app: [API] remove Main

All platforms already allow the omission of the call to Main and running
Windows on the main goroutine. This change just gets rid of Main, and
documents the special requirement on Window.Event.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

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

@@ -56,6 +56,13 @@ type FrameEvent struct {
 	Source input.Source
 }
 
+// ViewEvent provides handles to the underlying window objects for the
+// current display protocol.
+type ViewEvent interface {
+	implementsViewEvent()
+	ImplementsEvent()
+}
+
 // Insets is the space taken up by
 // system decoration such as translucent
 // system bars and software keyboards.
@@ -113,18 +120,6 @@ func DataDir() (string, error) {
 	return dataDir()
 }
 
-// Main must be called last from the program main function.
-// On most platforms Main blocks forever, for Android and
-// iOS it returns immediately to give control of the main
-// thread back to the system.
-//
-// Calling Main is necessary because some operating systems
-// require control of the main thread of the program for
-// running windows.
-func Main() {
-	osMain()
-}
-
 func (FrameEvent) ImplementsEvent() {}
 
 func init() {

app/doc.go

@@ -8,18 +8,19 @@ See https://gioui.org for instructions to set up and run Gio programs.
 
 # Windows
 
-Create a new [Window] by calling [NewWindow]. On mobile platforms or when Gio
+A Window is run by calling its Event method in a loop. The first time a
-is embedded in another project, NewWindow merely connects with a previously
+method on Window is called, a new GUI window is created and shown. On mobile
-created window.
+platforms or when Gio is embedded in another project, Window merely connects
+with a previously created GUI window.
 
-A Window is run by calling its NextEvent method in a loop. The most important event is
+The most important event is [FrameEvent] that prompts an update of the window
-[FrameEvent] that prompts an update of the window contents.
+contents.
 
 For example:
 
-	w := app.NewWindow()
+	w := new(app.Window)
 	for {
-		e := w.NextEvent()
+		e := w.Event()
 		if e, ok := e.(app.FrameEvent); ok {
 			ops.Reset()
 			// Add operations to ops.
@@ -32,28 +33,12 @@ For example:
 A program must keep receiving events from the event channel until
 [DestroyEvent] is received.
 
-# Main
+# Main Thread
 
-The Main function must be called from a program's main function, to hand over
+Some GUI platform need access to the main thread of the program. To avoid a
-control of the main thread to operating systems that need it.
+deadlock on such platforms, at least one Window must have its Event method
-
+called by the main goroutine. It doesn't have to be any particular Window;
-Because Main is also blocking on some platforms, the event loop of a Window must run in a goroutine.
+even a destroyed Window suffices.
-
-For example, to display a blank but otherwise functional window:
-
-	package main
-
-	import "gioui.org/app"
-
-	func main() {
-		go func() {
-			w := app.NewWindow()
-			for {
-				w.NextEvent()
-			}
-		}()
-		app.Main()
-	}
 
 # Permissions
 

app/egl_wayland.go

@@ -69,7 +69,17 @@ func (c *wlContext) Refresh() error {
 	}
 	c.eglWin = eglWin
 	eglSurf := egl.NativeWindowType(uintptr(unsafe.Pointer(eglWin)))
-	return c.Context.CreateSurface(eglSurf, width, height)
+	if err := c.Context.CreateSurface(eglSurf, width, height); 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
 }
 
 func (c *wlContext) Lock() error {

app/egl_x11.go

@@ -46,8 +46,8 @@ func (c *x11Context) Refresh() error {
 	if err := c.Context.MakeCurrent(); err != nil {
 		return err
 	}
+	defer c.Context.ReleaseCurrent()
 	c.Context.EnableVSync(true)
-	c.Context.ReleaseCurrent()
 	return nil
 }
 

app/ime.go

@@ -0,0 +1,118 @@
+// 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/internal/log/log.go

@@ -1,7 +0,0 @@
-// 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/log_android.go

@@ -1,6 +1,6 @@
 // SPDX-License-Identifier: Unlicense OR MIT
 
-package log
+package app
 
 /*
 #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(appID)
+var logTag = C.CString(ID)
 
 func init() {
 	// Android's logcat already includes timestamps.

app/log_ios.go

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

app/log_windows.go

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

app/metal_darwin.go

@@ -60,8 +60,9 @@ 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

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

app/metal_macos.go

@@ -14,7 +14,11 @@ package app
 
 CALayer *gio_layerFactory(void) {
 	@autoreleasepool {
-		return [CAMetalLayer layer];
+		CAMetalLayer *l = [CAMetalLayer layer];
+		l.autoresizingMask = kCALayerHeightSizable|kCALayerWidthSizable;
+		l.needsDisplayOnBoundsChange = YES;
+		l.presentsWithTransaction = YES;
+		return l;
 	}
 }
 

app/os.go

@@ -7,7 +7,9 @@ import (
 	"image"
 	"image/color"
 
+	"gioui.org/io/event"
 	"gioui.org/io/key"
+	"gioui.org/op"
 
 	"gioui.org/gpu"
 	"gioui.org/io/pointer"
@@ -43,6 +45,8 @@ 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
@@ -131,6 +135,28 @@ 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
 
@@ -147,9 +173,19 @@ type context interface {
 	Unlock()
 }
 
-// Driver is the interface for the platform implementation
+// basicDriver is the subset of [driver] that may be called even after
+// a window is destroyed.
+type basicDriver interface {
+	// Event blocks until an even is available and returns it.
+	Event() event.Event
+	// Invalidate requests a FrameEvent.
+	Invalidate()
+}
+
+// driver is the interface for the platform implementation
 // of a window.
 type driver interface {
+	basicDriver
 	// SetAnimating sets the animation flag. When the window is animating,
 	// FrameEvents are delivered as fast as the display can handle them.
 	SetAnimating(anim bool)
@@ -166,17 +202,23 @@ type driver interface {
 	// 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
+	in      chan windowAndConfig
-	out  chan windowAndConfig
+	out     chan windowAndConfig
-	errs chan error
+	windows chan struct{}
 }
 
 type windowAndConfig struct {
@@ -186,32 +228,137 @@ type windowAndConfig struct {
 
 func newWindowRendezvous() *windowRendezvous {
 	wr := &windowRendezvous{
-		in:   make(chan windowAndConfig),
+		in:      make(chan windowAndConfig),
-		out:  make(chan windowAndConfig),
+		out:     make(chan windowAndConfig),
-		errs: make(chan error),
+		windows: make(chan struct{}),
 	}
 	go func() {
-		var main windowAndConfig
+		in := wr.in
+		var window windowAndConfig
 		var out chan windowAndConfig
 		for {
 			select {
-			case w := <-wr.in:
+			case w := <-in:
-				var err error
+				window = w
-				if main.window != nil {
-					err = errors.New("multiple windows are not supported")
-				}
-				wr.errs <- err
-				main = w
 				out = wr.out
-			case out <- main:
+			case out <- window:
 			}
 		}
 	}()
 	return wr
 }
 
-func (wakeupEvent) ImplementsEvent() {}
+func newEventLoop(w *callbacks, wakeup func()) *eventLoop {
-func (ConfigEvent) ImplementsEvent() {}
+	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 walkActions(actions system.Action, do func(system.Action)) {
 	for a := system.Action(1); actions != 0; a <<= 1 {
@@ -221,3 +368,6 @@ func walkActions(actions system.Action, do func(system.Action)) {
 		}
 	}
 }
+
+func (wakeupEvent) ImplementsEvent() {}
+func (ConfigEvent) ImplementsEvent() {}

app/os_android.go

@@ -137,8 +137,10 @@ import (
 	"unsafe"
 
 	"gioui.org/internal/f32color"
+	"gioui.org/op"
 
 	"gioui.org/f32"
+	"gioui.org/io/event"
 	"gioui.org/io/input"
 	"gioui.org/io/key"
 	"gioui.org/io/pointer"
@@ -150,6 +152,7 @@ import (
 
 type window struct {
 	callbacks *callbacks
+	loop      *eventLoop
 
 	view   C.jobject
 	handle cgo.Handle
@@ -158,12 +161,13 @@ type window struct {
 	fontScale float32
 	insets    pixelInsets
 
-	stage     Stage
+	visible   bool
 	started   bool
 	animating bool
 
-	win    *C.ANativeWindow
+	win       *C.ANativeWindow
-	config Config
+	config    Config
+	inputHint key.InputHint
 
 	semantic struct {
 		hoverID input.SemanticID
@@ -201,9 +205,9 @@ type pixelInsets struct {
 	top, bottom, left, right int
 }
 
-// ViewEvent is sent whenever the Window's underlying Android view
+// AndroidViewEvent is sent whenever the Window's underlying Android view
 // changes.
-type ViewEvent struct {
+type AndroidViewEvent 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.
@@ -487,24 +491,30 @@ 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.Configure(wopts.options)
+	w.setConfig(env, cnf)
-	w.SetInputHint(key.HintAny)
+	w.SetInputHint(w.inputHint)
-	w.setStage(StagePaused)
+	w.processEvent(AndroidViewEvent{View: uintptr(view)})
-	w.callbacks.Event(ViewEvent{View: uintptr(view)})
 	return C.jlong(w.handle)
 }
 
@@ -518,7 +528,7 @@ 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.setStage(StagePaused)
+	w.visible = false
 }
 
 //export Java_org_gioui_GioView_onStartView
@@ -534,7 +544,7 @@ 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.setStage(StagePaused)
+	w.visible = false
 }
 
 //export Java_org_gioui_GioView_onSurfaceChanged
@@ -556,9 +566,7 @@ 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)
-	if w.stage >= StageInactive {
+	w.draw(env, true)
-		w.draw(env, true)
-	}
 }
 
 //export Java_org_gioui_GioView_onFrameCallback
@@ -567,10 +575,7 @@ func Java_org_gioui_GioView_onFrameCallback(env *C.JNIEnv, class C.jclass, view
 	if !exist {
 		return
 	}
-	if w.stage < StageInactive {
+	if w.visible && w.animating {
-		return
-	}
-	if w.animating {
 		w.draw(env, false)
 		callVoidMethod(env, w.view, gioView.postFrameCallback)
 	}
@@ -579,7 +584,7 @@ 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.callbacks.Event(key.Event{Name: key.NameBack}) {
+	if w.processEvent(key.Event{Name: key.NameBack}) {
 		return C.JNI_TRUE
 	}
 	return C.JNI_FALSE
@@ -588,7 +593,8 @@ 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.callbacks.Event(key.FocusEvent{Focus: focus == C.JNI_TRUE})
+	w.config.Focused = focus == C.JNI_TRUE
+	w.processEvent(ConfigEvent{Config: w.config})
 }
 
 //export Java_org_gioui_GioView_onWindowInsets
@@ -600,9 +606,7 @@ func Java_org_gioui_GioView_onWindowInsets(env *C.JNIEnv, class C.jclass, view C
 		left:   int(left),
 		right:  int(right),
 	}
-	if w.stage >= StageInactive {
+	w.draw(env, true)
-		w.draw(env, true)
-	}
 }
 
 //export Java_org_gioui_GioView_initializeAccessibilityNodeInfo
@@ -663,6 +667,34 @@ 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 {
 	for _, ch := range sem.Children {
 		err := callVoidMethod(env, info, android.accessibilityNodeInfo.addChild, jvalue(w.view), jvalue(w.virtualIDFor(ch.ID)))
@@ -767,8 +799,7 @@ func (w *window) semIDFor(virtID C.jint) input.SemanticID {
 
 func (w *window) detach(env *C.JNIEnv) {
 	callVoidMethod(env, w.view, gioView.unregister)
-	w.callbacks.Event(ViewEvent{})
+	w.processEvent(AndroidViewEvent{})
-	w.callbacks.SetDriver(nil)
 	w.handle.Delete()
 	C.jni_DeleteGlobalRef(env, w.view)
 	w.view = 0
@@ -779,18 +810,10 @@ func (w *window) setVisible(env *C.JNIEnv) {
 	if width == 0 || height == 0 {
 		return
 	}
-	w.setStage(StageRunning)
+	w.visible = true
 	w.draw(env, true)
 }
 
-func (w *window) setStage(stage Stage) {
-	if stage == w.stage {
-		return
-	}
-	w.stage = stage
-	w.callbacks.Event(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")
@@ -827,10 +850,13 @@ 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.callbacks.Event(ConfigEvent{Config: w.config})
+		w.processEvent(ConfigEvent{Config: w.config})
 	}
 	if size.X == 0 || size.Y == 0 {
 		return
@@ -844,7 +870,7 @@ func (w *window) draw(env *C.JNIEnv, sync bool) {
 		Left:   unit.Dp(w.insets.left) * dppp,
 		Right:  unit.Dp(w.insets.right) * dppp,
 	}
-	w.callbacks.Event(frameEvent{
+	w.processEvent(frameEvent{
 		FrameEvent: FrameEvent{
 			Now:    time.Now(),
 			Size:   w.config.Size,
@@ -944,7 +970,7 @@ func Java_org_gioui_GioView_onKeyEvent(env *C.JNIEnv, class C.jclass, handle C.j
 		if pressed == C.JNI_TRUE {
 			state = key.Press
 		}
-		w.callbacks.Event(key.Event{Name: n, State: state})
+		w.processEvent(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)))
@@ -994,7 +1020,7 @@ func Java_org_gioui_GioView_onTouchEvent(env *C.JNIEnv, class C.jclass, handle C
 	default:
 		return
 	}
-	w.callbacks.Event(pointer.Event{
+	w.processEvent(pointer.Event{
 		Kind:      kind,
 		Source:    src,
 		Buttons:   btns,
@@ -1146,6 +1172,8 @@ 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
@@ -1289,12 +1317,9 @@ func findClass(env *C.JNIEnv, name string) C.jclass {
 	return C.jni_FindClass(env, cn)
 }
 
-func osMain() {
+func newWindow(window *callbacks, options []Option) {
-}
-
-func newWindow(window *callbacks, options []Option) error {
 	mainWindow.in <- windowAndConfig{window, options}
-	return <-mainWindow.errs
+	<-mainWindow.windows
 }
 
 func (w *window) WriteClipboard(mime string, s []byte) {
@@ -1313,7 +1338,7 @@ func (w *window) ReadClipboard() {
 			return
 		}
 		content := goString(env, C.jstring(c))
-		w.callbacks.Event(transfer.DataEvent{
+		w.processEvent(transfer.DataEvent{
 			Type: "application/text",
 			Open: func() io.ReadCloser {
 				return io.NopCloser(strings.NewReader(content))
@@ -1323,42 +1348,46 @@ func (w *window) ReadClipboard() {
 }
 
 func (w *window) Configure(options []Option) {
+	cnf := w.config
+	cnf.apply(unit.Metric{}, options)
 	runInJVM(javaVM(), func(env *C.JNIEnv) {
-		prev := w.config
+		w.setConfig(env, cnf)
-		cnf := w.config
-		cnf.apply(unit.Metric{}, options)
-		// 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 cnf.Decorated != prev.Decorated {
-			w.config.Decorated = cnf.Decorated
-		}
-		w.callbacks.Event(ConfigEvent{Config: w.config})
 	})
 }
 
+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 cnf.Decorated != prev.Decorated {
+		w.config.Decorated = cnf.Decorated
+	}
+	w.processEvent(ConfigEvent{Config: w.config})
+}
+
 func (w *window) Perform(system.Action) {}
 
 func (w *window) SetCursor(cursor pointer.Cursor) {
@@ -1367,9 +1396,10 @@ func (w *window) SetCursor(cursor pointer.Cursor) {
 	})
 }
 
-func (w *window) Wakeup() {
+func (w *window) wakeup() {
 	runOnMain(func(env *C.JNIEnv) {
-		w.callbacks.Event(wakeupEvent{})
+		w.loop.Wakeup()
+		w.loop.FlushEvents()
 	})
 }
 
