widget: test update-only editor logic

Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>

.builds/linux.yml

@@ -67,11 +67,6 @@ tasks:
      CGO_ENABLED=1 GOARCH=386 go test ./...
      GOOS=windows go test -exec=wine ./...
      GOOS=js GOARCH=wasm go build -o /dev/null ./...
- - install_chrome: |
-     curl -s https://dl.google.com/linux/linux_signing_key.pub | sudo apt-key add -
-     sudo sh -c 'echo "deb [arch=amd64] https://dl-ssl.google.com/linux/chrome/deb/ stable main" >> /etc/apt/sources.list.d/google.list'
-     sudo apt-get -qq update
-     sudo apt-get -qq install -y google-chrome-stable
  - install_jdk8: |
      curl -so jdk.deb "https://cdn.azul.com/zulu/bin/zulu8.42.0.21-ca-jdk8.0.232-linux_amd64.deb"
      sudo apt-get -qq install -y -f ./jdk.deb

app/doc.go

@@ -12,16 +12,16 @@ Create a new Window by calling NewWindow. On mobile platforms or when Gio
 is embedded in another project, NewWindow merely connects with a previously
 created window.
 
-A Window is run by receiving events from its Events channel. The most
+A Window is run by calling NextEvent in a loop. The most important event is
-important event is FrameEvent that prompts an update of the window
+FrameEvent that prompts an update of the window contents.
-contents and state.
 
 For example:
 
 	import "gioui.org/unit"
 
 	w := app.NewWindow()
-	for e := range w.Events() {
+	for {
+		e := w.NextEvent()
 		if e, ok := e.(system.FrameEvent); ok {
 			ops.Reset()
 			// Add operations to ops.
@@ -50,7 +50,8 @@ For example, to display a blank but otherwise functional window:
 	func main() {
 		go func() {
 			w := app.NewWindow()
-			for range w.Events() {
+			for {
+				w.NextEvent()
 			}
 		}()
 		app.Main()

app/internal/windows/windows.go

@@ -76,6 +76,21 @@ type MinMaxInfo struct {
 	PtMaxTrackSize Point
 }
 
+type NCCalcSizeParams struct {
+	Rgrc  [3]Rect
+	LpPos *WindowPos
+}
+
+type WindowPos struct {
+	HWND            syscall.Handle
+	HWNDInsertAfter syscall.Handle
+	x               int32
+	y               int32
+	cx              int32
+	cy              int32
+	flags           uint32
+}
+
 type WindowPlacement struct {
 	length           uint32
 	flags            uint32
@@ -331,6 +346,7 @@ var (
 	_DispatchMessage             = user32.NewProc("DispatchMessageW")
 	_EmptyClipboard              = user32.NewProc("EmptyClipboard")
 	_GetWindowRect               = user32.NewProc("GetWindowRect")
+	_GetClientRect               = user32.NewProc("GetClientRect")
 	_GetClipboardData            = user32.NewProc("GetClipboardData")
 	_GetDC                       = user32.NewProc("GetDC")
 	_GetDpiForWindow             = user32.NewProc("GetDpiForWindow")
@@ -463,6 +479,12 @@ func GetWindowRect(hwnd syscall.Handle) Rect {
 	return r
 }
 
+func GetClientRect(hwnd syscall.Handle) Rect {
+	var r Rect
+	_GetClientRect.Call(uintptr(hwnd), uintptr(unsafe.Pointer(&r)))
+	return r
+}
+
 func GetClipboardData(format uint32) (syscall.Handle, error) {
 	r, _, err := _GetClipboardData.Call(uintptr(format))
 	if r == 0 {

app/internal/xkb/xkb_unix.go

@@ -242,6 +242,9 @@ func convertKeysym(s C.xkb_keysym_t) (string, bool) {
 	if 'a' <= s && s <= 'z' {
 		return string(rune(s - 'a' + 'A')), true
 	}
+	if C.XKB_KEY_KP_0 <= s && s <= C.XKB_KEY_KP_9 {
+		return string(rune(s - C.XKB_KEY_KP_0 + '0')), true
+	}
 	if ' ' < s && s <= '~' {
 		return string(rune(s)), true
 	}
@@ -255,8 +258,6 @@ func convertKeysym(s C.xkb_keysym_t) (string, bool) {
 		n = key.NameRightArrow
 	case C.XKB_KEY_Return:
 		n = key.NameReturn
-	case C.XKB_KEY_KP_Enter:
-		n = key.NameEnter
 	case C.XKB_KEY_Up:
 		n = key.NameUpArrow
 	case C.XKB_KEY_Down:
@@ -297,9 +298,9 @@ func convertKeysym(s C.xkb_keysym_t) (string, bool) {
 		n = key.NameF11
 	case C.XKB_KEY_F12:
 		n = key.NameF12
-	case C.XKB_KEY_Tab, C.XKB_KEY_KP_Tab, C.XKB_KEY_ISO_Left_Tab:
+	case C.XKB_KEY_Tab, C.XKB_KEY_ISO_Left_Tab:
 		n = key.NameTab
-	case 0x20, C.XKB_KEY_KP_Space:
+	case 0x20:
 		n = key.NameSpace
 	case C.XKB_KEY_Control_L, C.XKB_KEY_Control_R:
 		n = key.NameCtrl
@@ -309,6 +310,64 @@ func convertKeysym(s C.xkb_keysym_t) (string, bool) {
 		n = key.NameAlt
 	case C.XKB_KEY_Super_L, C.XKB_KEY_Super_R:
 		n = key.NameSuper
+
+	case C.XKB_KEY_KP_Space:
+		n = key.NameSpace
+	case C.XKB_KEY_KP_Tab:
+		n = key.NameTab
+	case C.XKB_KEY_KP_Enter:
+		n = key.NameEnter
+	case C.XKB_KEY_KP_F1:
+		n = key.NameF1
+	case C.XKB_KEY_KP_F2:
+		n = key.NameF2
+	case C.XKB_KEY_KP_F3:
+		n = key.NameF3
+	case C.XKB_KEY_KP_F4:
+		n = key.NameF4
+	case C.XKB_KEY_KP_Home:
+		n = key.NameHome
+	case C.XKB_KEY_KP_Left:
+		n = key.NameLeftArrow
+	case C.XKB_KEY_KP_Up:
+		n = key.NameUpArrow
+	case C.XKB_KEY_KP_Right:
+		n = key.NameRightArrow
+	case C.XKB_KEY_KP_Down:
+		n = key.NameDownArrow
+	case C.XKB_KEY_KP_Prior:
+		// not supported
+		return "", false
+	case C.XKB_KEY_KP_Next:
+		// not supported
+		return "", false
+	case C.XKB_KEY_KP_End:
+		n = key.NameEnd
+	case C.XKB_KEY_KP_Begin:
+		n = key.NameHome
+	case C.XKB_KEY_KP_Insert:
+		// not supported
+		return "", false
+	case C.XKB_KEY_KP_Delete:
+		n = key.NameDeleteForward
+	case C.XKB_KEY_KP_Multiply:
+		n = "*"
+	case C.XKB_KEY_KP_Add:
+		n = "+"
+	case C.XKB_KEY_KP_Separator:
+		// not supported
+		return "", false
+	case C.XKB_KEY_KP_Subtract:
+		n = "-"
+	case C.XKB_KEY_KP_Decimal:
+		// TODO(dh): does a German keyboard layout also translate the numpad key to XKB_KEY_KP_DECIMAL? Because in
+		// German, the decimal is a comma, not a period.
+		n = "."
+	case C.XKB_KEY_KP_Divide:
+		n = "/"
+	case C.XKB_KEY_KP_Equal:
+		n = "="
+
 	default:
 		return "", false
 	}

app/os_android.go

@@ -953,18 +953,18 @@ func Java_org_gioui_GioView_onKeyEvent(env *C.JNIEnv, class C.jclass, handle C.j
 //export Java_org_gioui_GioView_onTouchEvent
 func Java_org_gioui_GioView_onTouchEvent(env *C.JNIEnv, class C.jclass, handle C.jlong, action, pointerID, tool C.jint, x, y, scrollX, scrollY C.jfloat, jbtns C.jint, t C.jlong) {
 	w := cgo.Handle(handle).Value().(*window)
-	var typ pointer.Type
+	var kind pointer.Kind
 	switch action {
 	case C.AMOTION_EVENT_ACTION_DOWN, C.AMOTION_EVENT_ACTION_POINTER_DOWN:
-		typ = pointer.Press
+		kind = pointer.Press
 	case C.AMOTION_EVENT_ACTION_UP, C.AMOTION_EVENT_ACTION_POINTER_UP:
-		typ = pointer.Release
+		kind = pointer.Release
 	case C.AMOTION_EVENT_ACTION_CANCEL:
-		typ = pointer.Cancel
+		kind = pointer.Cancel
 	case C.AMOTION_EVENT_ACTION_MOVE:
-		typ = pointer.Move
+		kind = pointer.Move
 	case C.AMOTION_EVENT_ACTION_SCROLL:
-		typ = pointer.Scroll
+		kind = pointer.Scroll
 	default:
 		return
 	}
@@ -994,7 +994,7 @@ func Java_org_gioui_GioView_onTouchEvent(env *C.JNIEnv, class C.jclass, handle C
 		return
 	}
 	w.callbacks.Event(pointer.Event{
-		Type:      typ,
+		Kind:      kind,
 		Source:    src,
 		Buttons:   btns,
 		PointerID: pointer.ID(pointerID),

app/os_darwin.go

@@ -124,7 +124,7 @@ func stringToNSString(str string) C.CFTypeRef {
 	return C.newNSString(chars, C.NSUInteger(len(u16)))
 }
 
-func NewDisplayLink(callback func()) (*displayLink, error) {
+func newDisplayLink(callback func()) (*displayLink, error) {
 	d := &displayLink{
 		callback: callback,
 		done:     make(chan struct{}),

app/os_ios.go

@@ -117,7 +117,7 @@ func onCreate(view, controller C.CFTypeRef) {
 	w := &window{
 		view: view,
 	}
-	dl, err := NewDisplayLink(func() {
+	dl, err := newDisplayLink(func() {
 		w.draw(false)
 	})
 	if err != nil {
@@ -236,16 +236,16 @@ func onText(view, str C.CFTypeRef) {
 
 //export onTouch
 func onTouch(last C.int, view, touchRef C.CFTypeRef, phase C.NSInteger, x, y C.CGFloat, ti C.double) {
-	var typ pointer.Type
+	var kind pointer.Kind
 	switch phase {
 	case C.UITouchPhaseBegan:
-		typ = pointer.Press
+		kind = pointer.Press
 	case C.UITouchPhaseMoved:
-		typ = pointer.Move
+		kind = pointer.Move
 	case C.UITouchPhaseEnded:
-		typ = pointer.Release
+		kind = pointer.Release
 	case C.UITouchPhaseCancelled:
-		typ = pointer.Cancel
+		kind = pointer.Cancel
 	default:
 		return
 	}
@@ -253,7 +253,7 @@ func onTouch(last C.int, view, touchRef C.CFTypeRef, phase C.NSInteger, x, y C.C
 	t := time.Duration(float64(ti) * float64(time.Second))
 	p := f32.Point{X: float32(x), Y: float32(y)}
 	w.w.Event(pointer.Event{
-		Type:      typ,
+		Kind:      kind,
 		Source:    pointer.Touch,
 		PointerID: w.lookupTouch(last != 0, touchRef),
 		Position:  p,

app/os_js.go

@@ -275,7 +275,7 @@ func (w *window) addEventListeners() {
 		}
 		w.touches = w.touches[:0]
 		w.w.Event(pointer.Event{
-			Type:   pointer.Cancel,
+			Kind:   pointer.Cancel,
 			Source: pointer.Touch,
 		})
 		return nil
@@ -398,7 +398,7 @@ func modifiersFor(e js.Value) key.Modifiers {
 	return mods
 }
 
-func (w *window) touchEvent(typ pointer.Type, e js.Value) {
+func (w *window) touchEvent(kind pointer.Kind, e js.Value) {
 	e.Call("preventDefault")
 	t := time.Duration(e.Get("timeStamp").Int()) * time.Millisecond
 	changedTouches := e.Get("changedTouches")
@@ -426,7 +426,7 @@ func (w *window) touchEvent(typ pointer.Type, e js.Value) {
 			Y: float32(y) * scale,
 		}
 		w.w.Event(pointer.Event{
-			Type:      typ,
+			Kind:      kind,
 			Source:    pointer.Touch,
 			Position:  pos,
 			PointerID: pid,
@@ -448,7 +448,7 @@ func (w *window) touchIDFor(touch js.Value) pointer.ID {
 	return pid
 }
 
-func (w *window) pointerEvent(typ pointer.Type, dx, dy float32, e js.Value) {
+func (w *window) pointerEvent(kind pointer.Kind, dx, dy float32, e js.Value) {
 	e.Call("preventDefault")
 	x, y := e.Get("clientX").Float(), e.Get("clientY").Float()
 	rect := w.cnv.Call("getBoundingClientRect")
@@ -476,7 +476,7 @@ func (w *window) pointerEvent(typ pointer.Type, dx, dy float32, e js.Value) {
 		btns |= pointer.ButtonTertiary
 	}
 	w.w.Event(pointer.Event{
-		Type:      typ,
+		Kind:      kind,
 		Source:    pointer.Mouse,
 		Buttons:   btns,
 		Position:  pos,

app/os_macos.go

@@ -297,7 +297,9 @@ func (w *window) contextView() C.CFTypeRef {
 
 func (w *window) ReadClipboard() {
 	cstr := C.readClipboard()
-	defer C.CFRelease(cstr)
+	if cstr != 0 {
+		defer C.CFRelease(cstr)
+	}
 	content := nsstringToString(cstr)
 	w.w.Event(clipboard.Event{Text: content})
 }
@@ -365,11 +367,11 @@ func (w *window) Configure(options []Option) {
 		case Minimized:
 			C.unhideWindow(window)
 		case Maximized:
+			if C.isWindowZoomed(window) != 0 {
+				C.zoomWindow(window)
+			}
 		}
 		w.config.Mode = Windowed
-		if C.isWindowZoomed(window) != 0 {
-			C.zoomWindow(window)
-		}
 		w.setTitle(prev, cnf)
 		if prev.Size != cnf.Size {
 			w.config.Size = cnf.Size
@@ -526,7 +528,7 @@ func gio_onMouse(view, evt C.CFTypeRef, cdir C.int, cbtn C.NSInteger, x, y, dx,
 	case 2:
 		btn = pointer.ButtonTertiary
 	}
-	var typ pointer.Type
+	var typ pointer.Kind
 	switch cdir {
 	case C.MOUSE_MOVE:
 		typ = pointer.Move
@@ -550,7 +552,7 @@ func gio_onMouse(view, evt C.CFTypeRef, cdir C.int, cbtn C.NSInteger, x, y, dx,
 		panic("invalid direction")
 	}
 	w.w.Event(pointer.Event{
-		Type:      typ,
+		Kind:      typ,
 		Source:    pointer.Mouse,
 		Time:      t,
 		Buttons:   w.pointerBtns,
@@ -884,7 +886,7 @@ func newOSWindow() (*window, error) {
 		scale:  scale,
 		redraw: make(chan struct{}, 1),
 	}
-	dl, err := NewDisplayLink(func() {
+	dl, err := newDisplayLink(func() {
 		select {
 		case w.redraw <- struct{}{}:
 		default:

app/os_wayland.go

@@ -94,10 +94,7 @@ type wlDisplay struct {
 
 	// Notification pipe fds.
 	notify struct {
-		read int
+		read, write int
-
-		mu    sync.Mutex
-		write int
 	}
 
 	repeat repeatState
@@ -794,7 +791,7 @@ func gio_onTouchDown(data unsafe.Pointer, touch *C.struct_wl_touch, serial, t C.
 		Y: fromFixed(y) * float32(w.scale),
 	}
 	w.w.Event(pointer.Event{
-		Type:      pointer.Press,
+		Kind:      pointer.Press,
 		Source:    pointer.Touch,
 		Position:  w.lastTouch,
 		PointerID: pointer.ID(id),
@@ -810,7 +807,7 @@ func gio_onTouchUp(data unsafe.Pointer, touch *C.struct_wl_touch, serial, t C.ui
 	w := s.touchFoci[id]
 	delete(s.touchFoci, id)
 	w.w.Event(pointer.Event{
-		Type:      pointer.Release,
+		Kind:      pointer.Release,
 		Source:    pointer.Touch,
 		Position:  w.lastTouch,
 		PointerID: pointer.ID(id),
@@ -828,7 +825,7 @@ func gio_onTouchMotion(data unsafe.Pointer, touch *C.struct_wl_touch, t C.uint32
 		Y: fromFixed(y) * float32(w.scale),
 	}
 	w.w.Event(pointer.Event{
-		Type:      pointer.Move,
+		Kind:      pointer.Move,
 		Position:  w.lastTouch,
 		Source:    pointer.Touch,
 		PointerID: pointer.ID(id),
@@ -847,7 +844,7 @@ func gio_onTouchCancel(data unsafe.Pointer, touch *C.struct_wl_touch) {
 	for id, w := range s.touchFoci {
 		delete(s.touchFoci, id)
 		w.w.Event(pointer.Event{
-			Type:   pointer.Cancel,
+			Kind:   pointer.Cancel,
 			Source: pointer.Touch,
 		})
 	}
@@ -872,7 +869,7 @@ func gio_onPointerLeave(data unsafe.Pointer, p *C.struct_wl_pointer, serial C.ui
 	s.serial = serial
 	if w.inCompositor {
 		w.inCompositor = false
-		w.w.Event(pointer.Event{Type: pointer.Cancel})
+		w.w.Event(pointer.Event{Kind: pointer.Cancel})
 	}
 }
 
@@ -920,21 +917,21 @@ func gio_onPointerButton(data unsafe.Pointer, p *C.struct_wl_pointer, serial, t,
 			}
 		}
 	}
-	var typ pointer.Type
+	var kind pointer.Kind
 	switch state {
 	case 0:
 		w.pointerBtns &^= btn
-		typ = pointer.Release
+		kind = pointer.Release
 		// Move or resize gestures no longer applies.
 		w.inCompositor = false
 	case 1:
 		w.pointerBtns |= btn
-		typ = pointer.Press
+		kind = pointer.Press
 	}
 	w.flushScroll()
 	w.resetFling()
 	w.w.Event(pointer.Event{
-		Type:      typ,
+		Kind:      kind,
 		Source:    pointer.Mouse,
 		Buttons:   w.pointerBtns,
 		Position:  w.lastPos,
@@ -1445,11 +1442,6 @@ func (w *window) SetAnimating(anim bool) {
 // Wakeup wakes up the event loop through the notification pipe.
 func (d *wlDisplay) wakeup() {
 	oneByte := make([]byte, 1)
-	d.notify.mu.Lock()
-	defer d.notify.mu.Unlock()
-	if d.notify.write == 0 {
-		return
-	}
 	if _, err := syscall.Write(d.notify.write, oneByte); err != nil && err != syscall.EAGAIN {
 		panic(fmt.Errorf("failed to write to pipe: %v", err))
 	}
@@ -1581,7 +1573,7 @@ func (w *window) flushScroll() {
 		return
 	}
 	w.w.Event(pointer.Event{
-		Type:      pointer.Scroll,
+		Kind:      pointer.Scroll,
 		Source:    pointer.Mouse,
 		Buttons:   w.pointerBtns,
 		Position:  w.lastPos,
@@ -1604,7 +1596,7 @@ func (w *window) onPointerMotion(x, y C.wl_fixed_t, t C.uint32_t) {
 		Y: fromFixed(y) * float32(w.scale),
 	}
 	w.w.Event(pointer.Event{
-		Type:      pointer.Move,
+		Kind:      pointer.Move,
 		Position:  w.lastPos,
 		Buttons:   w.pointerBtns,
 		Source:    pointer.Mouse,
@@ -1828,12 +1820,10 @@ func newWLDisplay() (*wlDisplay, error) {
 }
 
 func (d *wlDisplay) destroy() {
-	d.notify.mu.Lock()
 	if d.notify.write != 0 {
 		syscall.Close(d.notify.write)
 		d.notify.write = 0
 	}
-	d.notify.mu.Unlock()
 	if d.notify.read != 0 {
 		syscall.Close(d.notify.read)
 		d.notify.read = 0

app/os_windows.go

@@ -32,11 +32,6 @@ type ViewEvent struct {
 	HWND uintptr
 }
 
-type winDeltas struct {
-	width  int32
-	height int32
-}
-
 type window struct {
 	hwnd        syscall.Handle
 	hdc         syscall.Handle
@@ -55,7 +50,6 @@ type window struct {
 	animating bool
 	focused   bool
 
-	deltas     winDeltas
 	borderSize image.Point
 	config     Config
 }
@@ -192,22 +186,12 @@ func createNativeWindow() (*window, error) {
 // It reads the window style and size/position and updates w.config.
 // If anything has changed it emits a ConfigEvent to notify the application.
 func (w *window) update() {
-	r := windows.GetWindowRect(w.hwnd)
+	cr := windows.GetClientRect(w.hwnd)
-	size := image.Point{
+	w.config.Size = image.Point{
-		X: int(r.Right - r.Left - w.deltas.width),
+		X: int(cr.Right - cr.Left),
-		Y: int(r.Bottom - r.Top - w.deltas.height),
+		Y: int(cr.Bottom - cr.Top),
 	}
 
-	// Check the window mode.
-	style := windows.GetWindowLong(w.hwnd, windows.GWL_STYLE)
-	if style&windows.WS_OVERLAPPEDWINDOW == 0 {
-		size = image.Point{
-			X: int(r.Right - r.Left),
-			Y: int(r.Bottom - r.Top),
-		}
-	}
-	w.config.Size = size
-
 	w.borderSize = image.Pt(
 		windows.GetSystemMetrics(windows.SM_CXSIZEFRAME),
 		windows.GetSystemMetrics(windows.SM_CYSIZEFRAME),
@@ -275,7 +259,7 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 		w.pointerButton(pointer.ButtonTertiary, false, lParam, getModifiers())
 	case windows.WM_CANCELMODE:
 		w.w.Event(pointer.Event{
-			Type: pointer.Cancel,
+			Kind: pointer.Cancel,
 		})
 	case windows.WM_SETFOCUS:
 		w.focused = true
@@ -304,7 +288,7 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 		x, y := coordsFromlParam(lParam)
 		p := f32.Point{X: float32(x), Y: float32(y)}
 		w.w.Event(pointer.Event{
-			Type:      pointer.Move,
+			Kind:      pointer.Move,
 			Source:    pointer.Mouse,
 			Position:  p,
 			Buttons:   w.pointerBtns,
@@ -326,10 +310,27 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 		w.hwnd = 0
 		windows.PostQuitMessage(0)
 	case windows.WM_NCCALCSIZE:
-		if !w.config.Decorated {
+		if w.config.Decorated {
-			// No client areas; we draw decorations ourselves.
+			// Let Windows handle decorations.
+			break
+		}
+		// No client areas; we draw decorations ourselves.
+		if wParam != 1 {
 			return 0
 		}
+		// lParam contains an NCCALCSIZE_PARAMS for us to adjust.
+		place := windows.GetWindowPlacement(w.hwnd)
+		if !place.IsMaximized() {
+			// Nothing do adjust.
+			return 0
+		}
+		// 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)))
+		mi := windows.GetMonitorInfo(w.hwnd)
+		szp.Rgrc[0] = mi.WorkArea
+		return 0
 	case windows.WM_PAINT:
 		w.draw(true)
 	case windows.WM_SIZE:
@@ -349,18 +350,26 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 		}
 	case windows.WM_GETMINMAXINFO:
 		mm := (*windows.MinMaxInfo)(unsafe.Pointer(uintptr(lParam)))
+		var bw, bh int32
+		if w.config.Decorated {
+			r := windows.GetWindowRect(w.hwnd)
+			cr := windows.GetClientRect(w.hwnd)
+			bw = r.Right - r.Left - (cr.Right - cr.Left)
+			bh = r.Bottom - r.Top - (cr.Bottom - cr.Top)
+		}
 		if p := w.config.MinSize; p.X > 0 || p.Y > 0 {
 			mm.PtMinTrackSize = windows.Point{
-				X: int32(p.X) + w.deltas.width,
+				X: int32(p.X) + bw,
-				Y: int32(p.Y) + w.deltas.height,
+				Y: int32(p.Y) + bh,
 			}
 		}
 		if p := w.config.MaxSize; p.X > 0 || p.Y > 0 {
 			mm.PtMaxTrackSize = windows.Point{
-				X: int32(p.X) + w.deltas.width,
+				X: int32(p.X) + bw,
-				Y: int32(p.Y) + w.deltas.height,
+				Y: int32(p.Y) + bh,
 			}
 		}
+		return 0
 	case windows.WM_SETCURSOR:
 		w.cursorIn = (lParam & 0xffff) == windows.HTCLIENT
 		if w.cursorIn {
@@ -492,15 +501,15 @@ func (w *window) pointerButton(btn pointer.Buttons, press bool, lParam uintptr,
 		windows.SetFocus(w.hwnd)
 	}
 
