ImplementsCommand()    {}
-func (SnippetCmd) ImplementsCommand()      {}
-
-func (Filter) ImplementsFilter()      {}
-func (FocusFilter) ImplementsFilter() {}
+func (e Event) String() string {
+	return fmt.Sprintf("%v %v %v}", e.Name, e.Modifiers, e.State)
+}
 
 func (m Modifiers) String() string {
 	var strs []string
 	if m.Contain(ModCtrl) {
-		strs = append(strs, string(NameCtrl))
+		strs = append(strs, NameCtrl)
 	}
 	if m.Contain(ModCommand) {
-		strs = append(strs, string(NameCommand))
+		strs = append(strs, NameCommand)
 	}
 	if m.Contain(ModShift) {
-		strs = append(strs, string(NameShift))
+		strs = append(strs, NameShift)
 	}
 	if m.Contain(ModAlt) {
-		strs = append(strs, string(NameAlt))
+		strs = append(strs, NameAlt)
 	}
 	if m.Contain(ModSuper) {
-		strs = append(strs, string(NameSuper))
+		strs = append(strs, NameSuper)
 	}
 	return strings.Join(strs, "-")
 }

io/key/key_test.go

@@ -0,0 +1,35 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package key
+
+import (
+	"testing"
+)
+
+func TestKeySet(t *testing.T) {
+	const allMods = ModAlt | ModShift | ModSuper | ModCtrl | ModCommand
+	tests := []struct {
+		Set        Set
+		Matches    []Event
+		Mismatches []Event
+	}{
+		{"A", []Event{{Name: "A"}}, []Event{{Name: "A", Modifiers: ModShift}}},
+		{"[A,B,C]", []Event{{Name: "A"}, {Name: "B"}}, []Event{}},
+		{"Short-A", []Event{{Name: "A", Modifiers: ModShortcut}}, []Event{{Name: "A", Modifiers: ModShift}}},
+		{"(Ctrl)-A", []Event{{Name: "A", Modifiers: ModCtrl}, {Name: "A"}}, []Event{{Name: "A", Modifiers: ModShift}}},
+		{"Shift-[A,B,C]", []Event{{Name: "A", Modifiers: ModShift}}, []Event{{Name: "B", Modifiers: ModShift | ModCtrl}}},
+		{Set(allMods.String() + "-A"), []Event{{Name: "A", Modifiers: allMods}}, []Event{}},
+	}
+	for _, tst := range tests {
+		for _, e := range tst.Matches {
+			if !tst.Set.Contains(e.Name, e.Modifiers) {
+				t.Errorf("key set %q didn't contain %+v", tst.Set, e)
+			}
+		}
+		for _, e := range tst.Mismatches {
+			if tst.Set.Contains(e.Name, e.Modifiers) {
+				t.Errorf("key set %q contains %+v", tst.Set, e)
+			}
+		}
+	}
+}

io/pointer/doc.go

@@ -5,19 +5,36 @@ Package pointer implements pointer events and operations.
 A pointer is either a mouse controlled cursor or a touch
 object such as a finger.
 
-The [event.Op] operation is used to declare a handler ready for pointer
-events.
+The InputOp operation is used to declare a handler ready for pointer
+events. Use an event.Queue to receive events.
+
+# Kinds
+
+Only events that match a specified list of types are delivered to a handler.
+
+For example, to receive Press, Drag, and Release events (but not Move, Enter,
+Leave, or Scroll):
+
+	var ops op.Ops
+	var h *Handler = ...
+
+	pointer.InputOp{
+		Tag:   h,
+		Kinds: pointer.Press | pointer.Drag | pointer.Release,
+	}.Add(ops)
+
+Cancel events are always delivered.
 
 # Hit areas
 
-Clip operations from package [op/clip] are used for specifying
-hit areas where handlers may receive events.
+Clip operations from package op/clip are used for specifying
+hit areas where subsequent InputOps are active.
 
 For example, to set up a handler with a rectangular hit area:
 
 	r := image.Rectangle{...}
 	area := clip.Rect(r).Push(ops)
-	event.Op{Tag: h}.Add(ops)
+	pointer.InputOp{Tag: h}.Add(ops)
 	area.Pop()
 
 Note that hit areas behave similar to painting: the effective area of a stack
@@ -37,11 +54,11 @@ For example:
 	var h1, h2 *Handler
 
 	area := clip.Rect(...).Push(ops)
-	event.Op(Ops, h1)
+	pointer.InputOp{Tag: h1}.Add(Ops)
 	area.Pop()
 
 	area := clip.Rect(...).Push(ops)
-	event.Op(Ops, h2)
+	pointer.InputOp{Tag: h2}.Add(ops)
 	area.Pop()
 
 implies a tree of two inner nodes, each with one pointer handler attached.

io/pointer/pointer.go

@@ -3,6 +3,9 @@
 package pointer
 
 import (
+	"encoding/binary"
+	"fmt"
+	"image"
 	"strings"
 	"time"
 
@@ -53,32 +56,21 @@ type PassStack struct {
 	macroID uint32
 }
 
-// Filter matches every [Event] that target the Tag and whose kind is
-// included in Kinds. Note that only tags specified in [event.Op] can
-// be targeted by pointer events.
-type Filter struct {
-	Target event.Tag
-	// Kinds is a bitwise-or of event types to match.
-	Kinds Kind
-	// ScrollX and ScrollY constrain the range of scrolling events delivered
-	// to Target. Specifically, any Event e delivered to Tag will satisfy
-	//
-	// ScrollX.Min <= e.Scroll.X <= ScrollX.Max (horizontal axis)
-	// ScrollY.Min <= e.Scroll.Y <= ScrollY.Max (vertical axis)
-	ScrollX ScrollRange
-	ScrollY ScrollRange
-}
-
-// ScrollRange describes the range of scrolling distances in an
-// axis.
-type ScrollRange struct {
-	Min, Max int
-}
-
-// GrabCmd requests a pointer grab on the pointer identified by ID.
-type GrabCmd struct {
+// InputOp declares an input handler ready for pointer
+// events.
+type InputOp struct {
 	Tag event.Tag
-	ID  ID
+	// Grab, if set, request that the handler get
+	// Grabbed priority.
+	Grab bool
+	// Kinds is a bitwise-or of event types to receive.
+	Kinds Kind
+	// ScrollBounds describe the maximum scrollable distances in both
+	// axes. Specifically, any Event e delivered to Tag will satisfy
+	//
+	// ScrollBounds.Min.X <= e.Scroll.X <= ScrollBounds.Max.X (horizontal axis)
+	// ScrollBounds.Min.Y <= e.Scroll.Y <= ScrollBounds.Max.Y (vertical axis)
+	ScrollBounds image.Rectangle
 }
 
 type ID uint16
@@ -179,7 +171,7 @@ const (
 const (
 	// A Cancel event is generated when the current gesture is
 	// interrupted by other handlers or the system.
-	Cancel Kind = 1 << iota
+	Cancel Kind = (1 << iota) >> 1
 	// Press of a pointer.
 	Press
 	// Release of a pointer.
@@ -225,13 +217,6 @@ const (
 	ButtonTertiary
 )
 
-func (s ScrollRange) Union(s2 ScrollRange) ScrollRange {
-	return ScrollRange{
-		Min: min(s.Min, s2.Min),
-		Max: max(s.Max, s2.Max),
-	}
-}
-
 // Push the current pass mode to the pass stack and set the pass mode.
 func (p PassOp) Push(o *op.Ops) PassStack {
 	id, mid := ops.PushOp(&o.Internal, ops.PassStack)
@@ -252,6 +237,30 @@ func (op Cursor) Add(o *op.Ops) {
 	data[1] = byte(op)
 }
 
+// Add panics if the scroll range does not contain zero.
+func (op InputOp) Add(o *op.Ops) {
+	if op.Tag == nil {
+		panic("Tag must be non-nil")
+	}
+	if b := op.ScrollBounds; b.Min.X > 0 || b.Max.X < 0 || b.Min.Y > 0 || b.Max.Y < 0 {
+		panic(fmt.Errorf("invalid scroll range value %v", b))
+	}
+	if op.Kinds>>16 > 0 {
+		panic(fmt.Errorf("value in Types overflows uint16"))
+	}
+	data := ops.Write1(&o.Internal, ops.TypePointerInputLen, op.Tag)
+	data[0] = byte(ops.TypePointerInput)
+	if op.Grab {
+		data[1] = 1
+	}
+	bo := binary.LittleEndian
+	bo.PutUint16(data[2:], uint16(op.Kinds))
+	bo.PutUint32(data[4:], uint32(op.ScrollBounds.Min.X))
+	bo.PutUint32(data[8:], uint32(op.ScrollBounds.Min.Y))
+	bo.PutUint32(data[12:], uint32(op.ScrollBounds.Max.X))
+	bo.PutUint32(data[16:], uint32(op.ScrollBounds.Max.Y))
+}
+
 func (t Kind) String() string {
 	if t == Cancel {
 		return "Cancel"
@@ -395,7 +404,3 @@ func (c Cursor) String() string {
 }
 
 func (Event) ImplementsEvent() {}
-
-func (GrabCmd) ImplementsCommand() {}
-
-func (Filter) ImplementsFilter() {}

io/profile/profile.go

@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+// Package profiles provides access to rendering
+// profiles.
+package profile
+
+import (
+	"gioui.org/internal/ops"
+	"gioui.org/io/event"
+	"gioui.org/op"
+)
+
+// Op registers a handler for receiving
+// Events.
+type Op struct {
+	Tag event.Tag
+}
+
+// Event contains profile data from a single
+// rendered frame.
+type Event struct {
+	// Timings. Very likely to change.
+	Timings string
+}
+
+func (p Op) Add(o *op.Ops) {
+	data := ops.Write1(&o.Internal, ops.TypeProfileLen, p.Tag)
+	data[0] = byte(ops.TypeProfile)
+}
+
+func (p Event) ImplementsEvent() {}

io/router/clipboard.go

@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package router
+
+import (
+	"gioui.org/io/event"
+)
+
+type clipboardQueue struct {
+	receivers map[event.Tag]struct{}
+	// request avoid read clipboard every frame while waiting.
+	requested bool
+	text      *string
+}
+
+// WriteClipboard returns the most recent text to be copied
+// to the clipboard, if any.
+func (q *clipboardQueue) WriteClipboard() (string, bool) {
+	if q.text == nil {
+		return "", false
+	}
+	text := *q.text
+	q.text = nil
+	return text, true
+}
+
+// ReadClipboard reports if any new handler is waiting
+// to read the clipboard.
+func (q *clipboardQueue) ReadClipboard() bool {
+	if len(q.receivers) == 0 || q.requested {
+		return false
+	}
+	q.requested = true
+	return true
+}
+
+func (q *clipboardQueue) Push(e event.Event, events *handlerEvents) {
+	for r := range q.receivers {
+		events.Add(r, e)
+		delete(q.receivers, r)
+	}
+}
+
+func (q *clipboardQueue) ProcessWriteClipboard(refs []interface{}) {
+	q.text = refs[0].(*string)
+}
+
+func (q *clipboardQueue) ProcessReadClipboard(refs []interface{}) {
+	if q.receivers == nil {
+		q.receivers = make(map[event.Tag]struct{})
+	}
+	tag := refs[0].(event.Tag)
+	if _, ok := q.receivers[tag]; !ok {
+		q.receivers[tag] = struct{}{}
+		q.requested = false
+	}
+}

io/router/clipboard_test.go

@@ -0,0 +1,154 @@
+package router
+
+import (
+	"testing"
+
+	"gioui.org/io/clipboard"
+	"gioui.org/io/event"
+	"gioui.org/op"
+)
+
+func TestClipboardDuplicateEvent(t *testing.T) {
+	ops, router, handler := new(op.Ops), new(Router), make([]int, 2)
+
+	// Both must receive the event once
+	clipboard.ReadOp{Tag: &handler[0]}.Add(ops)
+	clipboard.ReadOp{Tag: &handler[1]}.Add(ops)
+
+	router.Frame(ops)
+	event := clipboard.Event{Text: "Test"}
+	router.Queue(event)
+	assertClipboardReadOp(t, router, 0)
+	assertClipboardEvent(t, router.Events(&handler[0]), true)
+	assertClipboardEvent(t, router.Events(&handler[1]), true)
+	ops.Reset()
+
+	// No ReadOp
+
+	router.Frame(ops)
+	assertClipboardReadOp(t, router, 0)
+	assertClipboardEvent(t, router.Events(&handler[0]), false)
+	assertClipboardEvent(t, router.Events(&handler[1]), false)
+	ops.Reset()
+
+	clipboard.ReadOp{Tag: &handler[0]}.Add(ops)
+
+	router.Frame(ops)
+	// No ClipboardEvent sent
+	assertClipboardReadOp(t, router, 1)
+	assertClipboardEvent(t, router.Events(&handler[0]), false)
+	assertClipboardEvent(t, router.Events(&handler[1]), false)
+	ops.Reset()
+}
+
+func TestQueueProcessReadClipboard(t *testing.T) {
+	ops, router, handler := new(op.Ops), new(Router), make([]int, 2)
+	ops.Reset()
+
+	// Request read
+	clipboard.ReadOp{Tag: &handler[0]}.Add(ops)
+
+	router.Frame(ops)
+	assertClipboardReadOp(t, router, 1)
+	ops.Reset()
+
+	for i := 0; i < 3; i++ {
+		// No ReadOp
+		// One receiver must still wait for response
+
+		router.Frame(ops)
+		assertClipboardReadOpDuplicated(t, router, 1)
+		ops.Reset()
+	}
+
+	router.Frame(ops)
+	// Send the clipboard event
+	event := clipboard.Event{Text: "Text 2"}
+	router.Queue(event)
+	assertClipboardReadOp(t, router, 0)
+	assertClipboardEvent(t, router.Events(&handler[0]), true)
+	ops.Reset()
+
+	// No ReadOp
+	// There's no receiver waiting
+
+	router.Frame(ops)
+	assertClipboardReadOp(t, router, 0)
+	assertClipboardEvent(t, router.Events(&handler[0]), false)
+	ops.Reset()
+}
+
+func TestQueueProcessWriteClipboard(t *testing.T) {
+	ops, router := new(op.Ops), new(Router)
+	ops.Reset()
+
+	clipboard.WriteOp{Text: "Write 1"}.Add(ops)
+
+	router.Frame(ops)
+	assertClipboardWriteOp(t, router, "Write 1")
+	ops.Reset()
+
+	// No WriteOp
+
+	router.Frame(ops)
+	assertClipboardWriteOp(t, router, "")
+	ops.Reset()
+
+	clipboard.WriteOp{Text: "Write 2"}.Add(ops)
+
+	router.Frame(ops)
+	assertClipboardReadOp(t, router, 0)
+	assertClipboardWriteOp(t, router, "Write 2")
+	ops.Reset()
+}
+
+func assertClipboardEvent(t *testing.T, events []event.Event, expected bool) {
+	t.Helper()
+	var evtClipboard int
+	for _, e := range events {
+		switch e.(type) {
+		case clipboard.Event:
+			evtClipboard++
+		}
+	}
+	if evtClipboard <= 0 && expected {
+		t.Error("expected to receive some event")
+	}
+	if evtClipboard > 0 && !expected {
+		t.Error("unexpected event received")
+	}
+}
+
+func assertClipboardReadOp(t *testing.T, router *Router, expected int) {
+	t.Helper()
+	if len(router.cqueue.receivers) != expected {
+		t.Error("unexpected number of receivers")
+	}
+	if router.cqueue.ReadClipboard() != (expected > 0) {
+		t.Error("missing requests")
+	}
+}
+
+func assertClipboardReadOpDuplicated(t *testing.T, router *Router, expected int) {
+	t.Helper()
+	if len(router.cqueue.receivers) != expected {
+		t.Error("receivers removed")
+	}
+	if router.cqueue.ReadClipboard() != false {
+		t.Error("duplicated requests")
+	}
+}
+
+func assertClipboardWriteOp(t *testing.T, router *Router, expected string) {
+	t.Helper()
+	if (router.cqueue.text != nil) != (expected != "") {
+		t.Error("text not defined")
+	}
+	text, ok := router.cqueue.WriteClipboard()
+	if ok != (expected != "") {
+		t.Error("duplicated requests")
+	}
+	if text != expected {
+		t.Errorf("got text %s, expected %s", text, expected)
+	}
+}

io/router/key.go

@@ -0,0 +1,353 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package router
+
+import (
+	"image"
+	"sort"
+
+	"gioui.org/f32"
+	"gioui.org/io/event"
+	"gioui.org/io/key"
+)
+
+// EditorState represents the state of an editor needed by input handlers.
+type EditorState struct {
+	Selection struct {
+		Transform f32.Affine2D
+		key.Range
+		key.Caret
+	}
+	Snippet key.Snippet
+}
+
+type TextInputState uint8
+
+type keyQueue struct {
+	focus    event.Tag
+	order    []event.Tag
+	dirOrder []dirFocusEntry
+	handlers map[event.Tag]*keyHandler
+	state    TextInputState
+	hint     key.InputHint
+	content  EditorState
+}
+
+type keyHandler struct {
+	// visible will be true if the InputOp is present
+	// in the current frame.
+	visible  bool
+	new      bool
+	hint     key.InputHint
+	order    int
+	dirOrder int
+	filter   key.Set
+}
+
+// keyCollector tracks state required to update a keyQueue
+// from key ops.
+type keyCollector struct {
+	q       *keyQueue
+	focus   event.Tag
+	changed bool
+}
+
+type dirFocusEntry struct {
+	tag    event.Tag
+	row    int
+	area   int
+	bounds image.Rectangle
+}
+
+const (
+	TextInputKeep TextInputState = iota
+	TextInputClose
+	TextInputOpen
+)
+
+type FocusDirection int
+
+const (
+	FocusRight FocusDirection = iota
+	FocusLeft
+	FocusUp
+	FocusDown
+	FocusForward
+	FocusBackward
+)
+
+// InputState returns the last text input state as
+// determined in Frame.
+func (q *keyQueue) InputState() TextInputState {
+	state := q.state
+	q.state = TextInputKeep
+	return state
+}
+
+// InputHint returns the input mode from the most recent key.InputOp.
+func (q *keyQueue) InputHint() (key.InputHint, bool) {
+	if q.focus == nil {
+		return q.hint, false
+	}
+	focused, ok := q.handlers[q.focus]
+	if !ok {
+		return q.hint, false
+	}
+	old := q.hint
+	q.hint = focused.hint
+	return q.hint, old != q.hint
+}
+
+func (q *keyQueue) Reset() {
+	if q.handlers == nil {
+		q.handlers = make(map[event.Tag]*keyHandler)
+	}
+	for _, h := range q.handlers {
+		h.visible, h.new = false, false
+		h.order = -1
+	}
+	q.order = q.order[:0]
+	q.dirOrder = q.dirOrder[:0]
+}
+
+func (q *keyQueue) Frame(events *handlerEvents, collector keyCollector) {
+	changed, focus := collector.changed, collector.focus
+	for k, h := range q.handlers {
+		if !h.visible {
+			delete(q.handlers, k)
+			if q.focus == k {
+				// Remove focus from the handler that is no longer visible.
+				q.focus = nil
+				q.state = TextInputClose
+			}
+		} else if h.new && k != focus {
+			// Reset the handler on (each) first appearance, but don't trigger redraw.
+			events.AddNoRedraw(k, key.FocusEvent{Focus: false})
+		}
+	}
+	if changed {
+		q.setFocus(focus, events)
+	}
+	q.updateFocusLayout()
+}
+
+// updateFocusLayout partitions input handlers handlers into rows
+// for directional focus moves.
+//
+// The approach is greedy: pick the topmost handler and create a row
+// containing it. Then, extend the handler bounds to a horizontal beam
+// and add to the row every handler whose center intersect it. Repeat
+// until no handlers remain.
+func (q *keyQueue) updateFocusLayout() {
+	order := q.dirOrder
+	// Sort by ascending y position.
+	sort.SliceStable(order, func(i, j int) bool {
+		return order[i].bounds.Min.Y < order[j].bounds.Min.Y
+	})
+	row := 0
+	for len(order) > 0 {
+		h := &order[0]
+		h.row = row
+		bottom := h.bounds.Max.Y
+		end := 1
+		for ; end < len(order); end++ {
+			h := &order[end]
+			center := (h.bounds.Min.Y + h.bounds.Max.Y) / 2
+			if center > bottom {
+				break
+			}
+			h.row = row
+		}
+		// Sort row by ascending x position.
+		sort.SliceStable(order[:end], func(i, j int) bool {
+			return order[i].bounds.Min.X < order[j].bounds.Min.X
+		})
+		order = order[end:]
+		row++
+	}
+	for i, o := range q.dirOrder {
+		q.handlers[o.tag].dirOrder = i
+	}
+}
+
+// MoveFocus attempts to move the focus in the direction of dir, returning true if it succeeds.
+func (q *keyQueue) MoveFocus(dir FocusDirection, events *handlerEvents) bool {
+	if len(q.dirOrder) == 0 {
+		return false
+	}
+	order := 0
+	if q.focus != nil {
+		order = q.handlers[q.focus].dirOrder
+	}
+	focus := q.dirOrder[order]
+	switch dir {
+	case FocusForward, FocusBackward:
+		if len(q.order) == 0 {
+			break
+		}
+		order := 0
+		if dir == FocusBackward {
+			order = -1
+		}
+		if q.focus != nil {
+			order = q.handlers[q.focus].order
+			if dir == FocusForward {
+				order++
+			} else {
+				order--
+			}
+		}
+		order = (order + len(q.order)) % len(q.order)
+		q.setFocus(q.order[order], events)
+		return true
+	case FocusRight, FocusLeft:
+		next := order
+		if q.focus != nil {
+			next = order + 1
+			if dir == FocusLeft {
+				next = order - 1
+			}
+		}
+		if 0 <= next && next < len(q.dirOrder) {
+			newFocus := q.dirOrder[next]
+			if newFocus.row == focus.row {
+				q.setFocus(newFocus.tag, events)
+				return true
+			}
+		}
+	case FocusUp, FocusDown:
+		delta := +1
+		if dir == FocusUp {
+			delta = -1
+		}
+		nextRow := 0
+		if q.focus != nil {
+			nextRow = focus.row + delta
+		}
+		var closest event.Tag
+		dist := int(1e6)
+		center := (focus.bounds.Min.X + focus.bounds.Max.X) / 2
+	loop:
+		for 0 <= order && order < len(q.dirOrder) {
+			next := q.dirOrder[order]
+			switch next.row {
+			case nextRow:
+				nextCenter := (next.bounds.Min.X + next.bounds.Max.X) / 2
+				d := center - nextCenter
+				if d < 0 {
+					d = -d
+				}
+				if d > dist {
+					break loop
+				}
+				dist = d
+				closest = next.tag
+			case nextRow + delta:
+				break loop
+			}
+			order += delta
+		}
+		if closest != nil {
+			q.setFocus(closest, events)
+			return true
+		}
+	}
+	return false
+}
+
+func (q *keyQueue) BoundsFor(t event.Tag) image.Rectangle {
+	order := q.handlers[t].dirOrder
+	return q.dirOrder[order].bounds
+}
+
+func (q *keyQueue) AreaFor(t event.Tag) int {
+	order := q.handlers[t].dirOrder
+	return q.dirOrder[order].area
+}
+
+func (q *keyQueue) Accepts(t event.Tag, e key.Event) bool {
+	return q.handlers[t].filter.Contains(e.Name, e.Modifiers)
+}
+
+func (q *keyQueue) setFocus(focus event.Tag, events *handlerEvents) {
+	if focus != nil {
+		if _, exists := q.handlers[focus]; !exists {
+			focus = nil
+		}
+	}
+	if focus == q.focus {
+		return
+	}
+	q.content = EditorState{}
+	if q.focus != nil {
+		events.Add(q.focus, key.FocusEvent{Focus: false})
+	}
+	q.focus = focus
+	if q.focus != nil {
+		events.Add(q.focus, key.FocusEvent{Focus: true})
+	}
+	if q.focus == nil || q.state == TextInputKeep {
+		q.state = TextInputClose
+	}
+}
+
+func (k *keyCollector) focusOp(tag event.Tag) {
+	k.focus = tag
+	k.changed = true
+}
+
+func (k *keyCollector) softKeyboard(show bool) {
+	if show {
+		k.q.state = TextInputOpen
+	} else {
+		k.q.state = TextInputClose
+	}
+}
+
+func (k *keyCollector) handlerFor(tag event.Tag, area int, bounds image.Rectangle) *keyHandler {
+	h, ok := k.q.handlers[tag]
+	if !ok {
+		h = &keyHandler{new: true, order: -1}
+		k.q.handlers[tag] = h
+	}
+	if h.order == -1 {
+		h.order = len(k.q.order)
+		k.q.order = append(k.q.order, tag)
+		k.q.dirOrder = append(k.q.dirOrder, dirFocusEntry{tag: tag, area: area, bounds: bounds})
+	}
+	return h
+}
+
+func (k *keyCollector) inputOp(op key.InputOp, area int, bounds image.Rectangle) {
+	h := k.handlerFor(op.Tag, area, bounds)
+	h.visible = true
+	h.hint = op.Hint
+	h.filter = op.Keys
+}
+
+func (k *keyCollector) selectionOp(t f32.Affine2D, op key.SelectionOp) {
+	if op.Tag == k.q.focus {
+		k.q.content.Selection.Range = op.Range
+		k.q.content.Selection.Caret = op.Caret
+		k.q.content.Selection.Transform = t
+	}
+}
+
+func (k *keyCollector) snippetOp(op key.SnippetOp) {
+	if op.Tag == k.q.focus {
+		k.q.content.Snippet = op.Snippet
+	}
+}
+
+func (t TextInputState) String() string {
+	switch t {
+	case TextInputKeep:
+		return "Keep"
+	case TextInputClose:
+		return "Close"
+	case TextInputOpen:
+		return "Open"
+	default:
+		panic("unexpected value")
+	}
+}