@@ -1460,4 +1490,5 @@ func Java_org_gioui_Gio_scheduleMainFuncs(env *C.JNIEnv, cls C.jclass) {
 	}
 }
 
-func (_ ViewEvent) ImplementsEvent() {}
+func (AndroidViewEvent) implementsViewEvent() {}
+func (AndroidViewEvent) ImplementsEvent()     {}

app/os_darwin.go

@@ -15,8 +15,8 @@ __attribute__ ((visibility ("hidden"))) void gio_hideCursor();
 __attribute__ ((visibility ("hidden"))) void gio_showCursor();
 __attribute__ ((visibility ("hidden"))) void gio_setCursor(NSUInteger curID);
 
-static bool isMainThread() {
+static int isMainThread() {
-	return [NSThread isMainThread];
+	return [NSThread isMainThread] ? 1 : 0;
 }
 
 static NSUInteger nsstringLength(CFTypeRef cstr) {
@@ -77,7 +77,7 @@ var mainFuncs = make(chan func(), 1)
 
 // runOnMain runs the function on the main thread.
 func runOnMain(f func()) {
-	if C.isMainThread() {
+	if isMainThread() {
 		f()
 		return
 	}
@@ -87,6 +87,10 @@ func runOnMain(f func()) {
 	}()
 }
 
+func isMainThread() bool {
+	return C.isMainThread() != 0
+}
+
 //export gio_dispatchMainFuncs
 func gio_dispatchMainFuncs() {
 	for {
@@ -259,9 +263,3 @@ func windowSetCursor(from, to pointer.Cursor) pointer.Cursor {
 	C.gio_setCursor(C.NSUInteger(macosCursorID[to]))
 	return to
 }
-
-func (w *window) Wakeup() {
-	runOnMain(func() {
-		w.w.Event(wakeupEvent{})
-	})
-}

app/os_darwin.m

@@ -1,11 +0,0 @@
-// SPDX-License-Identifier: Unlicense OR MIT
-
-#import <Foundation/Foundation.h>
-
-#include "_cgo_export.h"
-
-void gio_wakeupMainThread(void) {
-	dispatch_async(dispatch_get_main_queue(), ^{
-		gio_dispatchMainFuncs();
-	});
-}

app/os_ios.go

@@ -12,6 +12,8 @@ package app
 #include <UIKit/UIKit.h>
 #include <stdint.h>
 
+__attribute__ ((visibility ("hidden"))) void gio_viewSetHandle(CFTypeRef viewRef, uintptr_t handle);
+
 struct drawParams {
 	CGFloat dpi, sdpi;
 	CGFloat width, height;
@@ -74,6 +76,7 @@ import (
 	"image"
 	"io"
 	"runtime"
+	"runtime/cgo"
 	"runtime/debug"
 	"strings"
 	"time"
@@ -81,14 +84,16 @@ import (
 	"unsafe"
 
 	"gioui.org/f32"
+	"gioui.org/io/event"
 	"gioui.org/io/key"
 	"gioui.org/io/pointer"
 	"gioui.org/io/system"
 	"gioui.org/io/transfer"
+	"gioui.org/op"
 	"gioui.org/unit"
 )
 
-type ViewEvent struct {
+type UIKitViewEvent struct {
 	// ViewController is a CFTypeRef for the UIViewController backing a Window.
 	ViewController uintptr
 }
@@ -97,18 +102,17 @@ type window struct {
 	view        C.CFTypeRef
 	w           *callbacks
 	displayLink *displayLink
+	loop        *eventLoop
 
-	visible bool
+	hidden bool
-	cursor  pointer.Cursor
+	cursor pointer.Cursor
-	config  Config
+	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()
@@ -116,48 +120,52 @@ 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 {
-		panic(err)
+		w.w.ProcessEvent(DestroyEvent{Err: err})
+		return
 	}
 	w.displayLink = dl
-	wopts := <-mainWindow.out
+	C.gio_viewSetHandle(view, C.uintptr_t(cgo.NewHandle(w)))
-	w.w = wopts.window
-	w.w.SetDriver(w)
-	views[view] = w
 	w.Configure(wopts.options)
-	w.w.Event(StageEvent{Stage: StagePaused})
+	w.ProcessEvent(UIKitViewEvent{ViewController: uintptr(controller)})
-	w.w.Event(ViewEvent{ViewController: uintptr(controller)})
+}
+
+func viewFor(h C.uintptr_t) *window {
+	return cgo.Handle(h).Value().(*window)
 }
 
 //export gio_onDraw
-func gio_onDraw(view C.CFTypeRef) {
+func gio_onDraw(h C.uintptr_t) {
-	w := views[view]
+	w := viewFor(h)
 	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(StageEvent{Stage: 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.w.Event(frameEvent{
+	w.ProcessEvent(frameEvent{
 		FrameEvent: FrameEvent{
 			Now: time.Now(),
 			Size: image.Point{
@@ -177,26 +185,34 @@ func (w *window) draw(sync bool) {
 }
 
 //export onStop
-func onStop(view C.CFTypeRef) {
+func onStop(h C.uintptr_t) {
-	w := views[view]
+	w := viewFor(h)
-	w.visible = false
+	w.hidden = true
-	w.w.Event(StageEvent{Stage: StagePaused})
+}
+
+//export onStart
+func onStart(h C.uintptr_t) {
+	w := viewFor(h)
+	w.hidden = false
+	w.draw(true)
 }
 
 //export onDestroy
-func onDestroy(view C.CFTypeRef) {
+func onDestroy(h C.uintptr_t) {
-	w := views[view]
+	w := viewFor(h)
-	delete(views, view)
+	w.ProcessEvent(UIKitViewEvent{})
-	w.w.Event(ViewEvent{})
+	w.ProcessEvent(DestroyEvent{})
-	w.w.Event(DestroyEvent{})
 	w.displayLink.Close()
+	w.displayLink = nil
+	cgo.Handle(h).Delete()
 	w.view = 0
 }
 
 //export onFocus
-func onFocus(view C.CFTypeRef, focus int) {
+func onFocus(h C.uintptr_t, focus int) {
-	w := views[view]
+	w := viewFor(h)
-	w.w.Event(key.FocusEvent{Focus: focus != 0})
+	w.config.Focused = focus != 0
+	w.ProcessEvent(ConfigEvent{Config: w.config})
 }
 
 //export onLowMemory
@@ -206,38 +222,38 @@ func onLowMemory() {
 }
 
 //export onUpArrow
-func onUpArrow(view C.CFTypeRef) {
+func onUpArrow(h C.uintptr_t) {
-	views[view].onKeyCommand(key.NameUpArrow)
+	viewFor(h).onKeyCommand(key.NameUpArrow)
 }
 
 //export onDownArrow
-func onDownArrow(view C.CFTypeRef) {
+func onDownArrow(h C.uintptr_t) {
-	views[view].onKeyCommand(key.NameDownArrow)
+	viewFor(h).onKeyCommand(key.NameDownArrow)
 }
 
 //export onLeftArrow
-func onLeftArrow(view C.CFTypeRef) {
+func onLeftArrow(h C.uintptr_t) {
-	views[view].onKeyCommand(key.NameLeftArrow)
+	viewFor(h).onKeyCommand(key.NameLeftArrow)
 }
 
 //export onRightArrow
-func onRightArrow(view C.CFTypeRef) {
+func onRightArrow(h C.uintptr_t) {
-	views[view].onKeyCommand(key.NameRightArrow)
+	viewFor(h).onKeyCommand(key.NameRightArrow)
 }
 
 //export onDeleteBackward
-func onDeleteBackward(view C.CFTypeRef) {
+func onDeleteBackward(h C.uintptr_t) {
-	views[view].onKeyCommand(key.NameDeleteBackward)
+	viewFor(h).onKeyCommand(key.NameDeleteBackward)
 }
 
 //export onText
-func onText(view, str C.CFTypeRef) {
+func onText(h C.uintptr_t, str C.CFTypeRef) {
-	w := views[view]
+	w := viewFor(h)
 	w.w.EditorInsert(nsstringToString(str))
 }
 
 //export onTouch
-func onTouch(last C.int, view, touchRef C.CFTypeRef, phase C.NSInteger, x, y C.CGFloat, ti C.double) {
+func onTouch(h C.uintptr_t, last C.int, touchRef C.CFTypeRef, phase C.NSInteger, x, y C.CGFloat, ti C.double) {
 	var kind pointer.Kind
 	switch phase {
 	case C.UITouchPhaseBegan:
@@ -251,10 +267,10 @@ func onTouch(last C.int, view, touchRef C.CFTypeRef, phase C.NSInteger, x, y C.C
 	default:
 		return
 	}
-	w := views[view]
+	w := viewFor(h)
 	t := time.Duration(float64(ti) * float64(time.Second))
 	p := f32.Point{X: float32(x), Y: float32(y)}
-	w.w.Event(pointer.Event{
+	w.ProcessEvent(pointer.Event{
 		Kind:      kind,
 		Source:    pointer.Touch,
 		PointerID: w.lookupTouch(last != 0, touchRef),
@@ -267,7 +283,7 @@ func (w *window) ReadClipboard() {
 	cstr := C.readClipboard()
 	defer C.CFRelease(cstr)
 	content := nsstringToString(cstr)
-	w.w.Event(transfer.DataEvent{
+	w.ProcessEvent(transfer.DataEvent{
 		Type: "application/text",
 		Open: func() io.ReadCloser {
 			return io.NopCloser(strings.NewReader(content))
@@ -287,7 +303,7 @@ func (w *window) WriteClipboard(mime string, s []byte) {
 func (w *window) Configure([]Option) {
 	// Decorations are never disabled.
 	w.config.Decorated = true
-	w.w.Event(ConfigEvent{Config: w.config})
+	w.ProcessEvent(ConfigEvent{Config: w.config})
 }
 
 func (w *window) EditorStateChanged(old, new editorState) {}
@@ -295,10 +311,6 @@ 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 {
@@ -311,7 +323,7 @@ func (w *window) SetCursor(cursor pointer.Cursor) {
 }
 
 func (w *window) onKeyCommand(name key.Name) {
-	w.w.Event(key.Event{
+	w.ProcessEvent(key.Event{
 		Name: name,
 	})
 }
@@ -350,12 +362,30 @@ func (w *window) ShowTextInput(show bool) {
 
 func (w *window) SetInputHint(_ key.InputHint) {}
 
-func newWindow(win *callbacks, options []Option) error {
+func (w *window) ProcessEvent(e event.Event) {
-	mainWindow.in <- windowAndConfig{win, options}
+	w.w.ProcessEvent(e)
-	return <-mainWindow.errs
+	w.loop.FlushEvents()
 }
 
-func osMain() {
+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) {
+	mainWindow.in <- windowAndConfig{win, options}
+	<-mainWindow.windows
 }
 
 //export gio_runMain
@@ -363,4 +393,12 @@ func gio_runMain() {
 	runMain()
 }
 
-func (_ ViewEvent) ImplementsEvent() {}
+func (w *window) wakeup() {
+	runOnMain(func() {
+		w.loop.Wakeup()
+		w.loop.FlushEvents()
+	})
+}
+
+func (UIKitViewEvent) implementsViewEvent() {}
+func (UIKitViewEvent) ImplementsEvent()     {}

app/os_ios.m

@@ -11,6 +11,7 @@
 __attribute__ ((visibility ("hidden"))) Class gio_layerClass(void);
 
 @interface GioView: UIView <UIKeyInput>
+@property uintptr_t handle;
 @end
 
 @implementation GioViewController
@@ -54,33 +55,33 @@ CGFloat _keyboardHeight;
 }
 
 - (void)applicationWillEnterForeground:(UIApplication *)application {
-	UIView *drawView = self.view.subviews[0];
+	GioView *view = (GioView *)self.view.subviews[0];
-	if (drawView != nil) {
+	if (view != nil) {
-		gio_onDraw((__bridge CFTypeRef)drawView);
+		onStart(view.handle);
 	}
 }
 
 - (void)applicationDidEnterBackground:(UIApplication *)application {
-	UIView *drawView = self.view.subviews[0];
+	GioView *view = (GioView *)self.view.subviews[0];
-	if (drawView != nil) {
+	if (view != nil) {
-		onStop((__bridge CFTypeRef)drawView);
+		onStop(view.handle);
 	}
 }
 
 - (void)viewDidDisappear:(BOOL)animated {
 	[super viewDidDisappear:animated];
-	CFTypeRef viewRef = (__bridge CFTypeRef)self.view.subviews[0];
+	GioView *view = (GioView *)self.view.subviews[0];
-	onDestroy(viewRef);
+	onDestroy(view.handle);
 }
 
 - (void)viewDidLayoutSubviews {
 	[super viewDidLayoutSubviews];
-	UIView *view = self.view.subviews[0];
+	GioView *view = (GioView *)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((__bridge CFTypeRef)view);
+	gio_onDraw(view.handle);
 }
 
 - (void)didReceiveMemoryWarning {
@@ -101,11 +102,10 @@ CGFloat _keyboardHeight;
 }
 @end
 
-static void handleTouches(int last, UIView *view, NSSet<UITouch *> *touches, UIEvent *event) {
+static void handleTouches(int last, GioView *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++;
@@ -116,7 +116,7 @@ static void handleTouches(int last, UIView *view, NSSet<UITouch *> *touches, UIE
 			CGPoint loc = [coalescedTouch locationInView:view];
 			j++;
 			int lastTouch = last && i == n && j == m;
-			onTouch(lastTouch, viewRef, touchRef, touch.phase, loc.x*scale, loc.y*scale, [coalescedTouch timestamp]);
+			onTouch(view.handle, lastTouch, touchRef, touch.phase, loc.x*scale, loc.y*scale, [coalescedTouch timestamp]);
 		}
 	}
 }
@@ -151,13 +151,13 @@ NSArray<UIKeyCommand *> *_keyCommands;
 
 - (void)onWindowDidBecomeKey:(NSNotification *)note {
 	if (self.isFirstResponder) {
-		onFocus((__bridge CFTypeRef)self, YES);
+		onFocus(self.handle, YES);
 	}
 }
 
 - (void)onWindowDidResignKey:(NSNotification *)note {
 	if (self.isFirstResponder) {
-		onFocus((__bridge CFTypeRef)self, NO);
+		onFocus(self.handle, NO);
 	}
 }
 
@@ -178,7 +178,7 @@ NSArray<UIKeyCommand *> *_keyCommands;
 }
 
 - (void)insertText:(NSString *)text {
-	onText((__bridge CFTypeRef)self, (__bridge CFTypeRef)text);
+	onText(self.handle, (__bridge CFTypeRef)text);
 }
 
 - (BOOL)canBecomeFirstResponder {
@@ -190,23 +190,23 @@ NSArray<UIKeyCommand *> *_keyCommands;
 }
 
 - (void)deleteBackward {
-	onDeleteBackward((__bridge CFTypeRef)self);
+	onDeleteBackward(self.handle);
 }
 
 - (void)onUpArrow {
-	onUpArrow((__bridge CFTypeRef)self);
+	onUpArrow(self.handle);
 }
 
 - (void)onDownArrow {
-	onDownArrow((__bridge CFTypeRef)self);
+	onDownArrow(self.handle);
 }
 
 - (void)onLeftArrow {
-	onLeftArrow((__bridge CFTypeRef)self);
+	onLeftArrow(self.handle);
 }
 
 - (void)onRightArrow {
-	onRightArrow((__bridge CFTypeRef)self);
+	onRightArrow(self.handle);
 }
 
 - (NSArray<UIKeyCommand *> *)keyCommands {
@@ -271,3 +271,14 @@ 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;
+}
+
+void gio_wakeupMainThread(void) {
+	dispatch_async(dispatch_get_main_queue(), ^{
+		gio_dispatchMainFuncs();
+	});
+}

app/os_js.go

@@ -14,8 +14,10 @@ import (
 	"unicode/utf8"
 