-	var typ pointer.Type
+	var kind pointer.Kind
 	if press {
-		typ = pointer.Press
+		kind = pointer.Press
 		if w.pointerBtns == 0 {
 			windows.SetCapture(w.hwnd)
 		}
 		w.pointerBtns |= btn
 	} else {
-		typ = pointer.Release
+		kind = pointer.Release
 		w.pointerBtns &^= btn
 		if w.pointerBtns == 0 {
 			windows.ReleaseCapture()
@@ -509,7 +518,7 @@ 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{
-		Type:      typ,
+		Kind:      kind,
 		Source:    pointer.Mouse,
 		Position:  p,
 		Buttons:   w.pointerBtns,
@@ -544,7 +553,7 @@ func (w *window) scrollEvent(wParam, lParam uintptr, horizontal bool, kmods key.
 		}
 	}
 	w.w.Event(pointer.Event{
-		Type:      pointer.Scroll,
+		Kind:      pointer.Scroll,
 		Source:    pointer.Mouse,
 		Position:  p,
 		Buttons:   w.pointerBtns,
@@ -686,31 +695,26 @@ func (w *window) Configure(options []Option) {
 		showMode = windows.SW_SHOWMAXIMIZED
 
 	case Windowed:
-		windows.SetWindowText(w.hwnd, w.config.Title)
 		style |= winStyle
 		showMode = windows.SW_SHOWNORMAL
-		// Get target for client areaa size.
+		// Get target for client area size.
 		width = int32(w.config.Size.X)
 		height = int32(w.config.Size.Y)
 		// Get the current window size and position.
 		wr := windows.GetWindowRect(w.hwnd)
-		// Set desired window size.
-		wr.Right = wr.Left + width
-		wr.Bottom = wr.Top + height
-		// Compute client size and position. Note that the client size is
-		// equal to the window size when we are in control of decorations.
-		r := wr
-		if w.config.Decorated {
-			windows.AdjustWindowRectEx(&r, uint32(style), 0, dwExStyle)
-		}
-		// Calculate difference between client and full window sizes.
-		w.deltas.width = r.Right - wr.Right + wr.Left - r.Left
-		w.deltas.height = r.Bottom - wr.Bottom + wr.Top - r.Top
-		// Set new window size and position.
 		x = wr.Left
 		y = wr.Top
-		width = r.Right - r.Left
+		if w.config.Decorated {
-		height = r.Bottom - r.Top
+			// Compute client size and position. Note that the client size is
+			// equal to the window size when we are in control of decorations.
+			r := windows.Rect{
+				Right:  width,
+				Bottom: height,
+			}
+			windows.AdjustWindowRectEx(&r, uint32(style), 0, dwExStyle)
+			width = r.Right - r.Left
+			height = r.Bottom - r.Top
+		}
 		if !w.config.Decorated {
 			// Enable drop shadows when we draw decorations.
 			windows.DwmExtendFrameIntoClientArea(w.hwnd, windows.Margins{-1, -1, -1, -1})
@@ -727,7 +731,7 @@ func (w *window) Configure(options []Option) {
 	windows.SetWindowPos(w.hwnd, 0, x, y, width, height, swpStyle)
 	windows.ShowWindow(w.hwnd, showMode)
 
-	w.w.Event(ConfigEvent{Config: w.config})
+	w.update()
 }
 
 func (w *window) WriteClipboard(s string) {

app/os_x11.go

@@ -547,7 +547,7 @@ func (h *x11EventHandler) handleEvents() bool {
 		case C.ButtonPress, C.ButtonRelease:
 			bevt := (*C.XButtonEvent)(unsafe.Pointer(xev))
 			ev := pointer.Event{
-				Type:   pointer.Press,
+				Kind:   pointer.Press,
 				Source: pointer.Mouse,
 				Position: f32.Point{
 					X: float32(bevt.x),
@@ -557,7 +557,7 @@ func (h *x11EventHandler) handleEvents() bool {
 				Modifiers: w.xkb.Modifiers(),
 			}
 			if bevt._type == C.ButtonRelease {
-				ev.Type = pointer.Release
+				ev.Kind = pointer.Release
 			}
 			var btn pointer.Buttons
 			const scrollScale = 10
@@ -569,7 +569,7 @@ func (h *x11EventHandler) handleEvents() bool {
 			case C.Button3:
 				btn = pointer.ButtonSecondary
 			case C.Button4:
-				ev.Type = pointer.Scroll
+				ev.Kind = pointer.Scroll
 				// scroll up or left (if shift is pressed).
 				if ev.Modifiers == key.ModShift {
 					ev.Scroll.X = -scrollScale
@@ -578,7 +578,7 @@ func (h *x11EventHandler) handleEvents() bool {
 				}
 			case C.Button5:
 				// scroll down or right (if shift is pressed).
-				ev.Type = pointer.Scroll
+				ev.Kind = pointer.Scroll
 				if ev.Modifiers == key.ModShift {
 					ev.Scroll.X = +scrollScale
 				} else {
@@ -587,11 +587,11 @@ func (h *x11EventHandler) handleEvents() bool {
 			case 6:
 				// http://xahlee.info/linux/linux_x11_mouse_button_number.html
 				// scroll left.
-				ev.Type = pointer.Scroll
+				ev.Kind = pointer.Scroll
 				ev.Scroll.X = -scrollScale * 2
 			case 7:
 				// scroll right
-				ev.Type = pointer.Scroll
+				ev.Kind = pointer.Scroll
 				ev.Scroll.X = +scrollScale * 2
 			default:
 				continue
@@ -607,7 +607,7 @@ func (h *x11EventHandler) handleEvents() bool {
 		case C.MotionNotify:
 			mevt := (*C.XMotionEvent)(unsafe.Pointer(xev))
 			w.w.Event(pointer.Event{
-				Type:    pointer.Move,
+				Kind:    pointer.Move,
 				Source:  pointer.Mouse,
 				Buttons: w.pointerBtns,
 				Position: f32.Point{

app/window.go

@@ -61,6 +61,8 @@ type Window struct {
 	// actions are the actions waiting to be performed.
 	actions chan system.Action
 
+	// out is where the platform backend delivers events bound for the
+	// user program.
 	out      chan event.Event
 	frames   chan *op.Ops
 	frameAck chan struct{}
@@ -107,6 +109,16 @@ type Window struct {
 	}
 
 	imeState editorState
+
+	// event stores the state required for processing and delivering events
+	// from NextEvent. If we had support for range over func, this would
+	// be the iterator state.
+	eventState struct {
+		created     bool
+		initialOpts []Option
+		wakeup      func()
+		timer       *time.Timer
+	}
 }
 
 type editorState struct {
@@ -185,7 +197,7 @@ func NewWindow(options ...Option) *Window {
 	w.imeState.compose = key.Range{Start: -1, End: -1}
 	w.semantic.ids = make(map[router.SemanticID]router.SemanticNode)
 	w.callbacks.w = w
-	go w.run(options)
+	w.eventState.initialOpts = options
 	return w
 }
 
@@ -195,11 +207,6 @@ func decoHeightOpt(h unit.Dp) Option {
 	}
 }
 
-// Events returns the channel where events are delivered.
-func (w *Window) Events() <-chan event.Event {
-	return w.out
-}
-
 // update the window contents, input operations declare input handlers,
 // and so on. The supplied operations list completely replaces the window state
 // from previous calls.
@@ -713,7 +720,7 @@ func (w *Window) waitAck(d driver) {
 		select {
 		case f := <-w.driverFuncs:
 			f(d)
-		case w.out <- event.Event(nil):
+		case w.out <- theFlushEvent:
 			// A dummy event went through, so we know the application has processed the previous event.
 			return
 		case <-w.immediateRedraws:
@@ -747,7 +754,7 @@ func (w *Window) waitFrame(d driver) *op.Ops {
 		case frame := <-w.frames:
 			// The client called FrameEvent.Frame.
 			return frame
-		case w.out <- event.Event(nil):
+		case w.out <- theFlushEvent:
 			// The client ignored FrameEvent and continued processing
 			// events.
 			return nil
@@ -881,7 +888,6 @@ func (w *Window) processEvent(d driver, e event.Event) bool {
 		if err := w.validateAndProcess(d, viewSize, e2.Sync, wrapper, signal); err != nil {
 			w.destroyGPU()
 			w.out <- system.DestroyEvent{Err: err}
-			close(w.out)
 			close(w.destroy)
 			break
 		}
@@ -890,7 +896,6 @@ func (w *Window) processEvent(d driver, e event.Event) bool {
 	case system.DestroyEvent:
 		w.destroyGPU()
 		w.out <- e2
-		close(w.out)
 		close(w.destroy)
 	case ViewEvent:
 		w.out <- e2
@@ -938,43 +943,51 @@ func (w *Window) processEvent(d driver, e event.Event) bool {
 	return true
 }
 
-func (w *Window) run(options []Option) {
+// NextEvent blocks until an event is received from the window, such as
-	if err := newWindow(&w.callbacks, options); err != nil {
+// [io/system.FrameEvent]. It blocks forever if called after [io/system.DestroyEvent]
-		w.out <- system.DestroyEvent{Err: err}
+// has been returned.
-		close(w.out)
+func (w *Window) NextEvent() event.Event {
-		close(w.destroy)
+	state := &w.eventState
-		return
+	if !state.created {
+		state.created = true
+		if err := newWindow(&w.callbacks, state.initialOpts); err != nil {
+			close(w.destroy)
+			return system.DestroyEvent{Err: err}
+		}
 	}
-	var wakeup func()
-	var timer *time.Timer
 	for {
 		var (
 			wakeups <-chan struct{}
 			timeC   <-chan time.Time
 		)
-		if wakeup != nil {
+		if state.wakeup != nil {
 			wakeups = w.wakeups
-			if timer != nil {
+			if state.timer != nil {
-				timeC = timer.C
+				timeC = state.timer.C
 			}
 		}
 		select {
 		case t := <-w.scheduledRedraws:
-			if timer != nil {
+			if state.timer != nil {
-				timer.Stop()
+				state.timer.Stop()
 			}
-			timer = time.NewTimer(time.Until(t))
+			state.timer = time.NewTimer(time.Until(t))
-		case <-w.destroy:
+		case e := <-w.out:
-			return
+			// Receiving a flushEvent indicates to the platform backend that
+			// all previous events have been processed by the user program.
+			if _, ok := e.(flushEvent); ok {
+				break
+			}
+			return e
 		case <-timeC:
 			select {
 			case w.redraws <- struct{}{}:
-				wakeup()
+				state.wakeup()
 			default:
 			}
 		case <-wakeups:
-			wakeup()
+			state.wakeup()
-		case wakeup = <-w.wakeupFuncs:
+		case state.wakeup = <-w.wakeupFuncs:
 		}
 	}
 }
@@ -1024,7 +1037,7 @@ func (w *Window) decorate(d driver, e system.FrameEvent, o *op.Ops) (size, offse
 	}
 	style.Layout(gtx)
 	// Update the window based on the actions on the decorations.
-	w.Perform(deco.Actions())
+	w.Perform(deco.Update(gtx))
 	// Offset to place the frame content below the decorations.
 	decoHeight := gtx.Dp(w.decorations.Config.decoHeight)
 	if w.decorations.currentHeight != decoHeight {
@@ -1165,3 +1178,14 @@ func Decorated(enabled bool) Option {
 		cnf.Decorated = enabled
 	}
 }
+
+// flushEvent is sent to detect when the user program
+// has completed processing of all prior events. Its an
+// [io/event.Event] but only for internal use.
+type flushEvent struct{}
+
+func (t flushEvent) ImplementsEvent() {}
+
+// theFlushEvent avoids allocating garbage when sending
+// flushEvents.
+var theFlushEvent flushEvent

gesture/gesture.go

@@ -39,18 +39,18 @@ type Hover struct {
 func (h *Hover) Add(ops *op.Ops) {
 	pointer.InputOp{
 		Tag:   h,
-		Types: pointer.Enter | pointer.Leave,
+		Kinds: pointer.Enter | pointer.Leave,
 	}.Add(ops)
 }
 
-// Hovered returns whether a pointer is inside the area.
+// Update state and report whether a pointer is inside the area.
-func (h *Hover) Hovered(q event.Queue) bool {
+func (h *Hover) Update(q event.Queue) bool {
 	for _, ev := range q.Events(h) {
 		e, ok := ev.(pointer.Event)
 		if !ok {
 			continue
 		}
-		switch e.Type {
+		switch e.Kind {
 		case pointer.Leave, pointer.Cancel:
 			if h.entered && h.pid == e.PointerID {
 				h.entered = false
@@ -87,10 +87,10 @@ type Click struct {
 }
 
 // ClickEvent represent a click action, either a
-// TypePress for the beginning of a click or a
+// KindPress for the beginning of a click or a
-// TypeClick for a completed click.
+// KindClick for a completed click.
 type ClickEvent struct {
-	Type      ClickType
+	Kind      ClickKind
 	Position  image.Point
 	Source    pointer.Source
 	Modifiers key.Modifiers
@@ -99,7 +99,7 @@ type ClickEvent struct {
 	NumClicks int
 }
 
-type ClickType uint8
+type ClickKind uint8
 
 // Drag detects drag gestures in the form of pointer.Drag events.
 type Drag struct {
@@ -136,15 +136,15 @@ const (
 )
 
 const (
-	// TypePress is reported for the first pointer
+	// KindPress is reported for the first pointer
 	// press.
-	TypePress ClickType = iota
+	KindPress ClickKind = iota
-	// TypeClick is reported when a click action
+	// KindClick is reported when a click action
 	// is complete.
-	TypeClick
+	KindClick
-	// TypeCancel is reported when the gesture is
+	// KindCancel is reported when the gesture is
 	// cancelled.
-	TypeCancel
+	KindCancel
 )
 
 const (
@@ -163,7 +163,7 @@ const touchSlop = unit.Dp(3)
 func (c *Click) Add(ops *op.Ops) {
 	pointer.InputOp{
 		Tag:   c,
-		Types: pointer.Press | pointer.Release | pointer.Enter | pointer.Leave,
+		Kinds: pointer.Press | pointer.Release | pointer.Enter | pointer.Leave,
 	}.Add(ops)
 }
 
@@ -177,24 +177,24 @@ func (c *Click) Pressed() bool {
 	return c.pressed
 }
 
-// Events returns the next click events, if any.
+// Update state and return the click events.
-func (c *Click) Events(q event.Queue) []ClickEvent {
+func (c *Click) Update(q event.Queue) []ClickEvent {
 	var events []ClickEvent
 	for _, evt := range q.Events(c) {
 		e, ok := evt.(pointer.Event)
 		if !ok {
 			continue
 		}
-		switch e.Type {
+		switch e.Kind {
 		case pointer.Release:
 			if !c.pressed || c.pid != e.PointerID {
 				break
 			}
 			c.pressed = false
 			if !c.entered || c.hovered {
-				events = append(events, ClickEvent{Type: TypeClick, Position: e.Position.Round(), Source: e.Source, Modifiers: e.Modifiers, NumClicks: c.clicks})
+				events = append(events, ClickEvent{Kind: KindClick, Position: e.Position.Round(), Source: e.Source, Modifiers: e.Modifiers, NumClicks: c.clicks})
 			} else {
-				events = append(events, ClickEvent{Type: TypeCancel})
+				events = append(events, ClickEvent{Kind: KindCancel})
 			}
 		case pointer.Cancel:
 			wasPressed := c.pressed
@@ -202,7 +202,7 @@ func (c *Click) Events(q event.Queue) []ClickEvent {
 			c.hovered = false
 			c.entered = false
 			if wasPressed {
-				events = append(events, ClickEvent{Type: TypeCancel})
+				events = append(events, ClickEvent{Kind: KindCancel})
 			}
 		case pointer.Press:
 			if c.pressed {
@@ -224,7 +224,7 @@ func (c *Click) Events(q event.Queue) []ClickEvent {
 				c.clicks = 1
 			}
 			c.clickedAt = e.Time
-			events = append(events, ClickEvent{Type: TypePress, Position: e.Position.Round(), Source: e.Source, Modifiers: e.Modifiers, NumClicks: c.clicks})
+			events = append(events, ClickEvent{Kind: KindPress, Position: e.Position.Round(), Source: e.Source, Modifiers: e.Modifiers, NumClicks: c.clicks})
 		case pointer.Leave:
 			if !c.pressed {
 				c.pid = e.PointerID
@@ -254,7 +254,7 @@ func (s *Scroll) Add(ops *op.Ops, bounds image.Rectangle) {
 	oph := pointer.InputOp{
 		Tag:          s,
 		Grab:         s.grab,
-		Types:        pointer.Press | pointer.Drag | pointer.Release | pointer.Scroll,
+		Kinds:        pointer.Press | pointer.Drag | pointer.Release | pointer.Scroll,
 		ScrollBounds: bounds,
 	}
 	oph.Add(ops)
@@ -268,9 +268,8 @@ func (s *Scroll) Stop() {
 	s.flinger = fling.Animation{}
 }
 
-// Scroll detects the scrolling distance from the available events and
+// Update state and report the scroll distance along axis.
-// ongoing fling gestures.
+func (s *Scroll) Update(cfg unit.Metric, q event.Queue, t time.Time, axis Axis) int {
-func (s *Scroll) Scroll(cfg unit.Metric, q event.Queue, t time.Time, axis Axis) int {
 	if s.axis != axis {
 		s.axis = axis
 		return 0
@@ -281,7 +280,7 @@ func (s *Scroll) Scroll(cfg unit.Metric, q event.Queue, t time.Time, axis Axis)
 		if !ok {
 			continue
 		}
-		switch e.Type {
+		switch e.Kind {
 		case pointer.Press:
 			if s.dragging {
 				break
@@ -368,12 +367,12 @@ func (d *Drag) Add(ops *op.Ops) {
 	pointer.InputOp{
 		Tag:   d,
 		Grab:  d.grab,
-		Types: pointer.Press | pointer.Drag | pointer.Release,
+		Kinds: pointer.Press | pointer.Drag | pointer.Release,
 	}.Add(ops)
 }
 
-// Events returns the next drag events, if any.
+// Update state and return the drag events.
-func (d *Drag) Events(cfg unit.Metric, q event.Queue, axis Axis) []pointer.Event {
+func (d *Drag) Update(cfg unit.Metric, q event.Queue, axis Axis) []pointer.Event {
 	var events []pointer.Event
 	for _, e := range q.Events(d) {
 		e, ok := e.(pointer.Event)
@@ -381,7 +380,7 @@ func (d *Drag) Events(cfg unit.Metric, q event.Queue, axis Axis) []pointer.Event
 			continue
 		}
 
-		switch e.Type {
+		switch e.Kind {
 		case pointer.Press:
 			if !(e.Buttons == pointer.ButtonPrimary || e.Source == pointer.Touch) {
 				continue
@@ -444,13 +443,13 @@ func (a Axis) String() string {
 	}
 }
 
-func (ct ClickType) String() string {
+func (ct ClickKind) String() string {
 	switch ct {
-	case TypePress:
+	case KindPress:
 		return "TypePress"
-	case TypeClick:
+	case KindClick:
 		return "TypeClick"
-	case TypeCancel:
+	case KindCancel:
 		return "TypeCancel"
 	default:
 		panic("invalid ClickType")

gesture/gesture_test.go

@@ -26,16 +26,16 @@ func TestHover(t *testing.T) {
 	r.Frame(ops)
 
 	r.Queue(
-		pointer.Event{Type: pointer.Move, Position: f32.Pt(30, 30)},
+		pointer.Event{Kind: pointer.Move, Position: f32.Pt(30, 30)},
 	)
-	if !h.Hovered(r) {
+	if !h.Update(r) {
 		t.Fatal("expected hovered")
 	}
 
 	r.Queue(
-		pointer.Event{Type: pointer.Move, Position: f32.Pt(50, 50)},
+		pointer.Event{Kind: pointer.Move, Position: f32.Pt(50, 50)},
 	)
-	if h.Hovered(r) {
+	if h.Update(r) {
 		t.Fatal("expected not hovered")
 	}
 }
@@ -75,7 +75,7 @@ func TestMouseClicks(t *testing.T) {
 			r.Frame(&ops)
 			r.Queue(tc.events...)
 