io/router/key_test.go

@@ -0,0 +1,427 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+package router
+
+import (
+	"image"
+	"reflect"
+	"testing"
+
+	"gioui.org/f32"
+	"gioui.org/io/event"
+	"gioui.org/io/key"
+	"gioui.org/io/pointer"
+	"gioui.org/op"
+	"gioui.org/op/clip"
+)
+
+func TestKeyWakeup(t *testing.T) {
+	handler := new(int)
+	var ops op.Ops
+	key.InputOp{Tag: handler}.Add(&ops)
+
+	var r Router
+	// Test that merely adding a handler doesn't trigger redraw.
+	r.Frame(&ops)
+	if _, wake := r.WakeupTime(); wake {
+		t.Errorf("adding key.InputOp triggered a redraw")
+	}
+	// However, adding a handler queues a Focus(false) event.
+	if evts := r.Events(handler); len(evts) != 1 {
+		t.Errorf("no Focus event for newly registered key.InputOp")
+	}
+}
+
+func TestKeyMultiples(t *testing.T) {
+	handlers := make([]int, 3)
+	ops := new(op.Ops)
+	r := new(Router)
+
+	key.SoftKeyboardOp{Show: true}.Add(ops)
+	key.InputOp{Tag: &handlers[0]}.Add(ops)
+	key.FocusOp{Tag: &handlers[2]}.Add(ops)
+	key.InputOp{Tag: &handlers[1]}.Add(ops)
+
+	// The last one must be focused:
+	key.InputOp{Tag: &handlers[2]}.Add(ops)
+
+	r.Frame(ops)
+
+	assertKeyEvent(t, r.Events(&handlers[0]), false)
+	assertKeyEvent(t, r.Events(&handlers[1]), false)
+	assertKeyEvent(t, r.Events(&handlers[2]), true)
+	assertFocus(t, r, &handlers[2])
+	assertKeyboard(t, r, TextInputOpen)
+}
+
+func TestKeyStacked(t *testing.T) {
+	handlers := make([]int, 4)
+	ops := new(op.Ops)
+	r := new(Router)
+
+	key.InputOp{Tag: &handlers[0]}.Add(ops)
+	key.FocusOp{Tag: nil}.Add(ops)
+	key.SoftKeyboardOp{Show: false}.Add(ops)
+	key.InputOp{Tag: &handlers[1]}.Add(ops)
+	key.FocusOp{Tag: &handlers[1]}.Add(ops)
+	key.InputOp{Tag: &handlers[2]}.Add(ops)
+	key.SoftKeyboardOp{Show: true}.Add(ops)
+	key.InputOp{Tag: &handlers[3]}.Add(ops)
+
+	r.Frame(ops)
+
+	assertKeyEvent(t, r.Events(&handlers[0]), false)
+	assertKeyEvent(t, r.Events(&handlers[1]), true)
+	assertKeyEvent(t, r.Events(&handlers[2]), false)
+	assertKeyEvent(t, r.Events(&handlers[3]), false)
+	assertFocus(t, r, &handlers[1])
+	assertKeyboard(t, r, TextInputOpen)
+}
+
+func TestKeySoftKeyboardNoFocus(t *testing.T) {
+	ops := new(op.Ops)
+	r := new(Router)
+
+	// It's possible to open the keyboard
+	// without any active focus:
+	key.SoftKeyboardOp{Show: true}.Add(ops)
+
+	r.Frame(ops)
+
+	assertFocus(t, r, nil)
+	assertKeyboard(t, r, TextInputOpen)
+}
+
+func TestKeyRemoveFocus(t *testing.T) {
+	handlers := make([]int, 2)
+	ops := new(op.Ops)
+	r := new(Router)
+
+	// New InputOp with Focus and Keyboard:
+	key.InputOp{Tag: &handlers[0], Keys: "Short-Tab"}.Add(ops)
+	key.FocusOp{Tag: &handlers[0]}.Add(ops)
+	key.SoftKeyboardOp{Show: true}.Add(ops)
+
+	// New InputOp without any focus:
+	key.InputOp{Tag: &handlers[1], Keys: "Short-Tab"}.Add(ops)
+
+	r.Frame(ops)
+
+	// Add some key events:
+	event := event.Event(key.Event{Name: key.NameTab, Modifiers: key.ModShortcut, State: key.Press})
+	r.Queue(event)
+
+	assertKeyEvent(t, r.Events(&handlers[0]), true, event)
+	assertKeyEvent(t, r.Events(&handlers[1]), false)
+	assertFocus(t, r, &handlers[0])
+	assertKeyboard(t, r, TextInputOpen)
+
+	ops.Reset()
+
+	// Will get the focus removed:
+	key.InputOp{Tag: &handlers[0]}.Add(ops)
+
+	// Unchanged:
+	key.InputOp{Tag: &handlers[1]}.Add(ops)
+
+	// Remove focus by focusing on a tag that don't exist.
+	key.FocusOp{Tag: new(int)}.Add(ops)
+
+	r.Frame(ops)
+
+	assertKeyEventUnexpected(t, r.Events(&handlers[1]))
+	assertFocus(t, r, nil)
+	assertKeyboard(t, r, TextInputClose)
+
+	ops.Reset()
+
+	key.InputOp{Tag: &handlers[0]}.Add(ops)
+
+	key.InputOp{Tag: &handlers[1]}.Add(ops)
+
+	r.Frame(ops)
+
+	assertKeyEventUnexpected(t, r.Events(&handlers[0]))
+	assertKeyEventUnexpected(t, r.Events(&handlers[1]))
+	assertFocus(t, r, nil)
+	assertKeyboard(t, r, TextInputClose)
+
+	ops.Reset()
+
+	// Set focus to InputOp which already
+	// exists in the previous frame:
+	key.FocusOp{Tag: &handlers[0]}.Add(ops)
+	key.InputOp{Tag: &handlers[0]}.Add(ops)
+	key.SoftKeyboardOp{Show: true}.Add(ops)
+
+	// Remove focus.
+	key.InputOp{Tag: &handlers[1]}.Add(ops)
+	key.FocusOp{Tag: nil}.Add(ops)
+
+	r.Frame(ops)
+
+	assertKeyEventUnexpected(t, r.Events(&handlers[1]))
+	assertFocus(t, r, nil)
+	assertKeyboard(t, r, TextInputOpen)
+}
+
+func TestKeyFocusedInvisible(t *testing.T) {
+	handlers := make([]int, 2)
+	ops := new(op.Ops)
+	r := new(Router)
+
+	// Set new InputOp with focus:
+	key.FocusOp{Tag: &handlers[0]}.Add(ops)
+	key.InputOp{Tag: &handlers[0]}.Add(ops)
+	key.SoftKeyboardOp{Show: true}.Add(ops)
+
+	// Set new InputOp without focus:
+	key.InputOp{Tag: &handlers[1]}.Add(ops)
+
+	r.Frame(ops)
+
+	assertKeyEvent(t, r.Events(&handlers[0]), true)
+	assertKeyEvent(t, r.Events(&handlers[1]), false)
+	assertFocus(t, r, &handlers[0])
+	assertKeyboard(t, r, TextInputOpen)
+
+	ops.Reset()
+
+	//
+	// Removed first (focused) element!
+	//
+
+	// Unchanged:
+	key.InputOp{Tag: &handlers[1]}.Add(ops)
+
+	r.Frame(ops)
+
+	assertKeyEventUnexpected(t, r.Events(&handlers[0]))
+	assertKeyEventUnexpected(t, r.Events(&handlers[1]))
+	assertFocus(t, r, nil)
+	assertKeyboard(t, r, TextInputClose)
+
+	ops.Reset()
+
+	// Respawn the first element:
+	// It must receive one `Event{Focus: false}`.
+	key.InputOp{Tag: &handlers[0]}.Add(ops)
+
+	// Unchanged
+	key.InputOp{Tag: &handlers[1]}.Add(ops)
+
+	r.Frame(ops)
+
+	assertKeyEvent(t, r.Events(&handlers[0]), false)
+	assertKeyEventUnexpected(t, r.Events(&handlers[1]))
+	assertFocus(t, r, nil)
+	assertKeyboard(t, r, TextInputClose)
+
+}
+
+func TestNoOps(t *testing.T) {
+	r := new(Router)
+	r.Frame(nil)
+}
+
+func TestDirectionalFocus(t *testing.T) {
+	ops := new(op.Ops)
+	r := new(Router)
+	handlers := []image.Rectangle{
+		image.Rect(10, 10, 50, 50),
+		image.Rect(50, 20, 100, 80),
+		image.Rect(20, 26, 60, 80),
+		image.Rect(10, 60, 50, 100),
+	}
+
+	for i, bounds := range handlers {
+		cl := clip.Rect(bounds).Push(ops)
+		key.InputOp{Tag: &handlers[i]}.Add(ops)
+		cl.Pop()
+	}
+	r.Frame(ops)
+
+	r.MoveFocus(FocusLeft)
+	assertFocus(t, r, &handlers[0])
+	r.MoveFocus(FocusLeft)
+	assertFocus(t, r, &handlers[0])
+	r.MoveFocus(FocusRight)
+	assertFocus(t, r, &handlers[1])
+	r.MoveFocus(FocusRight)
+	assertFocus(t, r, &handlers[1])
+	r.MoveFocus(FocusDown)
+	assertFocus(t, r, &handlers[2])
+	r.MoveFocus(FocusDown)
+	assertFocus(t, r, &handlers[2])
+	r.MoveFocus(FocusLeft)
+	assertFocus(t, r, &handlers[3])
+	r.MoveFocus(FocusUp)
+	assertFocus(t, r, &handlers[0])
+
+	r.MoveFocus(FocusForward)
+	assertFocus(t, r, &handlers[1])
+	r.MoveFocus(FocusBackward)
+	assertFocus(t, r, &handlers[0])
+}
+
+func TestFocusScroll(t *testing.T) {
+	ops := new(op.Ops)
+	r := new(Router)
+	h := new(int)
+
+	parent := clip.Rect(image.Rect(1, 1, 14, 39)).Push(ops)
+	cl := clip.Rect(image.Rect(10, -20, 20, 30)).Push(ops)
+	key.InputOp{Tag: h}.Add(ops)
+	pointer.InputOp{
+		Tag:          h,
+		Kinds:        pointer.Scroll,
+		ScrollBounds: image.Rect(-100, -100, 100, 100),
+	}.Add(ops)
+	// Test that h is scrolled even if behind another handler.
+	pointer.InputOp{
+		Tag: new(int),
+	}.Add(ops)
+	cl.Pop()
+	parent.Pop()
+	r.Frame(ops)
+
+	r.MoveFocus(FocusLeft)
+	r.RevealFocus(image.Rect(0, 0, 15, 40))
+	evts := r.Events(h)
+	assertScrollEvent(t, evts[len(evts)-1], f32.Pt(6, -9))
+}
+
+func TestFocusClick(t *testing.T) {
+	ops := new(op.Ops)
+	r := new(Router)
+	h := new(int)
+
+	cl := clip.Rect(image.Rect(0, 0, 10, 10)).Push(ops)
+	key.InputOp{Tag: h}.Add(ops)
+	pointer.InputOp{
+		Tag:   h,
+		Kinds: pointer.Press | pointer.Release,
+	}.Add(ops)
+	cl.Pop()
+	r.Frame(ops)
+
+	r.MoveFocus(FocusLeft)
+	r.ClickFocus()
+	assertEventPointerTypeSequence(t, r.Events(h), pointer.Cancel, pointer.Press, pointer.Release)
+}
+
+func TestNoFocus(t *testing.T) {
+	r := new(Router)
+	r.MoveFocus(FocusForward)
+}
+
+func TestKeyRouting(t *testing.T) {
+	handlers := make([]int, 5)
+	ops := new(op.Ops)
+	macroOps := new(op.Ops)
+	r := new(Router)
+
+	rect := clip.Rect{Max: image.Pt(10, 10)}
+
+	macro := op.Record(macroOps)
+	key.InputOp{Tag: &handlers[0], Keys: "A"}.Add(ops)
+	cl1 := rect.Push(ops)
+	key.InputOp{Tag: &handlers[1], Keys: "B"}.Add(ops)
+	key.InputOp{Tag: &handlers[2], Keys: "A"}.Add(ops)
+	cl1.Pop()
+	cl2 := rect.Push(ops)
+	key.InputOp{Tag: &handlers[3]}.Add(ops)
+	key.InputOp{Tag: &handlers[4], Keys: "A"}.Add(ops)
+	cl2.Pop()
+	call := macro.Stop()
+	call.Add(ops)
+
+	r.Frame(ops)
+
+	A, B := key.Event{Name: "A"}, key.Event{Name: "B"}
+	r.Queue(A, B)
+
+	// With no focus, the events should traverse the final branch of the hit tree
+	// searching for handlers.
+	assertKeyEvent(t, r.Events(&handlers[4]), false, A)
+	assertKeyEvent(t, r.Events(&handlers[3]), false)
+	assertKeyEvent(t, r.Events(&handlers[2]), false)
+	assertKeyEvent(t, r.Events(&handlers[1]), false, B)
+	assertKeyEvent(t, r.Events(&handlers[0]), false)
+
+	r2 := new(Router)
+
+	call.Add(ops)
+	key.FocusOp{Tag: &handlers[3]}.Add(ops)
+	r2.Frame(ops)
+
+	r2.Queue(A, B)
+
+	// With focus, the events should traverse the branch of the hit tree
+	// containing the focused element.
+	assertKeyEvent(t, r2.Events(&handlers[4]), false)
+	assertKeyEvent(t, r2.Events(&handlers[3]), true)
+	assertKeyEvent(t, r2.Events(&handlers[2]), false)
+	assertKeyEvent(t, r2.Events(&handlers[1]), false)
+	assertKeyEvent(t, r2.Events(&handlers[0]), false, A)
+}
+
+func assertKeyEvent(t *testing.T, events []event.Event, expectedFocus bool, expectedInputs ...event.Event) {
+	t.Helper()
+	var evtFocus int
+	var evtKeyPress int
+	for _, e := range events {
+		switch ev := e.(type) {
+		case key.FocusEvent:
+			if ev.Focus != expectedFocus {
+				t.Errorf("focus is expected to be %v, got %v", expectedFocus, ev.Focus)
+			}
+			evtFocus++
+		case key.Event, key.EditEvent:
+			if len(expectedInputs) <= evtKeyPress {
+				t.Fatalf("unexpected key events")
+			}
+			if !reflect.DeepEqual(ev, expectedInputs[evtKeyPress]) {
+				t.Errorf("expected %v events, got %v", expectedInputs[evtKeyPress], ev)
+			}
+			evtKeyPress++
+		}
+	}
+	if evtFocus <= 0 {
+		t.Errorf("expected focus event")
+	}
+	if evtFocus > 1 {
+		t.Errorf("expected single focus event")
+	}
+	if evtKeyPress != len(expectedInputs) {
+		t.Errorf("expected key events")
+	}
+}
+
+func assertKeyEventUnexpected(t *testing.T, events []event.Event) {
+	t.Helper()
+	var evtFocus int
+	for _, e := range events {
+		switch e.(type) {
+		case key.FocusEvent:
+			evtFocus++
+		}
+	}
+	if evtFocus > 1 {
+		t.Errorf("unexpected focus event")
+	}
+}
+
+func assertFocus(t *testing.T, router *Router, expected event.Tag) {
+	t.Helper()
+	if got := router.key.queue.focus; got != expected {
+		t.Errorf("expected %v to be focused, got %v", expected, got)
+	}
+}
+
+func assertKeyboard(t *testing.T, router *Router, expected TextInputState) {
+	t.Helper()
+	if got := router.key.queue.state; got != expected {
+		t.Errorf("expected %v keyboard, got %v", expected, got)
+	}
+}

io/router/pointer.go

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: Unlicense OR MIT
 
-package input
+package router
 
 import (
 	"image"
@@ -10,6 +10,7 @@ import (
 	f32internal "gioui.org/internal/f32"
 	"gioui.org/internal/ops"
 	"gioui.org/io/event"
+	"gioui.org/io/key"
 	"gioui.org/io/pointer"
 	"gioui.org/io/semantic"
 	"gioui.org/io/system"
@@ -17,8 +18,14 @@ import (
 )
 
 type pointerQueue struct {
-	hitTree []hitNode
-	areas   []areaNode
+	hitTree   []hitNode
+	areas     []areaNode
+	cursor    pointer.Cursor
+	handlers  map[event.Tag]*pointerHandler
+	pointers  []pointerInfo
+	transfers []io.ReadCloser // pending data transfers
+
+	scratch []event.Tag
 
 	semantic struct {
 		idsAssigned bool
@@ -36,15 +43,10 @@ type hitNode struct {
 
 	// For handler nodes.
 	tag  event.Tag
+	ktag event.Tag
 	pass bool
 }
 
-// pointerState is the input state related to pointer events.
-type pointerState struct {
-	cursor   pointer.Cursor
-	pointers []pointerInfo
-}
-
 type pointerInfo struct {
 	id       pointer.ID
 	pressed  bool
@@ -61,21 +63,17 @@ type pointerInfo struct {
 }
 
 type pointerHandler struct {
-	// areaPlusOne is the index into the list of pointerQueue.areas, plus 1.
-	areaPlusOne int
-	// setup tracks whether the handler has received
-	// the pointer.Cancel event that resets its state.
-	setup bool
-}
-
-// pointerFilter represents the union of a set of pointer filters.
-type pointerFilter struct {
-	kinds pointer.Kind
+	area      int
+	active    bool
+	wantsGrab bool
+	types     pointer.Kind
 	// min and max horizontal/vertical scroll
-	scrollX, scrollY pointer.ScrollRange
+	scrollRange image.Rectangle
 
 	sourceMimes []string
 	targetMimes []string
+	offeredMime string
+	data        io.ReadCloser
 }
 
 type areaOp struct {
@@ -231,18 +229,33 @@ func (c *pointerCollector) addHitNode(n hitNode) {
 }
 
 // newHandler returns the current handler or a new one for tag.
-func (c *pointerCollector) newHandler(tag event.Tag, state *pointerHandler) {
+func (c *pointerCollector) newHandler(tag event.Tag, events *handlerEvents) *pointerHandler {
 	areaID := c.currentArea()
 	c.addHitNode(hitNode{
 		area: areaID,
 		tag:  tag,
 		pass: c.state.pass > 0,
 	})
-	state.areaPlusOne = areaID + 1
+	h, ok := c.q.handlers[tag]
+	if !ok {
+		h = new(pointerHandler)
+		c.q.handlers[tag] = h
+		// Cancel handlers on (each) first appearance, but don't
+		// trigger redraw.
+		events.AddNoRedraw(tag, pointer.Event{Kind: pointer.Cancel})
+	}
+	h.active = true
+	h.area = areaID
+	return h
 }
 
-func (s *pointerHandler) Reset() {
-	s.areaPlusOne = 0
+func (c *pointerCollector) keyInputOp(op key.InputOp) {
+	areaID := c.currentArea()
+	c.addHitNode(hitNode{
+		area: areaID,
+		ktag: op.Tag,
+		pass: true,
+	})
 }
 
 func (c *pointerCollector) actionInputOp(act system.Action) {
@@ -251,111 +264,21 @@ func (c *pointerCollector) actionInputOp(act system.Action) {
 	area.action = act
 }
 
-func (q *pointerQueue) grab(state pointerState, req pointer.GrabCmd) (pointerState, []taggedEvent) {
-	var evts []taggedEvent
-	for _, p := range state.pointers {
-		if !p.pressed || p.id != req.ID {
-			continue
-		}
-		// Drop other handlers that lost their grab.
-		for i := len(p.handlers) - 1; i >= 0; i-- {
-			if tag := p.handlers[i]; tag != req.Tag {
-				evts = append(evts, taggedEvent{
-					tag:   tag,
-					event: pointer.Event{Kind: pointer.Cancel},
-				})
-				state = dropHandler(state, tag)
-			}
-		}
-		break
-	}
-	return state, evts
-}
-
-func (c *pointerCollector) inputOp(tag event.Tag, state *pointerHandler) {
+func (c *pointerCollector) inputOp(op pointer.InputOp, events *handlerEvents) {
 	areaID := c.currentArea()
 	area := &c.q.areas[areaID]
-	area.semantic.content.tag = tag
-	c.newHandler(tag, state)
-}
-
-func (p *pointerFilter) Add(f event.Filter) {
-	switch f := f.(type) {
-	case transfer.SourceFilter:
-		for _, m := range p.sourceMimes {
-			if m == f.Type {
-				return
-			}
-		}
-		p.sourceMimes = append(p.sourceMimes, f.Type)
-	case transfer.TargetFilter:
-		for _, m := range p.targetMimes {
-			if m == f.Type {
-				return
-			}
-		}
-		p.targetMimes = append(p.targetMimes, f.Type)
-	case pointer.Filter:
-		p.kinds = p.kinds | f.Kinds
-		p.scrollX = p.scrollX.Union(f.ScrollX)
-		p.scrollY = p.scrollY.Union(f.ScrollY)
+	area.semantic.content.tag = op.Tag
+	if op.Kinds&(pointer.Press|pointer.Release) != 0 {
+		area.semantic.content.gestures |= ClickGesture
 	}
-}
-
-func (p *pointerFilter) Matches(e event.Event) bool {
-	switch e := e.(type) {
-	case pointer.Event:
-		return e.Kind&p.kinds == e.Kind
-	case transfer.CancelEvent, transfer.InitiateEvent:
-		return len(p.sourceMimes) > 0 || len(p.targetMimes) > 0
-	case transfer.RequestEvent:
-		for _, t := range p.sourceMimes {
-			if t == e.Type {
-				return true
-			}
-		}
-	case transfer.DataEvent:
-		for _, t := range p.targetMimes {
-			if t == e.Type {
-				return true
-			}
-		}
+	if op.Kinds&pointer.Scroll != 0 {
+		area.semantic.content.gestures |= ScrollGesture
 	}
-	return false
-}
-
-func (p *pointerFilter) Merge(p2 pointerFilter) {
-	p.kinds = p.kinds | p2.kinds
-	p.scrollX = p.scrollX.Union(p2.scrollX)
-	p.scrollY = p.scrollY.Union(p2.scrollY)
-	p.sourceMimes = append(p.sourceMimes, p2.sourceMimes...)
-	p.targetMimes = append(p.targetMimes, p2.targetMimes...)
-}
-
-// clampScroll splits a scroll distance in the remaining scroll and the
-// scroll accepted by the filter.
-func (p *pointerFilter) clampScroll(scroll f32.Point) (left, scrolled f32.Point) {
-	left.X, scrolled.X = clampSplit(scroll.X, p.scrollX.Min, p.scrollX.Max)
-	left.Y, scrolled.Y = clampSplit(scroll.Y, p.scrollY.Min, p.scrollY.Max)
-	return
-}
-
-func clampSplit(v float32, min, max int) (float32, float32) {
-	if m := float32(max); v > m {
-		return v - m, m
-	}
-	if m := float32(min); v < m {
-		return v - m, m
-	}
-	return 0, v
-}
-
-func (s *pointerHandler) ResetEvent() (event.Event, bool) {
-	if s.setup {
-		return nil, false
-	}
-	s.setup = true
-	return pointer.Event{Kind: pointer.Cancel}, true
+	area.semantic.valid = area.semantic.content.gestures != 0
+	h := c.newHandler(op.Tag, events)
+	h.wantsGrab = h.wantsGrab || op.Grab
+	h.types = h.types | op.Kinds
+	h.scrollRange = op.ScrollBounds
 }
 
 func (c *pointerCollector) semanticLabel(lbl string) {
@@ -399,28 +322,23 @@ func (c *pointerCollector) cursor(cursor pointer.Cursor) {
 	area.cursor = cursor
 }
 