 	"gioui.org/internal/f32color"
+	"gioui.org/op"
 
 	"gioui.org/f32"
+	"gioui.org/io/event"
 	"gioui.org/io/key"
 	"gioui.org/io/pointer"
 	"gioui.org/io/system"
@@ -23,7 +25,7 @@ import (
 	"gioui.org/unit"
 )
 
-type ViewEvent struct {
+type JSViewEvent struct {
 	Element js.Value
 }
 
@@ -54,9 +56,6 @@ type window struct {
 	composing             bool
 	requestFocus          bool
 
-	chanAnimation chan struct{}
-	chanRedraw    chan struct{}
-
 	config    Config
 	inset     f32.Point
 	scale     float32
@@ -69,7 +68,7 @@ type window struct {
 	contextStatus contextStatus
 }
 
-func newWindow(win *callbacks, options []Option) error {
+func newWindow(win *callbacks, options []Option) {
 	doc := js.Global().Get("document")
 	cont := getContainer(doc)
 	cnv := createCanvas(doc)
@@ -84,7 +83,9 @@ func newWindow(win *callbacks, options []Option) error {
 		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")
@@ -94,15 +95,13 @@ func newWindow(win *callbacks, options []Option) error {
 	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.chanAnimation <- struct{}{}
+		w.draw(false)
 		return nil
 	})
 	w.clipboardCallback = w.funcOf(func(this js.Value, args []js.Value) interface{} {
 		content := args[0].String()
-		go win.Event(transfer.DataEvent{
+		w.processEvent(transfer.DataEvent{
 			Type: "application/text",
 			Open: func() io.ReadCloser {
 				return io.NopCloser(strings.NewReader(content))
@@ -112,29 +111,12 @@ func newWindow(win *callbacks, options []Option) error {
 	})
 	w.addEventListeners()
 	w.addHistory()
-	w.w = win
 
-	go func() {
+	w.Configure(options)
-		defer w.cleanup()
+	w.blur()
-		w.w.SetDriver(w)
+	w.processEvent(JSViewEvent{Element: cont})
-		w.Configure(options)
+	w.resize()
-		w.blur()
+	w.draw(true)
-		w.w.Event(ViewEvent{Element: cont})
-		w.w.Event(StageEvent{Stage: 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 {
@@ -194,12 +176,12 @@ func (w *window) addEventListeners() {
 		w.cnv.Set("width", 0)
 		w.cnv.Set("height", 0)
 		w.resize()
-		w.requestRedraw()
+		w.draw(true)
 		return nil
 	})
 	w.addEventListener(w.visualViewport, "resize", func(this js.Value, args []js.Value) interface{} {
 		w.resize()
-		w.requestRedraw()
+		w.draw(true)
 		return nil
 	})
 	w.addEventListener(w.window, "contextmenu", func(this js.Value, args []js.Value) interface{} {
@@ -207,22 +189,11 @@ func (w *window) addEventListeners() {
 		return nil
 	})
 	w.addEventListener(w.window, "popstate", func(this js.Value, args []js.Value) interface{} {
-		if w.w.Event(key.Event{Name: key.NameBack}) {
+		if w.processEvent(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 := StageEvent{}
-		switch w.document.Get("visibilityState").String() {
-		case "hidden", "prerender", "unloaded":
-			ev.Stage = StagePaused
-		default:
-			ev.Stage = 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
@@ -280,18 +251,20 @@ func (w *window) addEventListeners() {
 			w.touches[i] = js.Null()
 		}
 		w.touches = w.touches[:0]
-		w.w.Event(pointer.Event{
+		w.processEvent(pointer.Event{
 			Kind:   pointer.Cancel,
 			Source: pointer.Touch,
 		})
 		return nil
 	})
 	w.addEventListener(w.tarea, "focus", func(this js.Value, args []js.Value) interface{} {
-		w.w.Event(key.FocusEvent{Focus: true})
+		w.config.Focused = true
+		w.processEvent(ConfigEvent{Config: w.config})
 		return nil
 	})
 	w.addEventListener(w.tarea, "blur", func(this js.Value, args []js.Value) interface{} {
-		w.w.Event(key.FocusEvent{Focus: false})
+		w.config.Focused = false
+		w.processEvent(ConfigEvent{Config: w.config})
 		w.blur()
 		return nil
 	})
@@ -380,10 +353,50 @@ func (w *window) keyEvent(e js.Value, ks key.State) {
 			Modifiers: modifiersFor(e),
 			State:     ks,
 		}
-		w.w.Event(cmd)
+		w.processEvent(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 {
@@ -431,7 +444,7 @@ func (w *window) touchEvent(kind pointer.Kind, e js.Value) {
 			X: float32(x) * scale,
 			Y: float32(y) * scale,
 		}
-		w.w.Event(pointer.Event{
+		w.processEvent(pointer.Event{
 			Kind:      kind,
 			Source:    pointer.Touch,
 			Position:  pos,
@@ -481,7 +494,7 @@ func (w *window) pointerEvent(kind pointer.Kind, dx, dy float32, e js.Value) {
 	if jbtns&4 != 0 {
 		btns |= pointer.ButtonTertiary
 	}
-	w.w.Event(pointer.Event{
+	w.processEvent(pointer.Event{
 		Kind:      kind,
 		Source:    pointer.Mouse,
 		Buttons:   btns,
@@ -508,17 +521,6 @@ 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) {
@@ -574,7 +576,7 @@ func (w *window) Configure(options []Option) {
 	if cnf.Decorated != prev.Decorated {
 		w.config.Decorated = cnf.Decorated
 	}
-	w.w.Event(ConfigEvent{Config: w.config})
+	w.processEvent(ConfigEvent{Config: w.config})
 }
 
 func (w *window) Perform(system.Action) {}
@@ -613,23 +615,14 @@ 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.
-	go func() {
+	if show {
-		if show {
+		w.focus()
-			w.focus()
+	} else {
-		} else {
+		w.blur()
-			w.blur()
+	}
-		}
-	}()
 }
 
 func (w *window) SetInputHint(mode key.InputHint) {
@@ -646,7 +639,7 @@ func (w *window) resize() {
 	}
 	if size != w.config.Size {
 		w.config.Size = size
-		w.w.Event(ConfigEvent{Config: w.config})
+		w.processEvent(ConfigEvent{Config: w.config})
 	}
 
 	if vx, vy := w.visualViewport.Get("width"), w.visualViewport.Get("height"); !vx.IsUndefined() && !vy.IsUndefined() {
@@ -666,12 +659,19 @@ 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.w.Event(frameEvent{
+	w.processEvent(frameEvent{
 		FrameEvent: FrameEvent{
 			Now:    time.Now(),
 			Size:   size,
@@ -741,17 +741,6 @@ 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
 
@@ -827,4 +816,5 @@ func translateKey(k string) (key.Name, bool) {
 	return n, true
 }
 
-func (_ ViewEvent) ImplementsEvent() {}
+func (JSViewEvent) implementsViewEvent() {}
+func (JSViewEvent) ImplementsEvent()     {}

app/os_macos.go

@@ -10,16 +10,19 @@ import (
 	"image"
 	"io"
 	"runtime"
+	"runtime/cgo"
 	"strings"
 	"time"
 	"unicode"
 	"unicode/utf8"
 
 	"gioui.org/internal/f32"
+	"gioui.org/io/event"
 	"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"
@@ -36,9 +39,10 @@ import (
 #define MOUSE_DOWN 3
 #define MOUSE_SCROLL 4
 
-__attribute__ ((visibility ("hidden"))) void gio_main(void);
+__attribute__ ((visibility ("hidden"))) void gio_initApp(void);
 __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 {
@@ -58,148 +62,204 @@ static CFTypeRef readClipboard(void) {
 }
 
 static CGFloat viewHeight(CFTypeRef viewRef) {
-	NSView *view = (__bridge NSView *)viewRef;
+	@autoreleasepool {
-	return [view bounds].size.height;
+		NSView *view = (__bridge NSView *)viewRef;
+		return [view bounds].size.height;
+	}
 }
 
 static CGFloat viewWidth(CFTypeRef viewRef) {
-	NSView *view = (__bridge NSView *)viewRef;
+	@autoreleasepool {
-	return [view bounds].size.width;
+		NSView *view = (__bridge NSView *)viewRef;
+		return [view bounds].size.width;
+	}
 }
 
 static CGFloat getScreenBackingScale(void) {
-	return [NSScreen.mainScreen backingScaleFactor];
+	@autoreleasepool {
+		return [NSScreen.mainScreen backingScaleFactor];
+	}
 }
 
 static CGFloat getViewBackingScale(CFTypeRef viewRef) {
-	NSView *view = (__bridge NSView *)viewRef;
+	@autoreleasepool {
-	return [view.window backingScaleFactor];
+		NSView *view = (__bridge NSView *)viewRef;
+		return [view.window backingScaleFactor];
+	}
 }
 
 static void setNeedsDisplay(CFTypeRef viewRef) {
-	NSView *view = (__bridge NSView *)viewRef;
+	@autoreleasepool {
-	[view setNeedsDisplay:YES];
+		NSView *view = (__bridge NSView *)viewRef;
+		[view setNeedsDisplay:YES];
+	}
 }
 
 static NSPoint cascadeTopLeftFromPoint(CFTypeRef windowRef, NSPoint topLeft) {
-	NSWindow *window = (__bridge NSWindow *)windowRef;
+	@autoreleasepool {
-	return [window cascadeTopLeftFromPoint:topLeft];
+		NSWindow *window = (__bridge NSWindow *)windowRef;
+		return [window cascadeTopLeftFromPoint:topLeft];
+	}
 }
 
 static void makeKeyAndOrderFront(CFTypeRef windowRef) {
-	NSWindow *window = (__bridge NSWindow *)windowRef;
+	@autoreleasepool {
-	[window makeKeyAndOrderFront:nil];
+		NSWindow *window = (__bridge NSWindow *)windowRef;
+		[window makeKeyAndOrderFront:nil];
+	}
 }
 
 static void toggleFullScreen(CFTypeRef windowRef) {
-	NSWindow *window = (__bridge NSWindow *)windowRef;
+	@autoreleasepool {
-	[window toggleFullScreen:nil];
+		NSWindow *window = (__bridge NSWindow *)windowRef;
+		[window toggleFullScreen:nil];
+	}
 }
 
 static NSWindowStyleMask getWindowStyleMask(CFTypeRef windowRef) {
-	NSWindow *window = (__bridge NSWindow *)windowRef;
+	@autoreleasepool {
-	return [window styleMask];
+		NSWindow *window = (__bridge NSWindow *)windowRef;
+		return [window styleMask];
+	}
 }
 
 static void setWindowStyleMask(CFTypeRef windowRef, NSWindowStyleMask mask) {
-	NSWindow *window = (__bridge NSWindow *)windowRef;
+	@autoreleasepool {
-	window.styleMask = mask;
+		NSWindow *window = (__bridge NSWindow *)windowRef;
+		window.styleMask = mask;
+	}
 }
 
 static void setWindowTitleVisibility(CFTypeRef windowRef, NSWindowTitleVisibility state) {
-	NSWindow *window = (__bridge NSWindow *)windowRef;
+	@autoreleasepool {
-	window.titleVisibility = state;
+		NSWindow *window = (__bridge NSWindow *)windowRef;
+		window.titleVisibility = state;
+	}
 }
 
 static void setWindowTitlebarAppearsTransparent(CFTypeRef windowRef, int transparent) {
-	NSWindow *window = (__bridge NSWindow *)windowRef;
+	@autoreleasepool {
-	window.titlebarAppearsTransparent = (BOOL)transparent;
+		NSWindow *window = (__bridge NSWindow *)windowRef;
+		window.titlebarAppearsTransparent = (BOOL)transparent;
+	}
 }
 
 static void setWindowStandardButtonHidden(CFTypeRef windowRef, NSWindowButton btn, int hide) {
-	NSWindow *window = (__bridge NSWindow *)windowRef;
+	@autoreleasepool {
-	[window standardWindowButton:btn].hidden = (BOOL)hide;
+		NSWindow *window = (__bridge NSWindow *)windowRef;
+		[window standardWindowButton:btn].hidden = (BOOL)hide;
+	}
 }
 
 static void performWindowDragWithEvent(CFTypeRef windowRef, CFTypeRef evt) {
-	NSWindow *window = (__bridge NSWindow *)windowRef;
+	@autoreleasepool {
-	[window performWindowDragWithEvent:(__bridge NSEvent*)evt];
+		NSWindow *window = (__bridge NSWindow *)windowRef;
+		[window performWindowDragWithEvent:(__bridge NSEvent*)evt];
+	}
 }
 
 static void closeWindow(CFTypeRef windowRef) {
-	NSWindow* window = (__bridge NSWindow *)windowRef;
+	@autoreleasepool {
-	[window performClose:nil];
+		NSWindow* window = (__bridge NSWindow *)windowRef;
+		[window performClose:nil];
+	}
 }
 
 static void setSize(CFTypeRef windowRef, CGFloat width, CGFloat height) {
-	NSWindow* window = (__bridge NSWindow *)windowRef;
+	@autoreleasepool {
-	NSSize size = NSMakeSize(width, height);
+		NSWindow* window = (__bridge NSWindow *)windowRef;
-	[window setContentSize:size];
+		NSSize size = NSMakeSize(width, height);
+		[window setContentSize:size];
+	}
 }
 
 static void setMinSize(CFTypeRef windowRef, CGFloat width, CGFloat height) {
-	NSWindow* window = (__bridge NSWindow *)windowRef;
+	@autoreleasepool {
-	window.contentMinSize = NSMakeSize(width, height);
+		NSWindow* window = (__bridge NSWindow *)windowRef;
+		window.contentMinSize = NSMakeSize(width, height);
+	}
 }
 
 static void setMaxSize(CFTypeRef windowRef, CGFloat width, CGFloat height) {
-	NSWindow* window = (__bridge NSWindow *)windowRef;
+	@autoreleasepool {
-	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) {
-	NSWindow* window = (__bridge NSWindow *)windowRef;
+	@autoreleasepool {
-	NSRect r = NSMakeRect(x, y, w, h);
+		NSWindow* window = (__bridge NSWindow *)windowRef;
-	[window setFrame:r display:YES];
+		NSRect r = NSMakeRect(x, y, w, h);
+		[window setFrame:r display:YES];
+	}
 }
 
 static void hideWindow(CFTypeRef windowRef) {
-	NSWindow* window = (__bridge NSWindow *)windowRef;
+	@autoreleasepool {
-	[window miniaturize:window];
+		NSWindow* window = (__bridge NSWindow *)windowRef;
+		[window miniaturize:window];
+	}
 }
 
 static void unhideWindow(CFTypeRef windowRef) {
-	NSWindow* window = (__bridge NSWindow *)windowRef;
+	@autoreleasepool {
-	[window deminiaturize:window];
+		NSWindow* window = (__bridge NSWindow *)windowRef;
+		[window deminiaturize:window];
+	}
 }
 
 static NSRect getScreenFrame(CFTypeRef windowRef) {
-	NSWindow* window = (__bridge NSWindow *)windowRef;
+	@autoreleasepool {
-	return [[window screen] frame];
+		NSWindow* window = (__bridge NSWindow *)windowRef;
+		return [[window screen] frame];
+	}
 }
 
 static void setTitle(CFTypeRef windowRef, CFTypeRef titleRef) {
-	NSWindow *window = (__bridge NSWindow *)windowRef;
+	@autoreleasepool {
-	window.title = (__bridge NSString *)titleRef;
+		NSWindow *window = (__bridge NSWindow *)windowRef;
+		window.title = (__bridge NSString *)titleRef;
+	}
 }
 