-			events := click.Events(&r)
+			events := click.Update(&r)
 			clicks := filterMouseClicks(events)
 			if got, want := len(clicks), len(tc.clicks); got != want {
 				t.Fatalf("got %d mouse clicks, expected %d", got, want)
@@ -92,7 +92,7 @@ func TestMouseClicks(t *testing.T) {
 
 func mouseClickEvents(times ...time.Duration) []event.Event {
 	press := pointer.Event{
-		Type:    pointer.Press,
+		Kind:    pointer.Press,
 		Source:  pointer.Mouse,
 		Buttons: pointer.ButtonPrimary,
 	}
@@ -101,7 +101,7 @@ func mouseClickEvents(times ...time.Duration) []event.Event {
 		press := press
 		press.Time = t
 		release := press
-		release.Type = pointer.Release
+		release.Kind = pointer.Release
 		events = append(events, press, release)
 	}
 	return events
@@ -110,7 +110,7 @@ func mouseClickEvents(times ...time.Duration) []event.Event {
 func filterMouseClicks(events []ClickEvent) []ClickEvent {
 	var clicks []ClickEvent
 	for _, ev := range events {
-		if ev.Type == TypeClick {
+		if ev.Kind == KindClick {
 			clicks = append(clicks, ev)
 		}
 	}

go.mod

@@ -5,7 +5,7 @@ go 1.19
 require (
 	eliasnaur.com/font v0.0.0-20230308162249-dd43949cb42d
 	gioui.org/cpu v0.0.0-20210817075930-8d6a761490d2
-	gioui.org/shader v1.0.6
+	gioui.org/shader v1.0.8
 	github.com/go-text/typesetting v0.0.0-20230803102845-24e03d8b5372
 	golang.org/x/exp v0.0.0-20221012211006-4de253d81b95
 	golang.org/x/exp/shiny v0.0.0-20220827204233-334a2380cb91

go.sum

@@ -3,8 +3,8 @@ eliasnaur.com/font v0.0.0-20230308162249-dd43949cb42d/go.mod h1:OYVuxibdk9OSLX8v
 gioui.org/cpu v0.0.0-20210808092351-bfe733dd3334/go.mod h1:A8M0Cn5o+vY5LTMlnRoK3O5kG+rH0kWfJjeKd9QpBmQ=
 gioui.org/cpu v0.0.0-20210817075930-8d6a761490d2 h1:AGDDxsJE1RpcXTAxPG2B4jrwVUJGFDjINIPi1jtO6pc=
 gioui.org/cpu v0.0.0-20210817075930-8d6a761490d2/go.mod h1:A8M0Cn5o+vY5LTMlnRoK3O5kG+rH0kWfJjeKd9QpBmQ=
-gioui.org/shader v1.0.6 h1:cvZmU+eODFR2545X+/8XucgZdTtEjR3QWW6W65b0q5Y=
+gioui.org/shader v1.0.8 h1:6ks0o/A+b0ne7RzEqRZK5f4Gboz2CfG+mVliciy6+qA=
-gioui.org/shader v1.0.6/go.mod h1:mWdiME581d/kV7/iEhLmUgUK5iZ09XR5XpduXzbePVM=
+gioui.org/shader v1.0.8/go.mod h1:mWdiME581d/kV7/iEhLmUgUK5iZ09XR5XpduXzbePVM=
 github.com/go-text/typesetting v0.0.0-20230803102845-24e03d8b5372 h1:FQivqchis6bE2/9uF70M2gmmLpe82esEm2QadL0TEJo=
 github.com/go-text/typesetting v0.0.0-20230803102845-24e03d8b5372/go.mod h1:evDBbvNR/KaVFZ2ZlDSOWWXIUKq0wCOEtzLxRM8SG3k=
 github.com/go-text/typesetting-utils v0.0.0-20230616150549-2a7df14b6a22 h1:LBQTFxP2MfsyEDqSKmUBZaDuDHN1vpqDyOZjcqS7MYI=

gpu/gpu.go

@@ -68,22 +68,40 @@ type renderer struct {
 	pather        *pather
 	packer        packer
 	intersections packer
+	layers        packer
+	layerFBOs     fboSet
 }
 
 type drawOps struct {
-	profile     bool
+	profile      bool
-	reader      ops.Reader
+	reader       ops.Reader
-	states      []f32.Affine2D
+	states       []f32.Affine2D
-	transStack  []f32.Affine2D
+	transStack   []f32.Affine2D
-	vertCache   []byte
+	layers       []opacityLayer
-	viewport    image.Point
+	opacityStack []int
-	clear       bool
+	vertCache    []byte
-	clearColor  f32color.RGBA
+	viewport     image.Point
-	imageOps    []imageOp
+	clear        bool
-	pathOps     []*pathOp
+	clearColor   f32color.RGBA
-	pathOpCache []pathOp
+	imageOps     []imageOp
-	qs          quadSplitter
+	pathOps      []*pathOp
-	pathCache   *opCache
+	pathOpCache  []pathOp
+	qs           quadSplitter
+	pathCache    *opCache
+}
+
+type opacityLayer struct {
+	opacity float32
+	parent  int
+	// depth of the opacity stack. Layers of equal depth are
+	// independent and may be packed into one atlas.
+	depth int
+	// opStart and opEnd denote the range of drawOps.imageOps
+	// that belong to the layer.
+	opStart, opEnd int
+	// clip of the layer operations.
+	clip  image.Rectangle
+	place placement
 }
 
 type drawState struct {
@@ -127,7 +145,12 @@ type imageOp struct {
 	clip     image.Rectangle
 	material material
 	clipType clipType
-	place    placement
+	// place is either a placement in the path fbos or intersection fbos,
+	// depending on clipType.
+	place placement
+	// layerOps is the number of operations this
+	// operation replaces.
+	layerOps int
 }
 
 func decodeStrokeOp(data []byte) float32 {
@@ -154,10 +177,12 @@ type material struct {
 	// For materialTypeColor.
 	color f32color.RGBA
 	// For materialTypeLinearGradient.
-	color1 f32color.RGBA
+	color1  f32color.RGBA
-	color2 f32color.RGBA
+	color2  f32color.RGBA
+	opacity float32
 	// For materialTypeTexture.
 	data    imageOpData
+	tex     driver.Texture
 	uvTrans f32.Affine2D
 }
 
@@ -222,8 +247,6 @@ func decodeLinearGradientOp(data []byte) linearGradientOpData {
 	}
 }
 
-type clipType uint8
-
 type resource interface {
 	release()
 }
@@ -273,6 +296,9 @@ type blitUniforms struct {
 	transform     [4]float32
 	uvTransformR1 [4]float32
 	uvTransformR2 [4]float32
+	opacity       float32
+	fbo           float32
+	_             [2]float32
 }
 
 type colorUniforms struct {
@@ -284,7 +310,7 @@ type gradientUniforms struct {
 	color2 f32color.RGBA
 }
 
-type materialType uint8
+type clipType uint8
 
 const (
 	clipTypeNone clipType = iota
@@ -292,6 +318,8 @@ const (
 	clipTypeIntersection
 )
 
+type materialType uint8
+
 const (
 	materialColor materialType = iota
 	materialLinearGradient
@@ -391,6 +419,8 @@ func (g *gpu) frame(target RenderTarget) error {
 	g.coverTimer.begin()
 	g.renderer.uploadImages(g.cache, g.drawOps.imageOps)
 	g.renderer.prepareDrawOps(g.cache, g.drawOps.imageOps)
+	g.drawOps.layers = g.renderer.packLayers(g.drawOps.layers)
+	g.renderer.drawLayers(g.cache, g.drawOps.layers, g.drawOps.imageOps)
 	d := driver.LoadDesc{
 		ClearColor: g.drawOps.clearColor,
 	}
@@ -400,7 +430,7 @@ func (g *gpu) frame(target RenderTarget) error {
 	}
 	g.ctx.BeginRenderPass(defFBO, d)
 	g.ctx.Viewport(0, 0, viewport.X, viewport.Y)
-	g.renderer.drawOps(g.cache, g.drawOps.imageOps)
+	g.renderer.drawOps(g.cache, false, image.Point{}, g.renderer.blitter.viewport, g.drawOps.imageOps)
 	g.coverTimer.end()
 	g.ctx.EndRenderPass()
 	g.cleanupTimer.begin()
@@ -464,15 +494,18 @@ func newRenderer(ctx driver.Device) *renderer {
 	if cap := 8192; maxDim > cap {
 		maxDim = cap
 	}
+	d := image.Pt(maxDim, maxDim)
 
-	r.packer.maxDims = image.Pt(maxDim, maxDim)
+	r.packer.maxDims = d
-	r.intersections.maxDims = image.Pt(maxDim, maxDim)
+	r.intersections.maxDims = d
+	r.layers.maxDims = d
 	return r
 }
 
 func (r *renderer) release() {
 	r.pather.release()
 	r.blitter.release()
+	r.layerFBOs.delete(r.ctx, 0)
 }
 
 func newBlitter(ctx driver.Device) *blitter {
@@ -747,8 +780,7 @@ func (r *renderer) packStencils(pops *[]*pathOp) {
 			ops = ops[:len(ops)-1]
 			continue
 		}
-		sz := image.Point{X: p.clip.Dx(), Y: p.clip.Dy()}
+		place, ok := r.packer.add(p.clip.Size())
-		place, ok := r.packer.add(sz)
 		if !ok {
 			// The clip area is at most the entire screen. Hopefully no
 			// screen is larger than GL_MAX_TEXTURE_SIZE.
@@ -760,6 +792,83 @@ func (r *renderer) packStencils(pops *[]*pathOp) {
 	*pops = ops
 }
 
+func (r *renderer) packLayers(layers []opacityLayer) []opacityLayer {
+	// Make every layer bounds contain nested layers; cull empty layers.
+	for i := len(layers) - 1; i >= 0; i-- {
+		l := layers[i]
+		if l.parent != -1 {
+			b := layers[l.parent].clip
+			layers[l.parent].clip = b.Union(l.clip)
+		}
+		if l.clip.Empty() {
+			layers = append(layers[:i], layers[i+1:]...)
+		}
+	}
+	// Pack layers.
+	r.layers.clear()
+	depth := 0
+	for i := range layers {
+		l := &layers[i]
+		// Only layers of the same depth may be packed together.
+		if l.depth != depth {
+			r.layers.newPage()
+		}
+		place, ok := r.layers.add(l.clip.Size())
+		if !ok {
+			// The layer area is at most the entire screen. Hopefully no
+			// screen is larger than GL_MAX_TEXTURE_SIZE.
+			panic(fmt.Errorf("layer size %v is larger than maximum texture size %v", l.clip.Size(), r.layers.maxDims))
+		}
+		l.place = place
+	}
+	return layers
+}
+
+func (r *renderer) drawLayers(cache *resourceCache, layers []opacityLayer, ops []imageOp) {
+	if len(r.layers.sizes) == 0 {
+		return
+	}
+	fbo := -1
+	r.layerFBOs.resize(r.ctx, driver.TextureFormatSRGBA, r.layers.sizes)
+	for i := len(layers) - 1; i >= 0; i-- {
+		l := layers[i]
+		if fbo != l.place.Idx {
+			if fbo != -1 {
+				r.ctx.EndRenderPass()
+				r.ctx.PrepareTexture(r.layerFBOs.fbos[fbo].tex)
+			}
+			fbo = l.place.Idx
+			f := r.layerFBOs.fbos[fbo]
+			r.ctx.BeginRenderPass(f.tex, driver.LoadDesc{Action: driver.LoadActionClear})
+		}
+		v := image.Rectangle{
+			Min: l.place.Pos,
+			Max: l.place.Pos.Add(l.clip.Size()),
+		}
+		r.ctx.Viewport(v.Min.X, v.Min.Y, v.Max.X, v.Max.Y)
+		f := r.layerFBOs.fbos[fbo]
+		r.drawOps(cache, true, l.clip.Min.Mul(-1), l.clip.Size(), ops[l.opStart:l.opEnd])
+		sr := f32.FRect(v)
+		uvScale, uvOffset := texSpaceTransform(sr, f.size)
+		uvTrans := f32.Affine2D{}.Scale(f32.Point{}, uvScale).Offset(uvOffset)
+		// Replace layer ops with one textured op.
+		ops[l.opStart] = imageOp{
+			clip: l.clip,
+			material: material{
+				material: materialTexture,
+				tex:      f.tex,
+				uvTrans:  uvTrans,
+				opacity:  l.opacity,
+			},
+			layerOps: l.opEnd - l.opStart - 1,
+		}
+	}
+	if fbo != -1 {
+		r.ctx.EndRenderPass()
+		r.ctx.PrepareTexture(r.layerFBOs.fbos[fbo].tex)
+	}
+}
+
 func (d *drawOps) reset(viewport image.Point) {
 	d.profile = false
 	d.viewport = viewport
@@ -768,6 +877,8 @@ func (d *drawOps) reset(viewport image.Point) {
 	d.pathOpCache = d.pathOpCache[:0]
 	d.vertCache = d.vertCache[:0]
 	d.transStack = d.transStack[:0]
+	d.layers = d.layers[:0]
+	d.opacityStack = d.opacityStack[:0]
 }
 
 func (d *drawOps) collect(root *op.Ops, viewport image.Point) {
@@ -866,6 +977,27 @@ loop:
 			state.t = d.transStack[n-1]
 			d.transStack = d.transStack[:n-1]
 
+		case ops.TypePushOpacity:
+			opacity := ops.DecodeOpacity(encOp.Data)
+			parent := -1
+			depth := len(d.opacityStack)
+			if depth > 0 {
+				parent = d.opacityStack[depth-1]
+			}
+			lidx := len(d.layers)
+			d.layers = append(d.layers, opacityLayer{
+				opacity: opacity,
+				parent:  parent,
+				depth:   depth,
+				opStart: len(d.imageOps),
+			})
+			d.opacityStack = append(d.opacityStack, lidx)
+		case ops.TypePopOpacity:
+			n := len(d.opacityStack)
+			idx := d.opacityStack[n-1]
+			d.layers[idx].opEnd = len(d.imageOps)
+			d.opacityStack = d.opacityStack[:n-1]
+
 		case ops.TypeStroke:
 			quads.key.strokeWidth = decodeStrokeOp(encOp.Data)
 
@@ -958,7 +1090,7 @@ loop:
 			mat := state.materialFor(bnd, off, partialTrans, bounds)
 
 			rect := state.cpath == nil || state.cpath.rect
-			if bounds.Min == (image.Point{}) && bounds.Max == d.viewport && rect && mat.opaque && (mat.material == materialColor) {
+			if bounds.Min == (image.Point{}) && bounds.Max == d.viewport && rect && mat.opaque && (mat.material == materialColor) && len(d.opacityStack) == 0 {
 				// The image is a uniform opaque color and takes up the whole screen.
 				// Scrap images up to and including this image and set clear color.
 				d.imageOps = d.imageOps[:0]
@@ -971,6 +1103,15 @@ loop:
 				clip:     bounds,
 				material: mat,
 			}
+			if n := len(d.opacityStack); n > 0 {
+				idx := d.opacityStack[n-1]
+				lb := d.layers[idx].clip
+				if lb.Empty() {
+					d.layers[idx].clip = img.clip
+				} else {
+					d.layers[idx].clip = lb.Union(img.clip)
+				}
+			}
 
 			d.imageOps = append(d.imageOps, img)
 			if clipData != nil {
@@ -1000,7 +1141,9 @@ func expandPathOp(p *pathOp, clip image.Rectangle) {
 }
 
 func (d *drawState) materialFor(rect f32.Rectangle, off f32.Point, partTrans f32.Affine2D, clip image.Rectangle) material {
-	var m material
+	m := material{
+		opacity: 1.,
+	}
 	switch d.matType {
 	case materialColor:
 		m.material = materialColor
@@ -1040,10 +1183,11 @@ func (d *drawState) materialFor(rect f32.Rectangle, off f32.Point, partTrans f32
 }
 
 func (r *renderer) uploadImages(cache *resourceCache, ops []imageOp) {
-	for _, img := range ops {
+	for i := range ops {
+		img := &ops[i]
 		m := img.material
 		if m.material == materialTexture {
-			r.texHandle(cache, m.data)
+			img.material.tex = r.texHandle(cache, m.data)
 		}
 	}
 }
@@ -1053,10 +1197,10 @@ func (r *renderer) prepareDrawOps(cache *resourceCache, ops []imageOp) {
 		m := img.material
 		switch m.material {
 		case materialTexture:
-			r.ctx.PrepareTexture(r.texHandle(cache, m.data))
+			r.ctx.PrepareTexture(m.tex)
 		}
 
-		var fbo stencilFBO
+		var fbo FBO
 		switch img.clipType {
 		case clipTypeNone:
 			continue
@@ -1069,24 +1213,26 @@ func (r *renderer) prepareDrawOps(cache *resourceCache, ops []imageOp) {
 	}
 }
 
-func (r *renderer) drawOps(cache *resourceCache, ops []imageOp) {
+func (r *renderer) drawOps(cache *resourceCache, isFBO bool, opOff image.Point, viewport image.Point, ops []imageOp) {
 	var coverTex driver.Texture
-	for _, img := range ops {
+	for i := 0; i < len(ops); i++ {
+		img := ops[i]
+		i += img.layerOps
 		m := img.material
 		switch m.material {
 		case materialTexture:
-			r.ctx.BindTexture(0, r.texHandle(cache, m.data))
+			r.ctx.BindTexture(0, m.tex)
 		}
-		drc := img.clip
+		drc := img.clip.Add(opOff)
 
-		scale, off := clipSpaceTransform(drc, r.blitter.viewport)
+		scale, off := clipSpaceTransform(drc, viewport)
-		var fbo stencilFBO
+		var fbo FBO
 		switch img.clipType {
 		case clipTypeNone:
 			p := r.blitter.pipelines[m.material]
 			r.ctx.BindPipeline(p.pipeline)
 			r.ctx.BindVertexBuffer(r.blitter.quadVerts, 0)
-			r.blitter.blit(m.material, m.color, m.color1, m.color2, scale, off, m.uvTrans)
+			r.blitter.blit(m.material, isFBO, m.color, m.color1, m.color2, scale, off, m.opacity, m.uvTrans)
 			continue
 		case clipTypePath:
 			fbo = r.pather.stenciler.cover(img.place.Idx)
@@ -1105,11 +1251,11 @@ func (r *renderer) drawOps(cache *resourceCache, ops []imageOp) {
 		p := r.pather.coverer.pipelines[m.material]
 		r.ctx.BindPipeline(p.pipeline)
 		r.ctx.BindVertexBuffer(r.blitter.quadVerts, 0)
-		r.pather.cover(m.material, m.color, m.color1, m.color2, scale, off, m.uvTrans, coverScale, coverOff)
+		r.pather.cover(m.material, isFBO, m.color, m.color1, m.color2, scale, off, m.uvTrans, coverScale, coverOff)
 	}
 }
 
-func (b *blitter) blit(mat materialType, col f32color.RGBA, col1, col2 f32color.RGBA, scale, off f32.Point, uvTrans f32.Affine2D) {
+func (b *blitter) blit(mat materialType, fbo bool, col f32color.RGBA, col1, col2 f32color.RGBA, scale, off f32.Point, opacity float32, uvTrans f32.Affine2D) {
 	p := b.pipelines[mat]
 	b.ctx.BindPipeline(p.pipeline)
 	var uniforms *blitUniforms
@@ -1119,18 +1265,23 @@ func (b *blitter) blit(mat materialType, col f32color.RGBA, col1, col2 f32color.
 		uniforms = &b.colUniforms.blitUniforms
 	case materialTexture:
 		t1, t2, t3, t4, t5, t6 := uvTrans.Elems()
-		b.texUniforms.blitUniforms.uvTransformR1 = [4]float32{t1, t2, t3, 0}
-		b.texUniforms.blitUniforms.uvTransformR2 = [4]float32{t4, t5, t6, 0}
 		uniforms = &b.texUniforms.blitUniforms
+		uniforms.uvTransformR1 = [4]float32{t1, t2, t3, 0}
+		uniforms.uvTransformR2 = [4]float32{t4, t5, t6, 0}
 	case materialLinearGradient:
 		b.linearGradientUniforms.color1 = col1
 		b.linearGradientUniforms.color2 = col2
 
 		t1, t2, t3, t4, t5, t6 := uvTrans.Elems()
-		b.linearGradientUniforms.blitUniforms.uvTransformR1 = [4]float32{t1, t2, t3, 0}
-		b.linearGradientUniforms.blitUniforms.uvTransformR2 = [4]float32{t4, t5, t6, 0}
 		uniforms = &b.linearGradientUniforms.blitUniforms
+		uniforms.uvTransformR1 = [4]float32{t1, t2, t3, 0}
+		uniforms.uvTransformR2 = [4]float32{t4, t5, t6, 0}
 	}
+	uniforms.fbo = 0
+	if fbo {
+		uniforms.fbo = 1
+	}
+	uniforms.opacity = opacity
 	uniforms.transform = [4]float32{scale.X, scale.Y, off.X, off.Y}
 	p.UploadUniforms(b.ctx)
 	b.ctx.DrawArrays(0, 4)

gpu/internal/rendertest/render_test.go

@@ -413,6 +413,22 @@ func TestGapsInPath(t *testing.T) {
 	})
 }
 
+func TestOpacity(t *testing.T) {
+	run(t, func(ops *op.Ops) {
+		opc1 := paint.PushOpacity(ops, .3)
+		// Fill screen to exercize the glClear optimization.
+		paint.FillShape(ops, color.NRGBA{R: 255, A: 255}, clip.Rect{Max: image.Pt(1024, 1024)}.Op())
+		opc2 := paint.PushOpacity(ops, .6)
+		paint.FillShape(ops, color.NRGBA{G: 255, A: 255}, clip.Rect{Min: image.Pt(20, 10), Max: image.Pt(64, 128)}.Op())
+		opc2.Pop()
+		opc1.Pop()
+		opc3 := paint.PushOpacity(ops, .6)
+		paint.FillShape(ops, color.NRGBA{G: 255, A: 255}, clip.Rect{Min: image.Pt(50+20, 10), Max: image.Pt(50+64, 128)}.Op())
+		opc3.Pop()
+	}, func(r result) {
+	})
+}
+
 // lerp calculates linear interpolation with color b and p.
 func lerp(a, b f32color.RGBA, p float32) f32color.RGBA {
 	return f32color.RGBA{

gpu/path.go

@@ -58,7 +58,7 @@ type coverUniforms struct {
 	uvCoverTransform [4]float32
 	uvTransformR1    [4]float32
 	uvTransformR2    [4]float32
-	_                float32
+	fbo              float32
 }
 
 type stenciler struct {
@@ -90,10 +90,10 @@ type intersectUniforms struct {
 }
 
 type fboSet struct {
-	fbos []stencilFBO
+	fbos []FBO
 }
 
-type stencilFBO struct {
+type FBO struct {
 	size image.Point
 	tex  driver.Texture
 }
@@ -247,10 +247,10 @@ func newStenciler(ctx driver.Device) *stenciler {
 	return st
 }
 
-func (s *fboSet) resize(ctx driver.Device, sizes []image.Point) {
+func (s *fboSet) resize(ctx driver.Device, format driver.TextureFormat, sizes []image.Point) {
 	// Add fbos.
 	for i := len(s.fbos); i < len(sizes); i++ {
-		s.fbos = append(s.fbos, stencilFBO{})
+		s.fbos = append(s.fbos, FBO{})
 	}
 	// Resize fbos.
 	for i, sz := range sizes {
@@ -273,7 +273,7 @@ func (s *fboSet) resize(ctx driver.Device, sizes []image.Point) {
 			if sz.X > max {
 				sz.X = max
 			}
-			tex, err := ctx.NewTexture(driver.TextureFormatFloat, sz.X, sz.Y, driver.FilterNearest, driver.FilterNearest,
+			tex, err := ctx.NewTexture(format, sz.X, sz.Y, driver.FilterNearest, driver.FilterNearest,
 				driver.BufferBindingTexture|driver.BufferBindingFramebuffer)
 			if err != nil {
 				panic(err)
@@ -340,15 +340,15 @@ func (s *stenciler) beginIntersect(sizes []image.Point) {
 	// 8 bit coverage is enough, but OpenGL ES only supports single channel
 	// floating point formats. Replace with GL_RGB+GL_UNSIGNED_BYTE if
 	// no floating point support is available.
-	s.intersections.resize(s.ctx, sizes)
+	s.intersections.resize(s.ctx, driver.TextureFormatFloat, sizes)
 }
 
-func (s *stenciler) cover(idx int) stencilFBO {
+func (s *stenciler) cover(idx int) FBO {
 	return s.fbos.fbos[idx]
 }
 
 func (s *stenciler) begin(sizes []image.Point) {
-	s.fbos.resize(s.ctx, sizes)
+	s.fbos.resize(s.ctx, driver.TextureFormatFloat, sizes)
 }
 
 func (s *stenciler) stencilPath(bounds image.Rectangle, offset f32.Point, uv image.Point, data pathData) {
@@ -375,11 +375,11 @@ func (s *stenciler) stencilPath(bounds image.Rectangle, offset f32.Point, uv ima
 	}
 }
 
-func (p *pather) cover(mat materialType, col f32color.RGBA, col1, col2 f32color.RGBA, scale, off f32.Point, uvTrans f32.Affine2D, coverScale, coverOff f32.Point) {
+func (p *pather) cover(mat materialType, isFBO bool, col f32color.RGBA, col1, col2 f32color.RGBA, scale, off f32.Point, uvTrans f32.Affine2D, coverScale, coverOff f32.Point) {
-	p.coverer.cover(mat, col, col1, col2, scale, off, uvTrans, coverScale, coverOff)
+	p.coverer.cover(mat, isFBO, col, col1, col2, scale, off, uvTrans, coverScale, coverOff)
 }
 
-func (c *coverer) cover(mat materialType, col f32color.RGBA, col1, col2 f32color.RGBA, scale, off f32.Point, uvTrans f32.Affine2D, coverScale, coverOff f32.Point) {
+func (c *coverer) cover(mat materialType, isFBO bool, col f32color.RGBA, col1, col2 f32color.RGBA, scale, off f32.Point, uvTrans f32.Affine2D, coverScale, coverOff f32.Point) {
 	var uniforms *coverUniforms
 	switch mat {
 	case materialColor:
@@ -399,6 +399,10 @@ func (c *coverer) cover(mat materialType, col f32color.RGBA, col1, col2 f32color
 		c.texUniforms.uvTransformR2 = [4]float32{t4, t5, t6, 0}
 		uniforms = &c.texUniforms.coverUniforms
 	}
+	uniforms.fbo = 0
+	if isFBO {
+		uniforms.fbo = 1
+	}
 	uniforms.transform = [4]float32{scale.X, scale.Y, off.X, off.Y}
 	uniforms.uvCoverTransform = [4]float32{coverScale.X, coverScale.Y, coverOff.X, coverOff.Y}
 	c.pipelines[mat].UploadUniforms(c.ctx)

internal/ops/ops.go

@@ -14,14 +14,25 @@ import (
 
 type Ops struct {
 	// version is incremented at each Reset.
-	version int
+	version uint32
 	// data contains the serialized operations.
 	data []byte
 	// refs hold external references for operations.
 	refs []interface{}
+	// stringRefs provides space for string references, pointers to which will
+	// be stored in refs. Storing a string directly in refs would cause a heap
+	// allocation, to store the string header in an interface value. The backing
+	// array of stringRefs, on the other hand, gets reused between calls to
+	// reset, making string references free on average.
+	//
+	// Appending to stringRefs might reallocate the backing array, which will
+	// leave pointers to the old array in refs. This temporarily causes a slight
+	// increase in memory usage, but this, too, amortizes away as the capacity
+	// of stringRefs approaches its stable maximum.
+	stringRefs []string
 	// nextStateID is the id allocated for the next
 	// StateOp.
-	nextStateID int
+	nextStateID uint32
 	// multipOp indicates a multi-op such as clip.Path is being added.
 	multipOp bool
 