-func (q *pointerQueue) offerData(handlers map[event.Tag]*handler, state pointerState, req transfer.OfferCmd) (pointerState, []taggedEvent) {
-	var evts []taggedEvent
-	for i, p := range state.pointers {
-		if p.dataSource != req.Tag {
-			continue
-		}
-		if p.dataTarget != nil {
-			evts = append(evts, taggedEvent{tag: p.dataTarget, event: transfer.DataEvent{
-				Type: req.Type,
-				Open: func() io.ReadCloser {
-					return req.Data
-				},
-			}})
-		}
-		state.pointers = append([]pointerInfo{}, state.pointers...)
-		state.pointers[i], evts = q.deliverTransferCancelEvent(handlers, p, evts)
-		break
-	}
-	return state, evts
+func (c *pointerCollector) sourceOp(op transfer.SourceOp, events *handlerEvents) {
+	h := c.newHandler(op.Tag, events)
+	h.sourceMimes = append(h.sourceMimes, op.Type)
 }
 
-func (c *pointerCollector) Reset() {
+func (c *pointerCollector) targetOp(op transfer.TargetOp, events *handlerEvents) {
+	h := c.newHandler(op.Tag, events)
+	h.targetMimes = append(h.targetMimes, op.Type)
+}
+
+func (c *pointerCollector) offerOp(op transfer.OfferOp, events *handlerEvents) {
+	h := c.newHandler(op.Tag, events)
+	h.offeredMime = op.Type
+	h.data = op.Data
+}
+
+func (c *pointerCollector) reset() {
 	c.q.reset()
 	c.resetState()
 	c.ensureRoot()
@@ -575,6 +493,20 @@ func (q *pointerQueue) hitTest(pos f32.Point, onNode func(*hitNode) bool) pointe
 	return cursor
 }
 
+func (q *pointerQueue) opHit(pos f32.Point) ([]event.Tag, pointer.Cursor) {
+	hits := q.scratch[:0]
+	cursor := q.hitTest(pos, func(n *hitNode) bool {
+		if n.tag != nil {
+			if _, exists := q.handlers[n.tag]; exists {
+				hits = addHandler(hits, n.tag)
+			}
+		}
+		return true
+	})
+	q.scratch = hits[:0]
+	return hits, cursor
+}
+
 func (q *pointerQueue) invTransform(areaIdx int, p f32.Point) f32.Point {
 	if areaIdx == -1 {
 		return p
@@ -599,6 +531,17 @@ func (q *pointerQueue) hit(areaIdx int, p f32.Point) (bool, pointer.Cursor) {
 }
 
 func (q *pointerQueue) reset() {
+	if q.handlers == nil {
+		q.handlers = make(map[event.Tag]*pointerHandler)
+	}
+	for _, h := range q.handlers {
+		// Reset handler.
+		h.active = false
+		h.wantsGrab = false
+		h.types = 0
+		h.sourceMimes = h.sourceMimes[:0]
+		h.targetMimes = h.targetMimes[:0]
+	}
 	q.hitTree = q.hitTree[:0]
 	q.areas = q.areas[:0]
 	q.semantic.idsAssigned = false
@@ -616,71 +559,80 @@ func (q *pointerQueue) reset() {
 			delete(q.semantic.contentIDs, k)
 		}
 	}
+	for _, rc := range q.transfers {
+		if rc != nil {
+			rc.Close()
+		}
+	}
+	q.transfers = nil
 }
 
-func (q *pointerQueue) Frame(handlers map[event.Tag]*handler, state pointerState) (pointerState, []taggedEvent) {
-	for _, h := range handlers {
-		if h.pointer.areaPlusOne != 0 {
-			area := &q.areas[h.pointer.areaPlusOne-1]
-			if h.filter.pointer.kinds&(pointer.Press|pointer.Release) != 0 {
-				area.semantic.content.gestures |= ClickGesture
+func (q *pointerQueue) Frame(events *handlerEvents) {
+	for k, h := range q.handlers {
+		if !h.active {
+			q.dropHandler(nil, k)
+			delete(q.handlers, k)
+		}
+		if h.wantsGrab {
+			for _, p := range q.pointers {
+				if !p.pressed {
+					continue
+				}
+				for i, k2 := range p.handlers {
+					if k2 == k {
+						// Drop other handlers that lost their grab.
+						dropped := q.scratch[:0]
+						dropped = append(dropped, p.handlers[:i]...)
+						dropped = append(dropped, p.handlers[i+1:]...)
+						for _, tag := range dropped {
+							q.dropHandler(events, tag)
+						}
+						break
+					}
+				}
 			}
-			if h.filter.pointer.kinds&pointer.Scroll != 0 {
-				area.semantic.content.gestures |= ScrollGesture
-			}
-			area.semantic.valid = area.semantic.content.gestures != 0
 		}
 	}
-	var evts []taggedEvent
-	for i, p := range state.pointers {
-		changed := false
-		p, evts, state.cursor, changed = q.deliverEnterLeaveEvents(handlers, state.cursor, p, evts, p.last)
-		if changed {
-			state.pointers = append([]pointerInfo{}, state.pointers...)
-			state.pointers[i] = p
-		}
+	for i := range q.pointers {
+		p := &q.pointers[i]
+		q.deliverEnterLeaveEvents(p, events, p.last)
+		q.deliverTransferDataEvent(p, events)
 	}
-	return state, evts
 }
 
-func dropHandler(state pointerState, tag event.Tag) pointerState {
-	pointers := state.pointers
-	state.pointers = nil
-	for _, p := range pointers {
-		handlers := p.handlers
-		p.handlers = nil
-		for _, h := range handlers {
-			if h != tag {
-				p.handlers = append(p.handlers, h)
-			}
-		}
-		entered := p.entered
-		p.entered = nil
-		for _, h := range entered {
-			if h != tag {
-				p.entered = append(p.entered, h)
-			}
-		}
-		state.pointers = append(state.pointers, p)
+func (q *pointerQueue) dropHandler(events *handlerEvents, tag event.Tag) {
+	if events != nil {
+		events.Add(tag, pointer.Event{Kind: pointer.Cancel})
+	}
+	for i := range q.pointers {
+		p := &q.pointers[i]
+		for i := len(p.handlers) - 1; i >= 0; i-- {
+			if p.handlers[i] == tag {
+				p.handlers = append(p.handlers[:i], p.handlers[i+1:]...)
+			}
+		}
+		for i := len(p.entered) - 1; i >= 0; i-- {
+			if p.entered[i] == tag {
+				p.entered = append(p.entered[:i], p.entered[i+1:]...)
+			}
+		}
 	}
-	return state
 }
 
 // pointerOf returns the pointerInfo index corresponding to the pointer in e.
-func (s pointerState) pointerOf(e pointer.Event) (pointerState, int) {
-	for i, p := range s.pointers {
+func (q *pointerQueue) pointerOf(e pointer.Event) int {
+	for i, p := range q.pointers {
 		if p.id == e.PointerID {
-			return s, i
+			return i
 		}
 	}
-	n := len(s.pointers)
-	s.pointers = append(s.pointers[:n:n], pointerInfo{id: e.PointerID})
-	return s, len(s.pointers) - 1
+	q.pointers = append(q.pointers, pointerInfo{id: e.PointerID})
+	return len(q.pointers) - 1
 }
 
 // Deliver is like Push, but delivers an event to a particular area.
-func (q *pointerQueue) Deliver(handlers map[event.Tag]*handler, areaIdx int, e pointer.Event) []taggedEvent {
-	scroll := e.Scroll
+func (q *pointerQueue) Deliver(areaIdx int, e pointer.Event, events *handlerEvents) {
+	var sx, sy = e.Scroll.X, e.Scroll.Y
 	idx := len(q.hitTree) - 1
 	// Locate first potential receiver.
 	for idx != -1 {
@@ -690,28 +642,31 @@ func (q *pointerQueue) Deliver(handlers map[event.Tag]*handler, areaIdx int, e p
 		}
 		idx--
 	}
-	var evts []taggedEvent
 	for idx != -1 {
 		n := &q.hitTree[idx]
 		idx = n.next
-		h, ok := handlers[n.tag]
-		if !ok || !h.filter.pointer.Matches(e) {
+		if n.tag == nil {
+			continue
+		}
+		h := q.handlers[n.tag]
+		if e.Kind&h.types == 0 {
 			continue
 		}
 		e := e
 		if e.Kind == pointer.Scroll {
-			if scroll == (f32.Point{}) {
+			if sx == 0 && sy == 0 {
 				break
 			}
-			scroll, e.Scroll = h.filter.pointer.clampScroll(scroll)
+			// Distribute the scroll to the handler based on its ScrollRange.
+			sx, e.Scroll.X = setScrollEvent(sx, h.scrollRange.Min.X, h.scrollRange.Max.X)
+			sy, e.Scroll.Y = setScrollEvent(sy, h.scrollRange.Min.Y, h.scrollRange.Max.Y)
 		}
-		e.Position = q.invTransform(h.pointer.areaPlusOne-1, e.Position)
-		evts = append(evts, taggedEvent{tag: n.tag, event: e})
+		e.Position = q.invTransform(h.area, e.Position)
+		events.Add(n.tag, e)
 		if e.Kind != pointer.Scroll {
 			break
 		}
 	}
-	return evts
 }
 
 // SemanticArea returns the sematic content for area, and its parent area.
@@ -727,129 +682,106 @@ func (q *pointerQueue) SemanticArea(areaIdx int) (semanticContent, int) {
 	return semanticContent{}, -1
 }
 
-func (q *pointerQueue) Push(handlers map[event.Tag]*handler, state pointerState, e pointer.Event) (pointerState, []taggedEvent) {
-	var evts []taggedEvent
+func (q *pointerQueue) Push(e pointer.Event, events *handlerEvents) {
 	if e.Kind == pointer.Cancel {
-		for k := range handlers {
-			evts = append(evts, taggedEvent{
-				event: pointer.Event{Kind: pointer.Cancel},
-				tag:   k,
-			})
+		q.pointers = q.pointers[:0]
+		for k := range q.handlers {
+			q.dropHandler(events, k)
 		}
-		state.pointers = nil
-		return state, evts
+		return
 	}
-	state, pidx := state.pointerOf(e)
-	p := state.pointers[pidx]
+	pidx := q.pointerOf(e)
+	p := &q.pointers[pidx]
+	p.last = e
 
 	switch e.Kind {
 	case pointer.Press:
-		p, evts, state.cursor, _ = q.deliverEnterLeaveEvents(handlers, state.cursor, p, evts, e)
+		q.deliverEnterLeaveEvents(p, events, e)
 		p.pressed = true
-		evts = q.deliverEvent(handlers, p, evts, e)
+		q.deliverEvent(p, events, e)
 	case pointer.Move:
 		if p.pressed {
 			e.Kind = pointer.Drag
 		}
-		p, evts, state.cursor, _ = q.deliverEnterLeaveEvents(handlers, state.cursor, p, evts, e)
-		evts = q.deliverEvent(handlers, p, evts, e)
+		q.deliverEnterLeaveEvents(p, events, e)
+		q.deliverEvent(p, events, e)
 		if p.pressed {
-			p, evts = q.deliverDragEvent(handlers, p, evts)
+			q.deliverDragEvent(p, events)
 		}
 	case pointer.Release:
-		evts = q.deliverEvent(handlers, p, evts, e)
+		q.deliverEvent(p, events, e)
 		p.pressed = false
-		p, evts, state.cursor, _ = q.deliverEnterLeaveEvents(handlers, state.cursor, p, evts, e)
-		p, evts = q.deliverDropEvent(handlers, p, evts)
+		q.deliverEnterLeaveEvents(p, events, e)
+		q.deliverDropEvent(p, events)
 	case pointer.Scroll:
-		p, evts, state.cursor, _ = q.deliverEnterLeaveEvents(handlers, state.cursor, p, evts, e)
-		evts = q.deliverEvent(handlers, p, evts, e)
+		q.deliverEnterLeaveEvents(p, events, e)
+		q.deliverEvent(p, events, e)
 	default:
 		panic("unsupported pointer event type")
 	}
 
-	p.last = e
-
 	if !p.pressed && len(p.entered) == 0 {
 		// No longer need to track pointer.
-		state.pointers = append(state.pointers[:pidx:pidx], state.pointers[pidx+1:]...)
-	} else {
-		state.pointers = append([]pointerInfo{}, state.pointers...)
-		state.pointers[pidx] = p
+		q.pointers = append(q.pointers[:pidx], q.pointers[pidx+1:]...)
 	}
-	return state, evts
 }
 
-func (q *pointerQueue) deliverEvent(handlers map[event.Tag]*handler, p pointerInfo, evts []taggedEvent, e pointer.Event) []taggedEvent {
+func (q *pointerQueue) deliverEvent(p *pointerInfo, events *handlerEvents, e pointer.Event) {
 	foremost := true
 	if p.pressed && len(p.handlers) == 1 {
 		e.Priority = pointer.Grabbed
 		foremost = false
 	}
-	scroll := e.Scroll
+	var sx, sy = e.Scroll.X, e.Scroll.Y
 	for _, k := range p.handlers {
-		h, ok := handlers[k]
-		if !ok {
-			continue
-		}
-		f := h.filter.pointer
-		if !f.Matches(e) {
-			continue
-		}
+		h := q.handlers[k]
 		if e.Kind == pointer.Scroll {
-			if scroll == (f32.Point{}) {
-				return evts
+			if sx == 0 && sy == 0 {
+				return
 			}
-			scroll, e.Scroll = f.clampScroll(scroll)
+			// Distribute the scroll to the handler based on its ScrollRange.
+			sx, e.Scroll.X = setScrollEvent(sx, h.scrollRange.Min.X, h.scrollRange.Max.X)
+			sy, e.Scroll.Y = setScrollEvent(sy, h.scrollRange.Min.Y, h.scrollRange.Max.Y)
+		}
+		if e.Kind&h.types == 0 {
+			continue
 		}
 		e := e
 		if foremost {
 			foremost = false
 			e.Priority = pointer.Foremost
 		}
-		e.Position = q.invTransform(h.pointer.areaPlusOne-1, e.Position)
-		evts = append(evts, taggedEvent{event: e, tag: k})
+		e.Position = q.invTransform(h.area, e.Position)
+		events.Add(k, e)
 	}
-	return evts
 }
 
-func (q *pointerQueue) deliverEnterLeaveEvents(handlers map[event.Tag]*handler, cursor pointer.Cursor, p pointerInfo, evts []taggedEvent, e pointer.Event) (pointerInfo, []taggedEvent, pointer.Cursor, bool) {
-	changed := false
+func (q *pointerQueue) deliverEnterLeaveEvents(p *pointerInfo, events *handlerEvents, e pointer.Event) {
 	var hits []event.Tag
 	if e.Source != pointer.Mouse && !p.pressed && e.Kind != pointer.Press {
 		// Consider non-mouse pointers leaving when they're released.
 	} else {
-		var transSrc *pointerFilter
-		if p.dataSource != nil {
-			transSrc = &handlers[p.dataSource].filter.pointer
-		}
-		cursor = q.hitTest(e.Position, func(n *hitNode) bool {
-			h, ok := handlers[n.tag]
-			if !ok {
-				return true
-			}
-			add := true
-			if p.pressed {
-				add = false
-				// Filter out non-participating handlers,
-				// except potential transfer targets when a transfer has been initiated.
-				if _, found := searchTag(p.handlers, n.tag); found {
-					add = true
-				}
-				if transSrc != nil {
-					if _, ok := firstMimeMatch(transSrc, &h.filter.pointer); ok {
-						add = true
+		hits, q.cursor = q.opHit(e.Position)
+		if p.pressed {
+			// Filter out non-participating handlers,
+			// except potential transfer targets when a transfer has been initiated.
+			var hitsHaveTarget bool
+			if p.dataSource != nil {
+				transferSource := q.handlers[p.dataSource]
+				for _, hit := range hits {
+					if _, ok := firstMimeMatch(transferSource, q.handlers[hit]); ok {
+						hitsHaveTarget = true
+						break
 					}
 				}
 			}
-			if add {
-				hits = addHandler(hits, n.tag)
+			for i := len(hits) - 1; i >= 0; i-- {
+				if _, found := searchTag(p.handlers, hits[i]); !found && !hitsHaveTarget {
+					hits = append(hits[:i], hits[i+1:]...)
+				}
 			}
-			return true
-		})
-		if !p.pressed {
-			changed = true
-			p.handlers = hits
+		} else {
+			p.handlers = append(p.handlers[:0], hits...)
 		}
 	}
 	// Deliver Leave events.
@@ -857,94 +789,111 @@ func (q *pointerQueue) deliverEnterLeaveEvents(handlers map[event.Tag]*handler,
 		if _, found := searchTag(hits, k); found {
 			continue
 		}
-		h, ok := handlers[k]
-		if !ok {
-			continue
-		}
-		changed = true
-		e := e
+		h := q.handlers[k]
 		e.Kind = pointer.Leave
 
-		if h.filter.pointer.Matches(e) {
-			e.Position = q.invTransform(h.pointer.areaPlusOne-1, e.Position)
-			evts = append(evts, taggedEvent{tag: k, event: e})
+		if e.Kind&h.types != 0 {
+			e := e
+			e.Position = q.invTransform(h.area, e.Position)
+			events.Add(k, e)
 		}
 	}
 	// Deliver Enter events.
 	for _, k := range hits {
+		h := q.handlers[k]
 		if _, found := searchTag(p.entered, k); found {
 			continue
 		}
-		h, ok := handlers[k]
-		if !ok {
-			continue
-		}
-		changed = true
-		e := e
 		e.Kind = pointer.Enter
 
-		if h.filter.pointer.Matches(e) {
-			e.Position = q.invTransform(h.pointer.areaPlusOne-1, e.Position)
-			evts = append(evts, taggedEvent{tag: k, event: e})
+		if e.Kind&h.types != 0 {
+			e := e
+			e.Position = q.invTransform(h.area, e.Position)
+			events.Add(k, e)
 		}
 	}
-	p.entered = hits
-	return p, evts, cursor, changed
+	p.entered = append(p.entered[:0], hits...)
 }
 
-func (q *pointerQueue) deliverDragEvent(handlers map[event.Tag]*handler, p pointerInfo, evts []taggedEvent) (pointerInfo, []taggedEvent) {
+func (q *pointerQueue) deliverDragEvent(p *pointerInfo, events *handlerEvents) {
 	if p.dataSource != nil {
-		return p, evts
+		return
 	}
 	// Identify the data source.
 	for _, k := range p.entered {
-		src := &handlers[k].filter.pointer
+		src := q.handlers[k]
 		if len(src.sourceMimes) == 0 {
 			continue
 		}
 		// One data source handler per pointer.
 		p.dataSource = k
 		// Notify all potential targets.
-		for k, tgt := range handlers {
-			if _, ok := firstMimeMatch(src, &tgt.filter.pointer); ok {
-				evts = append(evts, taggedEvent{tag: k, event: transfer.InitiateEvent{}})
+		for k, tgt := range q.handlers {
+			if _, ok := firstMimeMatch(src, tgt); ok {
+				events.Add(k, transfer.InitiateEvent{})
 			}
 		}
 		break
 	}
-	return p, evts
 }
 
-func (q *pointerQueue) deliverDropEvent(handlers map[event.Tag]*handler, p pointerInfo, evts []taggedEvent) (pointerInfo, []taggedEvent) {
+func (q *pointerQueue) deliverDropEvent(p *pointerInfo, events *handlerEvents) {
 	if p.dataSource == nil {
-		return p, evts
+		return
 	}
 	// Request data from the source.
-	src := &handlers[p.dataSource].filter.pointer
+	src := q.handlers[p.dataSource]
 	for _, k := range p.entered {
-		h := handlers[k]
-		if m, ok := firstMimeMatch(src, &h.filter.pointer); ok {
+		h := q.handlers[k]
+		if m, ok := firstMimeMatch(src, h); ok {
 			p.dataTarget = k
-			evts = append(evts, taggedEvent{tag: p.dataSource, event: transfer.RequestEvent{Type: m}})
-			return p, evts
+			events.Add(p.dataSource, transfer.RequestEvent{Type: m})
+			return
 		}
 	}
 	// No valid target found, abort.
-	return q.deliverTransferCancelEvent(handlers, p, evts)
+	q.deliverTransferCancelEvent(p, events)
 }
 
-func (q *pointerQueue) deliverTransferCancelEvent(handlers map[event.Tag]*handler, p pointerInfo, evts []taggedEvent) (pointerInfo, []taggedEvent) {
-	evts = append(evts, taggedEvent{tag: p.dataSource, event: transfer.CancelEvent{}})
+func (q *pointerQueue) deliverTransferDataEvent(p *pointerInfo, events *handlerEvents) {
+	if p.dataSource == nil {
+		return
+	}
+	src := q.handlers[p.dataSource]
+	if src.data == nil {
+		// Data not received yet.
+		return
+	}
+	if p.dataTarget == nil {
+		q.deliverTransferCancelEvent(p, events)
+		return
+	}
+	// Send the offered data to the target.
+	transferIdx := len(q.transfers)
+	events.Add(p.dataTarget, transfer.DataEvent{
+		Type: src.offeredMime,
+		Open: func() io.ReadCloser {
+			q.transfers[transferIdx] = nil
+			return src.data
+		},
+	})
+	q.transfers = append(q.transfers, src.data)
+	p.dataTarget = nil
+}
+
+func (q *pointerQueue) deliverTransferCancelEvent(p *pointerInfo, events *handlerEvents) {
+	events.Add(p.dataSource, transfer.CancelEvent{})
 	// Cancel all potential targets.
-	src := &handlers[p.dataSource].filter.pointer
-	for k, h := range handlers {
-		if _, ok := firstMimeMatch(src, &h.filter.pointer); ok {
-			evts = append(evts, taggedEvent{tag: k, event: transfer.CancelEvent{}})
+	src := q.handlers[p.dataSource]
+	for k, h := range q.handlers {
+		if _, ok := firstMimeMatch(src, h); ok {
+			events.Add(k, transfer.CancelEvent{})
 		}
 	}
+	src.offeredMime = ""
+	src.data = nil
 	p.dataSource = nil
 	p.dataTarget = nil
-	return p, evts
 }
 
 // ClipFor clips r to the parents of area.
@@ -979,7 +928,7 @@ func addHandler(tags []event.Tag, tag event.Tag) []event.Tag {
 }
 