 static int isWindowZoomed(CFTypeRef windowRef) {
-	NSWindow *window = (__bridge NSWindow *)windowRef;
+	@autoreleasepool {
-	return window.zoomed ? 1 : 0;
+		NSWindow *window = (__bridge NSWindow *)windowRef;
+		return window.zoomed ? 1 : 0;
+	}
 }
 
 static void zoomWindow(CFTypeRef windowRef) {
-	NSWindow *window = (__bridge NSWindow *)windowRef;
+	@autoreleasepool {
-	[window zoom:nil];
+		NSWindow *window = (__bridge NSWindow *)windowRef;
+		[window zoom:nil];
+	}
 }
 
 static CFTypeRef layerForView(CFTypeRef viewRef) {
-	NSView *view = (__bridge NSView *)viewRef;
+	@autoreleasepool {
-	return (__bridge CFTypeRef)view.layer;
+		NSView *view = (__bridge NSView *)viewRef;
+		return (__bridge CFTypeRef)view.layer;
+	}
 }
 
 static CFTypeRef windowForView(CFTypeRef viewRef) {
-	NSView *view = (__bridge NSView *)viewRef;
+	@autoreleasepool {
-	return (__bridge CFTypeRef)view.window;
+		NSView *view = (__bridge NSView *)viewRef;
+		return (__bridge CFTypeRef)view.window;
+	}
 }
 
 static void raiseWindow(CFTypeRef windowRef) {
-	NSRunningApplication *currentApp = [NSRunningApplication currentApplication];
+	@autoreleasepool {
-	if (![currentApp isActive]) {
+		NSRunningApplication *currentApp = [NSRunningApplication currentApplication];
-		[currentApp activateWithOptions:(NSApplicationActivateAllWindows | NSApplicationActivateIgnoringOtherApps)];
+		if (![currentApp isActive]) {
+			[currentApp activateWithOptions:(NSApplicationActivateAllWindows | NSApplicationActivateIgnoringOtherApps)];
+		}
+		NSWindow* window = (__bridge NSWindow *)windowRef;
+		[window makeKeyAndOrderFront:nil];
 	}
-	NSWindow* window = (__bridge NSWindow *)windowRef;
-	[window makeKeyAndOrderFront:nil];
 }
 
 static CFTypeRef createInputContext(CFTypeRef clientRef) {
@@ -211,23 +271,33 @@ 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];
 		}
-    }
+	}
+}
+
+static void dispatchEvent(void) {
+	@autoreleasepool {
+		NSEvent *event = [NSApp nextEventMatchingMask:NSEventMaskAny
+		                                        untilDate:[NSDate distantFuture]
+		                                           inMode:NSDefaultRunLoopMode
+		                                          dequeue:YES];
+		[NSApp sendEvent:event];
+	}
 }
 */
 import "C"
@@ -237,9 +307,9 @@ func init() {
 	runtime.LockOSThread()
 }
 
-// ViewEvent notified the client of changes to the window AppKit handles.
+// AppKitViewEvent notifies the client of changes to the window AppKit handles.
-// The handles are retained until another ViewEvent is sent.
+// The handles are retained until another AppKitViewEvent is sent.
-type ViewEvent struct {
+type AppKitViewEvent struct {
 	// View is a CFTypeRef for the NSView for the window.
 	View uintptr
 	// Layer is a CFTypeRef of the CALayer of View.
@@ -249,52 +319,32 @@ type ViewEvent struct {
 type window struct {
 	view        C.CFTypeRef
 	w           *callbacks
-	stage       Stage
+	anim        bool
+	visible     bool
 	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.
+// launched is closed after gio_initApp returns.
-var viewMap = make(map[C.CFTypeRef]*window)
-
-// launched is closed when applicationDidFinishLaunching is called.
 var launched = make(chan struct{})
 
 // nextTopLeft is the offset to use for the next window's call to
 // cascadeTopLeftFromPoint.
 var nextTopLeft C.NSPoint
 
-// mustView is like lookupView, except that it panics
+// mainThreadWindow is the window currently in control of the main thread.
-// if the view isn't mapped.
+var mainThreadWindow *window
-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) {
+func windowFor(h C.uintptr_t) *window {
-	w, exists := viewMap[view]
+	return cgo.Handle(h).Value().(*window)
-	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 {
@@ -307,7 +357,7 @@ func (w *window) ReadClipboard() {
 		defer C.CFRelease(cstr)
 	}
 	content := nsstringToString(cstr)
-	w.w.Event(transfer.DataEvent{
+	w.ProcessEvent(transfer.DataEvent{
 		Type: "application/text",
 		Open: func() io.ReadCloser {
 			return io.NopCloser(strings.NewReader(content))
@@ -420,7 +470,7 @@ func (w *window) Configure(options []Option) {
 		C.setWindowStandardButtonHidden(window, C.NSWindowMiniaturizeButton, barTrans)
 		C.setWindowStandardButtonHidden(window, C.NSWindowZoomButton, barTrans)
 	}
-	w.w.Event(ConfigEvent{Config: w.config})
+	w.ProcessEvent(ConfigEvent{Config: w.config})
 }
 
 func (w *window) setTitle(prev, cnf Config) {
@@ -471,7 +521,8 @@ func (w *window) ShowTextInput(show bool) {}
 func (w *window) SetInputHint(_ key.InputHint) {}
 
 func (w *window) SetAnimating(anim bool) {
-	if anim {
+	w.anim = anim
+	if w.anim && w.visible {
 		w.displayLink.Start()
 	} else {
 		w.displayLink.Stop()
@@ -488,26 +539,18 @@ func (w *window) runOnMain(f func()) {
 	})
 }
 
-func (w *window) setStage(stage Stage) {
-	if stage == w.stage {
-		return
-	}
-	w.stage = stage
-	w.w.Event(StageEvent{Stage: stage})
-}
-
 //export gio_onKeys
-func gio_onKeys(view, cstr C.CFTypeRef, ti C.double, mods C.NSUInteger, keyDown C.bool) {
+func gio_onKeys(h C.uintptr_t, 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 := mustView(view)
+	w := windowFor(h)
 	for _, k := range str {
 		if n, ok := convertKey(k); ok {
-			w.w.Event(key.Event{
+			w.ProcessEvent(key.Event{
 				Name:      n,
 				Modifiers: kmods,
 				State:     ks,
@@ -517,15 +560,15 @@ func gio_onKeys(view, cstr C.CFTypeRef, ti C.double, mods C.NSUInteger, keyDown
 }
 
 //export gio_onText
-func gio_onText(view, cstr C.CFTypeRef) {
+func gio_onText(h C.uintptr_t, cstr C.CFTypeRef) {
 	str := nsstringToString(cstr)
-	w := mustView(view)
+	w := windowFor(h)
 	w.w.EditorInsert(str)
 }
 
 //export gio_onMouse
-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) {
+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 := mustView(view)
+	w := windowFor(h)
 	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
@@ -562,7 +605,7 @@ func gio_onMouse(view, evt C.CFTypeRef, cdir C.int, cbtn C.NSInteger, x, y, dx,
 	default:
 		panic("invalid direction")
 	}
-	w.w.Event(pointer.Event{
+	w.ProcessEvent(pointer.Event{
 		Kind:      typ,
 		Source:    pointer.Mouse,
 		Time:      t,
@@ -574,35 +617,29 @@ func gio_onMouse(view, evt C.CFTypeRef, cdir C.int, cbtn C.NSInteger, x, y, dx,
 }
 
 //export gio_onDraw
-func gio_onDraw(view C.CFTypeRef) {
+func gio_onDraw(h C.uintptr_t) {
-	w := mustView(view)
+	w := windowFor(h)
 	w.draw()
 }
 
 //export gio_onFocus
-func gio_onFocus(view C.CFTypeRef, focus C.int) {
+func gio_onFocus(h C.uintptr_t, focus C.int) {
-	w := mustView(view)
+	w := windowFor(h)
-	w.w.Event(key.FocusEvent{Focus: focus == 1})
-	if w.stage >= StageInactive {
-		if focus == 0 {
-			w.setStage(StageInactive)
-		} else {
-			w.setStage(StageRunning)
-		}
-	}
 	w.SetCursor(w.cursor)
+	w.config.Focused = focus == 1
+	w.ProcessEvent(ConfigEvent{Config: w.config})
 }
 
 //export gio_onChangeScreen
-func gio_onChangeScreen(view C.CFTypeRef, did uint64) {
+func gio_onChangeScreen(h C.uintptr_t, did uint64) {
-	w := mustView(view)
+	w := windowFor(h)
 	w.displayLink.SetDisplayID(did)
 	C.setNeedsDisplay(w.view)
 }
 
 //export gio_hasMarkedText
-func gio_hasMarkedText(view C.CFTypeRef) C.int {
+func gio_hasMarkedText(h C.uintptr_t) C.int {
-	w := mustView(view)
+	w := windowFor(h)
 	state := w.w.EditorState()
 	if state.compose.Start != -1 {
 		return 1
@@ -611,8 +648,8 @@ func gio_hasMarkedText(view C.CFTypeRef) C.int {
 }
 
 //export gio_markedRange
-func gio_markedRange(view C.CFTypeRef) C.NSRange {
+func gio_markedRange(h C.uintptr_t) C.NSRange {
-	w := mustView(view)
+	w := windowFor(h)
 	state := w.w.EditorState()
 	rng := state.compose
 	start, end := rng.Start, rng.End
@@ -627,8 +664,8 @@ func gio_markedRange(view C.CFTypeRef) C.NSRange {
 }
 
 //export gio_selectedRange
-func gio_selectedRange(view C.CFTypeRef) C.NSRange {
+func gio_selectedRange(h C.uintptr_t) C.NSRange {
-	w := mustView(view)
+	w := windowFor(h)
 	state := w.w.EditorState()
 	rng := state.Selection
 	start, end := rng.Start, rng.End
@@ -643,14 +680,14 @@ func gio_selectedRange(view C.CFTypeRef) C.NSRange {
 }
 
 //export gio_unmarkText
-func gio_unmarkText(view C.CFTypeRef) {
+func gio_unmarkText(h C.uintptr_t) {
-	w := mustView(view)
+	w := windowFor(h)
 	w.w.SetComposingRegion(key.Range{Start: -1, End: -1})
 }
 
 //export gio_setMarkedText
-func gio_setMarkedText(view, cstr C.CFTypeRef, selRange C.NSRange, replaceRange C.NSRange) {
+func gio_setMarkedText(h C.uintptr_t, cstr C.CFTypeRef, selRange C.NSRange, replaceRange C.NSRange) {
-	w := mustView(view)
+	w := windowFor(h)
 	str := nsstringToString(cstr)
 	state := w.w.EditorState()
 	rng := state.compose
@@ -689,8 +726,8 @@ func gio_setMarkedText(view, cstr C.CFTypeRef, selRange C.NSRange, replaceRange
 }
 
 //export gio_substringForProposedRange
-func gio_substringForProposedRange(view C.CFTypeRef, crng C.NSRange, actual C.NSRangePointer) C.CFTypeRef {
+func gio_substringForProposedRange(h C.uintptr_t, crng C.NSRange, actual C.NSRangePointer) C.CFTypeRef {
-	w := mustView(view)
+	w := windowFor(h)
 	state := w.w.EditorState()
 	start, end := state.Snippet.Start, state.Snippet.End
 	if start > end {
@@ -710,8 +747,8 @@ func gio_substringForProposedRange(view C.CFTypeRef, crng C.NSRange, actual C.NS
 }
 
 //export gio_insertText
-func gio_insertText(view, cstr C.CFTypeRef, crng C.NSRange) {
+func gio_insertText(h C.uintptr_t, cstr C.CFTypeRef, crng C.NSRange) {
-	w := mustView(view)
+	w := windowFor(h)
 	state := w.w.EditorState()
 	rng := state.compose
 	if rng.Start == -1 {
@@ -735,13 +772,13 @@ func gio_insertText(view, cstr C.CFTypeRef, crng C.NSRange) {
 }
 
 //export gio_characterIndexForPoint
-func gio_characterIndexForPoint(view C.CFTypeRef, p C.NSPoint) C.NSUInteger {
+func gio_characterIndexForPoint(h C.uintptr_t, p C.NSPoint) C.NSUInteger {
 	return C.NSNotFound
 }
 
 //export gio_firstRectForCharacterRange
-func gio_firstRectForCharacterRange(view C.CFTypeRef, crng C.NSRange, actual C.NSRangePointer) C.NSRect {
+func gio_firstRectForCharacterRange(h C.uintptr_t, crng C.NSRange, actual C.NSRangePointer) C.NSRect {
-	w := mustView(view)
+	w := windowFor(h)
 	state := w.w.EditorState()
 	sel := state.Selection
 	u16start := state.UTF16Index(sel.Start)
@@ -768,6 +805,10 @@ 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{
@@ -776,14 +817,13 @@ func (w *window) draw() {
 	}
 	if sz != w.config.Size {
 		w.config.Size = sz
-		w.w.Event(ConfigEvent{Config: w.config})
+		w.ProcessEvent(ConfigEvent{Config: w.config})
 	}
 	if sz.X == 0 || sz.Y == 0 {
 		return
 	}
 	cfg := configFor(w.scale)
-	w.setStage(StageRunning)
+	w.ProcessEvent(frameEvent{
-	w.w.Event(frameEvent{
 		FrameEvent: FrameEvent{
 			Now:    time.Now(),
 			Size:   w.config.Size,
@@ -793,6 +833,55 @@ func (w *window) draw() {
 	})
 }
 
+func (w *window) ProcessEvent(e event.Event) {
+	w.w.ProcessEvent(e)
+	// The main thread window deliver events in Event.
+	if w != mainThreadWindow {
+		w.loop.FlushEvents()
+	}
+}
+
+func (w *window) Event() event.Event {
+	if !isMainThread() {
+		return w.loop.Event()
+	}
+	mainThreadWindow = w
+	defer func() { mainThreadWindow = nil }()
+	for {
+		if evt, ok := w.loop.win.nextEvent(); ok {
+			return evt
+		}
+		C.dispatchEvent()
+		gio_dispatchMainFuncs()
+	}
+}
+
+func (w *window) Invalidate() {
+	if isMainThread() {
+		mainThreadWindow = w
+		defer func() { mainThreadWindow = nil }()
+	}
+	w.loop.Invalidate()
+}
+
+func (w *window) Run(f func()) {
+	if isMainThread() {
+		mainThreadWindow = w
+		defer func() { mainThreadWindow = nil }()
+	}
+	w.loop.Run(f)
+}
+
+func (w *window) Frame(frame *op.Ops) {
+	if !isMainThread() {
+		w.loop.Frame(frame)
+		return
+	}
+	mainThreadWindow = w
+	defer func() { mainThreadWindow = nil }()
+	w.loop.win.ProcessFrame(frame, nil)
+}
+
 func configFor(scale float32) unit.Metric {
 	return unit.Metric{
 		PxPerDp: scale,
@@ -800,77 +889,87 @@ func configFor(scale float32) unit.Metric {
 	}
 }
 
-//export gio_onClose
+//export gio_onAttached
-func gio_onClose(view C.CFTypeRef) {
+func gio_onAttached(h C.uintptr_t, attached C.int) {
-	w := mustView(view)
+	w := windowFor(h)
-	w.w.Event(ViewEvent{})
+	if attached != 0 {
-	w.w.Event(DestroyEvent{})
+		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{})
 	w.displayLink.Close()
 	w.displayLink = nil
-	deleteView(view)
+	cgo.Handle(h).Delete()
-	C.CFRelease(w.view)
 	w.view = 0
 }
 
 //export gio_onHide
-func gio_onHide(view C.CFTypeRef) {
+func gio_onHide(h C.uintptr_t) {
-	w := mustView(view)
+	w := windowFor(h)
-	w.setStage(StagePaused)
+	w.visible = false
+	w.SetAnimating(w.anim)
 }
 