@@ -40,9 +51,10 @@ const (
 	TypeMacro OpType = iota + firstOpIndex
 	TypeCall
 	TypeDefer
-	TypePushTransform
 	TypeTransform
 	TypePopTransform
+	TypePushOpacity
+	TypePopOpacity
 	TypeInvalidate
 	TypeImage
 	TypePaint
@@ -72,30 +84,30 @@ const (
 	TypeSemanticDesc
 	TypeSemanticClass
 	TypeSemanticSelected
-	TypeSemanticDisabled
+	TypeSemanticEnabled
 	TypeSnippet
 	TypeSelection
 	TypeActionInput
 )
 
 type StackID struct {
-	id   int
+	id   uint32
-	prev int
+	prev uint32
 }
 
 // StateOp represents a saved operation snapshot to be restored
 // later.
 type StateOp struct {
-	id      int
+	id      uint32
-	macroID int
+	macroID uint32
 	ops     *Ops
 }
 
 // stack tracks the integer identities of stack operations to ensure correct
 // pairing of their push and pop methods.
 type stack struct {
-	currentID int
+	currentID uint32
-	nextID    int
+	nextID    uint32
 }
 
 type StackKind uint8
@@ -111,6 +123,7 @@ const (
 	ClipStack StackKind = iota
 	TransStack
 	PassStack
+	OpacityStack
 	_StackKind
 )
 
@@ -124,9 +137,10 @@ const (
 	TypeMacroLen            = 1 + 4 + 4
 	TypeCallLen             = 1 + 4 + 4 + 4 + 4
 	TypeDeferLen            = 1
-	TypePushTransformLen    = 1 + 4*6
 	TypeTransformLen        = 1 + 1 + 4*6
 	TypePopTransformLen     = 1
+	TypePushOpacityLen      = 1 + 4
+	TypePopOpacityLen       = 1
 	TypeRedrawLen           = 1 + 8
 	TypeImageLen            = 1
 	TypePaintLen            = 1
@@ -156,7 +170,7 @@ const (
 	TypeSemanticDescLen     = 1
 	TypeSemanticClassLen    = 2
 	TypeSemanticSelectedLen = 2
-	TypeSemanticDisabledLen = 2
+	TypeSemanticEnabledLen  = 2
 	TypeSnippetLen          = 1 + 4 + 4
 	TypeSelectionLen        = 1 + 2*4 + 2*4 + 4 + 4
 	TypeActionInputLen      = 1 + 1
@@ -183,8 +197,12 @@ func Reset(o *Ops) {
 	for i := range o.refs {
 		o.refs[i] = nil
 	}
+	for i := range o.stringRefs {
+		o.stringRefs[i] = ""
+	}
 	o.data = o.data[:0]
 	o.refs = o.refs[:0]
+	o.stringRefs = o.stringRefs[:0]
 	o.nextStateID = 0
 	o.version++
 }
@@ -248,11 +266,11 @@ func AddCall(o *Ops, callOps *Ops, pc PC, end PC) {
 	bo.PutUint32(data[13:], uint32(end.refs))
 }
 
-func PushOp(o *Ops, kind StackKind) (StackID, int) {
+func PushOp(o *Ops, kind StackKind) (StackID, uint32) {
 	return o.stacks[kind].push(), o.macroStack.currentID
 }
 
-func PopOp(o *Ops, kind StackKind, sid StackID, macroID int) {
+func PopOp(o *Ops, kind StackKind, sid StackID, macroID uint32) {
 	if o.macroStack.currentID != macroID {
 		panic("stack push and pop must not cross macro boundary")
 	}
@@ -265,12 +283,26 @@ func Write1(o *Ops, n int, ref1 interface{}) []byte {
 	return o.data[len(o.data)-n:]
 }
 
+func Write1String(o *Ops, n int, ref1 string) []byte {
+	o.data = append(o.data, make([]byte, n)...)
+	o.stringRefs = append(o.stringRefs, ref1)
+	o.refs = append(o.refs, &o.stringRefs[len(o.stringRefs)-1])
+	return o.data[len(o.data)-n:]
+}
+
 func Write2(o *Ops, n int, ref1, ref2 interface{}) []byte {
 	o.data = append(o.data, make([]byte, n)...)
 	o.refs = append(o.refs, ref1, ref2)
 	return o.data[len(o.data)-n:]
 }
 
+func Write2String(o *Ops, n int, ref1 interface{}, ref2 string) []byte {
+	o.data = append(o.data, make([]byte, n)...)
+	o.stringRefs = append(o.stringRefs, ref2)
+	o.refs = append(o.refs, ref1, &o.stringRefs[len(o.stringRefs)-1])
+	return o.data[len(o.data)-n:]
+}
+
 func Write3(o *Ops, n int, ref1, ref2, ref3 interface{}) []byte {
 	o.data = append(o.data, make([]byte, n)...)
 	o.refs = append(o.refs, ref1, ref2, ref3)
@@ -278,7 +310,7 @@ func Write3(o *Ops, n int, ref1, ref2, ref3 interface{}) []byte {
 }
 
 func PCFor(o *Ops) PC {
-	return PC{data: len(o.data), refs: len(o.refs)}
+	return PC{data: uint32(len(o.data)), refs: uint32(len(o.refs))}
 }
 
 func (s *stack) push() StackID {
@@ -354,6 +386,14 @@ func DecodeTransform(data []byte) (t f32.Affine2D, push bool) {
 	return f32.NewAffine2D(a, b, c, d, e, f), push
 }
 
+func DecodeOpacity(data []byte) float32 {
+	if OpType(data[0]) != TypePushOpacity {
+		panic("invalid op")
+	}
+	bo := binary.LittleEndian
+	return math.Float32frombits(bo.Uint32(data[1:]))
+}
+
 // DecodeSave decodes the state id of a save op.
 func DecodeSave(data []byte) int {
 	if OpType(data[0]) != TypeSave {
@@ -381,9 +421,10 @@ var opProps = [0x100]opProp{
 	TypeMacro:            {Size: TypeMacroLen, NumRefs: 0},
 	TypeCall:             {Size: TypeCallLen, NumRefs: 1},
 	TypeDefer:            {Size: TypeDeferLen, NumRefs: 0},
-	TypePushTransform:    {Size: TypePushTransformLen, NumRefs: 0},
 	TypeTransform:        {Size: TypeTransformLen, NumRefs: 0},
 	TypePopTransform:     {Size: TypePopTransformLen, NumRefs: 0},
+	TypePushOpacity:      {Size: TypePushOpacityLen, NumRefs: 0},
+	TypePopOpacity:       {Size: TypePopOpacityLen, NumRefs: 0},
 	TypeInvalidate:       {Size: TypeRedrawLen, NumRefs: 0},
 	TypeImage:            {Size: TypeImageLen, NumRefs: 2},
 	TypePaint:            {Size: TypePaintLen, NumRefs: 0},
@@ -413,23 +454,23 @@ var opProps = [0x100]opProp{
 	TypeSemanticDesc:     {Size: TypeSemanticDescLen, NumRefs: 1},
 	TypeSemanticClass:    {Size: TypeSemanticClassLen, NumRefs: 0},
 	TypeSemanticSelected: {Size: TypeSemanticSelectedLen, NumRefs: 0},
-	TypeSemanticDisabled: {Size: TypeSemanticDisabledLen, NumRefs: 0},
+	TypeSemanticEnabled:  {Size: TypeSemanticEnabledLen, NumRefs: 0},
 	TypeSnippet:          {Size: TypeSnippetLen, NumRefs: 2},
 	TypeSelection:        {Size: TypeSelectionLen, NumRefs: 1},
 	TypeActionInput:      {Size: TypeActionInputLen, NumRefs: 0},
 }
 
-func (t OpType) props() (size, numRefs int) {
+func (t OpType) props() (size, numRefs uint32) {
 	v := opProps[t]
-	return int(v.Size), int(v.NumRefs)
+	return uint32(v.Size), uint32(v.NumRefs)
 }
 
-func (t OpType) Size() int {
+func (t OpType) Size() uint32 {
-	return int(opProps[t].Size)
+	return uint32(opProps[t].Size)
 }
 
-func (t OpType) NumRefs() int {
+func (t OpType) NumRefs() uint32 {
-	return int(opProps[t].NumRefs)
+	return uint32(opProps[t].NumRefs)
 }
 
 func (t OpType) String() string {
@@ -440,12 +481,14 @@ func (t OpType) String() string {
 		return "Call"
 	case TypeDefer:
 		return "Defer"
-	case TypePushTransform:
-		return "PushTransform"
 	case TypeTransform:
 		return "Transform"
 	case TypePopTransform:
 		return "PopTransform"
+	case TypePushOpacity:
+		return "PushOpacity"
+	case TypePopOpacity:
+		return "PopOpacity"
 	case TypeInvalidate:
 		return "Invalidate"
 	case TypeImage:

internal/ops/reader.go

@@ -26,8 +26,8 @@ type EncodedOp struct {
 // Key is a unique key for a given op.
 type Key struct {
 	ops     *Ops
-	pc      int
+	pc      uint32
-	version int
+	version uint32
 }
 
 // Shadow of op.MacroOp.
@@ -39,8 +39,8 @@ type macroOp struct {
 
 // PC is an instruction counter for an operation list.
 type PC struct {
-	data int
+	data uint32
-	refs int
+	refs uint32
 }
 
 type macro struct {
@@ -128,7 +128,7 @@ func (r *Reader) Decode() (EncodedOp, bool) {
 				if nrefs != 1 {
 					panic("internal error: unexpected number of macro refs")
 				}
-				deferData := Write1(&r.deferOps, n, refs[0])
+				deferData := Write1(&r.deferOps, int(n), refs[0])
 				copy(deferData, data)
 				r.pc.data += n
 				r.pc.refs += nrefs
@@ -154,8 +154,8 @@ func (r *Reader) Decode() (EncodedOp, bool) {
 				r.pc = op.endpc
 			} else {
 				// Treat an incomplete macro as containing all remaining ops.
-				r.pc.data = len(r.ops.data)
+				r.pc.data = uint32(len(r.ops.data))
-				r.pc.refs = len(r.ops.refs)
+				r.pc.refs = uint32(len(r.ops.refs))
 			}
 			continue
 		}
@@ -171,8 +171,8 @@ func (op *opMacroDef) decode(data []byte) {
 	}
 	bo := binary.LittleEndian
 	data = data[:TypeMacroLen]
-	op.endpc.data = int(int32(bo.Uint32(data[1:])))
+	op.endpc.data = bo.Uint32(data[1:])
-	op.endpc.refs = int(int32(bo.Uint32(data[5:])))
+	op.endpc.refs = bo.Uint32(data[5:])
 }
 
 func (m *macroOp) decode(data []byte, refs []interface{}) {
@@ -183,8 +183,8 @@ func (m *macroOp) decode(data []byte, refs []interface{}) {
 	data = data[:TypeCallLen]
 
 	m.ops = refs[0].(*Ops)
-	m.start.data = int(int32(bo.Uint32(data[1:])))
+	m.start.data = bo.Uint32(data[1:])
-	m.start.refs = int(int32(bo.Uint32(data[5:])))
+	m.start.refs = bo.Uint32(data[5:])
-	m.end.data = int(int32(bo.Uint32(data[9:])))
+	m.end.data = bo.Uint32(data[9:])
-	m.end.refs = int(int32(bo.Uint32(data[13:])))
+	m.end.refs = bo.Uint32(data[13:])
 }

io/clipboard/clipboard.go

@@ -30,7 +30,7 @@ func (h ReadOp) Add(o *op.Ops) {
 }
 
 func (h WriteOp) Add(o *op.Ops) {
-	data := ops.Write1(&o.Internal, ops.TypeClipboardWriteLen, &h.Text)
+	data := ops.Write1String(&o.Internal, ops.TypeClipboardWriteLen, h.Text)
 	data[0] = byte(ops.TypeClipboardWrite)
 }
 

io/key/key.go

@@ -323,8 +323,7 @@ func (h InputOp) Add(o *op.Ops) {
 	if h.Tag == nil {
 		panic("Tag must be non-nil")
 	}
-	filter := h.Keys
+	data := ops.Write2String(&o.Internal, ops.TypeKeyInputLen, h.Tag, string(h.Keys))
-	data := ops.Write2(&o.Internal, ops.TypeKeyInputLen, h.Tag, &filter)
 	data[0] = byte(ops.TypeKeyInput)
 	data[1] = byte(h.Hint)
 }
@@ -343,7 +342,7 @@ func (h FocusOp) Add(o *op.Ops) {
 }
 
 func (s SnippetOp) Add(o *op.Ops) {
-	data := ops.Write2(&o.Internal, ops.TypeSnippetLen, s.Tag, &s.Text)
+	data := ops.Write2String(&o.Internal, ops.TypeSnippetLen, s.Tag, s.Text)
 	data[0] = byte(ops.TypeSnippet)
 	bo := binary.LittleEndian
 	bo.PutUint32(data[1:], uint32(s.Range.Start))

io/pointer/pointer.go

@@ -18,7 +18,7 @@ import (
 
 // Event is a pointer event.
 type Event struct {
-	Type   Type
+	Kind   Kind
 	Source Source
 	// PointerID is the id for the pointer and can be used
 	// to track a particular pointer from Press to
@@ -51,7 +51,7 @@ type PassOp struct {
 type PassStack struct {
 	ops     *ops.Ops
 	id      ops.StackID
-	macroID int
+	macroID uint32
 }
 
 // InputOp declares an input handler ready for pointer
@@ -61,8 +61,8 @@ type InputOp struct {
 	// Grab, if set, request that the handler get
 	// Grabbed priority.
 	Grab bool
-	// Types is a bitwise-or of event types to receive.
+	// Kinds is a bitwise-or of event types to receive.
-	Types Type
+	Kinds Kind
 	// ScrollBounds describe the maximum scrollable distances in both
 	// axes. Specifically, any Event e delivered to Tag will satisfy
 	//
@@ -73,8 +73,8 @@ type InputOp struct {
 
 type ID uint16
 
-// Type of an Event.
+// Kind of an Event.
-type Type uint
+type Kind uint
 
 // Priority of an Event.
 type Priority uint8
@@ -169,7 +169,7 @@ const (
 const (
 	// A Cancel event is generated when the current gesture is
 	// interrupted by other handlers or the system.
-	Cancel Type = (1 << iota) >> 1
+	Cancel Kind = (1 << iota) >> 1
 	// Press of a pointer.
 	Press
 	// Release of a pointer.
@@ -243,7 +243,7 @@ func (op InputOp) Add(o *op.Ops) {
 	if b := op.ScrollBounds; b.Min.X > 0 || b.Max.X < 0 || b.Min.Y > 0 || b.Max.Y < 0 {
 		panic(fmt.Errorf("invalid scroll range value %v", b))
 	}
-	if op.Types>>16 > 0 {
+	if op.Kinds>>16 > 0 {
 		panic(fmt.Errorf("value in Types overflows uint16"))
 	}
 	data := ops.Write1(&o.Internal, ops.TypePointerInputLen, op.Tag)
@@ -252,19 +252,19 @@ func (op InputOp) Add(o *op.Ops) {
 		data[1] = 1
 	}
 	bo := binary.LittleEndian
-	bo.PutUint16(data[2:], uint16(op.Types))
+	bo.PutUint16(data[2:], uint16(op.Kinds))
 	bo.PutUint32(data[4:], uint32(op.ScrollBounds.Min.X))
 	bo.PutUint32(data[8:], uint32(op.ScrollBounds.Min.Y))
 	bo.PutUint32(data[12:], uint32(op.ScrollBounds.Max.X))
 	bo.PutUint32(data[16:], uint32(op.ScrollBounds.Max.Y))
 }
 
-func (t Type) String() string {
+func (t Kind) String() string {
 	if t == Cancel {
 		return "Cancel"
 	}
 	var buf strings.Builder
-	for tt := Type(1); tt > 0; tt <<= 1 {
+	for tt := Kind(1); tt > 0; tt <<= 1 {
 		if t&tt > 0 {
 			if buf.Len() > 0 {
 				buf.WriteByte('|')
@@ -275,7 +275,7 @@ func (t Type) String() string {
 	return buf.String()
 }
 
-func (t Type) string() string {
+func (t Kind) string() string {
 	switch t {
 	case Press:
 		return "Press"

io/pointer/pointer_test.go

@@ -8,7 +8,7 @@ import (
 
 func TestTypeString(t *testing.T) {
 	for _, tc := range []struct {
-		typ Type
+		typ Kind
 		res string
 	}{
 		{Cancel, "Cancel"},

io/router/key_test.go

@@ -30,11 +30,6 @@ func TestKeyWakeup(t *testing.T) {
 	if evts := r.Events(handler); len(evts) != 1 {
 		t.Errorf("no Focus event for newly registered key.InputOp")
 	}
-	// Verify that r.Events does trigger a redraw.
-	r.Frame(&ops)
-	if _, wake := r.WakeupTime(); !wake {
-		t.Errorf("key.FocusEvent event didn't trigger a redraw")
-	}
 }
 
 func TestKeyMultiples(t *testing.T) {
@@ -279,7 +274,7 @@ func TestFocusScroll(t *testing.T) {
 	key.InputOp{Tag: h}.Add(ops)
 	pointer.InputOp{
 		Tag:          h,
-		Types:        pointer.Scroll,
+		Kinds:        pointer.Scroll,
 		ScrollBounds: image.Rect(-100, -100, 100, 100),
 	}.Add(ops)
 	// Test that h is scrolled even if behind another handler.
@@ -305,7 +300,7 @@ func TestFocusClick(t *testing.T) {
 	key.InputOp{Tag: h}.Add(ops)
 	pointer.InputOp{
 		Tag:   h,
-		Types: pointer.Press | pointer.Release,
+		Kinds: pointer.Press | pointer.Release,
 	}.Add(ops)
 	cl.Pop()
 	r.Frame(ops)

io/router/pointer.go

@@ -66,7 +66,7 @@ type pointerHandler struct {
 	area      int
 	active    bool
 	wantsGrab bool
-	types     pointer.Type
+	types     pointer.Kind
 	// min and max horizontal/vertical scroll
 	scrollRange image.Rectangle
 
@@ -242,7 +242,7 @@ func (c *pointerCollector) newHandler(tag event.Tag, events *handlerEvents) *poi
 		c.q.handlers[tag] = h
 		// Cancel handlers on (each) first appearance, but don't
 		// trigger redraw.
-		events.AddNoRedraw(tag, pointer.Event{Type: pointer.Cancel})
+		events.AddNoRedraw(tag, pointer.Event{Kind: pointer.Cancel})
 	}
 	h.active = true
 	h.area = areaID
@@ -268,16 +268,16 @@ func (c *pointerCollector) inputOp(op pointer.InputOp, events *handlerEvents) {
 	areaID := c.currentArea()
 	area := &c.q.areas[areaID]
 	area.semantic.content.tag = op.Tag
-	if op.Types&(pointer.Press|pointer.Release) != 0 {
+	if op.Kinds&(pointer.Press|pointer.Release) != 0 {
 		area.semantic.content.gestures |= ClickGesture
 	}
-	if op.Types&pointer.Scroll != 0 {
+	if op.Kinds&pointer.Scroll != 0 {
 		area.semantic.content.gestures |= ScrollGesture
 	}
 	area.semantic.valid = area.semantic.content.gestures != 0
 	h := c.newHandler(op.Tag, events)
 	h.wantsGrab = h.wantsGrab || op.Grab
-	h.types = h.types | op.Types
+	h.types = h.types | op.Kinds
 	h.scrollRange = op.ScrollBounds
 }
 
@@ -309,11 +309,11 @@ func (c *pointerCollector) semanticSelected(selected bool) {
 	area.semantic.content.selected = selected
 }
 
-func (c *pointerCollector) semanticDisabled(disabled bool) {
+func (c *pointerCollector) semanticEnabled(enabled bool) {
 	areaID := c.currentArea()
 	area := &c.q.areas[areaID]
 	area.semantic.valid = true
-	area.semantic.content.disabled = disabled
+	area.semantic.content.disabled = !enabled
 }
 
 func (c *pointerCollector) cursor(cursor pointer.Cursor) {
@@ -602,7 +602,7 @@ func (q *pointerQueue) Frame(events *handlerEvents) {
 
 func (q *pointerQueue) dropHandler(events *handlerEvents, tag event.Tag) {
 	if events != nil {
-		events.Add(tag, pointer.Event{Type: pointer.Cancel})
+		events.Add(tag, pointer.Event{Kind: pointer.Cancel})
 	}
 	for i := range q.pointers {
 		p := &q.pointers[i]
@@ -649,11 +649,11 @@ func (q *pointerQueue) Deliver(areaIdx int, e pointer.Event, events *handlerEven
 			continue
 		}
 		h := q.handlers[n.tag]
-		if e.Type&h.types == 0 {
+		if e.Kind&h.types == 0 {
 			continue
 		}
 		e := e
-		if e.Type == pointer.Scroll {
+		if e.Kind == pointer.Scroll {
 			if sx == 0 && sy == 0 {
 				break
 			}
@@ -663,7 +663,7 @@ func (q *pointerQueue) Deliver(areaIdx int, e pointer.Event, events *handlerEven
 		}
 		e.Position = q.invTransform(h.area, e.Position)
 		events.Add(n.tag, e)
-		if e.Type != pointer.Scroll {
+		if e.Kind != pointer.Scroll {
 			break
 		}
 	}
@@ -683,7 +683,7 @@ func (q *pointerQueue) SemanticArea(areaIdx int) (semanticContent, int) {
 }
 
 func (q *pointerQueue) Push(e pointer.Event, events *handlerEvents) {
-	if e.Type == pointer.Cancel {
+	if e.Kind == pointer.Cancel {
 		q.pointers = q.pointers[:0]
 		for k := range q.handlers {
 			q.dropHandler(events, k)
@@ -694,14 +694,14 @@ func (q *pointerQueue) Push(e pointer.Event, events *handlerEvents) {
 	p := &q.pointers[pidx]
 	p.last = e
 
-	switch e.Type {
+	switch e.Kind {
 	case pointer.Press:
 		q.deliverEnterLeaveEvents(p, events, e)
 		p.pressed = true
 		q.deliverEvent(p, events, e)
 	case pointer.Move:
 		if p.pressed {
-			e.Type = pointer.Drag
+			e.Kind = pointer.Drag
 		}
 		q.deliverEnterLeaveEvents(p, events, e)
 		q.deliverEvent(p, events, e)
@@ -735,7 +735,7 @@ func (q *pointerQueue) deliverEvent(p *pointerInfo, events *handlerEvents, e poi
 	var sx, sy = e.Scroll.X, e.Scroll.Y
 	for _, k := range p.handlers {
 		h := q.handlers[k]
-		if e.Type == pointer.Scroll {
+		if e.Kind == pointer.Scroll {
 			if sx == 0 && sy == 0 {
 				return
 			}
@@ -743,7 +743,7 @@ func (q *pointerQueue) deliverEvent(p *pointerInfo, events *handlerEvents, e poi
 			sx, e.Scroll.X = setScrollEvent(sx, h.scrollRange.Min.X, h.scrollRange.Max.X)
 			sy, e.Scroll.Y = setScrollEvent(sy, h.scrollRange.Min.Y, h.scrollRange.Max.Y)
 		}
-		if e.Type&h.types == 0 {
+		if e.Kind&h.types == 0 {
 			continue
 		}
 		e := e
@@ -758,7 +758,7 @@ func (q *pointerQueue) deliverEvent(p *pointerInfo, events *handlerEvents, e poi
 
 func (q *pointerQueue) deliverEnterLeaveEvents(p *pointerInfo, events *handlerEvents, e pointer.Event) {
 	var hits []event.Tag
-	if e.Source != pointer.Mouse && !p.pressed && e.Type != pointer.Press {
+	if e.Source != pointer.Mouse && !p.pressed && e.Kind != pointer.Press {
 		// Consider non-mouse pointers leaving when they're released.
 	} else {
 		hits, q.cursor = q.opHit(e.Position)
@@ -790,9 +790,9 @@ func (q *pointerQueue) deliverEnterLeaveEvents(p *pointerInfo, events *handlerEv
 			continue
 		}
 		h := q.handlers[k]
-		e.Type = pointer.Leave
+		e.Kind = pointer.Leave
 