 // firstMimeMatch returns the first type match between src and tgt.
-func firstMimeMatch(src, tgt *pointerFilter) (first string, matched bool) {
+func firstMimeMatch(src, tgt *pointerHandler) (first string, matched bool) {
 	for _, m1 := range tgt.targetMimes {
 		for _, m2 := range src.sourceMimes {
 			if m1 == m2 {
@@ -1016,3 +965,13 @@ func (a *areaNode) bounds() image.Rectangle {
 		Max: a.trans.Transform(f32internal.FPt(a.area.rect.Max)),
 	}.Round()
 }
+
+func setScrollEvent(scroll float32, min, max int) (left, scrolled float32) {
+	if v := float32(max); scroll > v {
+		return scroll - v, v
+	}
+	if v := float32(min); scroll < v {
+		return scroll - v, v
+	}
+	return 0, scroll
+}

io/router/router.go

@@ -0,0 +1,634 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+/*
+Package router implements Router, a event.Queue implementation
+that that disambiguates and routes events to handlers declared
+in operation lists.
+
+Router is used by app.Window and is otherwise only useful for
+using Gio with external window implementations.
+*/
+package router
+
+import (
+	"encoding/binary"
+	"image"
+	"io"
+	"math"
+	"strings"
+	"time"
+
+	"gioui.org/f32"
+	f32internal "gioui.org/internal/f32"
+	"gioui.org/internal/ops"
+	"gioui.org/io/clipboard"
+	"gioui.org/io/event"
+	"gioui.org/io/key"
+	"gioui.org/io/pointer"
+	"gioui.org/io/profile"
+	"gioui.org/io/semantic"
+	"gioui.org/io/system"
+	"gioui.org/io/transfer"
+	"gioui.org/op"
+)
+
+// Router is a Queue implementation that routes events
+// to handlers declared in operation lists.
+type Router struct {
+	savedTrans []f32.Affine2D
+	transStack []f32.Affine2D
+	pointer    struct {
+		queue     pointerQueue
+		collector pointerCollector
+	}
+	key struct {
+		queue     keyQueue
+		collector keyCollector
+	}
+	cqueue clipboardQueue
+
+	handlers handlerEvents
+
+	reader ops.Reader
+
+	// InvalidateOp summary.
+	wakeup     bool
+	wakeupTime time.Time
+
+	// ProfileOp summary.
+	profHandlers map[event.Tag]struct{}
+	profile      profile.Event
+}
+
+// SemanticNode represents a node in the tree describing the components
+// contained in a frame.
+type SemanticNode struct {
+	ID       SemanticID
+	ParentID SemanticID
+	Children []SemanticNode
+	Desc     SemanticDesc
+
+	areaIdx int
+}
+
+// SemanticDesc provides a semantic description of a UI component.
+type SemanticDesc struct {
+	Class       semantic.ClassOp
+	Description string
+	Label       string
+	Selected    bool
+	Disabled    bool
+	Gestures    SemanticGestures
+	Bounds      image.Rectangle
+}
+
+// SemanticGestures is a bit-set of supported gestures.
+type SemanticGestures int
+
+const (
+	ClickGesture SemanticGestures = 1 << iota
+	ScrollGesture
+)
+
+// SemanticID uniquely identifies a SemanticDescription.
+//
+// By convention, the zero value denotes the non-existent ID.
+type SemanticID uint64
+
+type handlerEvents struct {
+	handlers  map[event.Tag][]event.Event
+	hadEvents bool
+}
+
+// Events returns the available events for the handler key.
+func (q *Router) Events(k event.Tag) []event.Event {
+	events := q.handlers.Events(k)
+	if _, isprof := q.profHandlers[k]; isprof {
+		delete(q.profHandlers, k)
+		events = append(events, q.profile)
+	}
+	return events
+}
+
+// Frame replaces the declared handlers from the supplied
+// operation list. The text input state, wakeup time and whether
+// there are active profile handlers is also saved.
+func (q *Router) Frame(frame *op.Ops) {
+	q.handlers.Clear()
+	q.wakeup = false
+	for k := range q.profHandlers {
+		delete(q.profHandlers, k)
+	}
+	var ops *ops.Ops
+	if frame != nil {
+		ops = &frame.Internal
+	}
+	q.reader.Reset(ops)
+	q.collect()
+
+	q.pointer.queue.Frame(&q.handlers)
+	q.key.queue.Frame(&q.handlers, q.key.collector)
+	if q.handlers.HadEvents() {
+		q.wakeup = true
+		q.wakeupTime = time.Time{}
+	}
+}
+
+// Queue key events to the topmost handler.
+func (q *Router) QueueTopmost(events ...key.Event) bool {
+	var topmost event.Tag
+	pq := &q.pointer.queue
+	for _, h := range pq.hitTree {
+		if h.ktag != nil {
+			topmost = h.ktag
+			break
+		}
+	}
+	if topmost == nil {
+		return false
+	}
+	for _, e := range events {
+		q.handlers.Add(topmost, e)
+	}
+	return q.handlers.HadEvents()
+}
+
+// Queue events and report whether at least one handler had an event queued.
+func (q *Router) Queue(events ...event.Event) bool {
+	for _, e := range events {
+		switch e := e.(type) {
+		case profile.Event:
+			q.profile = e
+		case pointer.Event:
+			q.pointer.queue.Push(e, &q.handlers)
+		case key.Event:
+			q.queueKeyEvent(e)
+		case key.SnippetEvent:
+			// Expand existing, overlapping snippet.
+			if r := q.key.queue.content.Snippet.Range; rangeOverlaps(r, key.Range(e)) {
+				if e.Start > r.Start {
+					e.Start = r.Start
+				}
+				if e.End < r.End {
+					e.End = r.End
+				}
+			}
+			if f := q.key.queue.focus; f != nil {
+				q.handlers.Add(f, e)
+			}
+		case key.EditEvent, key.FocusEvent, key.SelectionEvent:
+			if f := q.key.queue.focus; f != nil {
+				q.handlers.Add(f, e)
+			}
+		case clipboard.Event:
+			q.cqueue.Push(e, &q.handlers)
+		}
+	}
+	return q.handlers.HadEvents()
+}
+
+func rangeOverlaps(r1, r2 key.Range) bool {
+	r1 = rangeNorm(r1)
+	r2 = rangeNorm(r2)
+	return r1.Start <= r2.Start && r2.Start < r1.End ||
+		r1.Start <= r2.End && r2.End < r1.End
+}
+
+func rangeNorm(r key.Range) key.Range {
+	if r.End < r.Start {
+		r.End, r.Start = r.Start, r.End
+	}
+	return r
+}
+
+func (q *Router) queueKeyEvent(e key.Event) {
+	kq := &q.key.queue
+	f := q.key.queue.focus
+	if f != nil && kq.Accepts(f, e) {
+		q.handlers.Add(f, e)
+		return
+	}
+	pq := &q.pointer.queue
+	idx := len(pq.hitTree) - 1
+	focused := f != nil
+	if focused {
+		// If there is a focused tag, traverse its ancestry through the
+		// hit tree to search for handlers.
+		for ; pq.hitTree[idx].ktag != f; idx-- {
+		}
+	}
+	for idx != -1 {
+		n := &pq.hitTree[idx]
+		if focused {
+			idx = n.next
+		} else {
+			idx--
+		}
+		if n.ktag == nil {
+			continue
+		}
+		if kq.Accepts(n.ktag, e) {
+			q.handlers.Add(n.ktag, e)
+			break
+		}
+	}
+}
+
+func (q *Router) MoveFocus(dir FocusDirection) bool {
+	return q.key.queue.MoveFocus(dir, &q.handlers)
+}
+
+// RevealFocus scrolls the current focus (if any) into viewport
+// if there are scrollable parent handlers.
+func (q *Router) RevealFocus(viewport image.Rectangle) {
+	focus := q.key.queue.focus
+	if focus == nil {
+		return
+	}
+	bounds := q.key.queue.BoundsFor(focus)
+	area := q.key.queue.AreaFor(focus)
+	viewport = q.pointer.queue.ClipFor(area, viewport)
+
+	topleft := bounds.Min.Sub(viewport.Min)
+	topleft = max(topleft, bounds.Max.Sub(viewport.Max))
+	topleft = min(image.Pt(0, 0), topleft)
+	bottomright := bounds.Max.Sub(viewport.Max)
+	bottomright = min(bottomright, bounds.Min.Sub(viewport.Min))
+	bottomright = max(image.Pt(0, 0), bottomright)
+	s := topleft
+	if s.X == 0 {
+		s.X = bottomright.X
+	}
+	if s.Y == 0 {
+		s.Y = bottomright.Y
+	}
+	q.ScrollFocus(s)
+}
+
+// ScrollFocus scrolls the focused widget, if any, by dist.
+func (q *Router) ScrollFocus(dist image.Point) {
+	focus := q.key.queue.focus
+	if focus == nil {
+		return
+	}
+	area := q.key.queue.AreaFor(focus)
+	q.pointer.queue.Deliver(area, pointer.Event{
+		Kind:   pointer.Scroll,
+		Source: pointer.Touch,
+		Scroll: f32internal.FPt(dist),
+	}, &q.handlers)
+}
+
+func max(p1, p2 image.Point) image.Point {
+	m := p1
+	if p2.X > m.X {
+		m.X = p2.X
+	}
+	if p2.Y > m.Y {
+		m.Y = p2.Y
+	}
+	return m
+}
+
+func min(p1, p2 image.Point) image.Point {
+	m := p1
+	if p2.X < m.X {
+		m.X = p2.X
+	}
+	if p2.Y < m.Y {
+		m.Y = p2.Y
+	}
+	return m
+}
+
+func (q *Router) ActionAt(p f32.Point) (system.Action, bool) {
+	return q.pointer.queue.ActionAt(p)
+}
+
+func (q *Router) ClickFocus() {
+	focus := q.key.queue.focus
+	if focus == nil {
+		return
+	}
+	bounds := q.key.queue.BoundsFor(focus)
+	center := bounds.Max.Add(bounds.Min).Div(2)
+	e := pointer.Event{
+		Position: f32.Pt(float32(center.X), float32(center.Y)),
+		Source:   pointer.Touch,
+	}
+	area := q.key.queue.AreaFor(focus)
+	e.Kind = pointer.Press
+	q.pointer.queue.Deliver(area, e, &q.handlers)
+	e.Kind = pointer.Release
+	q.pointer.queue.Deliver(area, e, &q.handlers)
+}
+
+// TextInputState returns the input state from the most recent
+// call to Frame.
+func (q *Router) TextInputState() TextInputState {
+	return q.key.queue.InputState()
+}
+
+// TextInputHint returns the input mode from the most recent key.InputOp.
+func (q *Router) TextInputHint() (key.InputHint, bool) {
+	return q.key.queue.InputHint()
+}
+
+// WriteClipboard returns the most recent text to be copied
+// to the clipboard, if any.
+func (q *Router) WriteClipboard() (string, bool) {
+	return q.cqueue.WriteClipboard()
+}
+
+// ReadClipboard reports if any new handler is waiting
+// to read the clipboard.
+func (q *Router) ReadClipboard() bool {
+	return q.cqueue.ReadClipboard()
+}
+
+// Cursor returns the last cursor set.
+func (q *Router) Cursor() pointer.Cursor {
+	return q.pointer.queue.cursor
+}
+
+// SemanticAt returns the first semantic description under pos, if any.
+func (q *Router) SemanticAt(pos f32.Point) (SemanticID, bool) {
+	return q.pointer.queue.SemanticAt(pos)
+}
+
+// AppendSemantics appends the semantic tree to nodes, and returns the result.
+// The root node is the first added.
+func (q *Router) AppendSemantics(nodes []SemanticNode) []SemanticNode {
+	q.pointer.collector.q = &q.pointer.queue
+	q.pointer.collector.ensureRoot()
+	return q.pointer.queue.AppendSemantics(nodes)
+}
+
+// EditorState returns the editor state for the focused handler, or the
+// zero value if there is none.
+func (q *Router) EditorState() EditorState {
+	return q.key.queue.content
+}
+
+func (q *Router) collect() {
+	q.transStack = q.transStack[:0]
+	pc := &q.pointer.collector
+	pc.q = &q.pointer.queue
+	pc.reset()
+	kc := &q.key.collector
+	*kc = keyCollector{q: &q.key.queue}
+	q.key.queue.Reset()
+	var t f32.Affine2D
+	bo := binary.LittleEndian
+	for encOp, ok := q.reader.Decode(); ok; encOp, ok = q.reader.Decode() {
+		switch ops.OpType(encOp.Data[0]) {
+		case ops.TypeInvalidate:
+			op := decodeInvalidateOp(encOp.Data)
+			if !q.wakeup || op.At.Before(q.wakeupTime) {
+				q.wakeup = true
+				q.wakeupTime = op.At
+			}
+		case ops.TypeProfile:
+			op := decodeProfileOp(encOp.Data, encOp.Refs)
+			if q.profHandlers == nil {
+				q.profHandlers = make(map[event.Tag]struct{})
+			}
+			q.profHandlers[op.Tag] = struct{}{}
+		case ops.TypeClipboardRead:
+			q.cqueue.ProcessReadClipboard(encOp.Refs)
+		case ops.TypeClipboardWrite:
+			q.cqueue.ProcessWriteClipboard(encOp.Refs)
+		case ops.TypeSave:
+			id := ops.DecodeSave(encOp.Data)
+			if extra := id - len(q.savedTrans) + 1; extra > 0 {
+				q.savedTrans = append(q.savedTrans, make([]f32.Affine2D, extra)...)
+			}
+			q.savedTrans[id] = t
+		case ops.TypeLoad:
+			id := ops.DecodeLoad(encOp.Data)
+			t = q.savedTrans[id]
+			pc.resetState()
+			pc.setTrans(t)
+
+		case ops.TypeClip:
+			var op ops.ClipOp
+			op.Decode(encOp.Data)
+			pc.clip(op)
+		case ops.TypePopClip:
+			pc.popArea()
+		case ops.TypeTransform:
+			t2, push := ops.DecodeTransform(encOp.Data)
+			if push {
+				q.transStack = append(q.transStack, t)
+			}
+			t = t.Mul(t2)
+			pc.setTrans(t)
+		case ops.TypePopTransform:
+			n := len(q.transStack)
+			t = q.transStack[n-1]
+			q.transStack = q.transStack[:n-1]
+			pc.setTrans(t)
+
+		// Pointer ops.
+		case ops.TypePass:
+			pc.pass()
+		case ops.TypePopPass:
+			pc.popPass()
+		case ops.TypePointerInput:
+			op := pointer.InputOp{
+				Tag:   encOp.Refs[0].(event.Tag),
+				Grab:  encOp.Data[1] != 0,
+				Kinds: pointer.Kind(bo.Uint16(encOp.Data[2:])),
+				ScrollBounds: image.Rectangle{
+					Min: image.Point{
+						X: int(int32(bo.Uint32(encOp.Data[4:]))),
+						Y: int(int32(bo.Uint32(encOp.Data[8:]))),
+					},
+					Max: image.Point{
+						X: int(int32(bo.Uint32(encOp.Data[12:]))),
+						Y: int(int32(bo.Uint32(encOp.Data[16:]))),
+					},
+				},
+			}
+			pc.inputOp(op, &q.handlers)
+		case ops.TypeCursor:
+			name := pointer.Cursor(encOp.Data[1])
+			pc.cursor(name)
+		case ops.TypeSource:
+			op := transfer.SourceOp{
+				Tag:  encOp.Refs[0].(event.Tag),
+				Type: encOp.Refs[1].(string),
+			}
+			pc.sourceOp(op, &q.handlers)
+		case ops.TypeTarget:
+			op := transfer.TargetOp{
+				Tag:  encOp.Refs[0].(event.Tag),
+				Type: encOp.Refs[1].(string),
+			}
+			pc.targetOp(op, &q.handlers)
+		case ops.TypeOffer:
+			op := transfer.OfferOp{
+				Tag:  encOp.Refs[0].(event.Tag),
+				Type: encOp.Refs[1].(string),
+				Data: encOp.Refs[2].(io.ReadCloser),
+			}
+			pc.offerOp(op, &q.handlers)
+		case ops.TypeActionInput:
+			act := system.Action(encOp.Data[1])
+			pc.actionInputOp(act)
+
+		// Key ops.
+		case ops.TypeKeyFocus:
+			tag, _ := encOp.Refs[0].(event.Tag)
+			op := key.FocusOp{
+				Tag: tag,
+			}
+			kc.focusOp(op.Tag)
+		case ops.TypeKeySoftKeyboard:
+			op := key.SoftKeyboardOp{
+				Show: encOp.Data[1] != 0,
+			}
+			kc.softKeyboard(op.Show)
+		case ops.TypeKeyInput:
+			filter := key.Set(*encOp.Refs[1].(*string))
+			op := key.InputOp{
+				Tag:  encOp.Refs[0].(event.Tag),
+				Hint: key.InputHint(encOp.Data[1]),
+				Keys: filter,
+			}
+			a := pc.currentArea()
+			b := pc.currentAreaBounds()
+			pc.keyInputOp(op)
+			kc.inputOp(op, a, b)
+		case ops.TypeSnippet:
+			op := key.SnippetOp{
+				Tag: encOp.Refs[0].(event.Tag),
+				Snippet: key.Snippet{
+					Range: key.Range{
+						Start: int(int32(bo.Uint32(encOp.Data[1:]))),
+						End:   int(int32(bo.Uint32(encOp.Data[5:]))),
+					},
+					Text: *(encOp.Refs[1].(*string)),
+				},
+			}
+			kc.snippetOp(op)
+		case ops.TypeSelection:
+			op := key.SelectionOp{
+				Tag: encOp.Refs[0].(event.Tag),
+				Range: key.Range{
+					Start: int(int32(bo.Uint32(encOp.Data[1:]))),
+					End:   int(int32(bo.Uint32(encOp.Data[5:]))),
+				},
+				Caret: key.Caret{
+					Pos: f32.Point{
+						X: math.Float32frombits(bo.Uint32(encOp.Data[9:])),
+						Y: math.Float32frombits(bo.Uint32(encOp.Data[13:])),
+					},
+					Ascent:  math.Float32frombits(bo.Uint32(encOp.Data[17:])),
+					Descent: math.Float32frombits(bo.Uint32(encOp.Data[21:])),
+				},
+			}
+			kc.selectionOp(t, op)
+
+		// Semantic ops.
+		case ops.TypeSemanticLabel:
+			lbl := *encOp.Refs[0].(*string)
+			pc.semanticLabel(lbl)
+		case ops.TypeSemanticDesc:
+			desc := *encOp.Refs[0].(*string)
+			pc.semanticDesc(desc)
+		case ops.TypeSemanticClass:
+			class := semantic.ClassOp(encOp.Data[1])
+			pc.semanticClass(class)
+		case ops.TypeSemanticSelected:
+			if encOp.Data[1] != 0 {
+				pc.semanticSelected(true)
+			} else {
+				pc.semanticSelected(false)
+			}
+		case ops.TypeSemanticEnabled:
+			if encOp.Data[1] != 0 {
+				pc.semanticEnabled(true)
+			} else {
+				pc.semanticEnabled(false)
+			}
+		}
+	}
+}
+
+// Profiling reports whether there was profile handlers in the
+// most recent Frame call.
+func (q *Router) Profiling() bool {
+	return len(q.profHandlers) > 0
+}
+
+// WakeupTime returns the most recent time for doing another frame,
+// as determined from the last call to Frame.
+func (q *Router) WakeupTime() (time.Time, bool) {
+	return q.wakeupTime, q.wakeup
+}
+
+func (h *handlerEvents) init() {
+	if h.handlers == nil {
+		h.handlers = make(map[event.Tag][]event.Event)
+	}
+}
+
+func (h *handlerEvents) AddNoRedraw(k event.Tag, e event.Event) {
+	h.init()
+	h.handlers[k] = append(h.handlers[k], e)
+}
+
+func (h *handlerEvents) Add(k event.Tag, e event.Event) {
+	h.AddNoRedraw(k, e)
+	h.hadEvents = true
+}
+
+func (h *handlerEvents) HadEvents() bool {
+	u := h.hadEvents
+	h.hadEvents = false
+	return u
+}
+
+func (h *handlerEvents) Events(k event.Tag) []event.Event {
+	if events, ok := h.handlers[k]; ok {
+		h.handlers[k] = h.handlers[k][:0]
+		return events
+	}
+	return nil
+}
+
+func (h *handlerEvents) Clear() {
+	for k := range h.handlers {
+		delete(h.handlers, k)
+	}
+}
+
+func decodeProfileOp(d []byte, refs []interface{}) profile.Op {
+	if ops.OpType(d[0]) != ops.TypeProfile {
+		panic("invalid op")
+	}
+	return profile.Op{
+		Tag: refs[0].(event.Tag),
+	}
+}
+
+func decodeInvalidateOp(d []byte) op.InvalidateOp {
+	bo := binary.LittleEndian
+	if ops.OpType(d[0]) != ops.TypeInvalidate {
+		panic("invalid op")
+	}
+	var o op.InvalidateOp
+	if nanos := bo.Uint64(d[1:]); nanos > 0 {
+		o.At = time.Unix(0, int64(nanos))
+	}
+	return o
+}
+
+func (s SemanticGestures) String() string {
+	var gestures []string
+	if s&ClickGesture != 0 {
+		gestures = append(gestures, "Click")
+	}
+	return strings.Join(gestures, ",")
+}

io/router/semantic_test.go

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: Unlicense OR MIT
 
-package input
+package router
 
 import (
 	"fmt"
@@ -9,7 +9,6 @@ import (
 	"testing"
 
 	"gioui.org/f32"
-	"gioui.org/io/event"
 	"gioui.org/io/pointer"
 	"gioui.org/io/semantic"
 	"gioui.org/op"
@@ -75,19 +74,13 @@ func TestSemanticTree(t *testing.T) {
 
 func TestSemanticDescription(t *testing.T) {
 	var ops op.Ops
-
-	h := new(int)
-	event.Op(&ops, h)
+	pointer.InputOp{Tag: new(int), Kinds: pointer.Press | pointer.Release}.Add(&ops)
 	semantic.DescriptionOp("description").Add(&ops)
 	semantic.LabelOp("label").Add(&ops)
 	semantic.Button.Add(&ops)
 	semantic.EnabledOp(false).Add(&ops)
 	semantic.SelectedOp(true).Add(&ops)
 	var r Router
-	events(&r, -1, pointer.Filter{
-		Target: h,
-		Kinds:  pointer.Press | pointer.Release,
-	})
 	r.Frame(&ops)
 	tree := r.AppendSemantics(nil)
 	got := tree[0].Desc

io/system/system.go

@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: Unlicense OR MIT
+
+// Package system contains events usually handled at the top-level
+// program level.
+package system
+
+import (
+	"image"
+	"time"
+
+	"gioui.org/io/event"
+	"gioui.org/op"
+	"gioui.org/unit"
+)
+
+// A FrameEvent requests a new frame in the form of a list of
+// operations that describes what to display and how to handle
+// input.
+type FrameEvent struct {
+	// Now is the current animation. Use Now instead of time.Now to
+	// synchronize animation and to avoid the time.Now call overhead.
+	Now time.Time
+	// Metric converts device independent dp and sp to device pixels.
+	Metric unit.Metric
+	// Size is the dimensions of the window.
+	Size image.Point
+	// Insets represent the space occupied by system decorations and controls.
+	Insets Insets
+	// Frame completes the FrameEvent by drawing the graphical operations
+	// from ops into the window.
+	Frame func(frame *op.Ops)
+	// Queue supplies the events for event handlers.
+	Queue event.Queue
+}
+
+// DestroyEvent is the last event sent through
+// a window event channel.
+type DestroyEvent struct {
+	// Err is nil for normal window closures. If a
+	// window is prematurely closed, Err is the cause.
+	Err error
+}
+
+// Insets is the space taken up by
+// system decoration such as translucent
+// system bars and software keyboards.
+type Insets struct {
+	// Values are in pixels.
+	Top, Bottom, Left, Right unit.Dp
+}
+
+// A StageEvent is generated whenever the stage of a
+// Window changes.
+type StageEvent struct {
+	Stage Stage
+}
+
+// Stage of a Window.
+type Stage uint8
+
+const (
+	// StagePaused is the stage for windows that have no on-screen representation.
+	// Paused windows don't receive FrameEvent.
+	StagePaused Stage = iota
+	// StageInactive is the stage for windows that are visible, but not active.
+	// Inactive windows receive FrameEvent.
+	StageInactive
+	// StageRunning is for active and visible Windows.
+	// Running windows receive FrameEvent.
+	StageRunning
+)
+
+// String implements fmt.Stringer.
+func (l Stage) String() string {
+	switch l {
+	case StagePaused:
+		return "StagePaused"
+	case StageInactive:
+		return "StageInactive"
+	case StageRunning:
+		return "StageRunning"
+	default:
+		panic("unexpected Stage value")
+	}
+}
+
+func (FrameEvent) ImplementsEvent()   {}
+func (StageEvent) ImplementsEvent()   {}
+func (DestroyEvent) ImplementsEvent() {}

io/transfer/transfer.go

@@ -2,11 +2,11 @@
 //
 // The transfer protocol is as follows:
 //
-//   - Data sources use [SourceFilter] to receive an [InitiateEvent] when a drag
-//     is initiated, and an [RequestEvent] for each initiation of a data transfer.
-//     Sources respond to requests with [OfferCmd].
-//   - Data targets use [TargetFilter] to receive an [DataEvent] for receiving data.
-//     The target must close the data event after use.
+//   - Data sources are registered with SourceOps, data targets with TargetOps.
+//   - A data source receives a RequestEvent when a transfer is initiated.
+//     It must respond with an OfferOp.
+//   - The target receives a DataEvent when transferring to it. It must close
+//     the event data after use.
 //
 // When a user initiates a pointer-guided drag and drop transfer, the
 // source as well as all potential targets receive an InitiateEvent.
@@ -20,11 +20,29 @@ package transfer
 import (
 	"io"
 