 //export gio_onShow
-func gio_onShow(view C.CFTypeRef) {
+func gio_onShow(h C.uintptr_t) {
-	w := mustView(view)
+	w := windowFor(h)
-	w.setStage(StageRunning)
+	w.draw()
 }
 
 //export gio_onFullscreen
-func gio_onFullscreen(view C.CFTypeRef) {
+func gio_onFullscreen(h C.uintptr_t) {
-	w := mustView(view)
+	w := windowFor(h)
 	w.config.Mode = Fullscreen
-	w.w.Event(ConfigEvent{Config: w.config})
+	w.ProcessEvent(ConfigEvent{Config: w.config})
 }
 
 //export gio_onWindowed
-func gio_onWindowed(view C.CFTypeRef) {
+func gio_onWindowed(h C.uintptr_t) {
-	w := mustView(view)
+	w := windowFor(h)
 	w.config.Mode = Windowed
-	w.w.Event(ConfigEvent{Config: w.config})
+	w.ProcessEvent(ConfigEvent{Config: w.config})
 }
 
-//export gio_onAppHide
+func newWindow(win *callbacks, options []Option) {
-func gio_onAppHide() {
+	w := &window{
-	for _, w := range viewMap {
+		redraw: make(chan struct{}, 1),
-		w.setStage(StagePaused)
+		w:      win,
 	}
-}
+	w.loop = newEventLoop(w.w, w.wakeup)
-
+	if isMainThread() {
-//export gio_onAppShow
+		mainThreadWindow = w
-func gio_onAppShow() {
+		defer func() { mainThreadWindow = nil }()
-	for _, w := range viewMap {
+		select {
-		w.setStage(StageRunning)
+		case <-launched:
+		default:
+			// If we're the main thread, initialize the GUI.
+			C.gio_initApp()
+			close(launched)
+		}
+	} else {
+		<-launched
 	}
-}
+	res := make(chan struct{}, 1)
-
-//export gio_onFinishLaunching
-func gio_onFinishLaunching() {
-	close(launched)
-}
-
-func newWindow(win *callbacks, options []Option) error {
-	<-launched
-	errch := make(chan error)
 	runOnMain(func() {
-		w, err := newOSWindow()
+		win.SetDriver(w)
-		if err != nil {
+		res <- struct{}{}
-			errch <- err
+		if err := w.init(); err != nil {
+			w.ProcessEvent(DestroyEvent{Err: 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,
@@ -880,23 +979,17 @@ func newWindow(win *callbacks, options []Option) error {
 		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)})
 	})
-	return <-errch
+	<-res
 }
 
-func newOSWindow() (*window, error) {
+func (w *window) init() error {
 	view := C.gio_createView()
 	if view == 0 {
-		return nil, errors.New("newOSWindows: failed to create view")
+		return errors.New("newOSWindow: failed to create view")
 	}
 	scale := float32(C.getViewBackingScale(view))
-	w := &window{
+	w.scale = scale
-		view:   view,
-		scale:  scale,
-		redraw: make(chan struct{}, 1),
-	}
 	dl, err := newDisplayLink(func() {
 		select {
 		case w.redraw <- struct{}{}:
@@ -904,20 +997,19 @@ func newOSWindow() (*window, error) {
 			return
 		}
 		w.runOnMain(func() {
-			C.setNeedsDisplay(w.view)
+			if w.visible {
+				C.setNeedsDisplay(w.view)
+			}
 		})
 	})
 	w.displayLink = dl
 	if err != nil {
 		C.CFRelease(view)
-		return nil, err
+		return err
 	}
-	insertView(view, w)
+	C.gio_viewSetHandle(view, C.uintptr_t(cgo.NewHandle(w)))
-	return w, nil
+	w.view = view
-}
+	return nil
-
-func osMain() {
-	C.gio_main()
 }
 
 func convertKey(k rune) (key.Name, bool) {
@@ -1004,4 +1096,14 @@ func convertMods(mods C.NSUInteger) key.Modifiers {
 	return kmods
 }
 
-func (_ ViewEvent) ImplementsEvent() {}
+func (w *window) wakeup() {
+	runOnMain(func() {
+		w.loop.Wakeup()
+		if w != mainThreadWindow {
+			w.loop.FlushEvents()
+		}
+	})
+}
+
+func (AppKitViewEvent) implementsViewEvent() {}
+func (AppKitViewEvent) ImplementsEvent()     {}

app/os_macos.m

@@ -14,40 +14,50 @@ __attribute__ ((visibility ("hidden"))) CALayer *gio_layerFactory(void);
 @interface GioWindowDelegate : NSObject<NSWindowDelegate>
 @end
 
+@interface GioView : NSView <CALayerDelegate,NSTextInputClient>
+@property uintptr_t handle;
+@end
+
 @implementation GioWindowDelegate
 - (void)windowWillMiniaturize:(NSNotification *)notification {
 	NSWindow *window = (NSWindow *)[notification object];
-	gio_onHide((__bridge CFTypeRef)window.contentView);
+  GioView *view = (GioView *)window.contentView;
+	gio_onHide(view.handle);
 }
 - (void)windowDidDeminiaturize:(NSNotification *)notification {
 	NSWindow *window = (NSWindow *)[notification object];
-	gio_onShow((__bridge CFTypeRef)window.contentView);
+  GioView *view = (GioView *)window.contentView;
+	gio_onShow(view.handle);
 }
 - (void)windowWillEnterFullScreen:(NSNotification *)notification {
 	NSWindow *window = (NSWindow *)[notification object];
-	gio_onFullscreen((__bridge CFTypeRef)window.contentView);
+  GioView *view = (GioView *)window.contentView;
+	gio_onFullscreen(view.handle);
 }
 - (void)windowWillExitFullScreen:(NSNotification *)notification {
 	NSWindow *window = (NSWindow *)[notification object];
-	gio_onWindowed((__bridge CFTypeRef)window.contentView);
+  GioView *view = (GioView *)window.contentView;
+	gio_onWindowed(view.handle);
 }
 - (void)windowDidChangeScreen:(NSNotification *)notification {
 	NSWindow *window = (NSWindow *)[notification object];
 	CGDirectDisplayID dispID = [[[window screen] deviceDescription][@"NSScreenNumber"] unsignedIntValue];
-	CFTypeRef view = (__bridge CFTypeRef)window.contentView;
+  GioView *view = (GioView *)window.contentView;
-	gio_onChangeScreen(view, dispID);
+	gio_onChangeScreen(view.handle, dispID);
 }
 - (void)windowDidBecomeKey:(NSNotification *)notification {
 	NSWindow *window = (NSWindow *)[notification object];
-	gio_onFocus((__bridge CFTypeRef)window.contentView, 1);
+  GioView *view = (GioView *)window.contentView;
+	gio_onFocus(view.handle, 1);
 }
 - (void)windowDidResignKey:(NSNotification *)notification {
 	NSWindow *window = (NSWindow *)[notification object];
-	gio_onFocus((__bridge CFTypeRef)window.contentView, 0);
+  GioView *view = (GioView *)window.contentView;
+	gio_onFocus(view.handle, 0);
 }
 @end
 
-static void handleMouse(NSView *view, NSEvent *event, int typ, CGFloat dx, CGFloat dy) {
+static void handleMouse(GioView *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.
@@ -56,10 +66,213 @@ static void handleMouse(NSView *view, NSEvent *event, int typ, CGFloat dx, CGFlo
 	}
 	// Origin is in the lower left corner. Convert to upper left.
 	CGFloat height = view.bounds.size.height;
-	gio_onMouse((__bridge CFTypeRef)view, (__bridge CFTypeRef)event, typ, event.buttonNumber, p.x, height - p.y, dx, dy, [event timestamp], [event modifierFlags]);
+	gio_onMouse(view.handle, (__bridge CFTypeRef)event, typ, event.buttonNumber, p.x, height - p.y, dx, dy, [event timestamp], [event modifierFlags]);
 }
 
-@interface GioView : NSView <CALayerDelegate,NSTextInputClient>
+@interface GioApplication: NSApplication
+@end
+
+// Variables for tracking resizes.
+static struct {
+	NSPoint dir;
+	NSEvent *lastMouseDown;
+	NSPoint off;
+} resizeState = {};
+
+static NSBitmapImageRep *nsImageBitmap(NSImage *img) {
+	NSArray<NSImageRep *> *reps = img.representations;
+	if ([reps count] == 0) {
+		return nil;
+	}
+	NSImageRep *rep = reps[0];
+	if (![rep isKindOfClass:[NSBitmapImageRep class]]) {
+		return nil;
+	}
+	return (NSBitmapImageRep *)rep;
+}
+
+static NSCursor *lookupPrivateNSCursor(SEL name) {
+	if (![NSCursor respondsToSelector:name]) {
+		return nil;
+	}
+	id obj = [NSCursor performSelector:name];
+	if (![obj isKindOfClass:[NSCursor class]]) {
+		return nil;
+	}
+	return (NSCursor *)obj;
+}
+
+static BOOL isEqualNSCursor(NSCursor *c1, SEL name2) {
+	NSCursor *c2 = lookupPrivateNSCursor(name2);
+	if (c2 == nil || !NSEqualPoints(c1.hotSpot, c2.hotSpot)) {
+		return NO;
+	}
+	NSImage *img1 = c1.image;
+	NSImage *img2 = c2.image;
+	if (!NSEqualSizes(img1.size, img2.size)) {
+		return NO;
+	}
+	NSBitmapImageRep *bit1 = nsImageBitmap(img1);
+	NSBitmapImageRep *bit2 = nsImageBitmap(img2);
+	if (bit1 == nil || bit2 == nil) {
+		return NO;
+	}
+	NSInteger n1 = bit1.numberOfPlanes*bit1.bytesPerPlane;
+	NSInteger n2 = bit1.numberOfPlanes*bit1.bytesPerPlane;
+	if (n1 != n2) {
+		return NO;
+	}
+	if (memcmp(bit1.bitmapData, bit2.bitmapData, n1) != 0) {
+		return NO;
+	}
+	return YES;
+}
+
+@implementation GioApplication
+- (NSEvent *)nextEventMatchingMask:(NSEventMask)mask
+                         untilDate:(NSDate *)expiration
+                            inMode:(NSRunLoopMode)mode
+                           dequeue:(BOOL)deqFlag {
+	if ([mode isEqualToString:NSEventTrackingRunLoopMode]) {
+		NSEvent *l = resizeState.lastMouseDown;
+		if (l != nil) {
+			//lastMouseDown = nil;
+			NSCursor *cur = [NSCursor currentSystemCursor];
+			NSPoint dir = {};
+			NSPoint off = {};
+			NSSize wsz = [l window].frame.size;
+			NSPoint center = NSMakePoint(wsz.width/2, wsz.height/2);
+			NSPoint p = [l locationInWindow];
+			if (p.x >= center.x) {
+				dir.x = 1;
+				off.x = p.x - wsz.width;
+			} else {
+				dir.x = -1;
+				off.x = p.x;
+			}
+			if (p.y >= center.y) {
+				dir.y = 1;
+				off.y = p.y - wsz.height;
+			} else {
+				dir.y = -1;
+				off.y = p.y;
+			}
+			// The button down coordinate distinguish the four quadrants. Use the
+			// cursor image to determine the precise direction.
+			SEL nw = @selector(_windowResizeNorthWestCursor);
+			SEL n = @selector(_windowResizeNorthCursor);
+			SEL ne = @selector(_windowResizeNorthEastCursor);
+			SEL e = @selector(_windowResizeEastCursor);
+			SEL se = @selector(_windowResizeSouthEastCursor);
+			SEL s = @selector(_windowResizeSouthCursor);
+			SEL sw = @selector(_windowResizeSouthWestCursor);
+			SEL w = @selector(_windowResizeWestCursor);
+			SEL ns = @selector(_windowResizeNorthSouthCursor);
+			SEL ew = @selector(_windowResizeEastWestCursor);
+			SEL nwse = @selector(_windowResizeNorthWestSouthEastCursor);
+			SEL nesw = @selector(_windowResizeNorthEastSouthWestCursor);
+			BOOL match = YES;
+			if (dir.x != 0 && (isEqualNSCursor(cur, ew) || isEqualNSCursor(cur, w) || isEqualNSCursor(cur, e))) {
+				dir.y = 0;
+			}
+			if (dir.y != 0 && (isEqualNSCursor(cur, ns) || isEqualNSCursor(cur, s) || isEqualNSCursor(cur, n))) {
+					dir.x = 0;
+			}
+			// If none of the cursors matched, we may deduce that the resize
+			// direction is one of the corners. However, to ensure that at least
+			// one cursor matches, check the corner cursors.
+			if (dir.x == 1 && dir.y == 1) {
+				if (!isEqualNSCursor(cur, nesw) && !isEqualNSCursor(cur, sw)) {
+					dir = NSZeroPoint;
+				}
+			} else if (dir.x == 1 && dir.y == -1) {
+				if (!isEqualNSCursor(cur, nwse) && !isEqualNSCursor(cur, nw)) {
+					dir = NSZeroPoint;
+				}
+			} else if (dir.x == -1 && dir.y == 1) {
+				if (!isEqualNSCursor(cur, nwse) && !isEqualNSCursor(cur, se)) {
+					dir = NSZeroPoint;
+				}
+			} else if (dir.x == -1 && dir.y == -1) {
+				if (!isEqualNSCursor(cur, nesw) && !isEqualNSCursor(cur, ne)) {
+					dir = NSZeroPoint;
+				}
+			}
+			if (!NSEqualPoints(dir, NSZeroPoint)) {
+				NSEvent *cancel = [NSEvent mouseEventWithType:NSEventTypeLeftMouseUp
+											                       location:l.locationInWindow
+											                  modifierFlags:l.modifierFlags
+											                      timestamp:l.timestamp
+											                   windowNumber:l.windowNumber
+											                        context:l.context
+											                    eventNumber:l.eventNumber
+											                     clickCount:l.clickCount
+											                       pressure:l.pressure];
+				resizeState.off = off;
+				resizeState.dir = dir;
+				return cancel;
+			}
+		}
+	}
+	return [super nextEventMatchingMask:mask untilDate:expiration inMode:mode dequeue:deqFlag];
+}
+@end
+
+@interface GioWindow: NSWindow
+@end
+
+@implementation GioWindow
+- (void)sendEvent:(NSEvent *)evt {
+	if (evt.type == NSEventTypeLeftMouseDown) {
+		resizeState.lastMouseDown = evt;
+	}
+	NSPoint dir = resizeState.dir;
+	if (NSEqualPoints(dir, NSZeroPoint)) {
+		[super sendEvent:evt];
+		return;
+	}
+	switch (evt.type) {
+	default:
+		return;
+	case NSEventTypeLeftMouseUp:
+		resizeState.dir = NSZeroPoint;
+		resizeState.lastMouseDown = nil;
+		return;
+	case NSEventTypeLeftMouseDragged:
+		// Ok to proceed.
+		break;
+	}
+	NSPoint loc = evt.locationInWindow;
+	NSPoint off = resizeState.off;
+	loc.x -= off.x;
+	loc.y -= off.y;
+	NSRect frame = [self frame];
+	NSSize min = [self minSize];
+	NSSize max = [self maxSize];
+	CGFloat width = frame.size.width;
+	if (dir.x > 0) {
+		width = loc.x;
+	} else if (dir.x < 0) {
+		width -= loc.x;
+	}
+	width = MIN(max.width, MAX(min.width, width));
+	if (dir.x < 0) {
+		frame.origin.x += frame.size.width - width;
+	}
+	frame.size.width = width;
+	CGFloat height = frame.size.height;
+	if (dir.y > 0) {
+		height = loc.y;
+	} else if (dir.y < 0) {
+		height -= loc.y;
+	}
+	height = MIN(max.height, MAX(min.height, height));
+	if (dir.y < 0) {
+		frame.origin.y += frame.size.height - height;
+	}
+	frame.size.height = height;
+	[self setFrame:frame display:YES animate:NO];
+}
 @end
 