-		if e.Type&h.types != 0 {
+		if e.Kind&h.types != 0 {
 			e := e
 			e.Position = q.invTransform(h.area, e.Position)
 			events.Add(k, e)
@@ -804,9 +804,9 @@ func (q *pointerQueue) deliverEnterLeaveEvents(p *pointerInfo, events *handlerEv
 		if _, found := searchTag(p.entered, k); found {
 			continue
 		}
-		e.Type = pointer.Enter
+		e.Kind = pointer.Enter
 
-		if e.Type&h.types != 0 {
+		if e.Kind&h.types != 0 {
 			e := e
 			e.Position = q.invTransform(h.area, e.Position)
 			events.Add(k, e)

io/router/pointer_test.go

@@ -33,11 +33,6 @@ func TestPointerWakeup(t *testing.T) {
 	}
 	// However, adding a handler queues a Cancel event.
 	assertEventPointerTypeSequence(t, r.Events(handler), pointer.Cancel)
-	// Verify that r.Events does trigger a redraw.
-	r.Frame(&ops)
-	if _, wake := r.WakeupTime(); !wake {
-		t.Errorf("pointer.Cancel event didn't trigger a redraw")
-	}
 }
 
 func TestPointerDrag(t *testing.T) {
@@ -50,12 +45,12 @@ func TestPointerDrag(t *testing.T) {
 	r.Queue(
 		// Press.
 		pointer.Event{
-			Type:     pointer.Press,
+			Kind:     pointer.Press,
 			Position: f32.Pt(50, 50),
 		},
 		// Move outside the area.
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(150, 150),
 		},
 	)
@@ -72,12 +67,12 @@ func TestPointerDragNegative(t *testing.T) {
 	r.Queue(
 		// Press.
 		pointer.Event{
-			Type:     pointer.Press,
+			Kind:     pointer.Press,
 			Position: f32.Pt(-50, -50),
 		},
 		// Move outside the area.
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(-150, -150),
 		},
 	)
@@ -92,15 +87,15 @@ func TestPointerGrab(t *testing.T) {
 
 	types := pointer.Press | pointer.Release
 
-	pointer.InputOp{Tag: handler1, Types: types, Grab: true}.Add(&ops)
+	pointer.InputOp{Tag: handler1, Kinds: types, Grab: true}.Add(&ops)
-	pointer.InputOp{Tag: handler2, Types: types}.Add(&ops)
+	pointer.InputOp{Tag: handler2, Kinds: types}.Add(&ops)
-	pointer.InputOp{Tag: handler3, Types: types}.Add(&ops)
+	pointer.InputOp{Tag: handler3, Kinds: types}.Add(&ops)
 
 	var r Router
 	r.Frame(&ops)
 	r.Queue(
 		pointer.Event{
-			Type:     pointer.Press,
+			Kind:     pointer.Press,
 			Position: f32.Pt(50, 50),
 		},
 	)
@@ -110,7 +105,7 @@ func TestPointerGrab(t *testing.T) {
 	r.Frame(&ops)
 	r.Queue(
 		pointer.Event{
-			Type:     pointer.Release,
+			Kind:     pointer.Release,
 			Position: f32.Pt(50, 50),
 		},
 	)
@@ -126,15 +121,15 @@ func TestPointerGrabSameHandlerTwice(t *testing.T) {
 
 	types := pointer.Press | pointer.Release
 
-	pointer.InputOp{Tag: handler1, Types: types, Grab: true}.Add(&ops)
+	pointer.InputOp{Tag: handler1, Kinds: types, Grab: true}.Add(&ops)
-	pointer.InputOp{Tag: handler1, Types: types}.Add(&ops)
+	pointer.InputOp{Tag: handler1, Kinds: types}.Add(&ops)
-	pointer.InputOp{Tag: handler2, Types: types}.Add(&ops)
+	pointer.InputOp{Tag: handler2, Kinds: types}.Add(&ops)
 
 	var r Router
 	r.Frame(&ops)
 	r.Queue(
 		pointer.Event{
-			Type:     pointer.Press,
+			Kind:     pointer.Press,
 			Position: f32.Pt(50, 50),
 		},
 	)
@@ -143,7 +138,7 @@ func TestPointerGrabSameHandlerTwice(t *testing.T) {
 	r.Frame(&ops)
 	r.Queue(
 		pointer.Event{
-			Type:     pointer.Release,
+			Kind:     pointer.Release,
 			Position: f32.Pt(50, 50),
 		},
 	)
@@ -160,10 +155,10 @@ func TestPointerMove(t *testing.T) {
 
 	// Handler 1 area: (0, 0) - (100, 100)
 	r1 := clip.Rect(image.Rect(0, 0, 100, 100)).Push(&ops)
-	pointer.InputOp{Tag: handler1, Types: types}.Add(&ops)
+	pointer.InputOp{Tag: handler1, Kinds: types}.Add(&ops)
 	// Handler 2 area: (50, 50) - (100, 100) (areas intersect).
 	r2 := clip.Rect(image.Rect(50, 50, 200, 200)).Push(&ops)
-	pointer.InputOp{Tag: handler2, Types: types}.Add(&ops)
+	pointer.InputOp{Tag: handler2, Kinds: types}.Add(&ops)
 	r2.Pop()
 	r1.Pop()
 
@@ -172,21 +167,21 @@ func TestPointerMove(t *testing.T) {
 	r.Queue(
 		// Hit both handlers.
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(50, 50),
 		},
 		// Hit handler 1.
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(49, 50),
 		},
 		// Hit no handlers.
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(100, 50),
 		},
 		pointer.Event{
-			Type: pointer.Cancel,
+			Kind: pointer.Cancel,
 		},
 	)
 	assertEventPointerTypeSequence(t, r.Events(handler1), pointer.Cancel, pointer.Enter, pointer.Move, pointer.Move, pointer.Leave, pointer.Cancel)
@@ -199,7 +194,7 @@ func TestPointerTypes(t *testing.T) {
 	r1 := clip.Rect(image.Rect(0, 0, 100, 100)).Push(&ops)
 	pointer.InputOp{
 		Tag:   handler,
-		Types: pointer.Press | pointer.Release,
+		Kinds: pointer.Press | pointer.Release,
 	}.Add(&ops)
 	r1.Pop()
 
@@ -207,15 +202,15 @@ func TestPointerTypes(t *testing.T) {
 	r.Frame(&ops)
 	r.Queue(
 		pointer.Event{
-			Type:     pointer.Press,
+			Kind:     pointer.Press,
 			Position: f32.Pt(50, 50),
 		},
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(150, 150),
 		},
 		pointer.Event{
-			Type:     pointer.Release,
+			Kind:     pointer.Release,
 			Position: f32.Pt(150, 150),
 		},
 	)
@@ -268,14 +263,14 @@ func TestPointerPriority(t *testing.T) {
 	r1 := clip.Rect(image.Rect(0, 0, 100, 100)).Push(&ops)
 	pointer.InputOp{
 		Tag:          handler1,
-		Types:        pointer.Scroll,
+		Kinds:        pointer.Scroll,
 		ScrollBounds: image.Rectangle{Max: image.Point{X: 100}},
 	}.Add(&ops)
 
 	r2 := clip.Rect(image.Rect(0, 0, 100, 50)).Push(&ops)
 	pointer.InputOp{
 		Tag:          handler2,
-		Types:        pointer.Scroll,
+		Kinds:        pointer.Scroll,
 		ScrollBounds: image.Rectangle{Max: image.Point{X: 20}},
 	}.Add(&ops)
 	r2.Pop()
@@ -284,7 +279,7 @@ func TestPointerPriority(t *testing.T) {
 	r3 := clip.Rect(image.Rect(0, 100, 100, 200)).Push(&ops)
 	pointer.InputOp{
 		Tag:          handler3,
-		Types:        pointer.Scroll,
+		Kinds:        pointer.Scroll,
 		ScrollBounds: image.Rectangle{Min: image.Point{X: -20, Y: -40}},
 	}.Add(&ops)
 	r3.Pop()
@@ -294,25 +289,25 @@ func TestPointerPriority(t *testing.T) {
 	r.Queue(
 		// Hit handler 1 and 2.
 		pointer.Event{
-			Type:     pointer.Scroll,
+			Kind:     pointer.Scroll,
 			Position: f32.Pt(50, 25),
 			Scroll:   f32.Pt(50, 0),
 		},
 		// Hit handler 1.
 		pointer.Event{
-			Type:     pointer.Scroll,
+			Kind:     pointer.Scroll,
 			Position: f32.Pt(50, 75),
 			Scroll:   f32.Pt(50, 50),
 		},
 		// Hit handler 3.
 		pointer.Event{
-			Type:     pointer.Scroll,
+			Kind:     pointer.Scroll,
 			Position: f32.Pt(50, 150),
 			Scroll:   f32.Pt(-30, -30),
 		},
 		// Hit no handlers.
 		pointer.Event{
-			Type:     pointer.Scroll,
+			Kind:     pointer.Scroll,
 			Position: f32.Pt(50, 225),
 		},
 	)
@@ -348,7 +343,7 @@ func TestPointerEnterLeave(t *testing.T) {
 	// Hit both handlers.
 	r.Queue(
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(50, 50),
 		},
 	)
@@ -361,7 +356,7 @@ func TestPointerEnterLeave(t *testing.T) {
 	// Leave the second area by moving into the first.
 	r.Queue(
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(45, 45),
 		},
 	)
@@ -372,7 +367,7 @@ func TestPointerEnterLeave(t *testing.T) {
 	// Move, but stay within the same hit area.
 	r.Queue(
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(40, 40),
 		},
 	)
@@ -382,7 +377,7 @@ func TestPointerEnterLeave(t *testing.T) {
 	// Move outside of both inputs.
 	r.Queue(
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(300, 300),
 		},
 	)
@@ -392,7 +387,7 @@ func TestPointerEnterLeave(t *testing.T) {
 	// Check that a Press event generates Enter Events.
 	r.Queue(
 		pointer.Event{
-			Type:     pointer.Press,
+			Kind:     pointer.Press,
 			Position: f32.Pt(125, 125),
 		},
 	)
@@ -403,12 +398,12 @@ func TestPointerEnterLeave(t *testing.T) {
 	r.Queue(
 		// Leave
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(25, 25),
 		},
 		// Enter
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(50, 50),
 		},
 	)
@@ -418,7 +413,7 @@ func TestPointerEnterLeave(t *testing.T) {
 	// Check that a Release event generates Enter/Leave Events.
 	r.Queue(
 		pointer.Event{
-			Type: pointer.Release,
+			Kind: pointer.Release,
 			Position: f32.Pt(25,
 				25),
 		},
@@ -446,15 +441,15 @@ func TestMultipleAreas(t *testing.T) {
 	// Hit first area, then second area, then both.
 	r.Queue(
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(25, 25),
 		},
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(150, 150),
 		},
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(50, 50),
 		},
 	)
@@ -470,11 +465,11 @@ func TestPointerEnterLeaveNested(t *testing.T) {
 
 	// Handler 1 area: (0, 0) - (100, 100)
 	r1 := clip.Rect(image.Rect(0, 0, 100, 100)).Push(&ops)
-	pointer.InputOp{Tag: handler1, Types: types}.Add(&ops)
+	pointer.InputOp{Tag: handler1, Kinds: types}.Add(&ops)
 
 	// Handler 2 area: (25, 25) - (75, 75) (nested within first).
 	r2 := clip.Rect(image.Rect(25, 25, 75, 75)).Push(&ops)
-	pointer.InputOp{Tag: handler2, Types: types}.Add(&ops)
+	pointer.InputOp{Tag: handler2, Kinds: types}.Add(&ops)
 	r2.Pop()
 	r1.Pop()
 
@@ -483,7 +478,7 @@ func TestPointerEnterLeaveNested(t *testing.T) {
 	// Hit both handlers.
 	r.Queue(
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(50, 50),
 		},
 	)
@@ -495,7 +490,7 @@ func TestPointerEnterLeaveNested(t *testing.T) {
 	// Leave the second area by moving into the first.
 	r.Queue(
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(20, 20),
 		},
 	)
@@ -505,7 +500,7 @@ func TestPointerEnterLeaveNested(t *testing.T) {
 	// Move, but stay within the same hit area.
 	r.Queue(
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(10, 10),
 		},
 	)
@@ -515,7 +510,7 @@ func TestPointerEnterLeaveNested(t *testing.T) {
 	// Move outside of both inputs.
 	r.Queue(
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(200, 200),
 		},
 	)
@@ -525,7 +520,7 @@ func TestPointerEnterLeaveNested(t *testing.T) {
 	// Check that a Press event generates Enter Events.
 	r.Queue(
 		pointer.Event{
-			Type:     pointer.Press,
+			Kind:     pointer.Press,
 			Position: f32.Pt(50, 50),
 		},
 	)
@@ -535,7 +530,7 @@ func TestPointerEnterLeaveNested(t *testing.T) {
 	// Check that a Release event generates Enter/Leave Events.
 	r.Queue(
 		pointer.Event{
-			Type:     pointer.Release,
+			Kind:     pointer.Release,
 			Position: f32.Pt(20, 20),
 		},
 	)
@@ -554,7 +549,7 @@ func TestPointerActiveInputDisappears(t *testing.T) {
 	r.Frame(&ops)
 	r.Queue(
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(25, 25),
 		},
 	)
@@ -565,7 +560,7 @@ func TestPointerActiveInputDisappears(t *testing.T) {
 	r.Frame(&ops)
 	r.Queue(
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(25, 25),
 		},
 	)
@@ -587,21 +582,21 @@ func TestMultitouch(t *testing.T) {
 	r.Frame(&ops)
 	r.Queue(
 		pointer.Event{
-			Type:      pointer.Press,
+			Kind:      pointer.Press,
 			Position:  h1pt,
 			PointerID: p1,
 		},
 	)
 	r.Queue(
 		pointer.Event{
-			Type:      pointer.Press,
+			Kind:      pointer.Press,
 			Position:  h2pt,
 			PointerID: p2,
 		},
 	)
 	r.Queue(
 		pointer.Event{
-			Type:      pointer.Release,
+			Kind:      pointer.Release,
 			Position:  h2pt,
 			PointerID: p2,
 		},
@@ -634,7 +629,7 @@ func TestCursor(t *testing.T) {
 
 	_at := func(x, y float32) pointer.Event {
 		return pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Source:   pointer.Mouse,
 			Buttons:  pointer.ButtonPrimary,
 			Position: f32.Pt(x, y),
@@ -734,14 +729,14 @@ func TestPassOp(t *testing.T) {
 	h1, h2, h3, h4 := new(int), new(int), new(int), new(int)
 	area := clip.Rect(image.Rect(0, 0, 100, 100))
 	root := area.Push(&ops)
-	pointer.InputOp{Tag: h1, Types: pointer.Press}.Add(&ops)
+	pointer.InputOp{Tag: h1, Kinds: pointer.Press}.Add(&ops)
 	child1 := area.Push(&ops)
-	pointer.InputOp{Tag: h2, Types: pointer.Press}.Add(&ops)
+	pointer.InputOp{Tag: h2, Kinds: pointer.Press}.Add(&ops)
 	child1.Pop()
 	child2 := area.Push(&ops)
 	pass := pointer.PassOp{}.Push(&ops)
-	pointer.InputOp{Tag: h3, Types: pointer.Press}.Add(&ops)
+	pointer.InputOp{Tag: h3, Kinds: pointer.Press}.Add(&ops)
-	pointer.InputOp{Tag: h4, Types: pointer.Press}.Add(&ops)
+	pointer.InputOp{Tag: h4, Kinds: pointer.Press}.Add(&ops)
 	pass.Pop()
 	child2.Pop()
 	root.Pop()
@@ -750,7 +745,7 @@ func TestPassOp(t *testing.T) {
 	r.Frame(&ops)
 	r.Queue(
 		pointer.Event{
-			Type: pointer.Press,
+			Kind: pointer.Press,
 		},
 	)
 	assertEventPointerTypeSequence(t, r.Events(h1), pointer.Cancel, pointer.Press)
@@ -763,13 +758,13 @@ func TestAreaPassthrough(t *testing.T) {
 	var ops op.Ops
 
 	h := new(int)
-	pointer.InputOp{Tag: h, Types: pointer.Press}.Add(&ops)
+	pointer.InputOp{Tag: h, Kinds: pointer.Press}.Add(&ops)
 	clip.Rect(image.Rect(0, 0, 100, 100)).Push(&ops).Pop()
 	var r Router
 	r.Frame(&ops)
 	r.Queue(
 		pointer.Event{
-			Type: pointer.Press,
+			Kind: pointer.Press,
 		},
 	)
 	assertEventPointerTypeSequence(t, r.Events(h), pointer.Cancel, pointer.Press)
@@ -780,7 +775,7 @@ func TestEllipse(t *testing.T) {
 
 	h := new(int)
 	cl := clip.Ellipse(image.Rect(0, 0, 100, 100)).Push(&ops)
-	pointer.InputOp{Tag: h, Types: pointer.Press}.Add(&ops)
+	pointer.InputOp{Tag: h, Kinds: pointer.Press}.Add(&ops)
 	cl.Pop()
 	var r Router
 	r.Frame(&ops)
@@ -788,15 +783,15 @@ func TestEllipse(t *testing.T) {
 		// Outside ellipse.
 		pointer.Event{
 			Position: f32.Pt(10, 10),
-			Type:     pointer.Press,
+			Kind:     pointer.Press,
 		},
 		pointer.Event{
-			Type: pointer.Release,
+			Kind: pointer.Release,
 		},
 		// Inside ellipse.
 		pointer.Event{
 			Position: f32.Pt(50, 50),
-			Type:     pointer.Press,
+			Kind:     pointer.Press,
 		},
 	)
 	assertEventPointerTypeSequence(t, r.Events(h), pointer.Cancel, pointer.Press)
@@ -825,7 +820,7 @@ func TestTransfer(t *testing.T) {
 		return src, tgt
 	}
 	// Cancel is received when the pointer is first seen.
-	cancel := pointer.Event{Type: pointer.Cancel}
+	cancel := pointer.Event{Kind: pointer.Cancel}
 
 	t.Run("transfer.Offer should panic on nil Data", func(t *testing.T) {
 		defer func() {
@@ -845,11 +840,11 @@ func TestTransfer(t *testing.T) {
 		r.Queue(
 			pointer.Event{
 				Position: f32.Pt(10, 10),
-				Type:     pointer.Press,
+				Kind:     pointer.Press,
 			},
 			pointer.Event{
 				Position: f32.Pt(10, 10),
-				Type:     pointer.Move,
+				Kind:     pointer.Move,
 			},
 		)
 		assertEventSequence(t, r.Events(src), cancel)
@@ -859,11 +854,11 @@ func TestTransfer(t *testing.T) {
 		r.Queue(
 			pointer.Event{
 				Position: f32.Pt(30, 10),
-				Type:     pointer.Move,
+				Kind:     pointer.Move,
 			},
 			pointer.Event{
 				Position: f32.Pt(30, 10),
-				Type:     pointer.Release,
+				Kind:     pointer.Release,
 			},
 		)
 		assertEventSequence(t, r.Events(src), transfer.CancelEvent{})
@@ -886,11 +881,11 @@ func TestTransfer(t *testing.T) {
 		r.Queue(
 			pointer.Event{
 				Position: f32.Pt(10, 10),
-				Type:     pointer.Press,
+				Kind:     pointer.Press,
 			},
 			pointer.Event{
 				Position: f32.Pt(10, 10),
-				Type:     pointer.Move,
+				Kind:     pointer.Move,
 			},
 		)
 		assertEventSequence(t, r.Events(src), cancel)
@@ -907,11 +902,11 @@ func TestTransfer(t *testing.T) {
 		r.Queue(
 			pointer.Event{
 				Position: f32.Pt(10, 10),
-				Type:     pointer.Press,
+				Kind:     pointer.Press,
 			},
 			pointer.Event{
 				Position: f32.Pt(10, 10),
-				Type:     pointer.Move,
+				Kind:     pointer.Move,
 			},
 		)
 		assertEventSequence(t, r.Events(src), cancel)
@@ -921,7 +916,7 @@ func TestTransfer(t *testing.T) {
 		r.Queue(
 			pointer.Event{
 				Position: f32.Pt(40, 10),
-				Type:     pointer.Release,
+				Kind:     pointer.Release,
 			},
 		)
 		assertEventSequence(t, r.Events(src), transfer.CancelEvent{})
@@ -944,11 +939,11 @@ func TestTransfer(t *testing.T) {
 		r.Queue(
 			pointer.Event{
 				Position: f32.Pt(10, 10),
-				Type:     pointer.Press,
+				Kind:     pointer.Press,
 			},
 			pointer.Event{
 				Position: f32.Pt(10, 10),
-				Type:     pointer.Move,
+				Kind:     pointer.Move,
 			},
 		)
 		assertEventSequence(t, r.Events(src), cancel)
@@ -958,7 +953,7 @@ func TestTransfer(t *testing.T) {
 		r.Queue(
 			pointer.Event{
 				Position: f32.Pt(40, 10),
-				Type:     pointer.Release,
+				Kind:     pointer.Release,
 			},
 		)
 		assertEventSequence(t, r.Events(src), transfer.RequestEvent{Type: "file"})
@@ -1011,15 +1006,15 @@ func TestTransfer(t *testing.T) {
 		r.Queue(
 			pointer.Event{
 				Position: f32.Pt(10, 10),
-				Type:     pointer.Press,
+				Kind:     pointer.Press,
 			},
 			pointer.Event{
 				Position: f32.Pt(10, 10),
-				Type:     pointer.Move,
+				Kind:     pointer.Move,
 			},
 			pointer.Event{
 				Position: f32.Pt(40, 10),
-				Type:     pointer.Release,
+				Kind:     pointer.Release,
 			},
 		)
 		ofr := &offer{data: "hello"}
@@ -1054,15 +1049,15 @@ func TestTransfer(t *testing.T) {
 		r.Queue(
 			pointer.Event{
 				Position: f32.Pt(10, 10),
-				Type:     pointer.Press,
+				Kind:     pointer.Press,
 			},
 			pointer.Event{
 				Position: f32.Pt(10, 10),
-				Type:     pointer.Move,
+				Kind:     pointer.Move,
 			},
 			pointer.Event{
 				Position: f32.Pt(40, 10),
-				Type:     pointer.Move,
+				Kind:     pointer.Move,
 			},
 		)
 		assertEventPointerTypeSequence(t, r.Events(&hover), pointer.Cancel, pointer.Enter)
@@ -1071,7 +1066,7 @@ func TestTransfer(t *testing.T) {
 		r.Queue(
 			pointer.Event{
 				Position: f32.Pt(40, 10),
-				Type:     pointer.Release,
+				Kind:     pointer.Release,
 			},
 		)
 
@@ -1102,15 +1097,15 @@ func TestTransfer(t *testing.T) {
 		r.Queue(
 			pointer.Event{
 				Position: f32.Pt(10, 10),
-				Type:     pointer.Press,
+				Kind:     pointer.Press,
 			},
 			pointer.Event{
 				Position: f32.Pt(10, 10),
-				Type:     pointer.Move,
+				Kind:     pointer.Move,
 			},
 			pointer.Event{
 				Position: f32.Pt(40, 10),
-				Type:     pointer.Move,
+				Kind:     pointer.Move,
 			},
 		)
 		assertEventPointerTypeSequence(t, r.Events(&hover), pointer.Cancel)
@@ -1119,7 +1114,7 @@ func TestTransfer(t *testing.T) {
 		r.Queue(
 			pointer.Event{
 				Position: f32.Pt(40, 10),
-				Type:     pointer.Release,
+				Kind:     pointer.Release,
 			},
 		)
 
@@ -1167,7 +1162,7 @@ func TestPassCursor(t *testing.T) {
 	r.Frame(&ops)
 	r.Queue(pointer.Event{
 		Position: f32.Pt(10, 10),
-		Type:     pointer.Move,
+		Kind:     pointer.Move,
 	})
 	if got := r.Cursor(); want != got {
 		t.Errorf("got cursor %v, want %v", got, want)
@@ -1192,18 +1187,18 @@ func addPointerHandler(ops *op.Ops, tag event.Tag, area image.Rectangle) {
 	defer clip.Rect(area).Push(ops).Pop()
 	pointer.InputOp{
 		Tag:   tag,
-		Types: pointer.Press | pointer.Release | pointer.Move | pointer.Drag | pointer.Enter | pointer.Leave,
+		Kinds: pointer.Press | pointer.Release | pointer.Move | pointer.Drag | pointer.Enter | pointer.Leave,
 	}.Add(ops)
 }
 