+	"gioui.org/internal/ops"
 	"gioui.org/io/event"
+	"gioui.org/op"
 )
 
-// OfferCmd is used by data sources as a response to a RequestEvent.
-type OfferCmd struct {
+// SourceOp registers a tag as a data source for a MIME type.
+// Use multiple SourceOps if a tag supports multiple types.
+type SourceOp struct {
+	Tag event.Tag
+	// Type is the MIME type supported by this source.
+	Type string
+}
+
+// TargetOp registers a tag as a data target.
+// Use multiple TargetOps if a tag supports multiple types.
+type TargetOp struct {
+	Tag event.Tag
+	// Type is the MIME type accepted by this target.
+	Type string
+}
+
+// OfferOp is used by data sources as a response to a RequestEvent.
+type OfferOp struct {
 	Tag event.Tag
 	// Type is the MIME type of Data.
 	// It must be the Type from the corresponding RequestEvent.
@@ -32,33 +50,32 @@ type OfferCmd struct {
 	// Data contains the offered data. It is closed when the
 	// transfer is complete or cancelled.
 	// Data must be kept valid until closed, and it may be used from
-	// a goroutine separate from the one processing the frame.
+	// a goroutine separate from the one processing the frame..
 	Data io.ReadCloser
 }
 
-func (OfferCmd) ImplementsCommand() {}
-
-// SourceFilter filters for any [RequestEvent] that match a MIME type
-// as well as [InitiateEvent] and [CancelEvent].
-// Use multiple filters to offer multiple types.
-type SourceFilter struct {
-	// Target is a tag included in a previous event.Op.
-	Target event.Tag
-	// Type is the MIME type supported by this source.
-	Type string
+func (op SourceOp) Add(o *op.Ops) {
+	data := ops.Write2(&o.Internal, ops.TypeSourceLen, op.Tag, op.Type)
+	data[0] = byte(ops.TypeSource)
 }
 
-// TargetFilter filters for any [DataEvent] whose type matches a MIME type
-// as well as [CancelEvent]. Use multiple filters to accept multiple types.
-type TargetFilter struct {
-	// Target is a tag included in a previous event.Op.
-	Target event.Tag
-	// Type is the MIME type accepted by this target.
-	Type string
+func (op TargetOp) Add(o *op.Ops) {
+	data := ops.Write2(&o.Internal, ops.TypeTargetLen, op.Tag, op.Type)
+	data[0] = byte(ops.TypeTarget)
+}
+
+// Add the offer to the list of operations.
+// It panics if the Data field is not set.
+func (op OfferOp) Add(o *op.Ops) {
+	if op.Data == nil {
+		panic("invalid nil data in OfferOp")
+	}
+	data := ops.Write3(&o.Internal, ops.TypeOfferLen, op.Tag, op.Type, op.Data)
+	data[0] = byte(ops.TypeOffer)
 }
 
 // RequestEvent requests data from a data source. The source must
-// respond with an OfferCmd.
+// respond with an OfferOp.
 type RequestEvent struct {
 	// Type is the first matched type between the source and the target.
 	Type string
@@ -90,6 +107,3 @@ type DataEvent struct {
 }
 
 func (DataEvent) ImplementsEvent() {}
-
-func (SourceFilter) ImplementsFilter() {}
-func (TargetFilter) ImplementsFilter() {}

layout/context.go

@@ -3,9 +3,10 @@
 package layout
 
 import (
+	"image"
 	"time"
 
-	"gioui.org/io/input"
+	"gioui.org/io/event"
 	"gioui.org/io/system"
 	"gioui.org/op"
 	"gioui.org/unit"
@@ -20,6 +21,9 @@ type Context struct {
 	Constraints Constraints
 
 	Metric unit.Metric
+	// By convention, a nil Queue is a signal to widgets to draw themselves
+	// in a disabled state.
+	Queue event.Queue
 	// Now is the animation time.
 	Now time.Time
 
@@ -28,10 +32,46 @@ type Context struct {
 	// Interested users must look up and populate these values manually.
 	Locale system.Locale
 
-	input.Source
 	*op.Ops
 }
 
+// NewContext is a shorthand for
+//
+//	Context{
+//	  Ops: ops,
+//	  Now: e.Now,
+//	  Queue: e.Queue,
+//	  Config: e.Config,
+//	  Constraints: Exact(e.Size),
+//	}
+//
+// NewContext calls ops.Reset and adjusts ops for e.Insets.
+func NewContext(ops *op.Ops, e system.FrameEvent) Context {
+	ops.Reset()
+
+	size := e.Size
+
+	if e.Insets != (system.Insets{}) {
+		left := e.Metric.Dp(e.Insets.Left)
+		top := e.Metric.Dp(e.Insets.Top)
+		op.Offset(image.Point{
+			X: left,
+			Y: top,
+		}).Add(ops)
+
+		size.X -= left + e.Metric.Dp(e.Insets.Right)
+		size.Y -= top + e.Metric.Dp(e.Insets.Bottom)
+	}
+
+	return Context{
+		Ops:         ops,
+		Now:         e.Now,
+		Queue:       e.Queue,
+		Metric:      e.Metric,
+		Constraints: Exact(size),
+	}
+}
+
 // Dp converts v to pixels.
 func (c Context) Dp(v unit.Dp) int {
 	return c.Metric.Dp(v)
@@ -42,9 +82,21 @@ func (c Context) Sp(v unit.Sp) int {
 	return c.Metric.Sp(v)
 }
 
-// Disabled returns a copy of this context with a disabled Source,
-// blocking widgets from changing its state and receiving events.
+// Events returns the events available for the key. If no
+// queue is configured, Events returns nil.
+func (c Context) Events(k event.Tag) []event.Event {
+	if c.Queue == nil {
+		return nil
+	}
+	return c.Queue.Events(k)
+}
+
+// Disabled returns a copy of this context with a nil Queue,
+// blocking events to widgets using it.
+//
+// By convention, a nil Queue is a signal to widgets to draw themselves
+// in a disabled state.
 func (c Context) Disabled() Context {
-	c.Source = input.Source{}
+	c.Queue = nil
 	return c
 }

layout/list.go

@@ -7,7 +7,6 @@ import (
 	"math"
 
 	"gioui.org/gesture"
-	"gioui.org/io/pointer"
 	"gioui.org/op"
 	"gioui.org/op/clip"
 )
@@ -145,26 +144,7 @@ func (l *List) Dragging() bool {
 }
 
 func (l *List) update(gtx Context) {
-	min, max := int(-inf), int(inf)
-	if l.Position.First == 0 {
-		// Use the size of the invisible part as scroll boundary.
-		min = -l.Position.Offset
-		if min > 0 {
-			min = 0
-		}
-	}
-	if l.Position.First+l.Position.Count == l.len {
-		max = -l.Position.OffsetLast
-		if max < 0 {
-			max = 0
-		}
-	}
-	xrange := pointer.ScrollRange{Min: min, Max: max}
-	yrange := pointer.ScrollRange{}
-	if l.Axis == Vertical {
-		xrange, yrange = yrange, xrange
-	}
-	d := l.scroll.Update(gtx.Metric, gtx.Source, gtx.Now, gesture.Axis(l.Axis), xrange, yrange)
+	d := l.scroll.Update(gtx.Metric, gtx, gtx.Now, gesture.Axis(l.Axis))
 	l.scrollDelta = d
 	l.Position.Offset += d
 }
@@ -352,7 +332,25 @@ func (l *List) layout(ops *op.Ops, macro op.MacroOp) Dimensions {
 	call := macro.Stop()
 	defer clip.Rect(image.Rectangle{Max: dims}).Push(ops).Pop()
 
-	l.scroll.Add(ops)
+	min, max := int(-inf), int(inf)
+	if l.Position.First == 0 {
+		// Use the size of the invisible part as scroll boundary.
+		min = -l.Position.Offset
+		if min > 0 {
+			min = 0
+		}
+	}
+	if l.Position.First+l.Position.Count == l.len {
+		max = -l.Position.OffsetLast
+		if max < 0 {
+			max = 0
+		}
+	}
+	scrollRange := image.Rectangle{
+		Min: l.Axis.Convert(image.Pt(min, 0)),
+		Max: l.Axis.Convert(image.Pt(max, 0)),
+	}
+	l.scroll.Add(ops, scrollRange)
 
 	call.Add(ops)
 	return Dimensions{Size: dims}

layout/list_test.go

@@ -8,8 +8,8 @@ import (
 
 	"gioui.org/f32"
 	"gioui.org/io/event"
-	"gioui.org/io/input"
 	"gioui.org/io/pointer"
+	"gioui.org/io/router"
 	"gioui.org/op"
 )
 
@@ -64,13 +64,13 @@ func TestListScrollToEnd(t *testing.T) {
 
 func TestListPosition(t *testing.T) {
 	_s := func(e ...event.Event) []event.Event { return e }
-	r := new(input.Router)
+	r := new(router.Router)
 	gtx := Context{
 		Ops: new(op.Ops),
 		Constraints: Constraints{
 			Max: image.Pt(20, 10),
 		},
-		Source: r.Source(),
+		Queue: r,
 	}
 	el := func(gtx Context, idx int) Dimensions {
 		return Dimensions{Size: image.Pt(10, 10)}

op/clip/clip.go

@@ -138,9 +138,6 @@ type Path struct {
 func (p *Path) Pos() f32.Point { return p.pen }
 
 // Begin the path, storing the path data and final Op into ops.
-//
-// Caller must also call End to finish the drawing.
-// Forgetting to call it will result in a "panic: cannot mix multi ops with single ones".
 func (p *Path) Begin(o *op.Ops) {
 	*p = Path{
 		ops:     &o.Internal,

op/op.go

@@ -53,6 +53,7 @@ The MacroOp records a list of operations to be executed later:
 	ops := new(op.Ops)
 	macro := op.Record(ops)
 	// Record operations by adding them.
+	op.InvalidateOp{}.Add(ops)
 	...
 	// End recording.
 	call := macro.Stop()
@@ -95,9 +96,9 @@ type CallOp struct {
 	end   ops.PC
 }
 
-// InvalidateCmd requests a redraw at the given time. Use
+// InvalidateOp requests a redraw at the given time. Use
 // the zero value to request an immediate redraw.
-type InvalidateCmd struct {
+type InvalidateOp struct {
 	At time.Time
 }
 
@@ -180,6 +181,19 @@ func (c CallOp) Add(o *Ops) {
 	ops.AddCall(&o.Internal, c.ops, c.start, c.end)
 }
 
+func (r InvalidateOp) Add(o *Ops) {
+	data := ops.Write(&o.Internal, ops.TypeRedrawLen)
+	data[0] = byte(ops.TypeInvalidate)
+	bo := binary.LittleEndian
+	// UnixNano cannot represent the zero time.
+	if t := r.At; !t.IsZero() {
+		nanos := t.UnixNano()
+		if nanos > 0 {
+			bo.PutUint64(data[1:], uint64(nanos))
+		}
+	}
+}
+
 // Offset converts an offset to a TransformOp.
 func Offset(off image.Point) TransformOp {
 	offf := f32.Pt(float32(off.X), float32(off.Y))
@@ -226,5 +240,3 @@ func (t TransformStack) Pop() {
 	data := ops.Write(t.ops, ops.TypePopTransformLen)
 	data[0] = byte(ops.TypePopTransform)
 }
-
-func (InvalidateCmd) ImplementsCommand() {}

text/gotext.go

@@ -4,7 +4,6 @@ package text
 
 import (
 	"bytes"
-	"fmt"
 	"image"
 	"io"
 	"log"
@@ -277,8 +276,7 @@ func newShaperImpl(systemFonts bool, collection []FontFace) *shaperImpl {
 // It returns whether the face is now available for use. FontFaces are prioritized
 // in the order in which they are loaded, with the first face being the default.
 func (s *shaperImpl) Load(f FontFace) {
-	desc := opentype.FontToDescription(f.Font)
-	s.fontMap.AddFace(f.Face.Face(), fontscan.Location{File: fmt.Sprint(desc)}, desc)
+	s.fontMap.AddFace(f.Face.Face(), opentype.FontToDescription(f.Font))
 	s.addFace(f.Face.Face(), f.Font)
 }
 

text/lru.go

@@ -163,6 +163,10 @@ type layoutKey struct {
 	lineHeightScale    float32
 }
 
+type pathKey struct {
+	gidHash uint64
+}
+
 const maxSize = 1000
 
 func gidsEqual(a []glyphInfo, glyphs []Glyph) bool {

widget/bool.go

@@ -16,7 +16,7 @@ type Bool struct {
 // Update the widget state and report whether Value was changed.
 func (b *Bool) Update(gtx layout.Context) bool {
 	changed := false
-	for b.clk.clicked(b, gtx) {
+	for b.clk.Clicked(gtx) {
 		b.Value = !b.Value
 		changed = true
 	}
@@ -33,15 +33,20 @@ func (b *Bool) Pressed() bool {
 	return b.clk.Pressed()
 }
 
+// Focused reports whether b has focus.
+func (b *Bool) Focused() bool {
+	return b.clk.Focused()
+}
+
 func (b *Bool) History() []Press {
 	return b.clk.History()
 }
 
 func (b *Bool) Layout(gtx layout.Context, w layout.Widget) layout.Dimensions {
 	b.Update(gtx)
-	dims := b.clk.layout(b, gtx, func(gtx layout.Context) layout.Dimensions {
+	dims := b.clk.Layout(gtx, func(gtx layout.Context) layout.Dimensions {
 		semantic.SelectedOp(b.Value).Add(gtx.Ops)
-		semantic.EnabledOp(gtx.Enabled()).Add(gtx.Ops)
+		semantic.EnabledOp(gtx.Queue != nil).Add(gtx.Ops)
 		return w(gtx)
 	})
 	return dims

widget/buffer.go

@@ -11,6 +11,9 @@ import (
 
 // editBuffer implements a gap buffer for text editing.
 type editBuffer struct {
+	// pos is the byte position for Read and ReadRune.
+	pos int
+
 	// The gap start and end in bytes.
 	gapstart, gapend int
 	text             []byte

widget/button.go

@@ -7,7 +7,6 @@ import (
 	"time"
 
 	"gioui.org/gesture"
-	"gioui.org/io/event"
 	"gioui.org/io/key"
 	"gioui.org/io/pointer"
 	"gioui.org/io/semantic"
@@ -18,11 +17,16 @@ import (
 
 // Clickable represents a clickable area.
 type Clickable struct {
-	click   gesture.Click
+	click gesture.Click
+	// clicks is for saved clicks to support Clicked.
+	clicks  []Click
 	history []Press
 
+	keyTag        struct{}
+	requestFocus  bool
 	requestClicks int
-	pressedKey    key.Name
+	focused       bool
+	pressedKey    string
 }
 
 // Click represents a click.
@@ -49,14 +53,19 @@ func (b *Clickable) Click() {
 	b.requestClicks++
 }
 
-// Clicked calls Update and reports whether a click was registered.
+// Clicked reports whether there are pending clicks. If so, Clicked
+// removes the earliest click.
 func (b *Clickable) Clicked(gtx layout.Context) bool {
-	return b.clicked(b, gtx)
-}
-
-func (b *Clickable) clicked(t event.Tag, gtx layout.Context) bool {
-	_, clicked := b.update(t, gtx)
-	return clicked
+	if len(b.clicks) > 0 {
+		b.clicks = b.clicks[1:]
+		return true
+	}
+	b.clicks = b.Update(gtx)
+	if len(b.clicks) > 0 {
+		b.clicks = b.clicks[1:]
+		return true
+	}
+	return false
 }
 
 // Hovered reports whether a pointer is over the element.
@@ -69,6 +78,16 @@ func (b *Clickable) Pressed() bool {
 	return b.click.Pressed()
 }
 
+// Focus requests the input focus for the element.
+func (b *Clickable) Focus() {
+	b.requestFocus = true
+}
+
+// Focused reports whether b has focus.
+func (b *Clickable) Focused() bool {
+	return b.focused
+}
+
 // History is the past pointer presses useful for drawing markers.
 // History is retained for a short duration (about a second).
 func (b *Clickable) History() []Press {
@@ -77,34 +96,36 @@ func (b *Clickable) History() []Press {
 
 // Layout and update the button state.
 func (b *Clickable) Layout(gtx layout.Context, w layout.Widget) layout.Dimensions {
-	return b.layout(b, gtx, w)
-}
-
-func (b *Clickable) layout(t event.Tag, gtx layout.Context, w layout.Widget) layout.Dimensions {
-	for {
-		_, ok := b.update(t, gtx)
-		if !ok {
-			break
-		}
-	}
+	b.Update(gtx)
 	m := op.Record(gtx.Ops)
 	dims := w(gtx)
 	c := m.Stop()
 	defer clip.Rect(image.Rectangle{Max: dims.Size}).Push(gtx.Ops).Pop()
-	semantic.EnabledOp(gtx.Enabled()).Add(gtx.Ops)
+	enabled := gtx.Queue != nil
+	semantic.EnabledOp(enabled).Add(gtx.Ops)
 	b.click.Add(gtx.Ops)
-	event.Op(gtx.Ops, t)
+	if enabled {
+		keys := key.Set("⏎|Space")
+		if !b.focused {
+			keys = ""
+		}
+		key.InputOp{Tag: &b.keyTag, Keys: keys}.Add(gtx.Ops)
+	}
 	c.Add(gtx.Ops)
 	return dims
 }
 
-// Update the button state by processing events, and return the next
-// click, if any.
-func (b *Clickable) Update(gtx layout.Context) (Click, bool) {
-	return b.update(b, gtx)
-}
-
-func (b *Clickable) update(t event.Tag, gtx layout.Context) (Click, bool) {
+// Update the button state by processing events, and return the resulting
+// clicks, if any.
+func (b *Clickable) Update(gtx layout.Context) []Click {
+	b.clicks = nil
+	if gtx.Queue == nil {
+		b.focused = false
+	}
+	if b.requestFocus {
+		key.FocusOp{Tag: &b.keyTag}.Add(gtx.Ops)
+		b.requestFocus = false
+	}
 	for len(b.history) > 0 {
 		c := b.history[0]
 		if c.End.IsZero() || gtx.Now.Sub(c.End) < 1*time.Second {
@@ -113,26 +134,23 @@ func (b *Clickable) update(t event.Tag, gtx layout.Context) (Click, bool) {
 		n := copy(b.history, b.history[1:])
 		b.history = b.history[:n]
 	}
+	var clicks []Click
 	if c := b.requestClicks; c > 0 {
 		b.requestClicks = 0
-		return Click{
+		clicks = append(clicks, Click{
 			NumClicks: c,
-		}, true
+		})
 	}
-	for {
-		e, ok := b.click.Update(gtx.Source)
-		if !ok {
-			break
-		}
+	for _, e := range b.click.Update(gtx) {
 		switch e.Kind {
 		case gesture.KindClick:
 			if l := len(b.history); l > 0 {
 				b.history[l-1].End = gtx.Now
 			}
-			return Click{
+			clicks = append(clicks, Click{
 				Modifiers: e.Modifiers,
 				NumClicks: e.NumClicks,
-			}, true
+			})
 		case gesture.KindCancel:
 			for i := range b.history {
 				b.history[i].Cancelled = true
@@ -142,7 +160,7 @@ func (b *Clickable) update(t event.Tag, gtx layout.Context) (Click, bool) {
 			}
 		case gesture.KindPress:
 			if e.Source == pointer.Mouse {
-				gtx.Execute(key.FocusCmd{Tag: t})
+				key.FocusOp{Tag: &b.keyTag}.Add(gtx.Ops)
 			}
 			b.history = append(b.history, Press{
 				Position: e.Position,
@@ -150,22 +168,15 @@ func (b *Clickable) update(t event.Tag, gtx layout.Context) (Click, bool) {
 			})
 		}
 	}
-	for {
-		e, ok := gtx.Event(
-			key.FocusFilter{Target: t},
-			key.Filter{Focus: t, Name: key.NameReturn},
-			key.Filter{Focus: t, Name: key.NameSpace},
-		)
-		if !ok {
-			break
-		}
+	for _, e := range gtx.Events(&b.keyTag) {
 		switch e := e.(type) {
 		case key.FocusEvent:
-			if e.Focus {
+			b.focused = e.Focus
+			if !b.focused {
 				b.pressedKey = ""
 			}
 		case key.Event:
-			if !gtx.Focused(t) {
+			if !b.focused {
 				break
 			}
 			if e.Name != key.NameReturn && e.Name != key.NameSpace {
@@ -180,12 +191,12 @@ func (b *Clickable) update(t event.Tag, gtx layout.Context) (Click, bool) {
 				}
 				// only register a key as a click if the key was pressed and released while this button was focused
 				b.pressedKey = ""
-				return Click{
+				clicks = append(clicks, Click{
 					Modifiers: e.Modifiers,
 					NumClicks: 1,
-				}, true
+				})
 			}
 		}
 	}
-	return Click{}, false
+	return clicks
 }

widget/button_test.go

@@ -6,8 +6,9 @@ import (
 	"image"
 	"testing"
 
-	"gioui.org/io/input"
 	"gioui.org/io/key"
+	"gioui.org/io/router"
+	"gioui.org/io/system"
 	"gioui.org/layout"
 	"gioui.org/op"
 	"gioui.org/widget"
@@ -15,14 +16,12 @@ import (
 
 func TestClickable(t *testing.T) {
 	var (
-		r  input.Router
-		b1 widget.Clickable
-		b2 widget.Clickable
+		ops op.Ops
+		r   router.Router
+		b1  widget.Clickable
+		b2  widget.Clickable
 	)
-	gtx := layout.Context{
-		Ops:    new(op.Ops),
-		Source: r.Source(),
-	}
+	gtx := layout.NewContext(&ops, system.FrameEvent{Queue: &r})
 	layout := func() {
 		b1.Layout(gtx, func(gtx layout.Context) layout.Dimensions {
 			return layout.Dimensions{Size: image.Pt(100, 100)}
@@ -33,18 +32,23 @@ func TestClickable(t *testing.T) {
 		})
 	}
 	frame := func() {
-		gtx.Reset()
+		ops.Reset()
 		layout()
 		r.Frame(gtx.Ops)
 	}
-	gtx.Execute(key.FocusCmd{Tag: &b1})
+	// frame: request focus for button 1
+	b1.Focus()
 	frame()
-	if !gtx.Focused(&b1) {
+	// frame: gain focus for button 1
+	frame()
+	if !b1.Focused() {
 		t.Error("button 1 did not gain focus")
 	}
-	if gtx.Focused(&b2) {
+	if b2.Focused() {
 		t.Error("button 2 should not have focus")
 	}
+	// frame: press & release return
+	frame()
 	r.Queue(
 		key.Event{
 			Name:  key.NameReturn,
@@ -61,30 +65,36 @@ func TestClickable(t *testing.T) {
 	if b2.Clicked(gtx) {
 		t.Error("button 2 got clicked when it did not have focus")
 	}
+	// frame: press return down
 	r.Queue(
 		key.Event{
 			Name:  key.NameReturn,
 			State: key.Press,
 		},
 	)
+	frame()
 	if b1.Clicked(gtx) {
 		t.Error("button 1 got clicked, even if it only got return press")
 	}
+	// frame: request focus for button 2
+	b2.Focus()
 	frame()
-	gtx.Execute(key.FocusCmd{Tag: &b2})
+	// frame: gain focus for button 2
 	frame()
-	if gtx.Focused(&b1) {
+	if b1.Focused() {
 		t.Error("button 1 should not have focus")
 	}
-	if !gtx.Focused(&b2) {
+	if !b2.Focused() {
 		t.Error("button 2 did not gain focus")
 	}
+	// frame: release return
 	r.Queue(
 		key.Event{
 			Name:  key.NameReturn,
 			State: key.Release,
 		},
 	)
+	frame()
 	if b1.Clicked(gtx) {
 		t.Error("button 1 got clicked, even if it had lost focus")
 	}

widget/decorations.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"math/bits"
 