 @implementation GioView
@@ -70,11 +283,11 @@ static void handleMouse(NSView *view, NSEvent *event, int typ, CGFloat dx, CGFlo
 // drawRect is called when OpenGL is used, displayLayer otherwise.
 // Don't know why.
 - (void)drawRect:(NSRect)r {
-	gio_onDraw((__bridge CFTypeRef)self);
+	gio_onDraw(self.handle);
 }
 - (void)displayLayer:(CALayer *)layer {
 	layer.contentsScale = self.window.backingScaleFactor;
-	gio_onDraw((__bridge CFTypeRef)self);
+	gio_onDraw(self.handle);
 }
 - (CALayer *)makeBackingLayer {
 	CALayer *layer = gio_layerFactory();
@@ -82,9 +295,7 @@ static void handleMouse(NSView *view, NSEvent *event, int typ, CGFloat dx, CGFlo
 	return layer;
 }
 - (void)viewDidMoveToWindow {
-	if (self.window == nil) {
+	gio_onAttached(self.handle, self.window != nil ? 1 : 0);
-		gio_onClose((__bridge CFTypeRef)self);
-	}
 }
 - (void)mouseDown:(NSEvent *)event {
 	handleMouse(self, event, MOUSE_DOWN, 0, 0);
@@ -124,32 +335,31 @@ static void handleMouse(NSView *view, NSEvent *event, int typ, CGFloat dx, CGFlo
 - (void)keyDown:(NSEvent *)event {
 	[self interpretKeyEvents:[NSArray arrayWithObject:event]];
 	NSString *keys = [event charactersIgnoringModifiers];
-	gio_onKeys((__bridge CFTypeRef)self, (__bridge CFTypeRef)keys, [event timestamp], [event modifierFlags], true);
+	gio_onKeys(self.handle, (__bridge CFTypeRef)keys, [event timestamp], [event modifierFlags], true);
 }
 - (void)keyUp:(NSEvent *)event {
 	NSString *keys = [event charactersIgnoringModifiers];
-	gio_onKeys((__bridge CFTypeRef)self, (__bridge CFTypeRef)keys, [event timestamp], [event modifierFlags], false);
+	gio_onKeys(self.handle, (__bridge CFTypeRef)keys, [event timestamp], [event modifierFlags], false);
 }
 - (void)insertText:(id)string {
-	gio_onText((__bridge CFTypeRef)self, (__bridge CFTypeRef)string);
+	gio_onText(self.handle, (__bridge CFTypeRef)string);
 }
 - (void)doCommandBySelector:(SEL)sel {
 	// Don't pass commands up the responder chain.
 	// They will end up in a beep.
 }
-
 - (BOOL)hasMarkedText {
-	int res = gio_hasMarkedText((__bridge CFTypeRef)self);
+	int res = gio_hasMarkedText(self.handle);
 	return res ? YES : NO;
 }
 - (NSRange)markedRange {
-	return gio_markedRange((__bridge CFTypeRef)self);
+	return gio_markedRange(self.handle);
 }
 - (NSRange)selectedRange {
-	return gio_selectedRange((__bridge CFTypeRef)self);
+	return gio_selectedRange(self.handle);
 }
 - (void)unmarkText {
-	gio_unmarkText((__bridge CFTypeRef)self);
+	gio_unmarkText(self.handle);
 }
 - (void)setMarkedText:(id)string
         selectedRange:(NSRange)selRange
@@ -161,14 +371,14 @@ static void handleMouse(NSView *view, NSEvent *event, int typ, CGFloat dx, CGFlo
 	} else {
 		str = string;
 	}
-	gio_setMarkedText((__bridge CFTypeRef)self, (__bridge CFTypeRef)str, selRange, replaceRange);
+	gio_setMarkedText(self.handle, (__bridge CFTypeRef)str, selRange, replaceRange);
 }
 - (NSArray<NSAttributedStringKey> *)validAttributesForMarkedText {
 	return nil;
 }
 - (NSAttributedString *)attributedSubstringForProposedRange:(NSRange)range
                                                 actualRange:(NSRangePointer)actualRange {
-	NSString *str = CFBridgingRelease(gio_substringForProposedRange((__bridge CFTypeRef)self, range, actualRange));
+	NSString *str = CFBridgingRelease(gio_substringForProposedRange(self.handle, range, actualRange));
 	return [[NSAttributedString alloc] initWithString:str attributes:nil];
 }
 - (void)insertText:(id)string
@@ -180,17 +390,26 @@ static void handleMouse(NSView *view, NSEvent *event, int typ, CGFloat dx, CGFlo
 	} else {
 		str = string;
 	}
-	gio_insertText((__bridge CFTypeRef)self, (__bridge CFTypeRef)str, replaceRange);
+	gio_insertText(self.handle, (__bridge CFTypeRef)str, replaceRange);
 }
 - (NSUInteger)characterIndexForPoint:(NSPoint)p {
-	return gio_characterIndexForPoint((__bridge CFTypeRef)self, p);
+	return gio_characterIndexForPoint(self.handle, p);
 }
 - (NSRect)firstRectForCharacterRange:(NSRange)rng
                          actualRange:(NSRangePointer)actual {
-    NSRect r = gio_firstRectForCharacterRange((__bridge CFTypeRef)self, rng, actual);
+    NSRect r = gio_firstRectForCharacterRange(self.handle, 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);
+}
 @end
 
 // Delegates are weakly referenced from their peers. Nothing
@@ -240,15 +459,12 @@ 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.
-void gio_trySetPrivateCursor(SEL cursorName, NSCursor* fallback) {
+static void trySetPrivateCursor(SEL cursorName, NSCursor* fallback) {
-	if ([NSCursor respondsToSelector:cursorName]) {
+	NSCursor *cur = lookupPrivateNSCursor(cursorName);
-		id object = [NSCursor performSelector:cursorName];
+	if (cur == nil) {
-		if ([object isKindOfClass:[NSCursor class]]) {
+		cur = fallback;
-			[(NSCursor*)object set];
-			return;
-		}
 	}
-	[fallback set];
+	[cur set];
 }
 
 void gio_setCursor(NSUInteger curID) {
@@ -272,7 +488,7 @@ void gio_setCursor(NSUInteger curID) {
 				break;
 			case 6: // pointer.CursorAllScroll
 				// For some reason, using _moveCursor fails on Monterey.
-				// gio_trySetPrivateCursor(@selector(_moveCursor), NSCursor.arrowCursor);
+				// trySetPrivateCursor(@selector(_moveCursor), NSCursor.arrowCursor);
 				[NSCursor.arrowCursor set];
 				break;
 			case 7: // pointer.CursorColResize
@@ -282,33 +498,31 @@ 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
-				gio_trySetPrivateCursor(@selector(busyButClickableCursor), NSCursor.arrowCursor);
+				trySetPrivateCursor(@selector(busyButClickableCursor), NSCursor.arrowCursor);
 				break;
 			case 13: // pointer.CursorProgress
-				gio_trySetPrivateCursor(@selector(busyButClickableCursor), NSCursor.arrowCursor);
+				trySetPrivateCursor(@selector(busyButClickableCursor), NSCursor.arrowCursor);
 				break;
 			case 14: // pointer.CursorNorthWestResize
-				gio_trySetPrivateCursor(@selector(_windowResizeNorthWestCursor), NSCursor.resizeUpDownCursor);
+				trySetPrivateCursor(@selector(_windowResizeNorthWestCursor), NSCursor.resizeUpDownCursor);
 				break;
 			case 15: // pointer.CursorNorthEastResize
-				gio_trySetPrivateCursor(@selector(_windowResizeNorthEastCursor), NSCursor.resizeUpDownCursor);
+				trySetPrivateCursor(@selector(_windowResizeNorthEastCursor), NSCursor.resizeUpDownCursor);
 				break;
 			case 16: // pointer.CursorSouthWestResize
-				gio_trySetPrivateCursor(@selector(_windowResizeSouthWestCursor), NSCursor.resizeUpDownCursor);
+				trySetPrivateCursor(@selector(_windowResizeSouthWestCursor), NSCursor.resizeUpDownCursor);
 				break;
 			case 17: // pointer.CursorSouthEastResize
-				gio_trySetPrivateCursor(@selector(_windowResizeSouthEastCursor), NSCursor.resizeUpDownCursor);
+				trySetPrivateCursor(@selector(_windowResizeSouthEastCursor), NSCursor.resizeUpDownCursor);
 				break;
 			case 18: // pointer.CursorNorthSouthResize
 				[NSCursor.resizeUpDownCursor set];
@@ -329,10 +543,10 @@ void gio_setCursor(NSUInteger curID) {
 				[NSCursor.resizeDownCursor set];
 				break;
 			case 24: // pointer.CursorNorthEastSouthWestResize
-				gio_trySetPrivateCursor(@selector(_windowResizeNorthEastSouthWestCursor), NSCursor.resizeUpDownCursor);
+				trySetPrivateCursor(@selector(_windowResizeNorthEastSouthWestCursor), NSCursor.resizeUpDownCursor);
 				break;
 			case 25: // pointer.CursorNorthWestSouthEastResize
-				gio_trySetPrivateCursor(@selector(_windowResizeNorthWestSouthEastCursor), NSCursor.resizeUpDownCursor);
+				trySetPrivateCursor(@selector(_windowResizeNorthWestSouthEastCursor), NSCursor.resizeUpDownCursor);
 				break;
 			default:
 				[NSCursor.arrowCursor set];
@@ -349,7 +563,7 @@ CFTypeRef gio_createWindow(CFTypeRef viewRef, CGFloat width, CGFloat height, CGF
 			NSMiniaturizableWindowMask |
 			NSClosableWindowMask;
 
-		NSWindow* window = [[NSWindow alloc] initWithContentRect:rect
+		GioWindow* window = [[GioWindow alloc] initWithContentRect:rect
 													   styleMask:styleMask
 														 backing:NSBackingStoreBuffered
 														   defer:NO];
@@ -374,27 +588,48 @@ CFTypeRef gio_createView(void) {
 		GioView* view = [[GioView alloc] initWithFrame:frame];
 		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();
+	// Force the [NSApp run] call to return.
-}
+	[NSApp stop:nil];
-- (void)applicationDidHide:(NSNotification *)aNotification {
+	NSEvent *dummy = [NSEvent otherEventWithType:NSEventTypeApplicationDefined
-	gio_onAppHide();
+	              location:NSZeroPoint
-}
+	         modifierFlags:0
-- (void)applicationWillUnhide:(NSNotification *)notification {
+	             timestamp:0
-	gio_onAppShow();
+	          windowNumber:0
+	               context:nil
+	               subtype:0
+	                 data1:0
+	                 data2:0];
+	[NSApp postEvent:dummy atStart:YES];
 }
 @end
 
-void gio_main() {
+void gio_initApp() {
 	@autoreleasepool {
-		[NSApplication sharedApplication];
+		[GioApplication sharedApplication];
 		GioAppDelegate *del = [[GioAppDelegate alloc] init];
 		[NSApp setDelegate:del];
 
@@ -416,6 +651,22 @@ void gio_main() {
 
 		globalWindowDel = [[GioWindowDelegate alloc] init];
 
+		// Runs until stopped by applicationDidFinishLaunching.
 		[NSApp run];
 	}
 }
+
+void gio_wakeupMainThread(void) {
+	@autoreleasepool {
+		NSEvent *dummy = [NSEvent otherEventWithType:NSEventTypeApplicationDefined
+		              location:NSZeroPoint
+		         modifierFlags:0
+		             timestamp:0
+		          windowNumber:0
+		               context:nil
+		               subtype:0
+		                 data1:0
+		                 data2:0];
+		[NSApp postEvent:dummy atStart:YES];
+	}
+}

app/os_unix.go

@@ -9,16 +9,10 @@ import (
 	"errors"
 	"unsafe"
 
+	"gioui.org/io/event"
 	"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
@@ -39,17 +33,13 @@ type WaylandViewEvent struct {
 func (WaylandViewEvent) implementsViewEvent() {}
 func (WaylandViewEvent) ImplementsEvent()     {}
 
-func osMain() {
-	select {}
-}
-
 type windowDriver func(*callbacks, []Option) error
 
 // Instead of creating files with build tags for each combination of wayland +/- x11
 // let each driver initialize these variables with their own version of createWindow.
 var wlDriver, x11Driver windowDriver
 
-func newWindow(window *callbacks, options []Option) error {
+func newWindow(window *callbacks, options []Option) {
 	var errFirst error
 	for _, d := range []windowDriver{wlDriver, x11Driver} {
 		if d == nil {
@@ -57,16 +47,39 @@ func newWindow(window *callbacks, options []Option) error {
 		}
 		err := d(window, options)
 		if err == nil {
-			return nil
+			return
 		}
 		if errFirst == nil {
 			errFirst = err
 		}
 	}
-	if errFirst != nil {
+	window.SetDriver(&dummyDriver{
-		return errFirst
+		win:     window,
+		wakeups: make(chan event.Event, 1),
+	})
+	if errFirst == nil {
+		errFirst = errors.New("app: no window driver available")
+	}
+	window.ProcessEvent(DestroyEvent{Err: errFirst})
+}
+
+type dummyDriver struct {
+	win     *callbacks
+	wakeups chan event.Event
+}
+
+func (d *dummyDriver) Event() event.Event {
+	if e, ok := d.win.nextEvent(); ok {
+		return e
+	}
+	return <-d.wakeups
+}
+
+func (d *dummyDriver) Invalidate() {
+	select {
+	case d.wakeups <- wakeupEvent{}:
+	default:
 	}
-	return errors.New("app: no window driver available")
 }
 
 // xCursor contains mapping from pointer.Cursor to XCursor.

app/os_wayland.go

@@ -15,6 +15,7 @@ import (
 	"math"
 	"os"
 	"os/exec"
+	"runtime"
 	"strconv"
 	"sync"
 	"time"
@@ -25,10 +26,12 @@ import (
 	"gioui.org/app/internal/xkb"
 	"gioui.org/f32"
 	"gioui.org/internal/fling"
+	"gioui.org/io/event"
 	"gioui.org/io/key"
 	"gioui.org/io/pointer"
 	"gioui.org/io/system"
 	"gioui.org/io/transfer"
+	"gioui.org/op"
 	"gioui.org/unit"
 )
 
@@ -97,7 +100,9 @@ type wlDisplay struct {
 		read, write int
 	}
 
-	repeat repeatState
+	repeat        repeatState
+	poller        poller
+	readClipClose chan struct{}
 }
 
 type wlSeat struct {
@@ -137,7 +142,7 @@ type repeatState struct {
 	delay time.Duration
 
 	key   uint32
-	win   *callbacks
+	win   *window
 	stopC chan struct{}
 
 	start time.Duration
@@ -194,12 +199,10 @@ type window struct {
 		dir            f32.Point
 	}
 
-	stage             Stage
+	configured        bool
-	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
@@ -212,6 +215,10 @@ type window struct {
 	clipReads chan transfer.DataEvent
 
 	wakeups chan struct{}
+
+	// invMu avoids the race between the destruction of disp and
+	// Invalidate waking it up.
+	invMu sync.Mutex
 }
 
 type poller struct {
@@ -260,25 +267,17 @@ func newWLWindow(callbacks *callbacks, options []Option) error {
 		return err
 	}
 	w.w = callbacks
-	go func() {
+	w.w.SetDriver(w)
-		defer d.destroy()
-		defer w.destroy()
 
-		w.w.SetDriver(w)
+	// Finish and commit setup from createNativeWindow.
+	w.Configure(options)
+	w.draw(true)
+	C.wl_surface_commit(w.surf)
 