 // pointerTypes converts a sequence of event.Event to their pointer.Types. It assumes
 // that all input events are of underlying type pointer.Event, and thus will
 // panic if some are not.
-func pointerTypes(events []event.Event) []pointer.Type {
+func pointerTypes(events []event.Event) []pointer.Kind {
-	var types []pointer.Type
+	var types []pointer.Kind
 	for _, e := range events {
 		if e, ok := e.(pointer.Event); ok {
-			types = append(types, e.Type)
+			types = append(types, e.Kind)
 		}
 	}
 	return types
@@ -1211,7 +1206,7 @@ func pointerTypes(events []event.Event) []pointer.Type {
 
 // assertEventPointerTypeSequence checks that the provided events match the expected pointer event types
 // in the provided order.
-func assertEventPointerTypeSequence(t *testing.T, events []event.Event, expected ...pointer.Type) {
+func assertEventPointerTypeSequence(t *testing.T, events []event.Event, expected ...pointer.Kind) {
 	t.Helper()
 	got := pointerTypes(events)
 	if !reflect.DeepEqual(got, expected) {
@@ -1239,7 +1234,7 @@ func eventsToString(evs []event.Event) string {
 	for _, ev := range evs {
 		switch e := ev.(type) {
 		case pointer.Event:
-			s = append(s, fmt.Sprintf("%T{%s}", e, e.Type.String()))
+			s = append(s, fmt.Sprintf("%T{%s}", e, e.Kind.String()))
 		default:
 			s = append(s, fmt.Sprintf("{%T}", e))
 		}
@@ -1308,7 +1303,7 @@ func BenchmarkRouterAdd(b *testing.B) {
 					Push(&ops)
 				pointer.InputOp{
 					Tag:   handlers[i],
-					Types: pointer.Move,
+					Kinds: pointer.Move,
 				}.Add(&ops)
 			}
 			var r Router
@@ -1318,7 +1313,7 @@ func BenchmarkRouterAdd(b *testing.B) {
 			for i := 0; i < b.N; i++ {
 				r.Queue(
 					pointer.Event{
-						Type:     pointer.Move,
+						Kind:     pointer.Move,
 						Position: f32.Pt(50, 50),
 					},
 				)

io/router/router.go

@@ -273,7 +273,7 @@ func (q *Router) ScrollFocus(dist image.Point) {
 	}
 	area := q.key.queue.AreaFor(focus)
 	q.pointer.queue.Deliver(area, pointer.Event{
-		Type:   pointer.Scroll,
+		Kind:   pointer.Scroll,
 		Source: pointer.Touch,
 		Scroll: f32internal.FPt(dist),
 	}, &q.handlers)
@@ -317,9 +317,9 @@ func (q *Router) ClickFocus() {
 		Source:   pointer.Touch,
 	}
 	area := q.key.queue.AreaFor(focus)
-	e.Type = pointer.Press
+	e.Kind = pointer.Press
 	q.pointer.queue.Deliver(area, e, &q.handlers)
-	e.Type = pointer.Release
+	e.Kind = pointer.Release
 	q.pointer.queue.Deliver(area, e, &q.handlers)
 }
 
@@ -438,7 +438,7 @@ func (q *Router) collect() {
 			op := pointer.InputOp{
 				Tag:   encOp.Refs[0].(event.Tag),
 				Grab:  encOp.Data[1] != 0,
-				Types: pointer.Type(bo.Uint16(encOp.Data[2:])),
+				Kinds: pointer.Kind(bo.Uint16(encOp.Data[2:])),
 				ScrollBounds: image.Rectangle{
 					Min: image.Point{
 						X: int(int32(bo.Uint32(encOp.Data[4:]))),
@@ -490,11 +490,11 @@ func (q *Router) collect() {
 			}
 			kc.softKeyboard(op.Show)
 		case ops.TypeKeyInput:
-			filter := encOp.Refs[1].(*key.Set)
+			filter := key.Set(*encOp.Refs[1].(*string))
 			op := key.InputOp{
 				Tag:  encOp.Refs[0].(event.Tag),
 				Hint: key.InputHint(encOp.Data[1]),
-				Keys: *filter,
+				Keys: filter,
 			}
 			a := pc.currentArea()
 			b := pc.currentAreaBounds()
@@ -532,10 +532,10 @@ func (q *Router) collect() {
 
 		// Semantic ops.
 		case ops.TypeSemanticLabel:
-			lbl := encOp.Refs[0].(string)
+			lbl := *encOp.Refs[0].(*string)
 			pc.semanticLabel(lbl)
 		case ops.TypeSemanticDesc:
-			desc := encOp.Refs[0].(string)
+			desc := *encOp.Refs[0].(*string)
 			pc.semanticDesc(desc)
 		case ops.TypeSemanticClass:
 			class := semantic.ClassOp(encOp.Data[1])
@@ -546,11 +546,11 @@ func (q *Router) collect() {
 			} else {
 				pc.semanticSelected(false)
 			}
-		case ops.TypeSemanticDisabled:
+		case ops.TypeSemanticEnabled:
 			if encOp.Data[1] != 0 {
-				pc.semanticDisabled(true)
+				pc.semanticEnabled(true)
 			} else {
-				pc.semanticDisabled(false)
+				pc.semanticEnabled(false)
 			}
 		}
 	}
@@ -593,16 +593,6 @@ func (h *handlerEvents) HadEvents() bool {
 func (h *handlerEvents) Events(k event.Tag) []event.Event {
 	if events, ok := h.handlers[k]; ok {
 		h.handlers[k] = h.handlers[k][:0]
-		// Schedule another frame if we delivered events to the user
-		// to flush half-updated state. This is important when an
-		// event changes UI state that has already been laid out. In
-		// the worst case, we waste a frame, increasing power usage.
-		//
-		// Gio is expected to grow the ability to construct
-		// frame-to-frame differences and only render to changed
-		// areas. In that case, the waste of a spurious frame should
-		// be minimal.
-		h.hadEvents = h.hadEvents || len(events) > 0
 		return events
 	}
 	return nil

io/router/semantic_test.go

@@ -74,11 +74,11 @@ func TestSemanticTree(t *testing.T) {
 
 func TestSemanticDescription(t *testing.T) {
 	var ops op.Ops
-	pointer.InputOp{Tag: new(int), Types: pointer.Press | pointer.Release}.Add(&ops)
+	pointer.InputOp{Tag: new(int), Kinds: pointer.Press | pointer.Release}.Add(&ops)
 	semantic.DescriptionOp("description").Add(&ops)
 	semantic.LabelOp("label").Add(&ops)
 	semantic.Button.Add(&ops)
-	semantic.DisabledOp(true).Add(&ops)
+	semantic.EnabledOp(false).Add(&ops)
 	semantic.SelectedOp(true).Add(&ops)
 	var r Router
 	r.Frame(&ops)

io/semantic/semantic.go

@@ -36,16 +36,16 @@ const (
 // boolean state.
 type SelectedOp bool
 
-// DisabledOp describes the disabled state.
+// EnabledOp describes the enabled state.
-type DisabledOp bool
+type EnabledOp bool
 
 func (l LabelOp) Add(o *op.Ops) {
-	data := ops.Write1(&o.Internal, ops.TypeSemanticLabelLen, string(l))
+	data := ops.Write1String(&o.Internal, ops.TypeSemanticLabelLen, string(l))
 	data[0] = byte(ops.TypeSemanticLabel)
 }
 
 func (d DescriptionOp) Add(o *op.Ops) {
-	data := ops.Write1(&o.Internal, ops.TypeSemanticDescLen, string(d))
+	data := ops.Write1String(&o.Internal, ops.TypeSemanticDescLen, string(d))
 	data[0] = byte(ops.TypeSemanticDesc)
 }
 
@@ -63,10 +63,10 @@ func (s SelectedOp) Add(o *op.Ops) {
 	}
 }
 
-func (d DisabledOp) Add(o *op.Ops) {
+func (e EnabledOp) Add(o *op.Ops) {
-	data := ops.Write(&o.Internal, ops.TypeSemanticDisabledLen)
+	data := ops.Write(&o.Internal, ops.TypeSemanticEnabledLen)
-	data[0] = byte(ops.TypeSemanticDisabled)
+	data[0] = byte(ops.TypeSemanticEnabled)
-	if d {
+	if e {
 		data[1] = 1
 	}
 }

layout/list.go

@@ -144,7 +144,7 @@ func (l *List) Dragging() bool {
 }
 
 func (l *List) update(gtx Context) {
-	d := l.scroll.Scroll(gtx.Metric, gtx, gtx.Now, gesture.Axis(l.Axis))
+	d := l.scroll.Update(gtx.Metric, gtx, gtx.Now, gesture.Axis(l.Axis))
 	l.scrollDelta = d
 	l.Position.Offset += d
 }

layout/list_test.go

@@ -93,18 +93,18 @@ func TestListPosition(t *testing.T) {
 				pointer.Event{
 					Source:   pointer.Mouse,
 					Buttons:  pointer.ButtonPrimary,
-					Type:     pointer.Press,
+					Kind:     pointer.Press,
 					Position: f32.Pt(0, 0),
 				},
 				pointer.Event{
 					Source: pointer.Mouse,
-					Type:   pointer.Scroll,
+					Kind:   pointer.Scroll,
 					Scroll: f32.Pt(5, 0),
 				},
 				pointer.Event{
 					Source:   pointer.Mouse,
 					Buttons:  pointer.ButtonPrimary,
-					Type:     pointer.Release,
+					Kind:     pointer.Release,
 					Position: f32.Pt(5, 0),
 				},
 			)},
@@ -113,18 +113,18 @@ func TestListPosition(t *testing.T) {
 				pointer.Event{
 					Source:   pointer.Mouse,
 					Buttons:  pointer.ButtonPrimary,
-					Type:     pointer.Press,
+					Kind:     pointer.Press,
 					Position: f32.Pt(0, 0),
 				},
 				pointer.Event{
 					Source: pointer.Mouse,
-					Type:   pointer.Scroll,
+					Kind:   pointer.Scroll,
 					Scroll: f32.Pt(3, 0),
 				},
 				pointer.Event{
 					Source:   pointer.Mouse,
 					Buttons:  pointer.ButtonPrimary,
-					Type:     pointer.Release,
+					Kind:     pointer.Release,
 					Position: f32.Pt(5, 0),
 				},
 			)},
@@ -133,18 +133,18 @@ func TestListPosition(t *testing.T) {
 				pointer.Event{
 					Source:   pointer.Mouse,
 					Buttons:  pointer.ButtonPrimary,
-					Type:     pointer.Press,
+					Kind:     pointer.Press,
 					Position: f32.Pt(0, 0),
 				},
 				pointer.Event{
 					Source: pointer.Mouse,
-					Type:   pointer.Scroll,
+					Kind:   pointer.Scroll,
 					Scroll: f32.Pt(10, 0),
 				},
 				pointer.Event{
 					Source:   pointer.Mouse,
 					Buttons:  pointer.ButtonPrimary,
-					Type:     pointer.Release,
+					Kind:     pointer.Release,
 					Position: f32.Pt(15, 0),
 				},
 			)},

op/clip/clip.go

@@ -29,7 +29,7 @@ type Op struct {
 type Stack struct {
 	ops     *ops.Ops
 	id      ops.StackID
-	macroID int
+	macroID uint32
 }
 
 var pathSeed maphash.Seed
@@ -204,6 +204,9 @@ func (p *Path) Line(delta f32.Point) {
 
 // LineTo moves the pen to the absolute point specified, recording a line.
 func (p *Path) LineTo(to f32.Point) {
+	if to == p.pen {
+		return
+	}
 	data := ops.WriteMulti(p.ops, scene.CommandSize+4)
 	bo := binary.LittleEndian
 	bo.PutUint32(data[0:], uint32(p.contour))
@@ -250,6 +253,9 @@ func (p *Path) Quad(ctrl, to f32.Point) {
 // QuadTo records a quadratic Bézier from the pen to end
 // with the control point ctrl, with absolute coordinates.
 func (p *Path) QuadTo(ctrl, to f32.Point) {
+	if ctrl == p.pen && to == p.pen {
+		return
+	}
 	data := ops.WriteMulti(p.ops, scene.CommandSize+4)
 	bo := binary.LittleEndian
 	bo.PutUint32(data[0:], uint32(p.contour))

op/op.go

@@ -111,7 +111,7 @@ type TransformOp struct {
 // TransformStack represents a TransformOp pushed on the transformation stack.
 type TransformStack struct {
 	id      ops.StackID
-	macroID int
+	macroID uint32
 	ops     *ops.Ops
 }
 

op/paint/paint.go

@@ -44,6 +44,14 @@ type LinearGradientOp struct {
 type PaintOp struct {
 }
 
+// OpacityStack represents an opacity applied to all painting operations
+// until Pop is called.
+type OpacityStack struct {
+	id      ops.StackID
+	macroID uint32
+	ops     *ops.Ops
+}
+
 // NewImageOp creates an ImageOp backed by src.
 //
 // NewImageOp assumes the backing image is immutable, and may cache a
@@ -145,3 +153,31 @@ func Fill(ops *op.Ops, c color.NRGBA) {
 	ColorOp{Color: c}.Add(ops)
 	PaintOp{}.Add(ops)
 }
+
+// PushOpacity creates a drawing layer with an opacity in the range [0;1].
+// The layer includes every subsequent drawing operation until [OpacityStack.Pop]
+// is called.
+//
+// The layer is drawn in two steps. First, the layer operations are
+// drawn to a separate image. Then, the image is blended on top of
+// the frame, with the opacity used as the blending factor.
+func PushOpacity(o *op.Ops, opacity float32) OpacityStack {
+	if opacity > 1 {
+		opacity = 1
+	}
+	if opacity < 0 {
+		opacity = 0
+	}
+	id, macroID := ops.PushOp(&o.Internal, ops.OpacityStack)
+	data := ops.Write(&o.Internal, ops.TypePushOpacityLen)
+	bo := binary.LittleEndian
+	data[0] = byte(ops.TypePushOpacity)
+	bo.PutUint32(data[1:], math.Float32bits(opacity))
+	return OpacityStack{ops: &o.Internal, id: id, macroID: macroID}
+}
+
+func (t OpacityStack) Pop() {
+	ops.PopOp(t.ops, ops.OpacityStack, t.id, t.macroID)
+	data := ops.Write(t.ops, ops.TypePopOpacityLen)
+	data[0] = byte(ops.TypePopOpacity)
+}

text/gotext.go

@@ -284,6 +284,7 @@ func (s *shaperImpl) addFace(f font.Face, md giofont.Font) {
 	if _, ok := s.faceToIndex[f.Font]; ok {
 		return
 	}
+	s.logger.Printf("loaded face %s(style:%s, weight:%d)", md.Typeface, md.Style, md.Weight)
 	idx := len(s.faces)
 	s.faceToIndex[f.Font] = idx
 	s.faces = append(s.faces, f)

text/lru.go

@@ -3,9 +3,8 @@
 package text
 
 import (
-	"encoding/binary"
-	"hash/maphash"
 	"image"
+	"sync/atomic"
 
 	giofont "gioui.org/font"
 	"gioui.org/io/system"
@@ -88,32 +87,32 @@ type glyphValue[V any] struct {
 }
 
 type glyphLRU[V any] struct {
-	seed  maphash.Seed
+	seed  uint64
 	cache lru[uint64, glyphValue[V]]
 }
 
+var seed uint32
+
 // hashGlyphs computes a hash key based on the ID and X offset of
 // every glyph in the slice.
 func (c *glyphLRU[V]) hashGlyphs(gs []Glyph) uint64 {
-	if c.seed == (maphash.Seed{}) {
+	if c.seed == 0 {
-		c.seed = maphash.MakeSeed()
+		c.seed = uint64(atomic.AddUint32(&seed, 3900798947))
 	}
-	var h maphash.Hash
+	if len(gs) == 0 {
-	h.SetSeed(c.seed)
+		return 0
-	var b [8]byte
-	firstX := fixed.Int26_6(0)
-	for i, g := range gs {
-		if i == 0 {
-			firstX = g.X
-		}
-		// Cache glyph X offsets relative to the first glyph.
-		binary.LittleEndian.PutUint32(b[:4], uint32(g.X-firstX))
-		h.Write(b[:4])
-		binary.LittleEndian.PutUint64(b[:], uint64(g.ID))
-		h.Write(b[:])
 	}
-	sum := h.Sum64()
+
-	return sum
+	h := c.seed
+	firstX := gs[0].X
+	for _, g := range gs {
+		h += uint64(g.X - firstX)
+		h *= 6585573582091643
+		h += uint64(g.ID)
+		h *= 3650802748644053
+	}
+
+	return h
 }
 
 func (c *glyphLRU[V]) Get(key uint64, gs []Glyph) (V, bool) {

text/shaper.go

@@ -121,7 +121,7 @@ type Glyph struct {
 	// belongs to. If Flags does not contain FlagClusterBreak, this value will
 	// always be zero. The final glyph in the cluster contains the runes count
 	// for the entire cluster.
-	Runes int
+	Runes uint16
 	// Flags encode special properties of this glyph.
 	Flags Flags
 }
@@ -469,7 +469,7 @@ func (l *Shaper) NextGlyph() (_ Glyph, ok bool) {
 			Ascent:  line.ascent,
 			Descent: line.descent,
 			Advance: g.xAdvance,
-			Runes:   g.runeCount,
+			Runes:   uint16(g.runeCount),
 			Offset: fixed.Point26_6{
 				X: g.xOffset,
 				Y: g.yOffset,
@@ -505,7 +505,7 @@ func (l *Shaper) NextGlyph() (_ Glyph, ok bool) {
 		if endOfCluster {
 			glyph.Flags |= FlagClusterBreak
 			if run.truncator {
-				glyph.Runes += l.txt.unreadRuneCount
+				glyph.Runes += uint16(l.txt.unreadRuneCount)
 			}
 		} else {
 			glyph.Runes = 0

text/shaper_test.go

@@ -51,9 +51,9 @@ func TestWrappingTruncation(t *testing.T) {
 			for g, ok := cache.NextGlyph(); ok; g, ok = cache.NextGlyph() {
 				glyphs = append(glyphs, g)
 				if g.Flags&FlagTruncator != 0 && g.Flags&FlagClusterBreak != 0 {
-					truncatedRunes += g.Runes
+					truncatedRunes += int(g.Runes)
 				} else {
-					untruncatedRunes += g.Runes
+					untruncatedRunes += int(g.Runes)
 				}
 				if g.Flags&FlagLineBreak != 0 {
 					lineCount++
@@ -117,9 +117,9 @@ func TestWrappingForcedTruncation(t *testing.T) {
 			for g, ok := cache.NextGlyph(); ok; g, ok = cache.NextGlyph() {
 				glyphs = append(glyphs, g)
 				if g.Flags&FlagTruncator != 0 && g.Flags&FlagClusterBreak != 0 {
-					truncatedRunes += g.Runes
+					truncatedRunes += int(g.Runes)
 				} else {
-					untruncatedRunes += g.Runes
+					untruncatedRunes += int(g.Runes)
 				}
 				if g.Flags&FlagLineBreak != 0 {
 					lineCount++
@@ -191,9 +191,9 @@ func TestShapingNewlineHandling(t *testing.T) {
 				for g, ok := cache.NextGlyph(); ok; g, ok = cache.NextGlyph() {
 					glyphs = append(glyphs, g)
 					if g.Flags&FlagTruncator == 0 {
-						runes += g.Runes
+						runes += int(g.Runes)
 					} else {
-						truncated += g.Runes
+						truncated += int(g.Runes)
 					}
 				}
 				if expected := len([]rune(tc.textInput)) - tc.expectedTruncated; expected != runes {
@@ -571,7 +571,7 @@ func TestShapeStringRuneAccounting(t *testing.T) {
 					}
 					totalRunes := 0
 					for _, g := range glyphs {
-						totalRunes += g.Runes
+						totalRunes += int(g.Runes)
 					}
 					if inputRunes := len([]rune(tc.input)); totalRunes != inputRunes {
 						t.Errorf("input contained %d runes, but glyphs contained %d", inputRunes, totalRunes)

widget/bool.go

@@ -11,15 +11,15 @@ type Bool struct {
 	Value bool
 
 	clk Clickable
-
-	changed bool
 }
 
-// Changed reports whether Value has changed since the last
+// Update the widget state and report whether Value was changed.
-// call to Changed.
+func (b *Bool) Update(gtx layout.Context) bool {
-func (b *Bool) Changed() bool {
+	changed := false
-	changed := b.changed
+	for b.clk.Clicked(gtx) {
-	b.changed = false
+		b.Value = !b.Value
+		changed = true
+	}
 	return changed
 }
 
@@ -43,13 +43,10 @@ func (b *Bool) History() []Press {
 }
 
 func (b *Bool) Layout(gtx layout.Context, w layout.Widget) layout.Dimensions {
+	b.Update(gtx)
 	dims := b.clk.Layout(gtx, func(gtx layout.Context) layout.Dimensions {
-		for b.clk.Clicked() {
-			b.Value = !b.Value
-			b.changed = true
-		}
 		semantic.SelectedOp(b.Value).Add(gtx.Ops)
-		semantic.DisabledOp(gtx.Queue == nil).Add(gtx.Ops)
+		semantic.EnabledOp(gtx.Queue != nil).Add(gtx.Ops)
 		return w(gtx)
 	})
 	return dims

widget/button.go

@@ -17,18 +17,16 @@ import (
 
 // Clickable represents a clickable area.
 type Clickable struct {
-	click  gesture.Click
+	click gesture.Click
-	clicks []Click
+	// clicks is for saved clicks to support Clicked.
-	// prevClicks is the index into clicks that marks the clicks
+	clicks  []Click
-	// from the most recent Layout call. prevClicks is used to keep
+	history []Press
-	// clicks bounded.
-	prevClicks int
-	history    []Press
 
-	keyTag       struct{}
+	keyTag        struct{}
-	requestFocus bool
+	requestFocus  bool
-	focused      bool
+	requestClicks int
-	pressedKey   string
+	focused       bool
+	pressedKey    string
 }
 
 // Click represents a click.
@@ -50,26 +48,24 @@ type Press struct {
 	Cancelled bool
 }
 
-// Click executes a simple programmatic click
+// Click executes a simple programmatic click.
 func (b *Clickable) Click() {
-	b.clicks = append(b.clicks, Click{
+	b.requestClicks++
-		Modifiers: 0,
-		NumClicks: 1,
-	})
 }
 
 // Clicked reports whether there are pending clicks as would be
 // reported by Clicks. If so, Clicked removes the earliest click.
-func (b *Clickable) Clicked() bool {
+func (b *Clickable) Clicked(gtx layout.Context) bool {
-	if len(b.clicks) == 0 {
+	if len(b.clicks) > 0 {
-		return false
+		b.clicks = b.clicks[1:]
+		return true
 	}
-	n := copy(b.clicks, b.clicks[1:])
+	b.clicks = b.Update(gtx)
-	b.clicks = b.clicks[:n]
+	if len(b.clicks) > 0 {
-	if b.prevClicks > 0 {
+		b.clicks = b.clicks[1:]
-		b.prevClicks--
+		return true
 	}
-	return true
+	return false
 }
 
 // Hovered reports whether a pointer is over the element.
@@ -92,44 +88,44 @@ func (b *Clickable) Focused() bool {
 	return b.focused
 }
 
-// Clicks returns and clear the clicks since the last call to Clicks.
-func (b *Clickable) Clicks() []Click {
-	clicks := b.clicks
-	b.clicks = nil
-	b.prevClicks = 0
-	return clicks
-}
-
 // History is the past pointer presses useful for drawing markers.
 // History is retained for a short duration (about a second).
 func (b *Clickable) History() []Press {
 	return b.history
 }
 