+	"gioui.org/gesture"
 	"gioui.org/io/system"
 	"gioui.org/layout"
 	"gioui.org/op/clip"
@@ -11,7 +12,11 @@ import (
 
 // Decorations handles the states of window decorations.
 type Decorations struct {
-	clicks    map[int]*Clickable
+	clicks map[int]*Clickable
+	resize [8]struct {
+		gesture.Hover
+		gesture.Drag
+	}
 	maximized bool
 }
 

widget/dnd.go

@@ -5,7 +5,6 @@ import (
 
 	"gioui.org/f32"
 	"gioui.org/gesture"
-	"gioui.org/io/event"
 	"gioui.org/io/pointer"
 	"gioui.org/io/transfer"
 	"gioui.org/layout"
@@ -18,20 +17,24 @@ type Draggable struct {
 	// Type contains the MIME type and matches transfer.SourceOp.
 	Type string
 
-	drag  gesture.Drag
-	click f32.Point
-	pos   f32.Point
+	handle struct{}
+	drag   gesture.Drag
+	click  f32.Point
+	pos    f32.Point
 }
 
 func (d *Draggable) Layout(gtx layout.Context, w, drag layout.Widget) layout.Dimensions {
-	if !gtx.Enabled() {
+	if gtx.Queue == nil {
 		return w(gtx)
 	}
 	dims := w(gtx)
 
 	stack := clip.Rect{Max: dims.Size}.Push(gtx.Ops)
 	d.drag.Add(gtx.Ops)
-	event.Op(gtx.Ops, d)
+	transfer.SourceOp{
+		Tag:  &d.handle,
+		Type: d.Type,
+	}.Add(gtx.Ops)
 	stack.Pop()
 
 	if drag != nil && d.drag.Pressed() {
@@ -53,11 +56,7 @@ func (d *Draggable) Dragging() bool {
 // requested to offer data, if any
 func (d *Draggable) Update(gtx layout.Context) (mime string, requested bool) {
 	pos := d.pos
-	for {
-		ev, ok := d.drag.Update(gtx.Metric, gtx.Source, gesture.Both)
-		if !ok {
-			break
-		}
+	for _, ev := range d.drag.Update(gtx.Metric, gtx.Queue, gesture.Both) {
 		switch ev.Kind {
 		case pointer.Press:
 			d.click = ev.Position
@@ -68,12 +67,8 @@ func (d *Draggable) Update(gtx layout.Context) (mime string, requested bool) {
 	}
 	d.pos = pos
 
-	for {
-		e, ok := gtx.Event(transfer.SourceFilter{Target: d, Type: d.Type})
-		if !ok {
-			break
-		}
-		if e, ok := e.(transfer.RequestEvent); ok {
+	for _, ev := range gtx.Queue.Events(&d.handle) {
+		if e, ok := ev.(transfer.RequestEvent); ok {
 			return e.Type, true
 		}
 	}
@@ -82,8 +77,12 @@ func (d *Draggable) Update(gtx layout.Context) (mime string, requested bool) {
 
 // Offer the data ready for a drop. Must be called after being Requested.
 // The mime must be one in the requested list.
-func (d *Draggable) Offer(gtx layout.Context, mime string, data io.ReadCloser) {
-	gtx.Execute(transfer.OfferCmd{Tag: d, Type: mime, Data: data})
+func (d *Draggable) Offer(ops *op.Ops, mime string, data io.ReadCloser) {
+	transfer.OfferOp{
+		Tag:  &d.handle,
+		Type: mime,
+		Data: data,
+	}.Add(ops)
 }
 
 // Pos returns the drag position relative to its initial click position.

widget/dnd_test.go

@@ -5,9 +5,8 @@ import (
 	"testing"
 
 	"gioui.org/f32"
-	"gioui.org/io/event"
-	"gioui.org/io/input"
 	"gioui.org/io/pointer"
+	"gioui.org/io/router"
 	"gioui.org/io/transfer"
 	"gioui.org/layout"
 	"gioui.org/op"
@@ -15,27 +14,27 @@ import (
 )
 
 func TestDraggable(t *testing.T) {
-	var r input.Router
+	var r router.Router
 	gtx := layout.Context{
 		Constraints: layout.Exact(image.Pt(100, 100)),
-		Source:      r.Source(),
+		Queue:       &r,
 		Ops:         new(op.Ops),
 	}
 
 	drag := &Draggable{
 		Type: "file",
 	}
-	tgt := new(int)
 	defer pointer.PassOp{}.Push(gtx.Ops).Pop()
 	dims := drag.Layout(gtx, func(gtx layout.Context) layout.Dimensions {
 		return layout.Dimensions{Size: gtx.Constraints.Min}
 	}, nil)
 	stack := clip.Rect{Max: dims.Size}.Push(gtx.Ops)
-	event.Op(gtx.Ops, tgt)
+	transfer.TargetOp{
+		Tag:  drag,
+		Type: drag.Type,
+	}.Add(gtx.Ops)
 	stack.Pop()
 
-	drag.Update(gtx)
-	r.Event(transfer.TargetFilter{Target: tgt, Type: drag.Type})
 	r.Frame(gtx.Ops)
 	r.Queue(
 		pointer.Event{
@@ -52,28 +51,21 @@ func TestDraggable(t *testing.T) {
 		},
 	)
 	ofr := &offer{data: "hello"}
-	drag.Update(gtx)
-	r.Event(transfer.TargetFilter{Target: tgt, Type: drag.Type})
-	drag.Offer(gtx, "file", ofr)
+	drag.Offer(gtx.Ops, "file", ofr)
+	r.Frame(gtx.Ops)
 
-	e, ok := r.Event(transfer.TargetFilter{Target: tgt, Type: drag.Type})
-	if !ok {
-		t.Fatalf("expected event")
+	evs := r.Events(drag)
+	if len(evs) != 1 {
+		t.Fatalf("expected 1 event, got %d", len(evs))
 	}
-	ev := e.(transfer.DataEvent)
+	ev := evs[0].(transfer.DataEvent)
+	ev.Open = nil
 	if got, want := ev.Type, "file"; got != want {
 		t.Errorf("expected %v; got %v", got, want)
 	}
 	if ofr.closed {
 		t.Error("offer closed prematurely")
 	}
-	e, ok = r.Event(transfer.TargetFilter{Target: tgt, Type: drag.Type})
-	if !ok {
-		t.Fatalf("expected event")
-	}
-	if _, ok := e.(transfer.CancelEvent); !ok {
-		t.Fatalf("expected transfer.CancelEvent event")
-	}
 	r.Frame(gtx.Ops)
 	if !ofr.closed {
 		t.Error("offer was not closed")

widget/doc.go

@@ -2,5 +2,5 @@
 
 // Package widget implements state tracking and event handling of
 // common user interface controls. To draw widgets, use a theme
-// packages such as package [gioui.org/widget/material].
+// packages such as package gioui.org/widget/material.
 package widget

widget/editor.go

@@ -21,7 +21,6 @@ import (
 	"gioui.org/io/pointer"
 	"gioui.org/io/semantic"
 	"gioui.org/io/system"
-	"gioui.org/io/transfer"
 	"gioui.org/layout"
 	"gioui.org/op"
 	"gioui.org/op/clip"
@@ -70,8 +69,11 @@ type Editor struct {
 	buffer *editBuffer
 	// scratch is a byte buffer that is reused to efficiently read portions of text
 	// from the textView.
-	scratch    []byte
-	blinkStart time.Time
+	scratch      []byte
+	eventKey     int
+	blinkStart   time.Time
+	focused      bool
+	requestFocus bool
 
 	// ime tracks the state relevant to input methods.
 	ime struct {
@@ -87,14 +89,16 @@ type Editor struct {
 
 	clicker gesture.Click
 
+	// events is the list of events not yet processed.
+	events []EditorEvent
+	// prevEvents is the number of events from the previous frame.
+	prevEvents int
 	// history contains undo history.
 	history []modification
 	// nextHistoryIdx is the index within the history of the next modification. This
 	// is only not len(history) immediately after undo operations occur. It is framed as the "next" value
 	// to make the zero value consistent.
 	nextHistoryIdx int
-
-	pending []EditorEvent
 }
 
 type offEntry struct {
@@ -187,37 +191,30 @@ const (
 	maxBlinkDuration = 10 * time.Second
 )
 
-func (e *Editor) processEvents(gtx layout.Context) (ev EditorEvent, ok bool) {
-	if len(e.pending) > 0 {
-		out := e.pending[0]
-		e.pending = e.pending[:copy(e.pending, e.pending[1:])]
-		return out, true
-	}
-	selStart, selEnd := e.Selection()
-	defer func() {
-		afterSelStart, afterSelEnd := e.Selection()
-		if selStart != afterSelStart || selEnd != afterSelEnd {
-			if ok {
-				e.pending = append(e.pending, SelectEvent{})
-			} else {
-				ev = SelectEvent{}
-				ok = true
-			}
-		}
-	}()
-
-	ev, ok = e.processPointer(gtx)
-	if ok {
-		return ev, ok
-	}
-	ev, ok = e.processKey(gtx)
-	if ok {
-		return ev, ok
-	}
-	return nil, false
+// Events returns available editor events.
+func (e *Editor) Events() []EditorEvent {
+	events := e.events
+	e.events = nil
+	e.prevEvents = 0
+	return events
 }
 
-func (e *Editor) processPointer(gtx layout.Context) (EditorEvent, bool) {
+func (e *Editor) processEvents(gtx layout.Context) {
+	// Flush events from before the previous Layout.
+	n := copy(e.events, e.events[e.prevEvents:])
+	e.events = e.events[:n]
+	e.prevEvents = n
+
+	oldStart, oldLen := min(e.text.Selection()), e.text.SelectionLen()
+	e.processPointer(gtx)
+	e.processKey(gtx)
+	// Queue a SelectEvent if the selection changed, including if it went away.
+	if newStart, newLen := min(e.text.Selection()), e.text.SelectionLen(); oldStart != newStart || oldLen != newLen {
+		e.events = append(e.events, SelectEvent{})
+	}
+}
+
+func (e *Editor) processPointer(gtx layout.Context) {
 	sbounds := e.text.ScrollBounds()
 	var smin, smax int
 	var axis gesture.Axis
@@ -228,19 +225,7 @@ func (e *Editor) processPointer(gtx layout.Context) (EditorEvent, bool) {
 		axis = gesture.Vertical
 		smin, smax = sbounds.Min.Y, sbounds.Max.Y
 	}
-	var scrollX, scrollY pointer.ScrollRange
-	textDims := e.text.FullDimensions()
-	visibleDims := e.text.Dimensions()
-	if e.SingleLine {
-		scrollOffX := e.text.ScrollOff().X
-		scrollX.Min = min(-scrollOffX, 0)
-		scrollX.Max = max(0, textDims.Size.X-(scrollOffX+visibleDims.Size.X))
-	} else {
-		scrollOffY := e.text.ScrollOff().Y
-		scrollY.Min = -scrollOffY
-		scrollY.Max = max(0, textDims.Size.Y-(scrollOffY+visibleDims.Size.Y))
-	}
-	sdist := e.scroller.Update(gtx.Metric, gtx.Source, gtx.Now, axis, scrollX, scrollY)
+	sdist := e.scroller.Update(gtx.Metric, gtx, gtx.Now, axis)
 	var soff int
 	if e.SingleLine {
 		e.text.ScrollRel(sdist, 0)
@@ -249,176 +234,115 @@ func (e *Editor) processPointer(gtx layout.Context) (EditorEvent, bool) {
 		e.text.ScrollRel(0, sdist)
 		soff = e.text.ScrollOff().Y
 	}
-	for {
-		evt, ok := e.clicker.Update(gtx.Source)
-		if !ok {
-			break
-		}
-		ev, ok := e.processPointerEvent(gtx, evt)
-		if ok {
-			return ev, ok
-		}
-	}
-	for {
-		evt, ok := e.dragger.Update(gtx.Metric, gtx.Source, gesture.Both)
-		if !ok {
-			break
-		}
-		ev, ok := e.processPointerEvent(gtx, evt)
-		if ok {
-			return ev, ok
+	for _, evt := range e.clickDragEvents(gtx) {
+		switch evt := evt.(type) {
+		case gesture.ClickEvent:
+			switch {
+			case evt.Kind == gesture.KindPress && evt.Source == pointer.Mouse,
+				evt.Kind == gesture.KindClick && evt.Source != pointer.Mouse:
+				prevCaretPos, _ := e.text.Selection()
+				e.blinkStart = gtx.Now
+				e.text.MoveCoord(image.Point{
+					X: int(math.Round(float64(evt.Position.X))),
+					Y: int(math.Round(float64(evt.Position.Y))),
+				})
+				e.requestFocus = true
+				if e.scroller.State() != gesture.StateFlinging {
+					e.scrollCaret = true
+				}
+
+				if evt.Modifiers == key.ModShift {
+					start, end := e.text.Selection()
+					// If they clicked closer to the end, then change the end to
+					// where the caret used to be (effectively swapping start & end).
+					if abs(end-start) < abs(start-prevCaretPos) {
+						e.text.SetCaret(start, prevCaretPos)
+					}
+				} else {
+					e.text.ClearSelection()
+				}
+				e.dragging = true
+
+				// Process multi-clicks.
+				switch {
+				case evt.NumClicks == 2:
+					e.text.MoveWord(-1, selectionClear)
+					e.text.MoveWord(1, selectionExtend)
+					e.dragging = false
+				case evt.NumClicks >= 3:
+					e.text.MoveStart(selectionClear)
+					e.text.MoveEnd(selectionExtend)
+					e.dragging = false
+				}
+			}
+		case pointer.Event:
+			release := false
+			switch {
+			case evt.Kind == pointer.Release && evt.Source == pointer.Mouse:
+				release = true
+				fallthrough
+			case evt.Kind == pointer.Drag && evt.Source == pointer.Mouse:
+				if e.dragging {
+					e.blinkStart = gtx.Now
+					e.text.MoveCoord(image.Point{
+						X: int(math.Round(float64(evt.Position.X))),
+						Y: int(math.Round(float64(evt.Position.Y))),
+					})
+					e.scrollCaret = true
+
+					if release {
+						e.dragging = false
+					}
+				}
+			}
 		}
 	}
 
 	if (sdist > 0 && soff >= smax) || (sdist < 0 && soff <= smin) {
 		e.scroller.Stop()
 	}
-	return nil, false
 }
 
-func (e *Editor) processPointerEvent(gtx layout.Context, ev event.Event) (EditorEvent, bool) {
-	switch evt := ev.(type) {
-	case gesture.ClickEvent:
-		switch {
-		case evt.Kind == gesture.KindPress && evt.Source == pointer.Mouse,
-			evt.Kind == gesture.KindClick && evt.Source != pointer.Mouse:
-			prevCaretPos, _ := e.text.Selection()
-			e.blinkStart = gtx.Now
-			e.text.MoveCoord(image.Point{
-				X: int(math.Round(float64(evt.Position.X))),
-				Y: int(math.Round(float64(evt.Position.Y))),
-			})
-			gtx.Execute(key.FocusCmd{Tag: e})
-			if !e.ReadOnly {
-				gtx.Execute(key.SoftKeyboardCmd{Show: true})
-			}
-			if e.scroller.State() != gesture.StateFlinging {
-				e.scrollCaret = true
-			}
-
-			if evt.Modifiers == key.ModShift {
-				start, end := e.text.Selection()
-				// If they clicked closer to the end, then change the end to
-				// where the caret used to be (effectively swapping start & end).
-				if abs(end-start) < abs(start-prevCaretPos) {
-					e.text.SetCaret(start, prevCaretPos)
-				}
-			} else {
-				e.text.ClearSelection()
-			}
-			e.dragging = true
-
-			// Process multi-clicks.
-			switch {
-			case evt.NumClicks == 2:
-				e.text.MoveWord(-1, selectionClear)
-				e.text.MoveWord(1, selectionExtend)
-				e.dragging = false
-			case evt.NumClicks >= 3:
-				e.text.MoveLineStart(selectionClear)
-				e.text.MoveLineEnd(selectionExtend)
-				e.dragging = false
-			}
-		}
-	case pointer.Event:
-		release := false
-		switch {
-		case evt.Kind == pointer.Release && evt.Source == pointer.Mouse:
-			release = true
-			fallthrough
-		case evt.Kind == pointer.Drag && evt.Source == pointer.Mouse:
-			if e.dragging {
-				e.blinkStart = gtx.Now
-				e.text.MoveCoord(image.Point{
-					X: int(math.Round(float64(evt.Position.X))),
-					Y: int(math.Round(float64(evt.Position.Y))),
-				})
-				e.scrollCaret = true
-
-				if release {
-					e.dragging = false
-				}
-			}
-		}
+func (e *Editor) clickDragEvents(gtx layout.Context) []event.Event {
+	var combinedEvents []event.Event
+	for _, evt := range e.clicker.Update(gtx) {
+		combinedEvents = append(combinedEvents, evt)
 	}
-	return nil, false
-}
-
-func condFilter(pred bool, f key.Filter) event.Filter {
-	if pred {
-		return f
-	} else {
-		return nil
+	for _, evt := range e.dragger.Update(gtx.Metric, gtx, gesture.Both) {
+		combinedEvents = append(combinedEvents, evt)
 	}
+	return combinedEvents
 }
 
-func (e *Editor) processKey(gtx layout.Context) (EditorEvent, bool) {
+func (e *Editor) processKey(gtx layout.Context) {
 	if e.text.Changed() {
-		return ChangeEvent{}, true
-	}
-	caret, _ := e.text.Selection()
-	atBeginning := caret == 0
-	atEnd := caret == e.text.Len()
-	if gtx.Locale.Direction.Progression() != system.FromOrigin {
-		atEnd, atBeginning = atBeginning, atEnd
-	}
-	filters := []event.Filter{
-		key.FocusFilter{Target: e},
-		transfer.TargetFilter{Target: e, Type: "application/text"},
-		key.Filter{Focus: e, Name: key.NameEnter, Optional: key.ModShift},
-		key.Filter{Focus: e, Name: key.NameReturn, Optional: key.ModShift},
-
-		key.Filter{Focus: e, Name: "Z", Required: key.ModShortcut, Optional: key.ModShift},
-		key.Filter{Focus: e, Name: "C", Required: key.ModShortcut},
-		key.Filter{Focus: e, Name: "V", Required: key.ModShortcut},
-		key.Filter{Focus: e, Name: "X", Required: key.ModShortcut},
-		key.Filter{Focus: e, Name: "A", Required: key.ModShortcut},
-
-		key.Filter{Focus: e, Name: key.NameDeleteBackward, Optional: key.ModShortcutAlt | key.ModShift},
-		key.Filter{Focus: e, Name: key.NameDeleteForward, Optional: key.ModShortcutAlt | key.ModShift},
-
-		key.Filter{Focus: e, Name: key.NameHome, Optional: key.ModShortcut | key.ModShift},
-		key.Filter{Focus: e, Name: key.NameEnd, Optional: key.ModShortcut | key.ModShift},
-		key.Filter{Focus: e, Name: key.NamePageDown, Optional: key.ModShift},
-		key.Filter{Focus: e, Name: key.NamePageUp, Optional: key.ModShift},
-		condFilter(!atBeginning, key.Filter{Focus: e, Name: key.NameLeftArrow, Optional: key.ModShortcutAlt | key.ModShift}),
-		condFilter(!atBeginning, key.Filter{Focus: e, Name: key.NameUpArrow, Optional: key.ModShortcutAlt | key.ModShift}),
-		condFilter(!atEnd, key.Filter{Focus: e, Name: key.NameRightArrow, Optional: key.ModShortcutAlt | key.ModShift}),
-		condFilter(!atEnd, key.Filter{Focus: e, Name: key.NameDownArrow, Optional: key.ModShortcutAlt | key.ModShift}),
+		e.events = append(e.events, ChangeEvent{})
 	}
 	// adjust keeps track of runes dropped because of MaxLen.
 	var adjust int
-	for {
-		ke, ok := gtx.Event(filters...)
-		if !ok {
-			break
-		}
+	for _, ke := range gtx.Events(&e.eventKey) {
 		e.blinkStart = gtx.Now
 		switch ke := ke.(type) {
 		case key.FocusEvent:
+			e.focused = ke.Focus
 			// Reset IME state.
 			e.ime.imeState = imeState{}
-			if ke.Focus && !e.ReadOnly {
-				gtx.Execute(key.SoftKeyboardCmd{Show: true})
-			}
 		case key.Event:
-			if !gtx.Focused(e) || ke.State != key.Press {
+			if !e.focused || ke.State != key.Press {
 				break
 			}
 			if !e.ReadOnly && e.Submit && (ke.Name == key.NameReturn || ke.Name == key.NameEnter) {
 				if !ke.Modifiers.Contain(key.ModShift) {
 					e.scratch = e.text.Text(e.scratch)
-					return SubmitEvent{
+					e.events = append(e.events, SubmitEvent{
 						Text: string(e.scratch),
-					}, true
+					})
+					continue
 				}
 			}
+			e.command(gtx, ke)
 			e.scrollCaret = true
 			e.scroller.Stop()
-			ev, ok := e.command(gtx, ke)
-			if ok {
-				return ev, ok
-			}
 		case key.SnippetEvent:
 			e.updateSnippet(gtx, ke.Start, ke.End)
 		case key.EditEvent:
@@ -445,26 +369,19 @@ func (e *Editor) processKey(gtx layout.Context) (EditorEvent, bool) {
 			// Reset caret xoff.
 			e.text.MoveCaret(0, 0)
 			if submit {
-				e.scratch = e.text.Text(e.scratch)
-				submitEvent := SubmitEvent{
-					Text: string(e.scratch),
-				}
 				if e.text.Changed() {
-					e.pending = append(e.pending, submitEvent)
-					return ChangeEvent{}, true
+					e.events = append(e.events, ChangeEvent{})
 				}
-				return submitEvent, true
+				e.scratch = e.text.Text(e.scratch)
+				e.events = append(e.events, SubmitEvent{
+					Text: string(e.scratch),
+				})
 			}
 		// Complete a paste event, initiated by Shortcut-V in Editor.command().
-		case transfer.DataEvent:
+		case clipboard.Event:
 			e.scrollCaret = true
 			e.scroller.Stop()
-			content, err := io.ReadAll(ke.Open())
-			if err == nil {
-				if e.Insert(string(content)) != 0 {
-					return ChangeEvent{}, true
-				}
-			}
+			e.Insert(ke.Text)
 		case key.SelectionEvent:
 			e.scrollCaret = true
 			e.scroller.Stop()
@@ -475,12 +392,11 @@ func (e *Editor) processKey(gtx layout.Context) (EditorEvent, bool) {
 		}
 	}
 	if e.text.Changed() {
-		return ChangeEvent{}, true
+		e.events = append(e.events, ChangeEvent{})
 	}
-	return nil, false
 }
 