-		// Finish and commit setup from createNativeWindow.
+	w.ProcessEvent(WaylandViewEvent{
-		w.Configure(options)
+		Display: unsafe.Pointer(w.display()),
-		C.wl_surface_commit(w.surf)
+		Surface: unsafe.Pointer(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(DestroyEvent{Err: err})
-	}()
 	return nil
 }
 
@@ -549,15 +548,15 @@ 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.setStage(StageRunning)
+	w.configured = true
+	w.draw(true)
 }
 
 //export gio_onToplevelClose
 func gio_onToplevelClose(data unsafe.Pointer, topLvl *C.struct_xdg_toplevel) {
 	w := callbackLoad(data).(*window)
-	w.dead = true
+	w.close(nil)
 }
 
 //export gio_onToplevelConfigure
@@ -586,8 +585,8 @@ func gio_onToplevelDecorationConfigure(data unsafe.Pointer, deco *C.struct_zxdg_
 		} else {
 			w.size.Y += int(w.config.decoHeight)
 		}
-		w.w.Event(ConfigEvent{Config: w.config})
+		w.ProcessEvent(ConfigEvent{Config: w.config})
-		w.redraw = true
+		w.draw(true)
 	}
 }
 
@@ -645,7 +644,7 @@ 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.w.Event(ConfigEvent{Config: w.config})
+		w.ProcessEvent(ConfigEvent{Config: w.config})
 	}
 }
 
@@ -790,7 +789,7 @@ 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.w.Event(pointer.Event{
+	w.ProcessEvent(pointer.Event{
 		Kind:      pointer.Press,
 		Source:    pointer.Touch,
 		Position:  w.lastTouch,
@@ -806,7 +805,7 @@ 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.w.Event(pointer.Event{
+	w.ProcessEvent(pointer.Event{
 		Kind:      pointer.Release,
 		Source:    pointer.Touch,
 		Position:  w.lastTouch,
@@ -824,7 +823,7 @@ 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.w.Event(pointer.Event{
+	w.ProcessEvent(pointer.Event{
 		Kind:      pointer.Move,
 		Position:  w.lastTouch,
 		Source:    pointer.Touch,
@@ -843,7 +842,7 @@ 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.w.Event(pointer.Event{
+		w.ProcessEvent(pointer.Event{
 			Kind:   pointer.Cancel,
 			Source: pointer.Touch,
 		})
@@ -869,7 +868,7 @@ func gio_onPointerLeave(data unsafe.Pointer, p *C.struct_wl_pointer, serial C.ui
 	s.serial = serial
 	if w.inCompositor {
 		w.inCompositor = false
-		w.w.Event(pointer.Event{Kind: pointer.Cancel})
+		w.ProcessEvent(pointer.Event{Kind: pointer.Cancel})
 	}
 }
 
@@ -930,7 +929,7 @@ func gio_onPointerButton(data unsafe.Pointer, p *C.struct_wl_pointer, serial, t,
 	}
 	w.flushScroll()
 	w.resetFling()
-	w.w.Event(pointer.Event{
+	w.ProcessEvent(pointer.Event{
 		Kind:      kind,
 		Source:    pointer.Mouse,
 		Buttons:   w.pointerBtns,
@@ -1018,8 +1017,11 @@ 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 {
 		return
 	}
@@ -1027,13 +1029,17 @@ func (w *window) ReadClipboard() {
 	go func() {
 		defer r.Close()
 		data, _ := io.ReadAll(r)
-		w.clipReads <- transfer.DataEvent{
+		e := transfer.DataEvent{
 			Type: "application/text",
 			Open: func() io.ReadCloser {
 				return io.NopCloser(bytes.NewReader(data))
 			},
 		}
-		w.Wakeup()
+		select {
+		case w.clipReads <- e:
+			w.disp.wakeup()
+		case <-w.disp.readClipClose:
+		}
 	}()
 }
 
@@ -1096,8 +1102,7 @@ func (w *window) Configure(options []Option) {
 		w.config.MaxSize = cnf.MaxSize
 		w.setWindowConstraints()
 	}
-	w.w.Event(ConfigEvent{Config: w.config})
+	w.ProcessEvent(ConfigEvent{Config: w.config})
-	w.redraw = true
 }
 
 func (w *window) setWindowConstraints() {
@@ -1134,7 +1139,7 @@ func (w *window) Perform(actions system.Action) {
 	walkActions(actions, func(action system.Action) {
 		switch action {
 		case system.ActionClose:
-			w.dead = true
+			w.close(nil)
 		}
 	})
 }
@@ -1217,7 +1222,8 @@ 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.w.Event(key.FocusEvent{Focus: true})
+	w.config.Focused = true
+	w.ProcessEvent(ConfigEvent{Config: w.config})
 }
 
 //export gio_onKeyboardLeave
@@ -1226,7 +1232,8 @@ func gio_onKeyboardLeave(data unsafe.Pointer, keyboard *C.struct_wl_keyboard, se
 	s.serial = serial
 	s.disp.repeat.Stop(0)
 	w := s.keyboardFocus
-	w.w.Event(key.FocusEvent{Focus: false})
+	w.config.Focused = false
+	w.ProcessEvent(ConfigEvent{Config: w.config})
 }
 
 //export gio_onKeyboardKey
@@ -1244,7 +1251,7 @@ 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.w.Event(e)
+			w.ProcessEvent(e)
 		}
 	}
 	if state != C.WL_KEYBOARD_KEY_STATE_PRESSED {
@@ -1279,7 +1286,7 @@ func (r *repeatState) Start(w *window, keyCode uint32, t time.Duration) {
 	r.now = 0
 	r.stopC = stopC
 	r.key = keyCode
-	r.win = w.w
+	r.win = w
 	rate, delay := r.rate, r.delay
 	go func() {
 		timer := time.NewTimer(delay)
@@ -1337,9 +1344,9 @@ 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.EditorInsert(ee.Text)
+				r.win.w.EditorInsert(ee.Text)
 			} else {
-				r.win.Event(e)
+				r.win.ProcessEvent(e)
 			}
 		}
 		r.last += delay
@@ -1352,28 +1359,76 @@ 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) loop() error {
+func (w *window) close(err error) {
-	var p poller
+	w.ProcessEvent(WaylandViewEvent{})
-	for {
+	w.ProcessEvent(DestroyEvent{Err: err})
-		if err := w.disp.dispatch(&p); err != nil {
+}
-			return err
+
-		}
+func (w *window) dispatch() {
-		select {
+	if w.disp == nil {
-		case e := <-w.clipReads:
+		<-w.wakeups
-			w.w.Event(e)
+		w.w.Invalidate()
-		case <-w.wakeups:
+		return
-			w.w.Event(wakeupEvent{})
-		default:
-		}
-		if w.dead {
-			break
-		}
-		w.draw()
 	}
-	return nil
+	if err := w.disp.dispatch(); err != nil {
+		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 {
+	for {
+		evt, ok := w.w.nextEvent()
+		if !ok {
+			w.dispatch()
+			continue
+		}
+		if _, destroy := evt.(DestroyEvent); destroy {
+			w.destroy()
+			w.invMu.Lock()
+			w.disp.destroy()
+			w.disp = nil
+			w.invMu.Unlock()
+		}
+		return evt
+	}
+}
+
+func (w *window) Invalidate() {
+	select {
+	case w.wakeups <- struct{}{}:
+	default:
+		return
+	}
+	w.invMu.Lock()
+	defer w.invMu.Unlock()
+	if w.disp != nil {
+		w.disp.wakeup()
+	}
+}
+
+func (w *window) Run(f func()) {
+	f()
+}
+
+func (w *window) Frame(frame *op.Ops) {
+	w.w.ProcessFrame(frame, nil)
 }
 
 // bindDataDevice initializes the dataDev field if and only if both
@@ -1389,13 +1444,21 @@ func (d *wlDisplay) bindDataDevice() {
 	}
 }
 
-func (d *wlDisplay) dispatch(p *poller) error {
+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()
+
 	dispfd := C.wl_display_get_fd(d.disp)
 	// Poll for events and notifications.
-	pollfds := append(p.pollfds[:0],
+	pollfds := append(d.poller.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 {
@@ -1406,11 +1469,25 @@ func (d *wlDisplay) dispatch(p *poller) 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, p.buf[:])
+		_, err := syscall.Read(d.notify.read, d.poller.buf[:])
 		if err == syscall.EAGAIN {
 			break
 		}
@@ -1418,29 +1495,15 @@ func (d *wlDisplay) dispatch(p *poller) 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.
@@ -1576,7 +1639,7 @@ func (w *window) flushScroll() {
 	if total == (f32.Point{}) {
 		return
 	}
-	w.w.Event(pointer.Event{
+	w.ProcessEvent(pointer.Event{
 		Kind:      pointer.Scroll,
 		Source:    pointer.Mouse,
 		Buttons:   w.pointerBtns,
@@ -1599,7 +1662,7 @@ 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.w.Event(pointer.Event{
+	w.ProcessEvent(pointer.Event{
 		Kind:      pointer.Move,
 		Position:  w.lastPos,
 		Buttons:   w.pointerBtns,
@@ -1620,7 +1683,8 @@ func (w *window) systemGesture() (*C.struct_wl_cursor, C.uint32_t) {
 	if w.config.Mode != Windowed || w.config.Decorated {
 		return nil, 0
 	}
-	border := w.w.w.metric.Dp(3)
+	_, cfg := w.getConfig()
+	border := cfg.Dp(3)
 	x, y, size := int(w.lastPos.X), int(w.lastPos.Y), w.config.Size
 	north := y <= border
 	south := y >= size.Y-border
@@ -1674,13 +1738,10 @@ 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.redraw = true
+		w.draw(true)
 	}
-	if !found {
+	if found {
-		w.setStage(StagePaused)
+		w.draw(true)
-	} else {
-		w.setStage(StageRunning)
-		w.redraw = true
 	}
 }
 
@@ -1692,7 +1753,10 @@ func (w *window) getConfig() (image.Point, unit.Metric) {
 	}
 }
 
-func (w *window) draw() {
+func (w *window) draw(sync bool) {
+	if !w.configured {
+		return
+	}
 	w.flushScroll()
 	size, cfg := w.getConfig()
 	if cfg == (unit.Metric{}) {
@@ -1700,11 +1764,9 @@ func (w *window) draw() {
 	}
 	if size != w.config.Size {
 		w.config.Size = size
-		w.w.Event(ConfigEvent{Config: w.config})
+		w.ProcessEvent(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 {
@@ -1715,7 +1777,7 @@ func (w *window) draw() {
 		// 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.w.Event(frameEvent{
+	w.ProcessEvent(frameEvent{
 		FrameEvent: FrameEvent{
 			Now:    time.Now(),
 			Size:   w.config.Size,
@@ -1725,14 +1787,6 @@ func (w *window) draw() {
 	})
 }
 
-func (w *window) setStage(s Stage) {
-	if s == w.stage {
-		return
-	}
-	w.stage = s
-	w.w.Event(StageEvent{Stage: s})
-}
-
 func (w *window) display() *C.struct_wl_display {
 	return w.disp.disp
 }
@@ -1824,6 +1878,10 @@ 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
@@ -1865,6 +1923,7 @@ 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

@@ -19,17 +19,19 @@ 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/key"
 	"gioui.org/io/pointer"
 	"gioui.org/io/system"
 	"gioui.org/io/transfer"
 )
 
-type ViewEvent struct {
+type Win32ViewEvent struct {
 	HWND uintptr
 }
 
@@ -37,7 +39,6 @@ type window struct {
 	hwnd        syscall.Handle
 	hdc         syscall.Handle
 	w           *callbacks
-	stage       Stage
 	pointerBtns pointer.Buttons
 
 	// cursorIn tracks whether the cursor was inside the window according
@@ -49,10 +50,13 @@ type window struct {
 	placement *windows.WindowPlacement
 
 	animating bool
-	focused   bool
 
 	borderSize image.Point
 	config     Config
+	loop       *eventLoop
+
+	// invMu avoids the race between destroying the window and Invalidate.
+	invMu sync.Mutex
 }
 
 const _WM_WAKEUP = windows.WM_USER + iota
@@ -81,40 +85,38 @@ var resources struct {
 	cursor syscall.Handle
 }
 
-func osMain() {
+func newWindow(win *callbacks, options []Option) {
-	select {}
+	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, err := createNativeWindow()
+
+		w := &window{
+			w: win,
+		}
+		w.loop = newEventLoop(w.w, w.wakeup)
+		w.w.SetDriver(w)
+		err := w.init()
+		done <- struct{}{}
 		if err != nil {
-			cerr <- err
+			w.ProcessEvent(DestroyEvent{Err: err})
 			return
 		}
-		cerr <- nil
 		winMap.Store(w.hwnd, w)
 		defer winMap.Delete(w.hwnd)
-		w.w = window
+		w.ProcessEvent(Win32ViewEvent{HWND: uintptr(w.hwnd)})
-		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)
-		if err := w.loop(); err != nil {
+		w.runLoop()
-			panic(err)
-		}
 	}()
-	return <-cerr
+	<-done
 }
 
 // initResources initializes the resources global.
@@ -149,13 +151,13 @@ func initResources() error {
 
 const dwExStyle = windows.WS_EX_APPWINDOW | windows.WS_EX_WINDOWEDGE
 
-func createNativeWindow() (*window, error) {
+func (w *window) init() error {
 	var resErr error
 	resources.once.Do(func() {
 		resErr = initResources()
 	})
 	if resErr != nil {
-		return nil, resErr
+		return resErr
 	}
 	const dwStyle = windows.WS_OVERLAPPEDWINDOW
 
@@ -171,16 +173,15 @@ func createNativeWindow() (*window, error) {
 		resources.handle,
 		0)
 	if err != nil {
-		return nil, err
+		return err
-	}
-	w := &window{
-		hwnd: hwnd,
 	}
 	w.hdc, err = windows.GetDC(hwnd)
 	if err != nil {
-		return nil, err
+		windows.DestroyWindow(hwnd)
+		return err
 	}
-	return w, nil
+	w.hwnd = hwnd
+	return nil
 }
 
 // update() handles changes done by the user, and updates the configuration.
@@ -197,7 +198,7 @@ func (w *window) update() {
 		windows.GetSystemMetrics(windows.SM_CXSIZEFRAME),
 		windows.GetSystemMetrics(windows.SM_CYSIZEFRAME),
 	)
-	w.w.Event(ConfigEvent{Config: w.config})
+	w.ProcessEvent(ConfigEvent{Config: w.config})
 }
 
 func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr {
@@ -238,7 +239,7 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 				e.State = key.Release
 			}
 