-// Layout and update the button state
+// Layout and update the button state.
 func (b *Clickable) Layout(gtx layout.Context, w layout.Widget) layout.Dimensions {
-	b.update(gtx)
+	b.Update(gtx)
 	m := op.Record(gtx.Ops)
 	dims := w(gtx)
 	c := m.Stop()
 	defer clip.Rect(image.Rectangle{Max: dims.Size}).Push(gtx.Ops).Pop()
-	disabled := gtx.Queue == nil
+	enabled := gtx.Queue != nil
-	semantic.DisabledOp(disabled).Add(gtx.Ops)
+	semantic.EnabledOp(enabled).Add(gtx.Ops)
 	b.click.Add(gtx.Ops)
-	if !disabled {
+	if enabled {
 		keys := key.Set("⏎|Space")
 		if !b.focused {
 			keys = ""
 		}
 		key.InputOp{Tag: &b.keyTag, Keys: keys}.Add(gtx.Ops)
-		if b.requestFocus {
-			key.FocusOp{Tag: &b.keyTag}.Add(gtx.Ops)
-			b.requestFocus = false
-		}
-	} else {
-		b.focused = false
 	}
 	c.Add(gtx.Ops)
+	return dims
+}
+
+// Update the button state by processing events, and return the resulting
+// clicks, if any.
+func (b *Clickable) Update(gtx layout.Context) []Click {
+	b.clicks = nil
+	if gtx.Queue == nil {
+		b.focused = false
+	}
+	if b.requestFocus {
+		key.FocusOp{Tag: &b.keyTag}.Add(gtx.Ops)
+		b.requestFocus = false
+	}
 	for len(b.history) > 0 {
 		c := b.history[0]
 		if c.End.IsZero() || gtx.Now.Sub(c.End) < 1*time.Second {
@@ -138,34 +134,31 @@ func (b *Clickable) Layout(gtx layout.Context, w layout.Widget) layout.Dimension
 		n := copy(b.history, b.history[1:])
 		b.history = b.history[:n]
 	}
-	return dims
+	var clicks []Click
-}
+	if c := b.requestClicks; c > 0 {
-
+		b.requestClicks = 0
-// update the button state by processing events.
+		clicks = append(clicks, Click{
-func (b *Clickable) update(gtx layout.Context) {
+			NumClicks: c,
-	// Flush clicks from before the last update.
+		})
-	n := copy(b.clicks, b.clicks[b.prevClicks:])
+	}
-	b.clicks = b.clicks[:n]
+	for _, e := range b.click.Update(gtx) {
-	b.prevClicks = n
+		switch e.Kind {
-
+		case gesture.KindClick:
-	for _, e := range b.click.Events(gtx) {
-		switch e.Type {
-		case gesture.TypeClick:
-			b.clicks = append(b.clicks, Click{
-				Modifiers: e.Modifiers,
-				NumClicks: e.NumClicks,
-			})
 			if l := len(b.history); l > 0 {
 				b.history[l-1].End = gtx.Now
 			}
-		case gesture.TypeCancel:
+			clicks = append(clicks, Click{
+				Modifiers: e.Modifiers,
+				NumClicks: e.NumClicks,
+			})
+		case gesture.KindCancel:
 			for i := range b.history {
 				b.history[i].Cancelled = true
 				if b.history[i].End.IsZero() {
 					b.history[i].End = gtx.Now
 				}
 			}
-		case gesture.TypePress:
+		case gesture.KindPress:
 			if e.Source == pointer.Mouse {
 				key.FocusOp{Tag: &b.keyTag}.Add(gtx.Ops)
 			}
@@ -198,11 +191,12 @@ func (b *Clickable) update(gtx layout.Context) {
 				}
 				// only register a key as a click if the key was pressed and released while this button was focused
 				b.pressedKey = ""
-				b.clicks = append(b.clicks, Click{
+				clicks = append(clicks, Click{
 					Modifiers: e.Modifiers,
 					NumClicks: 1,
 				})
 			}
 		}
 	}
+	return clicks
 }

widget/button_test.go

@@ -48,6 +48,7 @@ func TestClickable(t *testing.T) {
 		t.Error("button 2 should not have focus")
 	}
 	// frame: press & release return
+	frame()
 	r.Queue(
 		key.Event{
 			Name:  key.NameReturn,
@@ -58,11 +59,10 @@ func TestClickable(t *testing.T) {
 			State: key.Release,
 		},
 	)
-	frame()
+	if !b1.Clicked(gtx) {
-	if !b1.Clicked() {
 		t.Error("button 1 did not get clicked when it got return press & release")
 	}
-	if b2.Clicked() {
+	if b2.Clicked(gtx) {
 		t.Error("button 2 got clicked when it did not have focus")
 	}
 	// frame: press return down
@@ -73,7 +73,7 @@ func TestClickable(t *testing.T) {
 		},
 	)
 	frame()
-	if b1.Clicked() {
+	if b1.Clicked(gtx) {
 		t.Error("button 1 got clicked, even if it only got return press")
 	}
 	// frame: request focus for button 2
@@ -95,10 +95,10 @@ func TestClickable(t *testing.T) {
 		},
 	)
 	frame()
-	if b1.Clicked() {
+	if b1.Clicked(gtx) {
 		t.Error("button 1 got clicked, even if it had lost focus")
 	}
-	if b2.Clicked() {
+	if b2.Clicked(gtx) {
 		t.Error("button 2 should not have been clicked, as it only got return release")
 	}
 }

widget/decorations.go

@@ -12,12 +12,11 @@ import (
 
 // Decorations handles the states of window decorations.
 type Decorations struct {
-	clicks []Clickable
+	clicks map[int]*Clickable
 	resize [8]struct {
 		gesture.Hover
 		gesture.Drag
 	}
-	actions   system.Action
 	maximized bool
 }
 
@@ -35,22 +34,13 @@ func (d *Decorations) Clickable(action system.Action) *Clickable {
 		panic(fmt.Errorf("not a single action"))
 	}
 	idx := bits.TrailingZeros(uint(action))
-	if n := idx - len(d.clicks); n >= 0 {
+	click, found := d.clicks[idx]
-		d.clicks = append(d.clicks, make([]Clickable, n+1)...)
+	if !found {
-	}
+		click = new(Clickable)
-	click := &d.clicks[idx]
+		if d.clicks == nil {
-	if click.Clicked() {
+			d.clicks = make(map[int]*Clickable)
-		if action == system.ActionMaximize {
-			if d.maximized {
-				d.maximized = false
-				d.actions |= system.ActionUnmaximize
-			} else {
-				d.maximized = true
-				d.actions |= system.ActionMaximize
-			}
-		} else {
-			d.actions |= action
 		}
+		d.clicks[idx] = click
 	}
 	return click
 }
@@ -66,11 +56,27 @@ func (d *Decorations) Perform(actions system.Action) {
 	}
 }
 
-// Actions returns the set of actions activated by the user.
+// Update the state and return the set of actions activated by the user.
-func (d *Decorations) Actions() system.Action {
+func (d *Decorations) Update(gtx layout.Context) system.Action {
-	a := d.actions
+	var actions system.Action
-	d.actions = 0
+	for idx, clk := range d.clicks {
-	return a
+		if !clk.Clicked(gtx) {
+			continue
+		}
+		action := system.Action(1 << idx)
+		switch {
+		case action == system.ActionMaximize && d.maximized:
+			action = system.ActionUnmaximize
+		case action == system.ActionUnmaximize && !d.maximized:
+			action = system.ActionMaximize
+		}
+		switch action {
+		case system.ActionMaximize, system.ActionUnmaximize:
+			d.maximized = !d.maximized
+		}
+		actions |= action
+	}
+	return actions
 }
 
 // Maximized returns whether the window is maximized.

widget/dnd.go

@@ -17,41 +17,16 @@ type Draggable struct {
 	// Type contains the MIME type and matches transfer.SourceOp.
 	Type string
 
-	handle    struct{}
+	handle struct{}
-	drag      gesture.Drag
+	drag   gesture.Drag
-	click     f32.Point
+	click  f32.Point
-	pos       f32.Point
+	pos    f32.Point
-	requested bool
-	request   string
 }
 
 func (d *Draggable) Layout(gtx layout.Context, w, drag layout.Widget) layout.Dimensions {
 	if gtx.Queue == nil {
 		return w(gtx)
 	}
-	pos := d.pos
-	for _, ev := range d.drag.Events(gtx.Metric, gtx.Queue, gesture.Both) {
-		switch ev.Type {
-		case pointer.Press:
-			d.click = ev.Position
-			pos = f32.Point{}
-		case pointer.Drag, pointer.Release:
-			pos = ev.Position.Sub(d.click)
-		}
-	}
-	d.pos = pos
-
-	for _, ev := range gtx.Queue.Events(&d.handle) {
-		switch e := ev.(type) {
-		case transfer.RequestEvent:
-			d.requested = true
-			d.request = e.Type
-		case transfer.CancelEvent:
-			d.requested = false
-			d.request = ""
-		}
-	}
-
 	dims := w(gtx)
 
 	stack := clip.Rect{Max: dims.Size}.Push(gtx.Ops)
@@ -64,7 +39,7 @@ func (d *Draggable) Layout(gtx layout.Context, w, drag layout.Widget) layout.Dim
 
 	if drag != nil && d.drag.Pressed() {
 		rec := op.Record(gtx.Ops)
-		op.Offset(pos.Round()).Add(gtx.Ops)
+		op.Offset(d.pos.Round()).Add(gtx.Ops)
 		drag(gtx)
 		op.Defer(gtx.Ops, rec.Stop())
 	}
@@ -77,13 +52,27 @@ func (d *Draggable) Dragging() bool {
 	return d.drag.Dragging()
 }
 
-// Requested returns the MIME type, if any, for which the Draggable was requested to offer data.
+// Update the draggable and returns the MIME type for which the Draggable was
-func (d *Draggable) Requested() (mime string, requested bool) {
+// requested to offer data, if any
-	mime = d.request
+func (d *Draggable) Update(gtx layout.Context) (mime string, requested bool) {
-	requested = d.requested
+	pos := d.pos
-	d.requested = false
+	for _, ev := range d.drag.Update(gtx.Metric, gtx.Queue, gesture.Both) {
-	d.request = ""
+		switch ev.Kind {
-	return
+		case pointer.Press:
+			d.click = ev.Position
+			pos = f32.Point{}
+		case pointer.Drag, pointer.Release:
+			pos = ev.Position.Sub(d.click)
+		}
+	}
+	d.pos = pos
+
+	for _, ev := range gtx.Queue.Events(&d.handle) {
+		if e, ok := ev.(transfer.RequestEvent); ok {
+			return e.Type, true
+		}
+	}
+	return "", false
 }
 
 // Offer the data ready for a drop. Must be called after being Requested.

widget/dnd_test.go

@@ -39,15 +39,15 @@ func TestDraggable(t *testing.T) {
 	r.Queue(
 		pointer.Event{
 			Position: f32.Pt(10, 10),
-			Type:     pointer.Press,
+			Kind:     pointer.Press,
 		},
 		pointer.Event{
 			Position: f32.Pt(20, 10),
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 		},
 		pointer.Event{
 			Position: f32.Pt(20, 10),
-			Type:     pointer.Release,
+			Kind:     pointer.Release,
 		},
 	)
 	ofr := &offer{data: "hello"}

widget/editor.go

@@ -225,7 +225,7 @@ func (e *Editor) processPointer(gtx layout.Context) {
 		axis = gesture.Vertical
 		smin, smax = sbounds.Min.Y, sbounds.Max.Y
 	}
-	sdist := e.scroller.Scroll(gtx.Metric, gtx, gtx.Now, axis)
+	sdist := e.scroller.Update(gtx.Metric, gtx, gtx.Now, axis)
 	var soff int
 	if e.SingleLine {
 		e.text.ScrollRel(sdist, 0)
@@ -238,8 +238,8 @@ func (e *Editor) processPointer(gtx layout.Context) {
 		switch evt := evt.(type) {
 		case gesture.ClickEvent:
 			switch {
-			case evt.Type == gesture.TypePress && evt.Source == pointer.Mouse,
+			case evt.Kind == gesture.KindPress && evt.Source == pointer.Mouse,
-				evt.Type == gesture.TypeClick && evt.Source != pointer.Mouse:
+				evt.Kind == gesture.KindClick && evt.Source != pointer.Mouse:
 				prevCaretPos, _ := e.text.Selection()
 				e.blinkStart = gtx.Now
 				e.text.MoveCoord(image.Point{
@@ -278,10 +278,10 @@ func (e *Editor) processPointer(gtx layout.Context) {
 		case pointer.Event:
 			release := false
 			switch {
-			case evt.Type == pointer.Release && evt.Source == pointer.Mouse:
+			case evt.Kind == pointer.Release && evt.Source == pointer.Mouse:
 				release = true
 				fallthrough
-			case evt.Type == pointer.Drag && evt.Source == pointer.Mouse:
+			case evt.Kind == pointer.Drag && evt.Source == pointer.Mouse:
 				if e.dragging {
 					e.blinkStart = gtx.Now
 					e.text.MoveCoord(image.Point{
@@ -305,10 +305,10 @@ func (e *Editor) processPointer(gtx layout.Context) {
 
 func (e *Editor) clickDragEvents(gtx layout.Context) []event.Event {
 	var combinedEvents []event.Event
-	for _, evt := range e.clicker.Events(gtx) {
+	for _, evt := range e.clicker.Update(gtx) {
 		combinedEvents = append(combinedEvents, evt)
 	}
-	for _, evt := range e.dragger.Events(gtx.Metric, gtx, gesture.Both) {
+	for _, evt := range e.dragger.Update(gtx.Metric, gtx, gesture.Both) {
 		combinedEvents = append(combinedEvents, evt)
 	}
 	return combinedEvents
@@ -517,15 +517,10 @@ func (e *Editor) initBuffer() {
 	e.text.WrapPolicy = e.WrapPolicy
 }
 
-// Layout lays out the editor using the provided textMaterial as the paint material
+// Update the state of the editor in response to input events.
-// for the text glyphs+caret and the selectMaterial as the paint material for the
+func (e *Editor) Update(gtx layout.Context) {
-// selection rectangle.
-func (e *Editor) Layout(gtx layout.Context, lt *text.Shaper, font font.Font, size unit.Sp, textMaterial, selectMaterial op.CallOp) layout.Dimensions {
 	e.initBuffer()
-	e.text.Update(gtx, lt, font, size, e.processEvents)
+	e.processEvents(gtx)
-
-	dims := e.layout(gtx, textMaterial, selectMaterial)
-
 	if e.focused {
 		// Notify IME of selection if it changed.
 		newSel := e.ime.selection
@@ -551,8 +546,16 @@ func (e *Editor) Layout(gtx layout.Context, lt *text.Shaper, font font.Font, siz
 
 		e.updateSnippet(gtx, e.ime.start, e.ime.end)
 	}
+}
 
-	return dims
+// Layout lays out the editor using the provided textMaterial as the paint material
+// for the text glyphs+caret and the selectMaterial as the paint material for the
+// selection rectangle.
+func (e *Editor) Layout(gtx layout.Context, lt *text.Shaper, font font.Font, size unit.Sp, textMaterial, selectMaterial op.CallOp) layout.Dimensions {
+	e.Update(gtx)
+
+	e.text.Layout(gtx, lt, font, size)
+	return e.layout(gtx, textMaterial, selectMaterial)
 }
 
 // updateSnippet adds a key.SnippetOp if the snippet content or position

widget/editor_test.go

@@ -139,7 +139,7 @@ func TestEditorReadOnly(t *testing.T) {
 	// Type some new characters.
 	gtx.Ops.Reset()
 	gtx.Queue = &testQueue{events: []event.Event{key.EditEvent{Range: key.Range{Start: cStart2, End: cEnd2}, Text: "something else"}}}
-	e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
+	e.Update(gtx)
 	textContent2 := e.Text()
 	if textContent2 != textContent {
 		t.Errorf("readonly editor modified by key.EditEvent")
@@ -159,22 +159,22 @@ func TestEditorReadOnly(t *testing.T) {
 	gtx.Ops.Reset()
 	gtx.Queue = &testQueue{events: []event.Event{
 		pointer.Event{
-			Type:     pointer.Press,
+			Kind:     pointer.Press,
 			Buttons:  pointer.ButtonPrimary,
 			Position: f32.Pt(float32(dims.Size.X)*.5, 5),
 		},
 		pointer.Event{
-			Type:     pointer.Drag,
+			Kind:     pointer.Drag,
 			Buttons:  pointer.ButtonPrimary,
 			Position: layout.FPt(dims.Size).Mul(.5),
 		},
 		pointer.Event{
-			Type:     pointer.Release,
+			Kind:     pointer.Release,
 			Buttons:  pointer.ButtonPrimary,
 			Position: layout.FPt(dims.Size).Mul(.5),
 		},
 	}}
-	e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
+	e.Update(gtx)
 	cStart3, cEnd3 := e.Selection()
 	if cStart3 == cStart2 || cEnd3 == cEnd2 {
 		t.Errorf("expected mouse interaction to change selection.")
@@ -285,44 +285,10 @@ func TestEditor(t *testing.T) {
 	e.MoveCaret(-3, -3)
 	assertCaret(t, e, 1, 1, len("æbc\na"))
 	e.text.Mask = '*'
-	e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
+	e.Update(gtx)
 	assertCaret(t, e, 1, 1, len("æbc\na"))
 	e.MoveCaret(-3, -3)
 	assertCaret(t, e, 0, 2, len("æb"))
-	/*
-		    NOTE(whereswaldon): it isn't possible to check the raw glyph data
-		    like this anymore. How should we handle this?
-			e.Mask = '\U0001F92B'
-			e.Layout(gtx, cache, font, fontSize, op.CallOp{},op.CallOp{})
-			e.moveEnd(selectionClear)
-			assertCaret(t, e, 0, 3, len("æbc"))
-
-			// When a password mask is applied, it should replace all visible glyphs
-			spaces := 0
-			for _, r := range textSample {
-				if unicode.IsSpace(r) {
-					spaces++
-				}
-			}
-			nonSpaces := len([]rune(textSample)) - spaces
-			glyphCounts := make(map[int]int)
-			// This loop assumes a single-run text, which we know is safe here.
-			for _, line := range e.lines {
-				for _, glyph := range line.Runs[0].Glyphs {
-					glyphCounts[int(glyph.ID)]++
-				}
-			}
-			if len(glyphCounts) > 2 {
-				t.Errorf("masked text contained glyphs other than mask and whitespace")
-			}
-
-			for gid, count := range glyphCounts {
-				if count != spaces && count != nonSpaces {
-					t.Errorf("glyph with id %d occurred %d times, expected either %d or %d", gid, count, spaces, nonSpaces)
-				}
-			}
-
-	*/
 	// Test that moveLine applies x offsets from previous moves.
 	e.SetText("long line\nshort")
 	e.SetCaret(0, 0)
@@ -680,11 +646,8 @@ func TestEditorMoveWord(t *testing.T) {
 			Constraints: layout.Exact(image.Pt(100, 100)),
 			Locale:      english,
 		}
-		cache := text.NewShaper(text.NoSystemFonts(), text.WithCollection(gofont.Collection()))
-		fontSize := unit.Sp(10)
-		font := font.Font{}
 		e.SetText(t)
-		e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
+		e.Update(gtx)
 		return e
 	}
 	for ii, tt := range tests {
@@ -785,11 +748,8 @@ func TestEditorInsert(t *testing.T) {
 			Constraints: layout.Exact(image.Pt(100, 100)),
 			Locale:      english,
 		}
-		cache := text.NewShaper(text.NoSystemFonts(), text.WithCollection(gofont.Collection()))
-		fontSize := unit.Sp(10)
-		font := font.Font{}
 		e.SetText(t)
-		e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
+		e.Update(gtx)
 		return e
 	}
 	for ii, tt := range tests {
@@ -875,11 +835,8 @@ func TestEditorDeleteWord(t *testing.T) {
 			Constraints: layout.Exact(image.Pt(100, 100)),
 			Locale:      english,
 		}
-		cache := text.NewShaper(text.NoSystemFonts(), text.WithCollection(gofont.Collection()))
-		fontSize := unit.Sp(10)
-		font := font.Font{}
 		e.SetText(t)
-		e.Layout(gtx, cache, font, fontSize, op.CallOp{}, op.CallOp{})
+		e.Update(gtx)
 		return e
 	}
 	for ii, tt := range tests {
@@ -947,13 +904,13 @@ g 2 4 6 8 g
 			events: []event.Event{
 				pointer.Event{
 					Buttons:  pointer.ButtonPrimary,
-					Type:     pointer.Press,
+					Kind:     pointer.Press,
 					Source:   pointer.Mouse,
 					Time:     tim,
 					Position: f32.Pt(textWidth(e, startPos.lineCol.line, 0, startPos.lineCol.col), textBaseline(e, startPos.lineCol.line)),
 				},
 				pointer.Event{
-					Type:     pointer.Release,
+					Kind:     pointer.Release,
 					Source:   pointer.Mouse,
 					Time:     tim,
 					Position: f32.Pt(textWidth(e, endPos.lineCol.line, 0, endPos.lineCol.col), textBaseline(e, endPos.lineCol.line)),

widget/enum.go

@@ -20,8 +20,6 @@ type Enum struct {
 	focus   string
 	focused bool
 
-	changed bool
-
 	keys []*enumKey
 }
 
@@ -40,11 +38,55 @@ func (e *Enum) index(k string) *enumKey {
 	return nil
 }
 
-// Changed reports whether Value has changed by user interaction since the last
+// Update the state and report whether Value has changed by user interaction.
-// call to Changed.
+func (e *Enum) Update(gtx layout.Context) bool {
-func (e *Enum) Changed() bool {
+	if gtx.Queue == nil {
-	changed := e.changed
+		e.focused = false
-	e.changed = false
+	}
+	e.hovering = false
+	changed := false
+	for _, state := range e.keys {
+		for _, ev := range state.click.Update(gtx) {
+			switch ev.Kind {
+			case gesture.KindPress:
+				if ev.Source == pointer.Mouse {
+					key.FocusOp{Tag: &state.tag}.Add(gtx.Ops)
+				}
+			case gesture.KindClick:
+				if state.key != e.Value {
+					e.Value = state.key
+					changed = true
+				}
+			}
+		}
+		for _, ev := range gtx.Events(&state.tag) {
+			switch ev := ev.(type) {
+			case key.FocusEvent:
+				if ev.Focus {
+					e.focused = true
+					e.focus = state.key
+				} else if state.key == e.focus {
+					e.focused = false
+				}
+			case key.Event:
+				if !e.focused || ev.State != key.Release {
+					break
+				}
+				if ev.Name != key.NameReturn && ev.Name != key.NameSpace {
+					break
+				}
+				if state.key != e.Value {
+					e.Value = state.key
+					changed = true
+				}
+			}
+		}
+		if state.click.Hovered() {
+			e.hovered = state.key
+			e.hovering = true
+		}
+	}
+
 	return changed
 }
 
@@ -60,6 +102,7 @@ func (e *Enum) Focused() (string, bool) {
 
 // Layout adds the event handler for the key k.
 func (e *Enum) Layout(gtx layout.Context, k string, content layout.Widget) layout.Dimensions {
+	e.Update(gtx)
 	m := op.Record(gtx.Ops)
 	dims := content(gtx)
 	c := m.Stop()
@@ -73,57 +116,13 @@ func (e *Enum) Layout(gtx layout.Context, k string, content layout.Widget) layou
 		e.keys = append(e.keys, state)
 	}
 	clk := &state.click
-	for _, ev := range clk.Events(gtx) {
-		switch ev.Type {
-		case gesture.TypePress:
-			if ev.Source == pointer.Mouse {
-				key.FocusOp{Tag: &state.tag}.Add(gtx.Ops)
-			}
-		case gesture.TypeClick:
-			if state.key != e.Value {
-				e.Value = state.key
-				e.changed = true
-			}
-		}
-	}
-	for _, ev := range gtx.Events(&state.tag) {
-		switch ev := ev.(type) {
-		case key.FocusEvent:
-			if ev.Focus {
-				e.focused = true
-				e.focus = state.key
-			} else if state.key == e.focus {
-				e.focused = false
-			}
-		case key.Event:
-			if !e.focused || ev.State != key.Release {
-				break
-			}
-			if ev.Name != key.NameReturn && ev.Name != key.NameSpace {
-				break
-			}
-			if state.key != e.Value {
-				e.Value = state.key
-				e.changed = true
-			}
-		}
-	}
-	if clk.Hovered() {
-		e.hovered = k
-		e.hovering = true
-	} else if e.hovered == k {
-		e.hovering = false
-	}
-
 	clk.Add(gtx.Ops)
-	disabled := gtx.Queue == nil
+	enabled := gtx.Queue != nil
-	if !disabled {
+	if enabled {
 		key.InputOp{Tag: &state.tag, Keys: "⏎|Space"}.Add(gtx.Ops)
-	} else if e.focus == k {
-		e.focused = false
 	}
 	semantic.SelectedOp(k == e.Value).Add(gtx.Ops)
-	semantic.DisabledOp(disabled).Add(gtx.Ops)
+	semantic.EnabledOp(enabled).Add(gtx.Ops)
 	c.Add(gtx.Ops)
 
 	return dims

widget/example_test.go

@@ -47,23 +47,21 @@ func ExampleClickable_passthrough() {
 		pointer.Event{
 			Source:   pointer.Mouse,
 			Buttons:  pointer.ButtonPrimary,
-			Type:     pointer.Press,
+			Kind:     pointer.Press,
 			Position: f32.Pt(50, 50),
 		},
 		pointer.Event{
 			Source:   pointer.Mouse,
 			Buttons:  pointer.ButtonPrimary,
-			Type:     pointer.Release,
+			Kind:     pointer.Release,
 			Position: f32.Pt(50, 50),
 		},
 	)
-	// The second layout ensures that the click event is registered by the buttons.
-	widget()
 