-func (e *Editor) command(gtx layout.Context, k key.Event) (EditorEvent, bool) {
+func (e *Editor) command(gtx layout.Context, k key.Event) {
 	direction := 1
 	if gtx.Locale.Direction.Progression() == system.TowardOrigin {
 		direction = -1
@@ -496,17 +412,15 @@ func (e *Editor) command(gtx layout.Context, k key.Event) (EditorEvent, bool) {
 		// half is in Editor.processKey() under clipboard.Event.
 		case "V":
 			if !e.ReadOnly {
-				gtx.Execute(clipboard.ReadCmd{Tag: e})
+				clipboard.ReadOp{Tag: &e.eventKey}.Add(gtx.Ops)
 			}
 		// Copy or Cut selection -- ignored if nothing selected.
 		case "C", "X":
 			e.scratch = e.text.SelectedText(e.scratch)
 			if text := string(e.scratch); text != "" {
-				gtx.Execute(clipboard.WriteCmd{Type: "application/text", Data: io.NopCloser(strings.NewReader(text))})
+				clipboard.WriteOp{Text: text}.Add(gtx.Ops)
 				if k.Name == "X" && !e.ReadOnly {
-					if e.Delete(1) != 0 {
-						return ChangeEvent{}, true
-					}
+					e.Delete(1)
 				}
 			}
 		// Select all
@@ -515,51 +429,33 @@ func (e *Editor) command(gtx layout.Context, k key.Event) (EditorEvent, bool) {
 		case "Z":
 			if !e.ReadOnly {
 				if k.Modifiers.Contain(key.ModShift) {
-					if ev, ok := e.redo(); ok {
-						return ev, ok
-					}
+					e.redo()
 				} else {
-					if ev, ok := e.undo(); ok {
-						return ev, ok
-					}
+					e.undo()
 				}
 			}
-		case key.NameHome:
-			e.text.MoveTextStart(selAct)
-		case key.NameEnd:
-			e.text.MoveTextEnd(selAct)
 		}
-		return nil, false
+		return
 	}
 	switch k.Name {
 	case key.NameReturn, key.NameEnter:
 		if !e.ReadOnly {
-			if e.Insert("\n") != 0 {
-				return ChangeEvent{}, true
-			}
+			e.Insert("\n")
 		}
 	case key.NameDeleteBackward:
 		if !e.ReadOnly {
 			if moveByWord {
-				if e.deleteWord(-1) != 0 {
-					return ChangeEvent{}, true
-				}
+				e.deleteWord(-1)
 			} else {
-				if e.Delete(-1) != 0 {
-					return ChangeEvent{}, true
-				}
+				e.Delete(-1)
 			}
 		}
 	case key.NameDeleteForward:
 		if !e.ReadOnly {
 			if moveByWord {
-				if e.deleteWord(1) != 0 {
-					return ChangeEvent{}, true
-				}
+				e.deleteWord(1)
 			} else {
-				if e.Delete(1) != 0 {
-					return ChangeEvent{}, true
-				}
+				e.Delete(1)
 			}
 		}
 	case key.NameUpArrow:
@@ -589,11 +485,20 @@ func (e *Editor) command(gtx layout.Context, k key.Event) (EditorEvent, bool) {
 	case key.NamePageDown:
 		e.text.MovePages(+1, selAct)
 	case key.NameHome:
-		e.text.MoveLineStart(selAct)
+		e.text.MoveStart(selAct)
 	case key.NameEnd:
-		e.text.MoveLineEnd(selAct)
+		e.text.MoveEnd(selAct)
 	}
-	return nil, false
+}
+
+// Focus requests the input focus for the Editor.
+func (e *Editor) Focus() {
+	e.requestFocus = true
+}
+
+// Focused returns whether the editor is focused or not.
+func (e *Editor) Focused() bool {
+	return e.focused
 }
 
 // initBuffer should be invoked first in every exported function that accesses
@@ -612,51 +517,48 @@ func (e *Editor) initBuffer() {
 	e.text.WrapPolicy = e.WrapPolicy
 }
 
-// Update the state of the editor in response to input events. Update consumes editor
-// input events until there are no remaining events or an editor event is generated.
-// To fully update the state of the editor, callers should call Update until it returns
-// false.
-func (e *Editor) Update(gtx layout.Context) (EditorEvent, bool) {
+// Update the state of the editor in response to input events.
+func (e *Editor) Update(gtx layout.Context) {
 	e.initBuffer()
-	event, ok := e.processEvents(gtx)
-	// Notify IME of selection if it changed.
-	newSel := e.ime.selection
-	start, end := e.text.Selection()
-	newSel.rng = key.Range{
-		Start: start,
-		End:   end,
-	}
-	caretPos, carAsc, carDesc := e.text.CaretInfo()
-	newSel.caret = key.Caret{
-		Pos:     layout.FPt(caretPos),
-		Ascent:  float32(carAsc),
-		Descent: float32(carDesc),
-	}
-	if newSel != e.ime.selection {
-		e.ime.selection = newSel
-		gtx.Execute(key.SelectionCmd{Tag: e, Range: newSel.rng, Caret: newSel.caret})
-	}
+	e.processEvents(gtx)
+	if e.focused {
+		// Notify IME of selection if it changed.
+		newSel := e.ime.selection
+		start, end := e.text.Selection()
+		newSel.rng = key.Range{
+			Start: start,
+			End:   end,
+		}
+		caretPos, carAsc, carDesc := e.text.CaretInfo()
+		newSel.caret = key.Caret{
+			Pos:     layout.FPt(caretPos),
+			Ascent:  float32(carAsc),
+			Descent: float32(carDesc),
+		}
+		if newSel != e.ime.selection {
+			e.ime.selection = newSel
+			key.SelectionOp{
+				Tag:   &e.eventKey,
+				Range: newSel.rng,
+				Caret: newSel.caret,
+			}.Add(gtx.Ops)
+		}
 
-	e.updateSnippet(gtx, e.ime.start, e.ime.end)
-	return event, ok
+		e.updateSnippet(gtx, e.ime.start, e.ime.end)
+	}
 }
 
 // Layout lays out the editor using the provided textMaterial as the paint material
 // for the text glyphs+caret and the selectMaterial as the paint material for the
 // selection rectangle.
 func (e *Editor) Layout(gtx layout.Context, lt *text.Shaper, font font.Font, size unit.Sp, textMaterial, selectMaterial op.CallOp) layout.Dimensions {
-	for {
-		_, ok := e.Update(gtx)
-		if !ok {
-			break
-		}
-	}
+	e.Update(gtx)
 
 	e.text.Layout(gtx, lt, font, size)
 	return e.layout(gtx, textMaterial, selectMaterial)
 }
 
-// updateSnippet queues a key.SnippetCmd if the snippet content or position
+// updateSnippet adds a key.SnippetOp if the snippet content or position
 // have changed. off and len are in runes.
 func (e *Editor) updateSnippet(gtx layout.Context, start, end int) {
 	if start > end {
@@ -696,7 +598,10 @@ func (e *Editor) updateSnippet(gtx layout.Context, start, end int) {
 		return
 	}
 	e.ime.snippet = newSnip
-	gtx.Execute(key.SnippetCmd{Tag: e, Snippet: newSnip})
+	key.SnippetOp{
+		Tag:     &e.eventKey,
+		Snippet: newSnip,
+	}.Add(gtx.Ops)
 }
 
 func (e *Editor) layout(gtx layout.Context, textMaterial, selectMaterial op.CallOp) layout.Dimensions {
@@ -707,35 +612,79 @@ func (e *Editor) layout(gtx layout.Context, textMaterial, selectMaterial op.Call
 		e.scrollCaret = false
 		e.text.ScrollToCaret()
 	}
+	textDims := e.text.FullDimensions()
 	visibleDims := e.text.Dimensions()
 
 	defer clip.Rect(image.Rectangle{Max: visibleDims.Size}).Push(gtx.Ops).Pop()
 	pointer.CursorText.Add(gtx.Ops)
-	event.Op(gtx.Ops, e)
-	key.InputHintOp{Tag: e, Hint: e.InputHint}.Add(gtx.Ops)
+	var keys key.Set
+	if e.focused {
+		const keyFilterNoLeftUp = "(ShortAlt)-(Shift)-[→,↓]|(Shift)-[⏎,⌤]|(ShortAlt)-(Shift)-[⌫,⌦]|(Shift)-[⇞,⇟,⇱,⇲]|Short-[C,V,X,A]|Short-(Shift)-Z"
+		const keyFilterNoRightDown = "(ShortAlt)-(Shift)-[←,↑]|(Shift)-[⏎,⌤]|(ShortAlt)-(Shift)-[⌫,⌦]|(Shift)-[⇞,⇟,⇱,⇲]|Short-[C,V,X,A]|Short-(Shift)-Z"
+		const keyFilterNoArrows = "(Shift)-[⏎,⌤]|(ShortAlt)-(Shift)-[⌫,⌦]|(Shift)-[⇞,⇟,⇱,⇲]|Short-[C,V,X,A]|Short-(Shift)-Z"
+		const keyFilterAllArrows = "(ShortAlt)-(Shift)-[←,→,↑,↓]|(Shift)-[⏎,⌤]|(ShortAlt)-(Shift)-[⌫,⌦]|(Shift)-[⇞,⇟,⇱,⇲]|Short-[C,V,X,A]|Short-(Shift)-Z"
+		caret, _ := e.text.Selection()
+		switch {
+		case caret == 0 && caret == e.text.Len():
+			keys = keyFilterNoArrows
+		case caret == 0:
+			if gtx.Locale.Direction.Progression() == system.FromOrigin {
+				keys = keyFilterNoLeftUp
+			} else {
+				keys = keyFilterNoRightDown
+			}
+		case caret == e.text.Len():
+			if gtx.Locale.Direction.Progression() == system.FromOrigin {
+				keys = keyFilterNoRightDown
+			} else {
+				keys = keyFilterNoLeftUp
+			}
+		default:
+			keys = keyFilterAllArrows
+		}
+	}
+	key.InputOp{Tag: &e.eventKey, Hint: e.InputHint, Keys: keys}.Add(gtx.Ops)
+	if e.requestFocus {
+		key.FocusOp{Tag: &e.eventKey}.Add(gtx.Ops)
+		key.SoftKeyboardOp{Show: true}.Add(gtx.Ops)
+	}
+	e.requestFocus = false
 
-	e.scroller.Add(gtx.Ops)
+	var scrollRange image.Rectangle
+	if e.SingleLine {
+		scrollOffX := e.text.ScrollOff().X
+		scrollRange.Min.X = min(-scrollOffX, 0)
+		scrollRange.Max.X = max(0, textDims.Size.X-(scrollOffX+visibleDims.Size.X))
+	} else {
+		scrollOffY := e.text.ScrollOff().Y
+		scrollRange.Min.Y = -scrollOffY
+		scrollRange.Max.Y = max(0, textDims.Size.Y-(scrollOffY+visibleDims.Size.Y))
+	}
+	e.scroller.Add(gtx.Ops, scrollRange)
 
 	e.clicker.Add(gtx.Ops)
 	e.dragger.Add(gtx.Ops)
 	e.showCaret = false
-	if gtx.Focused(e) {
+	if e.focused {
 		now := gtx.Now
 		dt := now.Sub(e.blinkStart)
 		blinking := dt < maxBlinkDuration
 		const timePerBlink = time.Second / blinksPerSecond
 		nextBlink := now.Add(timePerBlink/2 - dt%(timePerBlink/2))
 		if blinking {
-			gtx.Execute(op.InvalidateCmd{At: nextBlink})
+			redraw := op.InvalidateOp{At: nextBlink}
+			redraw.Add(gtx.Ops)
 		}
-		e.showCaret = !blinking || dt%timePerBlink < timePerBlink/2
+		e.showCaret = e.focused && (!blinking || dt%timePerBlink < timePerBlink/2)
 	}
+	disabled := gtx.Queue == nil
+
 	semantic.Editor.Add(gtx.Ops)
 	if e.Len() > 0 {
 		e.paintSelection(gtx, selectMaterial)
 		e.paintText(gtx, textMaterial)
 	}
-	if gtx.Enabled() {
+	if !disabled {
 		e.paintCaret(gtx, textMaterial)
 	}
 	return visibleDims
@@ -745,7 +694,7 @@ func (e *Editor) layout(gtx layout.Context, textMaterial, selectMaterial op.Call
 // material to set the painting material for the selection.
 func (e *Editor) paintSelection(gtx layout.Context, material op.CallOp) {
 	e.initBuffer()
-	if !gtx.Focused(e) {
+	if !e.focused {
 		return
 	}
 	e.text.PaintSelection(gtx, material)
@@ -809,10 +758,10 @@ func (e *Editor) CaretCoords() f32.Point {
 //
 // If there is a selection, it is deleted and counts as a single grapheme
 // cluster.
-func (e *Editor) Delete(graphemeClusters int) (deletedRunes int) {
+func (e *Editor) Delete(graphemeClusters int) {
 	e.initBuffer()
 	if graphemeClusters == 0 {
-		return 0
+		return
 	}
 
 	start, end := e.text.Selection()
@@ -828,10 +777,9 @@ func (e *Editor) Delete(graphemeClusters int) (deletedRunes int) {
 	// Reset xoff.
 	e.text.MoveCaret(0, 0)
 	e.ClearSelection()
-	return end - start
 }
 
-func (e *Editor) Insert(s string) (insertedRunes int) {
+func (e *Editor) Insert(s string) {
 	e.initBuffer()
 	if e.SingleLine {
 		s = strings.ReplaceAll(s, "\n", " ")
@@ -845,7 +793,6 @@ func (e *Editor) Insert(s string) (insertedRunes int) {
 	e.text.MoveCaret(0, 0)
 	e.SetCaret(start+moves, start+moves)
 	e.scrollCaret = true
-	return moves
 }
 
 // modification represents a change to the contents of the editor buffer.
@@ -865,10 +812,10 @@ type modification struct {
 
 // undo applies the modification at e.history[e.historyIdx] and decrements
 // e.historyIdx.
-func (e *Editor) undo() (EditorEvent, bool) {
+func (e *Editor) undo() {
 	e.initBuffer()
 	if len(e.history) < 1 || e.nextHistoryIdx == 0 {
-		return nil, false
+		return
 	}
 	mod := e.history[e.nextHistoryIdx-1]
 	replaceEnd := mod.StartRune + utf8.RuneCountInString(mod.ApplyContent)
@@ -876,15 +823,14 @@ func (e *Editor) undo() (EditorEvent, bool) {
 	caretEnd := mod.StartRune + utf8.RuneCountInString(mod.ReverseContent)
 	e.SetCaret(caretEnd, mod.StartRune)
 	e.nextHistoryIdx--
-	return ChangeEvent{}, true
 }
 
 // redo applies the modification at e.history[e.historyIdx] and increments
 // e.historyIdx.
-func (e *Editor) redo() (EditorEvent, bool) {
+func (e *Editor) redo() {
 	e.initBuffer()
 	if len(e.history) < 1 || e.nextHistoryIdx == len(e.history) {
-		return nil, false
+		return
 	}
 	mod := e.history[e.nextHistoryIdx]
 	end := mod.StartRune + utf8.RuneCountInString(mod.ReverseContent)
@@ -892,7 +838,6 @@ func (e *Editor) redo() (EditorEvent, bool) {
 	caretEnd := mod.StartRune + utf8.RuneCountInString(mod.ApplyContent)
 	e.SetCaret(caretEnd, mod.StartRune)
 	e.nextHistoryIdx++
-	return ChangeEvent{}, true
 }
 
 // replace the text between start and end with s. Indices are in runes.
@@ -976,18 +921,18 @@ func (e *Editor) MoveCaret(startDelta, endDelta int) {
 // Positive is forward, negative is backward.
 // Absolute values greater than one will delete that many words.
 // The selection counts as a single word.
-func (e *Editor) deleteWord(distance int) (deletedRunes int) {
+func (e *Editor) deleteWord(distance int) {
 	if distance == 0 {
 		return
 	}
 
 	start, end := e.text.Selection()
 	if start != end {
-		deletedRunes = e.Delete(1)
+		e.Delete(1)
 		distance -= sign(distance)
 	}
 	if distance == 0 {
-		return deletedRunes
+		return
 	}
 
 	// split the distance information into constituent parts to be
@@ -1027,8 +972,7 @@ func (e *Editor) deleteWord(distance int) (deletedRunes int) {
 			runes += 1
 		}
 	}
-	deletedRunes += e.Delete(runes * direction)
-	return deletedRunes
+	e.Delete(runes * direction)
 }
 
 // SelectionLen returns the length of the selection, in runes; it is

widget/editor_test.go

@@ -20,7 +20,7 @@ import (
 	"gioui.org/font"
 	"gioui.org/font/gofont"
 	"gioui.org/font/opentype"
-	"gioui.org/io/input"
+	"gioui.org/io/event"
 	"gioui.org/io/key"
 	"gioui.org/io/pointer"
 	"gioui.org/io/system"
@@ -96,14 +96,17 @@ func assertContents(t *testing.T, e *Editor, contents string, selectionStart, se
 // TestEditorReadOnly ensures that mouse and keyboard interactions with readonly
 // editors do nothing but manipulate the text selection.
 func TestEditorReadOnly(t *testing.T) {
-	r := new(input.Router)
 	gtx := layout.Context{
 		Ops: new(op.Ops),
 		Constraints: layout.Constraints{
 			Max: image.Pt(100, 100),
 		},
 		Locale: english,
-		Source: r.Source(),
+	}
+	gtx.Queue = &testQueue{
+		events: []event.Event{
+			key.FocusEvent{Focus: true},
+		},
 	}
 	cache := text.NewShaper(text.NoSystemFonts(), text.WithCollection(gofont.Collection()))
 	fontSize := unit.Sp(10)
@@ -115,23 +118,12 @@ func TestEditorReadOnly(t *testing.T) {
 	if cStart != cEnd {
 		t.Errorf("unexpected initial caret positions")
 	}
-	gtx.Execute(key.FocusCmd{Tag: e})
-	layoutEditor := func() layout.Dimensions {
-		return e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
-	}
-	layoutEditor()
-	r.Frame(gtx.Ops)
-	gtx.Ops.Reset()
-	layoutEditor()
-	r.Frame(gtx.Ops)
-	gtx.Ops.Reset()
-	layoutEditor()
-	r.Frame(gtx.Ops)
+	e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
 
 	// Select everything.
 	gtx.Ops.Reset()
-	r.Queue(key.Event{Name: "A", Modifiers: key.ModShortcut})
-	layoutEditor()
+	gtx.Queue = &testQueue{events: []event.Event{key.Event{Name: "A", Modifiers: key.ModShortcut}}}
+	e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
 	textContent := e.Text()
 	cStart2, cEnd2 := e.Selection()
 	if cStart2 > cEnd2 {
@@ -146,7 +138,7 @@ func TestEditorReadOnly(t *testing.T) {
 
 	// Type some new characters.
 	gtx.Ops.Reset()
-	r.Queue(key.EditEvent{Range: key.Range{Start: cStart2, End: cEnd2}, Text: "something else"})
+	gtx.Queue = &testQueue{events: []event.Event{key.EditEvent{Range: key.Range{Start: cStart2, End: cEnd2}, Text: "something else"}}}
 	e.Update(gtx)
 	textContent2 := e.Text()
 	if textContent2 != textContent {
@@ -155,8 +147,8 @@ func TestEditorReadOnly(t *testing.T) {
 
 	// Try to delete selection.
 	gtx.Ops.Reset()
-	r.Queue(key.Event{Name: key.NameDeleteBackward})
-	dims := layoutEditor()
+	gtx.Queue = &testQueue{events: []event.Event{key.Event{Name: key.NameDeleteBackward}}}
+	dims := e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
 	textContent2 = e.Text()
 	if textContent2 != textContent {
 		t.Errorf("readonly editor modified by delete key.Event")
@@ -165,14 +157,14 @@ func TestEditorReadOnly(t *testing.T) {
 	// Click and drag from the middle of the first line
 	// to the center.
 	gtx.Ops.Reset()
-	r.Queue(
+	gtx.Queue = &testQueue{events: []event.Event{
 		pointer.Event{
 			Kind:     pointer.Press,
 			Buttons:  pointer.ButtonPrimary,
 			Position: f32.Pt(float32(dims.Size.X)*.5, 5),
 		},
 		pointer.Event{
-			Kind:     pointer.Move,
+			Kind:     pointer.Drag,
 			Buttons:  pointer.ButtonPrimary,
 			Position: layout.FPt(dims.Size).Mul(.5),
 		},
@@ -181,7 +173,7 @@ func TestEditorReadOnly(t *testing.T) {
 			Buttons:  pointer.ButtonPrimary,
 			Position: layout.FPt(dims.Size).Mul(.5),
 		},
-	)
+	}}
 	e.Update(gtx)
 	cStart3, cEnd3 := e.Selection()
 	if cStart3 == cStart2 || cEnd3 == cEnd2 {
@@ -256,7 +248,7 @@ func TestEditor(t *testing.T) {
 	// Regression test for bad in-cluster rune offset math.
 	e.SetText("æbc")
 	e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
-	e.text.MoveLineEnd(selectionClear)
+	e.text.MoveEnd(selectionClear)
 	assertCaret(t, e, 0, 3, len("æbc"))
 
 	textSample := "æbc\naøå••"
@@ -268,7 +260,7 @@ func TestEditor(t *testing.T) {
 	}
 	e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
 	assertCaret(t, e, 0, 0, 0)
-	e.text.MoveLineEnd(selectionClear)
+	e.text.MoveEnd(selectionClear)
 	assertCaret(t, e, 0, 3, len("æbc"))
 	e.MoveCaret(+1, +1)
 	assertCaret(t, e, 1, 0, len("æbc\n"))
@@ -276,7 +268,7 @@ func TestEditor(t *testing.T) {
 	assertCaret(t, e, 0, 3, len("æbc"))
 	e.text.MoveLines(+1, selectionClear)
 	assertCaret(t, e, 1, 4, len("æbc\naøå•"))
-	e.text.MoveLineEnd(selectionClear)
+	e.text.MoveEnd(selectionClear)
 	assertCaret(t, e, 1, 5, len("æbc\naøå••"))
 	e.MoveCaret(+1, +1)
 	assertCaret(t, e, 1, 5, len("æbc\naøå••"))
@@ -300,7 +292,7 @@ func TestEditor(t *testing.T) {
 	// Test that moveLine applies x offsets from previous moves.
 	e.SetText("long line\nshort")
 	e.SetCaret(0, 0)
-	e.text.MoveLineEnd(selectionClear)
+	e.text.MoveEnd(selectionClear)
 	e.text.MoveLines(+1, selectionClear)
 	e.text.MoveLines(-1, selectionClear)
 	assertCaret(t, e, 0, utf8.RuneCountInString("long line"), len("long line"))
@@ -342,14 +334,14 @@ func TestEditorRTL(t *testing.T) {
 	e.MoveCaret(+1, +1)
 	assertCaret(t, e, 0, 3, len("الح"))
 	// Move to the "end" of the line. This moves to the left edge of the line.
-	e.text.MoveLineEnd(selectionClear)
+	e.text.MoveEnd(selectionClear)
 	assertCaret(t, e, 0, 4, len("الحب"))
 
 	sentence := "الحب سماء لا\nتمط غير الأحلام"
 	e.SetText(sentence)
 	e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
 	assertCaret(t, e, 0, 0, 0)
-	e.text.MoveLineEnd(selectionClear)
+	e.text.MoveEnd(selectionClear)
 	assertCaret(t, e, 0, 12, len("الحب سماء لا"))
 	e.MoveCaret(+1, +1)
 	assertCaret(t, e, 1, 0, len("الحب سماء لا\n"))
@@ -361,7 +353,7 @@ func TestEditorRTL(t *testing.T) {
 	assertCaret(t, e, 0, 12, len("الحب سماء لا"))
 	e.text.MoveLines(+1, selectionClear)
 	assertCaret(t, e, 1, 14, len("الحب سماء لا\nتمط غير الأحلا"))
-	e.text.MoveLineEnd(selectionClear)
+	e.text.MoveEnd(selectionClear)
 	assertCaret(t, e, 1, 15, len("الحب سماء لا\nتمط غير الأحلام"))
 	e.MoveCaret(+1, +1)
 	assertCaret(t, e, 1, 15, len("الحب سماء لا\nتمط غير الأحلام"))
@@ -417,7 +409,7 @@ func TestEditorLigature(t *testing.T) {
 	assertCaret(t, e, 0, 0, 0)
 	e.SetText("fl") // just a ligature
 	e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
-	e.text.MoveLineEnd(selectionClear)
+	e.text.MoveEnd(selectionClear)
 	assertCaret(t, e, 0, 2, len("fl"))
 	e.MoveCaret(-1, -1)
 	assertCaret(t, e, 0, 1, len("f"))
@@ -428,7 +420,7 @@ func TestEditorLigature(t *testing.T) {
 	e.SetText("flaffl•ffi\n•fflfi") // 3 ligatures on line 0, 2 on line 1
 	e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
 	assertCaret(t, e, 0, 0, 0)
-	e.text.MoveLineEnd(selectionClear)
+	e.text.MoveEnd(selectionClear)
 	assertCaret(t, e, 0, 10, len("ffaffl•ffi"))
 	e.MoveCaret(+1, +1)
 	assertCaret(t, e, 1, 0, len("ffaffl•ffi\n"))
@@ -481,7 +473,7 @@ func TestEditorLigature(t *testing.T) {
 	e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
 	// Ensure that all runes in the final cluster of a line are properly
 	// decoded when moving to the end of the line. This is a regression test.
-	e.text.MoveLineEnd(selectionClear)
+	e.text.MoveEnd(selectionClear)
 	// The first line was broken by line wrapping, not a newline character, and has a trailing
 	// whitespace. However, we should never be able to reach the "other side" of such a trailing
 	// whitespace glyph.
@@ -504,22 +496,22 @@ func TestEditorLigature(t *testing.T) {
 