-			w.w.Event(e)
+			w.ProcessEvent(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
@@ -259,23 +260,15 @@ 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.w.Event(pointer.Event{
+		w.ProcessEvent(pointer.Event{
 			Kind: pointer.Cancel,
 		})
 	case windows.WM_SETFOCUS:
-		w.focused = true
+		w.config.Focused = true
-		w.w.Event(key.FocusEvent{Focus: true})
+		w.ProcessEvent(ConfigEvent{Config: w.config})
 	case windows.WM_KILLFOCUS:
-		w.focused = false
+		w.config.Focused = false
-		w.w.Event(key.FocusEvent{Focus: false})
+		w.ProcessEvent(ConfigEvent{Config: w.config})
-	case windows.WM_NCACTIVATE:
-		if w.stage >= StageInactive {
-			if wParam == windows.TRUE {
-				w.setStage(StageRunning)
-			} else {
-				w.setStage(StageInactive)
-			}
-		}
 	case windows.WM_NCHITTEST:
 		if w.config.Decorated {
 			// Let the system handle it.
@@ -288,7 +281,7 @@ 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.w.Event(pointer.Event{
+		w.ProcessEvent(pointer.Event{
 			Kind:      pointer.Move,
 			Source:    pointer.Mouse,
 			Position:  p,
@@ -301,14 +294,16 @@ 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.w.Event(ViewEvent{})
+		w.ProcessEvent(Win32ViewEvent{})
-		w.w.Event(DestroyEvent{})
+		w.ProcessEvent(DestroyEvent{})
 		if w.hdc != 0 {
 			windows.ReleaseDC(w.hdc)
 			w.hdc = 0
 		}
+		w.invMu.Lock()
 		// The system destroys the HWND for us.
 		w.hwnd = 0
+		w.invMu.Unlock()
 		windows.PostQuitMessage(0)
 	case windows.WM_NCCALCSIZE:
 		if w.config.Decorated {
@@ -328,7 +323,7 @@ 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(uintptr(lParam)))
+		szp := (*windows.NCCalcSizeParams)(unsafe.Pointer(lParam))
 		mi := windows.GetMonitorInfo(w.hwnd)
 		szp.Rgrc[0] = mi.WorkArea
 		return 0
@@ -339,18 +334,15 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 		switch wParam {
 		case windows.SIZE_MINIMIZED:
 			w.config.Mode = Minimized
-			w.setStage(StagePaused)
 		case windows.SIZE_MAXIMIZED:
 			w.config.Mode = Maximized
-			w.setStage(StageRunning)
 		case windows.SIZE_RESTORED:
 			if w.config.Mode != Fullscreen {
 				w.config.Mode = Windowed
 			}
-			w.setStage(StageRunning)
 		}
 	case windows.WM_GETMINMAXINFO:
-		mm := (*windows.MinMaxInfo)(unsafe.Pointer(uintptr(lParam)))
+		mm := (*windows.MinMaxInfo)(unsafe.Pointer(lParam))
 		var bw, bh int32
 		if w.config.Decorated {
 			r := windows.GetWindowRect(w.hwnd)
@@ -378,7 +370,8 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 			return windows.TRUE
 		}
 	case _WM_WAKEUP:
-		w.w.Event(wakeupEvent{})
+		w.loop.Wakeup()
+		w.loop.FlushEvents()
 	case windows.WM_IME_STARTCOMPOSITION:
 		imc := windows.ImmGetContext(w.hwnd)
 		if imc == 0 {
@@ -498,7 +491,7 @@ func (w *window) hitTest(x, y int) uintptr {
 }
 
 func (w *window) pointerButton(btn pointer.Buttons, press bool, lParam uintptr, kmods key.Modifiers) {
-	if !w.focused {
+	if !w.config.Focused {
 		windows.SetFocus(w.hwnd)
 	}
 
@@ -518,7 +511,7 @@ 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.w.Event(pointer.Event{
+	w.ProcessEvent(pointer.Event{
 		Kind:      kind,
 		Source:    pointer.Mouse,
 		Position:  p,
@@ -553,7 +546,7 @@ func (w *window) scrollEvent(wParam, lParam uintptr, horizontal bool, kmods key.
 			sp.Y = -dist
 		}
 	}
-	w.w.Event(pointer.Event{
+	w.ProcessEvent(pointer.Event{
 		Kind:      pointer.Scroll,
 		Source:    pointer.Mouse,
 		Position:  p,
@@ -565,7 +558,7 @@ 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) loop() error {
+func (w *window) runLoop() {
 	msg := new(windows.Msg)
 loop:
 	for {
@@ -576,7 +569,7 @@ loop:
 		}
 		switch ret := windows.GetMessage(msg, 0, 0, 0); ret {
 		case -1:
-			return errors.New("GetMessage failed")
+			panic(errors.New("GetMessage failed"))
 		case 0:
 			// WM_QUIT received.
 			break loop
@@ -584,7 +577,6 @@ loop:
 		windows.TranslateMessage(msg)
 		windows.DispatchMessage(msg)
 	}
-	return nil
 }
 
 func (w *window) EditorStateChanged(old, new editorState) {
@@ -602,16 +594,37 @@ func (w *window) SetAnimating(anim bool) {
 	w.animating = anim
 }
 
-func (w *window) Wakeup() {
+func (w *window) ProcessEvent(e event.Event) {
-	if err := windows.PostMessage(w.hwnd, _WM_WAKEUP, 0, 0); err != nil {
+	w.w.ProcessEvent(e)
-		panic(err)
+	w.loop.FlushEvents()
-	}
 }
 
-func (w *window) setStage(s Stage) {
+func (w *window) Event() event.Event {
-	if s != w.stage {
+	return w.loop.Event()
-		w.stage = s
+}
-		w.w.Event(StageEvent{Stage: s})
+
+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() {
+	w.invMu.Lock()
+	defer w.invMu.Unlock()
+	if w.hwnd == 0 {
+		w.loop.Wakeup()
+		w.loop.FlushEvents()
+		return
+	}
+	if err := windows.PostMessage(w.hwnd, _WM_WAKEUP, 0, 0); err != nil {
+		panic(err)
 	}
 }
 
@@ -621,7 +634,7 @@ func (w *window) draw(sync bool) {
 	}
 	dpi := windows.GetWindowDPI(w.hwnd)
 	cfg := configForDPI(dpi)
-	w.w.Event(frameEvent{
+	w.ProcessEvent(frameEvent{
 		FrameEvent: FrameEvent{
 			Now:    time.Now(),
 			Size:   w.config.Size,
@@ -668,7 +681,7 @@ func (w *window) readClipboard() error {
 	}
 	defer windows.GlobalUnlock(mem)
 	content := gowindows.UTF16PtrToString((*uint16)(unsafe.Pointer(ptr)))
-	w.w.Event(transfer.DataEvent{
+	w.ProcessEvent(transfer.DataEvent{
 		Type: "application/text",
 		Open: func() io.ReadCloser {
 			return io.NopCloser(strings.NewReader(content))
@@ -974,4 +987,5 @@ func configForDPI(dpi int) unit.Metric {
 	}
 }
 
-func (_ ViewEvent) ImplementsEvent() {}
+func (Win32ViewEvent) implementsViewEvent() {}
+func (Win32ViewEvent) ImplementsEvent()     {}

app/os_x11.go

@@ -38,10 +38,12 @@ import (
 	"unsafe"
 
 	"gioui.org/f32"
+	"gioui.org/io/event"
 	"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"
@@ -93,12 +95,10 @@ type x11Window struct {
 		// _NET_WM_STATE_MAXIMIZED_VERT
 		wmStateMaximizedVert C.Atom
 	}
-	stage  Stage
 	metric unit.Metric
 	notify struct {
 		read, write int
 	}
-	dead bool
 
 	animating bool
 
@@ -111,6 +111,11 @@ type x11Window struct {
 	config Config
 
 	wakeups chan struct{}
+	handler x11EventHandler
+	buf     [100]byte
+
+	// invMy avoids the race between destroy and Invalidate.
+	invMu sync.Mutex
 }
 
 var (
@@ -234,7 +239,7 @@ func (w *x11Window) Configure(options []Option) {
 	if cnf.Decorated != prev.Decorated {
 		w.config.Decorated = cnf.Decorated
 	}
-	w.w.Event(ConfigEvent{Config: w.config})
+	w.ProcessEvent(ConfigEvent{Config: w.config})
 }
 
 func (w *x11Window) setTitle(prev, cnf Config) {
@@ -377,11 +382,47 @@ func (w *x11Window) sendWMStateEvent(action C.long, atom1, atom2 C.ulong) {
 
 var x11OneByte = make([]byte, 1)
 
-func (w *x11Window) Wakeup() {
+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})
+}
+
+func (w *x11Window) Event() event.Event {
+	for {
+		evt, ok := w.w.nextEvent()
+		if !ok {
+			w.dispatch()
+			continue
+		}
+		if _, destroy := evt.(DestroyEvent); destroy {
+			w.destroy()
+		}
+		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() {
 	select {
 	case w.wakeups <- struct{}{}:
 	default:
 	}
+	w.invMu.Lock()
+	defer w.invMu.Unlock()
+	if w.x == nil {
+		return
+	}
 	if _, err := syscall.Write(w.notify.write, x11OneByte); err != nil && err != syscall.EAGAIN {
 		panic(fmt.Errorf("failed to write to pipe: %v", err))
 	}
@@ -395,16 +436,20 @@ func (w *x11Window) window() (C.Window, int, int) {
 	return w.xw, w.config.Size.X, w.config.Size.Y
 }
 
-func (w *x11Window) setStage(s Stage) {
+func (w *x11Window) dispatch() {
-	if s == w.stage {
+	if w.x == nil {
+		// Only Invalidate can wake us up.
+		<-w.wakeups
+		w.w.Invalidate()
 		return
 	}
-	w.stage = s
-	w.w.Event(StageEvent{Stage: s})
-}
 
-func (w *x11Window) loop() {
+	select {
-	h := x11EventHandler{w: w, xev: new(C.XEvent), text: make([]byte, 4)}
+	case <-w.wakeups:
+		w.w.Invalidate()
+	default:
+	}
+
 	xfd := C.XConnectionNumber(w.x)
 
 	// Poll for events and notifications.
@@ -414,64 +459,52 @@ func (w *x11Window) loop() {
 	}
 	xEvents := &pollfds[0].Revents
 	// Plenty of room for a backlog of notifications.
-	buf := make([]byte, 100)
 
-loop:
+	var syn, anim bool
-	for !w.dead {
+	// Check for pending draw events before checking animation or blocking.
-		var syn, anim bool
+	// This fixes an issue on Xephyr where on startup XPending() > 0 but
-		// Check for pending draw events before checking animation or blocking.
+	// poll will still block. This also prevents no-op calls to poll.
-		// This fixes an issue on Xephyr where on startup XPending() > 0 but
+	if syn = w.handler.handleEvents(); !syn {
-		// poll will still block. This also prevents no-op calls to poll.
+		anim = w.animating
-		if syn = h.handleEvents(); !syn {
+		if !anim {
-			anim = w.animating
+			// Clear poll events.
-			if !anim {
+			*xEvents = 0
-				// Clear poll events.
+			// Wait for X event or gio notification.
-				*xEvents = 0
+			if _, err := syscall.Poll(pollfds, -1); err != nil && err != syscall.EINTR {
-				// Wait for X event or gio notification.
+				panic(fmt.Errorf("x11 loop: poll failed: %w", err))
-				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:
-				switch {
+				syn = w.handler.handleEvents()
-				case *xEvents&syscall.POLLIN != 0:
+			case *xEvents&(syscall.POLLERR|syscall.POLLHUP) != 0:
-					syn = h.handleEvents()
-					if w.dead {
-						break loop
-					}
-				case *xEvents&(syscall.POLLERR|syscall.POLLHUP) != 0:
-					break loop
-				}
 			}
 		}
-		// Clear notifications.
+	}
-		for {
+	// Clear notifications.
-			_, err := syscall.Read(w.notify.read, buf)
+	for {
-			if err == syscall.EAGAIN {
+		_, err := syscall.Read(w.notify.read, w.buf[:])
-				break
+		if err == syscall.EAGAIN {
-			}
+			break
-			if err != nil {
-				panic(fmt.Errorf("x11 loop: read from notify pipe failed: %w", err))
-			}
 		}
-		select {
+		if err != nil {
-		case <-w.wakeups:
+			panic(fmt.Errorf("x11 loop: read from notify pipe failed: %w", err))
-			w.w.Event(wakeupEvent{})
-		default:
-		}
-
-		if (anim || syn) && w.config.Size.X != 0 && w.config.Size.Y != 0 {
-			w.w.Event(frameEvent{
-				FrameEvent: 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,
+		})
+	}
 }
 
 func (w *x11Window) destroy() {
+	w.invMu.Lock()
+	defer w.invMu.Unlock()
 	if w.notify.write != 0 {
 		syscall.Close(w.notify.write)
 		w.notify.write = 0
@@ -486,6 +519,7 @@ 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
@@ -543,7 +577,7 @@ func (h *x11EventHandler) handleEvents() bool {
 					// There's no support for IME yet.
 					w.w.EditorInsert(ee.Text)
 				} else {
-					w.w.Event(e)
+					w.ProcessEvent(e)
 				}
 			}
 		case C.ButtonPress, C.ButtonRelease:
@@ -605,10 +639,10 @@ func (h *x11EventHandler) handleEvents() bool {
 				w.pointerBtns &^= btn
 			}
 			ev.Buttons = w.pointerBtns
-			w.w.Event(ev)
+			w.ProcessEvent(ev)
 		case C.MotionNotify:
 			mevt := (*C.XMotionEvent)(unsafe.Pointer(xev))
-			w.w.Event(pointer.Event{
+			w.ProcessEvent(pointer.Event{
 				Kind:    pointer.Move,
 				Source:  pointer.Mouse,
 				Buttons: w.pointerBtns,
@@ -623,14 +657,16 @@ func (h *x11EventHandler) handleEvents() bool {
 			// redraw only on the last expose event
 			redraw = (*C.XExposeEvent)(unsafe.Pointer(xev)).count == 0
 		case C.FocusIn:
-			w.w.Event(key.FocusEvent{Focus: true})
+			w.config.Focused = true
+			w.ProcessEvent(ConfigEvent{Config: w.config})
 		case C.FocusOut:
-			w.w.Event(key.FocusEvent{Focus: false})
+			w.config.Focused = false
+			w.ProcessEvent(ConfigEvent{Config: w.config})
 		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.w.Event(ConfigEvent{Config: w.config})
+				w.ProcessEvent(ConfigEvent{Config: w.config})
 			}
 			// redraw will be done by a later expose event
 		case C.SelectionNotify:
@@ -652,7 +688,7 @@ func (h *x11EventHandler) handleEvents() bool {
 				break
 			}
 			str := C.GoStringN((*C.char)(unsafe.Pointer(text.value)), C.int(text.nitems))
-			w.w.Event(transfer.DataEvent{
+			w.ProcessEvent(transfer.DataEvent{
 				Type: "application/text",
 				Open: func() io.ReadCloser {
 					return io.NopCloser(strings.NewReader(str))
@@ -711,7 +747,7 @@ 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.dead = true
+				w.shutdown(nil)
 				return false
 			}
 		}
@@ -793,8 +829,10 @@ 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()
@@ -830,19 +868,10 @@ func newX11Window(gioWin *callbacks, options []Option) error {
 	// extensions
 	C.XSetWMProtocols(dpy, win, &w.atoms.evDelWindow, 1)
 
-	go func() {
+	// make the window visible on the screen
-		w.w.SetDriver(w)
+	C.XMapWindow(dpy, win)
-
+	w.Configure(options)
-		// make the window visible on the screen
+	w.ProcessEvent(X11ViewEvent{Display: unsafe.Pointer(dpy), Window: uintptr(win)})
-		C.XMapWindow(dpy, win)
-		w.Configure(options)
-		w.w.Event(X11ViewEvent{Display: unsafe.Pointer(dpy), Window: uintptr(win)})
-		w.setStage(StageRunning)
-		w.loop()
-		w.w.Event(X11ViewEvent{})
-		w.w.Event(DestroyEvent{Err: nil})
-		w.destroy()
-	}()
 	return nil
 }
 

app/runmain.go

@@ -25,6 +25,6 @@ func runMain() {
 		// Indirect call, since the linker does not know the address of main when
 		// laying down this package.
 		fn := mainMain
-		fn()
+		go fn()
 	})
 }

app/system.go

@@ -10,40 +10,4 @@ type DestroyEvent struct {
 	Err error
 }
 
-// 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 frames.
-	StagePaused Stage = iota
-	// StageInactive is the stage for windows that are visible, but not active.
-	// Inactive windows receive frames.
-	StageInactive
-	// StageRunning is for active and visible Windows.
-	// Running windows receive frames.
-	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 (StageEvent) ImplementsEvent()   {}
 func (DestroyEvent) ImplementsEvent() {}