-	if button1.Clicked() {
+	if button1.Clicked(gtx) {
 		fmt.Println("button1 clicked!")
 	}
-	if button2.Clicked() {
+	if button2.Clicked(gtx) {
 		fmt.Println("button2 clicked!")
 	}
 
@@ -95,7 +93,7 @@ func ExampleDraggable_Layout() {
 		drag.Layout(gtx, w, w)
 		// drag must respond with an Offer event when requested.
 		// Use the drag method for this.
-		if m, ok := drag.Requested(); ok {
+		if m, ok := drag.Update(gtx); ok {
 			drag.Offer(gtx.Ops, m, offer{Data: "hello world"})
 		}
 
@@ -125,15 +123,15 @@ func ExampleDraggable_Layout() {
 	// Send drag and drop gesture events.
 	r.Queue(
 		pointer.Event{
-			Type:     pointer.Press,
+			Kind:     pointer.Press,
 			Position: f32.Pt(5, 5), // in the drag area
 		},
 		pointer.Event{
-			Type:     pointer.Move,
+			Kind:     pointer.Move,
 			Position: f32.Pt(5, 5), // in the drop area
 		},
 		pointer.Event{
-			Type:     pointer.Release,
+			Kind:     pointer.Release,
 			Position: f32.Pt(30, 30), // in the drop area
 		},
 	)

widget/float.go

@@ -9,59 +9,29 @@ import (
 	"gioui.org/io/pointer"
 	"gioui.org/layout"
 	"gioui.org/op/clip"
+	"gioui.org/unit"
 )
 
 // Float is for selecting a value in a range.
 type Float struct {
+	// Value is the value of the Float, in the [0; 1] range.
 	Value float32
 
-	drag    gesture.Drag
+	drag   gesture.Drag
-	pos     float32 // position normalized to [0, 1]
+	axis   layout.Axis
-	length  float32
+	length float32
-	changed bool
 }
 
 // Dragging returns whether the value is being interacted with.
 func (f *Float) Dragging() bool { return f.drag.Dragging() }
 
-// Layout updates the value according to drag events along the f's main axis.
+func (f *Float) Layout(gtx layout.Context, axis layout.Axis, pointerMargin unit.Dp) layout.Dimensions {
-//
+	f.Update(gtx)
-// The range of f is set by the minimum constraints main axis value.
-func (f *Float) Layout(gtx layout.Context, axis layout.Axis, min, max float32, invert bool, pointerMargin int) layout.Dimensions {
 	size := gtx.Constraints.Min
 	f.length = float32(axis.Convert(size).X)
+	f.axis = axis
 
-	var de *pointer.Event
+	margin := axis.Convert(image.Pt(gtx.Dp(pointerMargin), 0))
-	for _, e := range f.drag.Events(gtx.Metric, gtx, gesture.Axis(axis)) {
-		if e.Type == pointer.Press || e.Type == pointer.Drag {
-			de = &e
-		}
-	}
-
-	value := f.Value
-	if de != nil {
-		xy := de.Position.X
-		if axis == layout.Vertical {
-			xy = f.length - de.Position.Y
-		}
-		if invert {
-			xy = f.length - xy
-		}
-		f.pos = xy / f.length
-		value = min + (max-min)*f.pos
-	} else if min != max {
-		f.pos = (value - min) / (max - min)
-	}
-	// Unconditionally call setValue in case min, max, or value changed.
-	f.setValue(value, min, max)
-
-	if f.pos < 0 {
-		f.pos = 0
-	} else if f.pos > 1 {
-		f.pos = 1
-	}
-
-	margin := axis.Convert(image.Pt(pointerMargin, 0))
 	rect := image.Rectangle{
 		Min: margin.Mul(-1),
 		Max: size.Add(margin),
@@ -72,30 +42,26 @@ func (f *Float) Layout(gtx layout.Context, axis layout.Axis, min, max float32, i
 	return layout.Dimensions{Size: size}
 }
 
-func (f *Float) setValue(value, min, max float32) {
+// Update the Value according to drag events along the f's main axis.
-	if min > max {
+// The return value reports whether the value was changed.
-		min, max = max, min
+//
+// The range of f is set by the minimum constraints main axis value.
+func (f *Float) Update(gtx layout.Context) bool {
+	changed := false
+	for _, e := range f.drag.Update(gtx.Metric, gtx, gesture.Axis(f.axis)) {
+		if f.length > 0 && (e.Kind == pointer.Press || e.Kind == pointer.Drag) {
+			pos := e.Position.X
+			if f.axis == layout.Vertical {
+				pos = f.length - e.Position.Y
+			}
+			f.Value = pos / f.length
+			if f.Value < 0 {
+				f.Value = 0
+			} else if f.Value > 1 {
+				f.Value = 1
+			}
+			changed = true
+		}
 	}
-	if value < min {
-		value = min
-	} else if value > max {
-		value = max
-	}
-	if f.Value != value {
-		f.Value = value
-		f.changed = true
-	}
-}
-
-// Pos reports the selected position.
-func (f *Float) Pos() float32 {
-	return f.pos * f.length
-}
-
-// Changed reports whether the value has changed since
-// the last call to Changed.
-func (f *Float) Changed() bool {
-	changed := f.changed
-	f.changed = false
 	return changed
 }

widget/label.go

@@ -134,17 +134,17 @@ type textIterator struct {
 
 // processGlyph checks whether the glyph is visible within the iterator's configured
 // viewport and (if so) updates the iterator's text dimensions to include the glyph.
-func (it *textIterator) processGlyph(g text.Glyph, ok bool) (_ text.Glyph, visibleOrBefore bool) {
+func (it *textIterator) processGlyph(g text.Glyph, ok bool) (visibleOrBefore bool) {
 	if it.maxLines > 0 {
 		if g.Flags&text.FlagTruncator != 0 && g.Flags&text.FlagClusterBreak != 0 {
 			// A glyph carrying both of these flags provides the count of truncated runes.
-			it.truncated = g.Runes
+			it.truncated = int(g.Runes)
 		}
 		if g.Flags&text.FlagLineBreak != 0 {
 			it.linesSeen++
 		}
 		if it.linesSeen == it.maxLines && g.Flags&text.FlagParagraphBreak != 0 {
-			return g, false
+			return false
 		}
 	}
 	// Compute the maximum extent to which glyphs overhang on the horizontal
@@ -191,7 +191,7 @@ func (it *textIterator) processGlyph(g text.Glyph, ok bool) (_ text.Glyph, visib
 		it.bounds.Max.X = max(it.bounds.Max.X, logicalBounds.Max.X)
 		it.bounds.Max.Y = max(it.bounds.Max.Y, logicalBounds.Max.Y)
 	}
-	return g, ok && !below
+	return ok && !below
 }
 
 func fixedToFloat(i fixed.Int26_6) float32 {
@@ -206,7 +206,7 @@ func fixedToFloat(i fixed.Int26_6) float32 {
 // This design is awkward, but prevents the line slice from escaping
 // to the heap.
 func (it *textIterator) paintGlyph(gtx layout.Context, shaper *text.Shaper, glyph text.Glyph, line []text.Glyph) ([]text.Glyph, bool) {
-	_, visibleOrBefore := it.processGlyph(glyph, true)
+	visibleOrBefore := it.processGlyph(glyph, true)
 	if it.visible {
 		if len(line) == 0 {
 			it.lineOff = f32.Point{X: fixedToFloat(glyph.X), Y: float32(glyph.Y)}.Sub(layout.FPt(it.viewport.Min))

widget/label_test.go

@@ -146,10 +146,7 @@ func TestGlyphIterator(t *testing.T) {
 			glyphs := getGlyphs(16, 0, maxWidth, text.Start, tc.str)
 			it := textIterator{viewport: tc.viewport, maxLines: tc.maxLines}
 			for i, g := range glyphs {
-				gOut, ok := it.processGlyph(g, true)
+				ok := it.processGlyph(g, true)
-				if gOut != g {
-					t.Errorf("textIterator modified glyphs[%d], original:\n%#+v, modified:\n%#+v", i, g, gOut)
-				}
 				if !ok && i != tc.stopAtGlyph {
 					t.Errorf("expected iterator to stop at glyph %d, stopped at %d", tc.stopAtGlyph, i)
 				}

widget/list.go

@@ -61,8 +61,8 @@ func (s *Scrollbar) Layout(gtx layout.Context, axis layout.Axis, viewportStart,
 	}
 
 	// Jump to a click in the track.
-	for _, event := range s.track.Events(gtx) {
+	for _, event := range s.track.Update(gtx) {
-		if event.Type != gesture.TypeClick ||
+		if event.Kind != gesture.KindClick ||
 			event.Modifiers != key.Modifiers(0) ||
 			event.NumClicks > 1 {
 			continue
@@ -80,8 +80,8 @@ func (s *Scrollbar) Layout(gtx layout.Context, axis layout.Axis, viewportStart,
 	}
 
 	// Offset to account for any drags.
-	for _, event := range s.drag.Events(gtx.Metric, gtx, gesture.Axis(axis)) {
+	for _, event := range s.drag.Update(gtx.Metric, gtx, gesture.Axis(axis)) {
-		switch event.Type {
+		switch event.Kind {
 		case pointer.Drag:
 		case pointer.Release, pointer.Cancel:
 			s.dragging = false
@@ -136,7 +136,7 @@ func (s *Scrollbar) Layout(gtx layout.Context, axis layout.Axis, viewportStart,
 
 	// Process events from the indicator so that hover is
 	// detected properly.
-	_ = s.indicator.Events(gtx)
+	_ = s.indicator.Update(gtx)
 
 	return layout.Dimensions{}
 }

widget/material/slider.go

@@ -16,10 +16,8 @@ import (
 )
 
 // Slider is for selecting a value in a range.
-func Slider(th *Theme, float *widget.Float, min, max float32) SliderStyle {
+func Slider(th *Theme, float *widget.Float) SliderStyle {
 	return SliderStyle{
-		Min:        min,
-		Max:        max,
 		Color:      th.Palette.ContrastBg,
 		Float:      float,
 		FingerSize: th.FingerSize,
@@ -27,35 +25,34 @@ func Slider(th *Theme, float *widget.Float, min, max float32) SliderStyle {
 }
 
 type SliderStyle struct {
-	Axis     layout.Axis
+	Axis  layout.Axis
-	Min, Max float32
+	Color color.NRGBA
-	Invert   bool
+	Float *widget.Float
-	Color    color.NRGBA
-	Float    *widget.Float
 
 	FingerSize unit.Dp
 }
 
 func (s SliderStyle) Layout(gtx layout.Context) layout.Dimensions {
-	thumbRadius := gtx.Dp(6)
+	const thumbRadius unit.Dp = 6
+	tr := gtx.Dp(thumbRadius)
 	trackWidth := gtx.Dp(2)
 
 	axis := s.Axis
 	// Keep a minimum length so that the track is always visible.
-	minLength := thumbRadius + 3*thumbRadius + thumbRadius
+	minLength := tr + 3*tr + tr
 	// Try to expand to finger size, but only if the constraints
 	// allow for it.
 	touchSizePx := min(gtx.Dp(s.FingerSize), axis.Convert(gtx.Constraints.Max).Y)
 	sizeMain := max(axis.Convert(gtx.Constraints.Min).X, minLength)
-	sizeCross := max(2*thumbRadius, touchSizePx)
+	sizeCross := max(2*tr, touchSizePx)
 	size := axis.Convert(image.Pt(sizeMain, sizeCross))
 
-	o := axis.Convert(image.Pt(thumbRadius, 0))
+	o := axis.Convert(image.Pt(tr, 0))
 	trans := op.Offset(o).Push(gtx.Ops)
-	gtx.Constraints.Min = axis.Convert(image.Pt(sizeMain-2*thumbRadius, sizeCross))
+	gtx.Constraints.Min = axis.Convert(image.Pt(sizeMain-2*tr, sizeCross))
-	s.Float.Layout(gtx, axis, s.Min, s.Max, s.Invert, thumbRadius)
+	dims := s.Float.Layout(gtx, axis, thumbRadius)
 	gtx.Constraints.Min = gtx.Constraints.Min.Add(axis.Convert(image.Pt(0, sizeCross)))
-	thumbPos := thumbRadius + int(s.Float.Pos())
+	thumbPos := tr + int(s.Float.Value*float32(axis.Convert(dims.Size).X))
 	trans.Pop()
 
 	color := s.Color
@@ -65,7 +62,7 @@ func (s SliderStyle) Layout(gtx layout.Context) layout.Dimensions {
 
 	rect := func(minx, miny, maxx, maxy int) image.Rectangle {
 		r := image.Rect(minx, miny, maxx, maxy)
-		if s.Invert != (axis == layout.Vertical) {
+		if axis == layout.Vertical {
 			r.Max.X, r.Min.X = sizeMain-r.Min.X, sizeMain-r.Max.X
 		}
 		r.Min = axis.Convert(r.Min)
@@ -75,7 +72,7 @@ func (s SliderStyle) Layout(gtx layout.Context) layout.Dimensions {
 
 	// Draw track before thumb.
 	track := rect(
-		thumbRadius, sizeCross/2-trackWidth/2,
+		tr, sizeCross/2-trackWidth/2,
 		thumbPos, sizeCross/2+trackWidth/2,
 	)
 	paint.FillShape(gtx.Ops, color, clip.Rect(track).Op())
@@ -83,15 +80,15 @@ func (s SliderStyle) Layout(gtx layout.Context) layout.Dimensions {
 	// Draw track after thumb.
 	track = rect(
 		thumbPos, axis.Convert(track.Min).Y,
-		sizeMain-thumbRadius, axis.Convert(track.Max).Y,
+		sizeMain-tr, axis.Convert(track.Max).Y,
 	)
 	paint.FillShape(gtx.Ops, f32color.MulAlpha(color, 96), clip.Rect(track).Op())
 
 	// Draw thumb.
 	pt := image.Pt(thumbPos, sizeCross/2)
 	thumb := rect(
-		pt.X-thumbRadius, pt.Y-thumbRadius,
+		pt.X-tr, pt.Y-tr,
-		pt.X+thumbRadius, pt.Y+thumbRadius,
+		pt.X+tr, pt.Y+tr,
 	)
 	paint.FillShape(gtx.Ops, color, clip.Ellipse(thumb).Op(gtx.Ops))
 

widget/selectable.go

@@ -182,25 +182,31 @@ func (l *Selectable) Truncated() bool {
 	return l.text.Truncated()
 }
 
+// Update the state of the selectable in response to input events.
+func (l *Selectable) Update(gtx layout.Context) {
+	l.initialize()
+	l.handleEvents(gtx)
+}
+
 // Layout clips to the dimensions of the selectable, updates the shaped text, configures input handling, and paints
 // the text and selection rectangles. The provided textMaterial and selectionMaterial ops are used to set the
 // paint material for the text and selection rectangles, respectively.
 func (l *Selectable) Layout(gtx layout.Context, lt *text.Shaper, font font.Font, size unit.Sp, textMaterial, selectionMaterial op.CallOp) layout.Dimensions {
-	l.initialize()
+	l.Update(gtx)
 	l.text.LineHeight = l.LineHeight
 	l.text.LineHeightScale = l.LineHeightScale
 	l.text.Alignment = l.Alignment
 	l.text.MaxLines = l.MaxLines
 	l.text.Truncator = l.Truncator
 	l.text.WrapPolicy = l.WrapPolicy
-	l.text.Update(gtx, lt, font, size, l.handleEvents)
+	l.text.Layout(gtx, lt, font, size)
 	dims := l.text.Dimensions()
 	defer clip.Rect(image.Rectangle{Max: dims.Size}).Push(gtx.Ops).Pop()
 	pointer.CursorText.Add(gtx.Ops)
 	var keys key.Set
 	if l.focused {
-		const keyFilterAllArrows = "(ShortAlt)-(Shift)-[←,→,↑,↓]|(Shift)-[⏎,⌤]|(ShortAlt)-(Shift)-[⌫,⌦]|(Shift)-[⇞,⇟,⇱,⇲]|Short-[C,V,X,A]|Short-(Shift)-Z"
+		const keyFilter = "(ShortAlt)-(Shift)-[←,→,↑,↓]|(Shift)-[⇞,⇟,⇱,⇲]|Short-[C,X,A]"
-		keys = keyFilterAllArrows
+		keys = keyFilter
 	}
 	key.InputOp{Tag: l, Keys: keys}.Add(gtx.Ops)
 	if l.requestFocus {
@@ -236,8 +242,8 @@ func (e *Selectable) processPointer(gtx layout.Context) {
 		switch evt := evt.(type) {
 		case gesture.ClickEvent:
 			switch {
-			case evt.Type == gesture.TypePress && evt.Source == pointer.Mouse,
+			case evt.Kind == gesture.KindPress && evt.Source == pointer.Mouse,
-				evt.Type == gesture.TypeClick && evt.Source != pointer.Mouse:
+				evt.Kind == gesture.KindClick && evt.Source != pointer.Mouse:
 				prevCaretPos, _ := e.text.Selection()
 				e.text.MoveCoord(image.Point{
 					X: int(math.Round(float64(evt.Position.X))),
@@ -271,10 +277,10 @@ func (e *Selectable) processPointer(gtx layout.Context) {
 		case pointer.Event:
 			release := false
 			switch {
-			case evt.Type == pointer.Release && evt.Source == pointer.Mouse:
+			case evt.Kind == pointer.Release && evt.Source == pointer.Mouse:
 				release = true
 				fallthrough
-			case evt.Type == pointer.Drag && evt.Source == pointer.Mouse:
+			case evt.Kind == pointer.Drag && evt.Source == pointer.Mouse:
 				if e.dragging {
 					e.text.MoveCoord(image.Point{
 						X: int(math.Round(float64(evt.Position.X))),
@@ -292,10 +298,10 @@ func (e *Selectable) processPointer(gtx layout.Context) {
 
 func (e *Selectable) clickDragEvents(gtx layout.Context) []event.Event {
 	var combinedEvents []event.Event
-	for _, evt := range e.clicker.Events(gtx) {
+	for _, evt := range e.clicker.Update(gtx) {
 		combinedEvents = append(combinedEvents, evt)
 	}
-	for _, evt := range e.dragger.Events(gtx.Metric, gtx, gesture.Both) {
+	for _, evt := range e.dragger.Update(gtx.Metric, gtx, gesture.Both) {
 		combinedEvents = append(combinedEvents, evt)
 	}
 	return combinedEvents

widget/text.go

@@ -228,10 +228,8 @@ func (e *textView) calculateViewSize(gtx layout.Context) image.Point {
 	return gtx.Constraints.Constrain(base)
 }
 
-// Update the text, reshaping it as necessary. If not nil, eventHandling will be invoked after reshaping the text to
+// Layout the text, reshaping it as necessary.
-// allow parent widgets to adapt to any changes in text content or positioning. If eventHandling modifies the contents
+func (e *textView) Layout(gtx layout.Context, lt *text.Shaper, font font.Font, size unit.Sp) {
-// of the textView, it is guaranteed to be reshaped (and ready for painting) before Update returns.
-func (e *textView) Update(gtx layout.Context, lt *text.Shaper, font font.Font, size unit.Sp, eventHandling func(gtx layout.Context)) {
 	if e.params.Locale != gtx.Locale {
 		e.params.Locale = gtx.Locale
 		e.invalidate()
@@ -289,10 +287,6 @@ func (e *textView) Update(gtx layout.Context, lt *text.Shaper, font font.Font, s
 	}
 
 	e.makeValid()
-	if eventHandling != nil {
-		eventHandling(gtx)
-		e.makeValid()
-	}
 
 	if viewSize := e.calculateViewSize(gtx); viewSize != e.viewSize {
 		e.viewSize = viewSize
@@ -492,14 +486,19 @@ func (e *textView) layoutText(lt *text.Shaper) {
 	it := textIterator{viewport: image.Rectangle{Max: image.Point{X: math.MaxInt, Y: math.MaxInt}}}
 	if lt != nil {
 		lt.Layout(e.params, r)
-		for glyph, ok := it.processGlyph(lt.NextGlyph()); ok; glyph, ok = it.processGlyph(lt.NextGlyph()) {
+		for {
-			e.index.Glyph(glyph)
+			g, ok := lt.NextGlyph()
+			if !it.processGlyph(g, ok) {
+				break
+			}
+			e.index.Glyph(g)
 		}
 	} else {
 		// Make a fake glyph for every rune in the reader.
 		b := bufio.NewReader(r)
 		for _, _, err := b.ReadRune(); err != io.EOF; _, _, err = b.ReadRune() {
-			g, _ := it.processGlyph(text.Glyph{Runes: 1, Flags: text.FlagClusterBreak}, true)
+			g := text.Glyph{Runes: 1, Flags: text.FlagClusterBreak}
+			_ = it.processGlyph(g, true)
 			e.index.Glyph(g)
 		}
 	}

widget/text_bench_test.go

@@ -7,7 +7,6 @@ import (
 	"os"
 	"sort"
 	"testing"
-	"time"
 
 	colEmoji "eliasnaur.com/font/noto/emoji/color"
 	"gioui.org/font"
@@ -48,10 +47,6 @@ var (
 	}()
 )
 
-func init() {
-	rand.Seed(int64(time.Now().Nanosecond()))
-}
-
 func runBenchmarkPermutations(b *testing.B, benchmark func(b *testing.B, runes int, locale system.Locale, document string)) {
 	docKeys := maps.Keys(documents)
 	sort.Strings(docKeys)
@@ -127,11 +122,12 @@ func BenchmarkLabelDynamic(b *testing.B) {
 		font := font.Font{}
 		runes := []rune(txt)[:runeCount]
 		l := Label{}
+		r := rand.New(rand.NewSource(42))
 		b.ResetTimer()
 		for i := 0; i < b.N; i++ {
 			// simulate a constantly changing string
-			a := rand.Intn(len(runes))
+			a := r.Intn(len(runes))
-			b := rand.Intn(len(runes))
+			b := r.Intn(len(runes))
 			runes[a], runes[b] = runes[b], runes[a]
 			l.Layout(gtx, cache, font, fontSize, string(runes), op.CallOp{})
 			if render {
@@ -196,11 +192,12 @@ func BenchmarkEditorDynamic(b *testing.B) {
 		runes := []rune(txt)[:runeCount]
 		e := Editor{}
 		e.SetText(string(runes))
+		r := rand.New(rand.NewSource(42))
 		b.ResetTimer()
 		for i := 0; i < b.N; i++ {
 			// simulate a constantly changing string
-			a := rand.Intn(e.Len())
+			a := r.Intn(e.Len())
-			b := rand.Intn(e.Len())
+			b := r.Intn(e.Len())
 			e.SetCaret(a, a+1)
 			takeStr := e.SelectedText()
 			e.Insert("")

widget/widget_test.go

@@ -35,12 +35,12 @@ func TestBool(t *testing.T) {
 	r.Queue(
 		pointer.Event{
 			Source:   pointer.Touch,
-			Type:     pointer.Press,
+			Kind:     pointer.Press,
 			Position: f32.Pt(50, 50),
 		},
 		pointer.Event{
 			Source:   pointer.Touch,
-			Type:     pointer.Release,
+			Kind:     pointer.Release,
 			Position: f32.Pt(50, 50),
 		},
 	)