 func TestEditorDimensions(t *testing.T) {
 	e := new(Editor)
-	r := new(input.Router)
+	tq := &testQueue{
+		events: []event.Event{
+			key.EditEvent{Text: "A"},
+		},
+	}
 	gtx := layout.Context{
 		Ops:         new(op.Ops),
 		Constraints: layout.Constraints{Max: image.Pt(100, 100)},
-		Source:      r.Source(),
+		Queue:       tq,
 		Locale:      english,
 	}
 	cache := text.NewShaper(text.NoSystemFonts(), text.WithCollection(gofont.Collection()))
 	fontSize := unit.Sp(10)
 	font := font.Font{}
-	gtx.Execute(key.FocusCmd{Tag: e})
-	e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
-	r.Frame(gtx.Ops)
-	r.Queue(key.EditEvent{Text: "A"})
 	dims := e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
-	if dims.Size.X < 5 {
+	if dims.Size.X == 0 {
 		t.Errorf("EditEvent was not reflected in Editor width")
 	}
 }
@@ -548,10 +540,8 @@ const (
 	moveRune
 	moveLine
 	movePage
-	moveTextStart
-	moveTextEnd
-	moveLineStart
-	moveLineEnd
+	moveStart
+	moveEnd
 	moveCoord
 	moveWord
 	deleteWord
@@ -601,14 +591,10 @@ func TestEditorCaretConsistency(t *testing.T) {
 				e.text.MoveLines(int(distance), selectionClear)
 			case movePage:
 				e.text.MovePages(int(distance), selectionClear)
-			case moveLineStart:
-				e.text.MoveLineStart(selectionClear)
-			case moveLineEnd:
-				e.text.MoveLineEnd(selectionClear)
-			case moveTextStart:
-				e.text.MoveTextStart(selectionClear)
-			case moveTextEnd:
-				e.text.MoveTextEnd(selectionClear)
+			case moveStart:
+				e.text.MoveStart(selectionClear)
+			case moveEnd:
+				e.text.MoveEnd(selectionClear)
 			case moveCoord:
 				e.text.MoveCoord(image.Pt(int(x), int(y)))
 			case moveWord:
@@ -885,7 +871,7 @@ func (editMutation) Generate(rand *rand.Rand, size int) reflect.Value {
 // to make it much narrower (which makes the lines in the editor reflow), and
 // then verifies that the updated (col, line) positions of the selected text
 // are where we expect.
-func TestEditorSelectReflow(t *testing.T) {
+func TestEditorSelect(t *testing.T) {
 	e := new(Editor)
 	e.SetText(`a 2 4 6 8 a
 b 2 4 6 8 b
@@ -896,11 +882,9 @@ f 2 4 6 8 f
 g 2 4 6 8 g
 `)
 
-	r := new(input.Router)
 	gtx := layout.Context{
 		Ops:    new(op.Ops),
 		Locale: english,
-		Source: r.Source(),
 	}
 	cache := text.NewShaper(text.NoSystemFonts(), text.WithCollection(gofont.Collection()))
 	font := font.Font{}
@@ -908,39 +892,42 @@ g 2 4 6 8 g
 
 	var tim time.Duration
 	selected := func(start, end int) string {
-		gtx.Execute(key.FocusCmd{Tag: e})
 		// Layout once with no events; populate e.lines.
+		gtx.Queue = nil
 		e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
+		_ = e.Events() // throw away any events from this layout
 
-		r.Frame(gtx.Ops)
-		gtx.Source = r.Source()
 		// Build the selection events
 		startPos := e.text.closestToRune(start)
 		endPos := e.text.closestToRune(end)
-		r.Queue(
-			pointer.Event{
-				Buttons:  pointer.ButtonPrimary,
-				Kind:     pointer.Press,
-				Source:   pointer.Mouse,
-				Time:     tim,
-				Position: f32.Pt(textWidth(e, startPos.lineCol.line, 0, startPos.lineCol.col), textBaseline(e, startPos.lineCol.line)),
+		tq := &testQueue{
+			events: []event.Event{
+				pointer.Event{
+					Buttons:  pointer.ButtonPrimary,
+					Kind:     pointer.Press,
+					Source:   pointer.Mouse,
+					Time:     tim,
+					Position: f32.Pt(textWidth(e, startPos.lineCol.line, 0, startPos.lineCol.col), textBaseline(e, startPos.lineCol.line)),
+				},
+				pointer.Event{
+					Kind:     pointer.Release,
+					Source:   pointer.Mouse,
+					Time:     tim,
+					Position: f32.Pt(textWidth(e, endPos.lineCol.line, 0, endPos.lineCol.col), textBaseline(e, endPos.lineCol.line)),
+				},
 			},
-			pointer.Event{
-				Kind:     pointer.Release,
-				Source:   pointer.Mouse,
-				Time:     tim,
-				Position: f32.Pt(textWidth(e, endPos.lineCol.line, 0, endPos.lineCol.col), textBaseline(e, endPos.lineCol.line)),
-			},
-		)
+		}
 		tim += time.Second // Avoid multi-clicks.
+		gtx.Queue = tq
 
-		for {
-			_, ok := e.Update(gtx) // throw away any events from this layout
-			if !ok {
-				break
+		e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
+		for _, evt := range e.Events() {
+			switch evt.(type) {
+			case SelectEvent:
+				return e.SelectedText()
 			}
 		}
-		return e.SelectedText()
+		return ""
 	}
 	type screenPos image.Point
 	logicalPosMatch := func(t *testing.T, n int, label string, expected screenPos, actual combinedPos) {
@@ -978,7 +965,7 @@ g 2 4 6 8 g
 		// Constrain the editor to roughly 6 columns wide and redraw
 		gtx.Constraints = layout.Exact(image.Pt(36, 36))
 		// Keep existing selection
-		gtx = gtx.Disabled()
+		gtx.Queue = nil
 		e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
 
 		caretStart := e.text.closestToRune(e.text.caret.start)
@@ -988,89 +975,24 @@ g 2 4 6 8 g
 	}
 }
 
-func TestEditorSelectShortcuts(t *testing.T) {
-	tFont := font.Font{}
-	tFontSize := unit.Sp(10)
-	tShaper := text.NewShaper(text.NoSystemFonts(), text.WithCollection(gofont.Collection()))
-	var tEditor = &Editor{
-		SingleLine: false,
-		ReadOnly:   true,
-	}
-	lines := "abc abc abc\ndef def def\nghi ghi ghi"
-	tEditor.SetText(lines)
-	type testCase struct {
-		// Initial text selection.
-		startPos, endPos int
-		// Keyboard shortcut to execute.
-		keyEvent key.Event
-		// Expected text selection.
-		selection string
-	}
-
-	pos1, pos2 := 14, 21
-	for n, tst := range []testCase{
-		{pos1, pos2, key.Event{Name: "A", Modifiers: key.ModShortcut}, lines},
-		{pos2, pos1, key.Event{Name: "A", Modifiers: key.ModShortcut}, lines},
-		{pos1, pos2, key.Event{Name: key.NameHome, Modifiers: key.ModShift}, "def def d"},
-		{pos1, pos2, key.Event{Name: key.NameEnd, Modifiers: key.ModShift}, "ef"},
-		{pos2, pos1, key.Event{Name: key.NameHome, Modifiers: key.ModShift}, "de"},
-		{pos2, pos1, key.Event{Name: key.NameEnd, Modifiers: key.ModShift}, "f def def"},
-		{pos1, pos2, key.Event{Name: key.NameHome, Modifiers: key.ModShortcut | key.ModShift}, "abc abc abc\ndef def d"},
-		{pos1, pos2, key.Event{Name: key.NameEnd, Modifiers: key.ModShortcut | key.ModShift}, "ef\nghi ghi ghi"},
-		{pos2, pos1, key.Event{Name: key.NameHome, Modifiers: key.ModShortcut | key.ModShift}, "abc abc abc\nde"},
-		{pos2, pos1, key.Event{Name: key.NameEnd, Modifiers: key.ModShortcut | key.ModShift}, "f def def\nghi ghi ghi"},
-	} {
-		tRouter := new(input.Router)
-		gtx := layout.Context{
-			Ops:         new(op.Ops),
-			Locale:      english,
-			Constraints: layout.Exact(image.Pt(100, 100)),
-			Source:      tRouter.Source(),
-		}
-		gtx.Execute(key.FocusCmd{Tag: tEditor})
-		tEditor.Layout(gtx, tShaper, tFont, tFontSize, op.CallOp{}, op.CallOp{})
-
-		tEditor.SetCaret(tst.startPos, tst.endPos)
-		if cStart, cEnd := tEditor.Selection(); cStart != tst.startPos || cEnd != tst.endPos {
-			t.Errorf("TestEditorSelect %d: initial selection", n)
-		}
-		tRouter.Queue(tst.keyEvent)
-		tEditor.Update(gtx)
-		if got := tEditor.SelectedText(); got != tst.selection {
-			t.Errorf("TestEditorSelect %d: Expected %q, got %q", n, tst.selection, got)
-		}
-	}
-}
-
 // Verify that an existing selection is dismissed when you press arrow keys.
 func TestSelectMove(t *testing.T) {
 	e := new(Editor)
 	e.SetText(`0123456789`)
 
-	r := new(input.Router)
 	gtx := layout.Context{
 		Ops:    new(op.Ops),
 		Locale: english,
-		Source: r.Source(),
 	}
 	cache := text.NewShaper(text.NoSystemFonts(), text.WithCollection(gofont.Collection()))
 	font := font.Font{}
 	fontSize := unit.Sp(10)
 
 	// Layout once to populate e.lines and get focus.
-	gtx.Execute(key.FocusCmd{Tag: e})
+	gtx.Queue = newQueue(key.FocusEvent{Focus: true})
 	e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
-	r.Frame(gtx.Ops)
-	// Set up selecton so the Editor key handler filters for all 4 directional keys.
-	e.SetCaret(3, 6)
-	gtx.Ops.Reset()
-	e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
-	r.Frame(gtx.Ops)
-	gtx.Ops.Reset()
-	e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
-	r.Frame(gtx.Ops)
 
-	for _, keyName := range []key.Name{key.NameLeftArrow, key.NameRightArrow, key.NameUpArrow, key.NameDownArrow} {
+	testKey := func(keyName string) {
 		// Select 345
 		e.SetCaret(3, 6)
 		if expected, got := "345", e.SelectedText(); expected != got {
@@ -1078,15 +1000,18 @@ func TestSelectMove(t *testing.T) {
 		}
 
 		// Press the key
-		r.Queue(key.Event{State: key.Press, Name: keyName})
-		gtx.Ops.Reset()
+		gtx.Queue = newQueue(key.Event{State: key.Press, Name: keyName})
 		e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
-		r.Frame(gtx.Ops)
 
 		if expected, got := "", e.SelectedText(); expected != got {
 			t.Errorf("KeyName %s, expected %q, got %q", keyName, expected, got)
 		}
 	}
+
+	testKey(key.NameLeftArrow)
+	testKey(key.NameRightArrow)
+	testKey(key.NameUpArrow)
+	testKey(key.NameDownArrow)
 }
 
 func TestEditor_Read(t *testing.T) {
@@ -1139,22 +1064,17 @@ func TestEditor_MaxLen(t *testing.T) {
 	}
 
 	e.SetText("2345678")
-	r := new(input.Router)
 	gtx := layout.Context{
 		Ops:         new(op.Ops),
 		Constraints: layout.Exact(image.Pt(100, 100)),
-		Source:      r.Source(),
+		Queue: newQueue(
+			key.EditEvent{Range: key.Range{Start: 0, End: 2}, Text: "1234"},
+			key.SelectionEvent{Start: 4, End: 4},
+		),
 	}
 	cache := text.NewShaper(text.NoSystemFonts(), text.WithCollection(gofont.Collection()))
 	fontSize := unit.Sp(10)
 	font := font.Font{}
-	gtx.Execute(key.FocusCmd{Tag: e})
-	e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
-	r.Frame(gtx.Ops)
-	r.Queue(
-		key.EditEvent{Range: key.Range{Start: 0, End: 2}, Text: "1234"},
-		key.SelectionEvent{Start: 4, End: 4},
-	)
 	e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
 
 	if got, want := e.Text(), "12345678"; got != want {
@@ -1175,22 +1095,17 @@ func TestEditor_Filter(t *testing.T) {
 	}
 
 	e.SetText("2345678")
-	r := new(input.Router)
 	gtx := layout.Context{
 		Ops:         new(op.Ops),
 		Constraints: layout.Exact(image.Pt(100, 100)),
-		Source:      r.Source(),
+		Queue: newQueue(
+			key.EditEvent{Range: key.Range{Start: 0, End: 0}, Text: "ab1"},
+			key.SelectionEvent{Start: 4, End: 4},
+		),
 	}
 	cache := text.NewShaper(text.NoSystemFonts(), text.WithCollection(gofont.Collection()))
 	fontSize := unit.Sp(10)
 	font := font.Font{}
-	gtx.Execute(key.FocusCmd{Tag: e})
-	e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
-	r.Frame(gtx.Ops)
-	r.Queue(
-		key.EditEvent{Range: key.Range{Start: 0, End: 0}, Text: "ab1"},
-		key.SelectionEvent{Start: 4, End: 4},
-	)
 	e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
 
 	if got, want := e.Text(), "12345678"; got != want {
@@ -1205,33 +1120,22 @@ func TestEditor_Submit(t *testing.T) {
 	e := new(Editor)
 	e.Submit = true
 
-	r := new(input.Router)
 	gtx := layout.Context{
 		Ops:         new(op.Ops),
 		Constraints: layout.Exact(image.Pt(100, 100)),
-		Source:      r.Source(),
+		Queue: newQueue(
+			key.EditEvent{Range: key.Range{Start: 0, End: 0}, Text: "ab1\n"},
+		),
 	}
 	cache := text.NewShaper(text.NoSystemFonts(), text.WithCollection(gofont.Collection()))
 	fontSize := unit.Sp(10)
 	font := font.Font{}
-	gtx.Execute(key.FocusCmd{Tag: e})
 	e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
-	r.Frame(gtx.Ops)
-	r.Queue(
-		key.EditEvent{Range: key.Range{Start: 0, End: 0}, Text: "ab1\n"},
-	)
 
-	got := []EditorEvent{}
-	for {
-		ev, ok := e.Update(gtx)
-		if !ok {
-			break
-		}
-		got = append(got, ev)
-	}
 	if got, want := e.Text(), "ab1"; got != want {
 		t.Errorf("editor failed to filter newline")
 	}
+	got := e.Events()
 	want := []EditorEvent{
 		ChangeEvent{},
 		SubmitEvent{Text: e.Text()},
@@ -1241,29 +1145,6 @@ func TestEditor_Submit(t *testing.T) {
 	}
 }
 
-func TestNoFilterAllocs(t *testing.T) {
-	b := testing.Benchmark(func(b *testing.B) {
-		r := new(input.Router)
-		e := new(Editor)
-		gtx := layout.Context{
-			Ops: new(op.Ops),
-			Constraints: layout.Constraints{
-				Max: image.Pt(100, 100),
-			},
-			Locale: english,
-			Source: r.Source(),
-		}
-		b.ReportAllocs()
-		b.ResetTimer()
-		for i := 0; i < b.N; i++ {
-			e.Update(gtx)
-		}
-	})
-	if allocs := b.AllocsPerOp(); allocs != 0 {
-		t.Fatalf("expected 0 AllocsPerOp, got %d", allocs)
-	}
-}
-
 // textWidth is a text helper for building simple selection events.
 // It assumes single-run lines, which isn't safe with non-test text
 // data.
@@ -1283,3 +1164,15 @@ func textBaseline(e *Editor, lineNum int) float32 {
 	start := e.text.closestToLineCol(lineNum, 0)
 	return float32(start.y)
 }
+
+type testQueue struct {
+	events []event.Event
+}
+
+func newQueue(e ...event.Event) *testQueue {
+	return &testQueue{events: e}
+}
+
+func (q *testQueue) Events(_ event.Tag) []event.Event {
+	return q.events
+}

widget/enum.go

@@ -4,7 +4,6 @@ package widget
 
 import (
 	"gioui.org/gesture"
-	"gioui.org/io/event"
 	"gioui.org/io/key"
 	"gioui.org/io/pointer"
 	"gioui.org/io/semantic"
@@ -41,21 +40,17 @@ func (e *Enum) index(k string) *enumKey {
 
 // Update the state and report whether Value has changed by user interaction.
 func (e *Enum) Update(gtx layout.Context) bool {
-	if !gtx.Enabled() {
+	if gtx.Queue == nil {
 		e.focused = false
 	}
 	e.hovering = false
 	changed := false
 	for _, state := range e.keys {
-		for {
-			ev, ok := state.click.Update(gtx.Source)
-			if !ok {
-				break
-			}
+		for _, ev := range state.click.Update(gtx) {
 			switch ev.Kind {
 			case gesture.KindPress:
 				if ev.Source == pointer.Mouse {
-					gtx.Execute(key.FocusCmd{Tag: &state.tag})
+					key.FocusOp{Tag: &state.tag}.Add(gtx.Ops)
 				}
 			case gesture.KindClick:
 				if state.key != e.Value {
@@ -64,15 +59,7 @@ func (e *Enum) Update(gtx layout.Context) bool {
 				}
 			}
 		}
-		for {
-			ev, ok := gtx.Event(
-				key.FocusFilter{Target: &state.tag},
-				key.Filter{Focus: &state.tag, Name: key.NameReturn},
-				key.Filter{Focus: &state.tag, Name: key.NameSpace},
-			)
-			if !ok {
-				break
-			}
+		for _, ev := range gtx.Events(&state.tag) {
 			switch ev := ev.(type) {
 			case key.FocusEvent:
 				if ev.Focus {
@@ -82,7 +69,7 @@ func (e *Enum) Update(gtx layout.Context) bool {
 					e.focused = false
 				}
 			case key.Event:
-				if ev.State != key.Release {
+				if !e.focused || ev.State != key.Release {
 					break
 				}
 				if ev.Name != key.NameReturn && ev.Name != key.NameSpace {
@@ -130,9 +117,12 @@ func (e *Enum) Layout(gtx layout.Context, k string, content layout.Widget) layou
 	}
 	clk := &state.click
 	clk.Add(gtx.Ops)
-	event.Op(gtx.Ops, &state.tag)
+	enabled := gtx.Queue != nil
+	if enabled {
+		key.InputOp{Tag: &state.tag, Keys: "⏎|Space"}.Add(gtx.Ops)
+	}
 	semantic.SelectedOp(k == e.Value).Add(gtx.Ops)
-	semantic.EnabledOp(gtx.Enabled()).Add(gtx.Ops)
+	semantic.EnabledOp(enabled).Add(gtx.Ops)
 	c.Add(gtx.Ops)
 
 	return dims

widget/example_test.go

@@ -5,13 +5,10 @@ package widget_test
 import (
 	"fmt"
 	"image"
-	"io"
-	"strings"
 
 	"gioui.org/f32"
-	"gioui.org/io/event"
-	"gioui.org/io/input"
 	"gioui.org/io/pointer"
+	"gioui.org/io/router"
 	"gioui.org/io/transfer"
 	"gioui.org/layout"
 	"gioui.org/op"
@@ -24,11 +21,11 @@ func ExampleClickable_passthrough() {
 	// pointer events can be passed down for the underlying
 	// widgets to pick them up.
 	var button1, button2 widget.Clickable
-	var r input.Router
+	var r router.Router
 	gtx := layout.Context{
 		Ops:         new(op.Ops),
 		Constraints: layout.Exact(image.Pt(100, 100)),
-		Source:      r.Source(),
+		Queue:       &r,
 	}
 
 	// widget lays out two buttons on top of each other.
@@ -74,15 +71,15 @@ func ExampleClickable_passthrough() {
 }
 
 func ExampleDraggable_Layout() {
-	var r input.Router
+	var r router.Router
 	gtx := layout.Context{
 		Ops:         new(op.Ops),
 		Constraints: layout.Exact(image.Pt(100, 100)),
-		Source:      r.Source(),
+		Queue:       &r,
 	}
 	// mime is the type used to match drag and drop operations.
 	// It could be left empty in this example.
-	const mime = "MyMime"
+	mime := "MyMime"
 	drag := &widget.Draggable{Type: mime}
 	var drop int
 	// widget lays out the drag and drop handlers and processes
@@ -97,7 +94,7 @@ func ExampleDraggable_Layout() {
 		// drag must respond with an Offer event when requested.
 		// Use the drag method for this.
 		if m, ok := drag.Update(gtx); ok {
-			drag.Offer(gtx, m, io.NopCloser(strings.NewReader("hello world")))
+			drag.Offer(gtx.Ops, m, offer{Data: "hello world"})
 		}
 
 		// Setup the area for drops.
@@ -105,21 +102,17 @@ func ExampleDraggable_Layout() {
 			Min: image.Pt(20, 20),
 			Max: image.Pt(40, 40),
 		}.Push(gtx.Ops)
-		event.Op(gtx.Ops, &drop)
+		transfer.TargetOp{
+			Tag:  &drop,
+			Type: mime, // this must match the drag Type for the drop to succeed
+		}.Add(gtx.Ops)
 		ds.Pop()
-
 		// Check for the received data.
-		for {
-			ev, ok := gtx.Event(transfer.TargetFilter{Target: &drop, Type: mime})
-			if !ok {
-				break
-			}
+		for _, ev := range gtx.Events(&drop) {
 			switch e := ev.(type) {
 			case transfer.DataEvent:
 				data := e.Open()
-				defer data.Close()
-				content, _ := io.ReadAll(data)
-				fmt.Println(string(content))
+				fmt.Println(data.(offer).Data)
 			}
 		}
 	}
@@ -152,3 +145,10 @@ func ExampleDraggable_Layout() {
 	// Output:
 	// hello world
 }
+
+type offer struct {
+	Data string
+}
+
+func (offer) Read([]byte) (int, error) { return 0, nil }
+func (offer) Close() error             { return nil }

widget/float.go

@@ -48,11 +48,7 @@ func (f *Float) Layout(gtx layout.Context, axis layout.Axis, pointerMargin unit.
 // The range of f is set by the minimum constraints main axis value.
 func (f *Float) Update(gtx layout.Context) bool {
 	changed := false
-	for {
-		e, ok := f.drag.Update(gtx.Metric, gtx.Source, gesture.Axis(f.axis))
-		if !ok {
-			break
-		}
+	for _, e := range f.drag.Update(gtx.Metric, gtx, gesture.Axis(f.axis)) {
 		if f.length > 0 && (e.Kind == pointer.Press || e.Kind == pointer.Drag) {
 			pos := e.Position.X
 			if f.axis == layout.Vertical {

widget/index.go

@@ -347,6 +347,10 @@ type Region struct {
 	Baseline int
 }
 
+// region is identical to Region except that its coordinates are in document
+// space instead of a widget coordinate space.
+type region = Region
+
 // locate returns highlight regions covering the glyphs that represent the runes in
 // [startRune,endRune). If the rects parameter is non-nil, locate will use it to
 // return results instead of allocating, provided that there is enough capacity.