app: [API] remove StageEvent and Stage

StageEvent served only redundant purposes:

- To detect whether the window has focus. That is covered by
  key.FocusEvent.
- To detect whether the window is currently visible. That is covered by
  the absence or presence of FrameEvents.
- To detect when the window native handle is valid. That is
  covered by ViewEvent.

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

app/os_android.go

@@ -161,7 +161,7 @@ type window struct {
 	fontScale float32
 	insets    pixelInsets
 
-	stage     Stage
+	visible   bool
 	started   bool
 	animating bool
 
@@ -509,11 +509,11 @@ func Java_org_gioui_GioView_onCreateView(env *C.JNIEnv, class C.jclass, view C.j
 		w.detach(env)
 	}
 	w.view = view
+	w.visible = false
 	w.handle = cgo.NewHandle(w)
 	w.loadConfig(env, class)
 	w.setConfig(env, cnf)
 	w.SetInputHint(w.inputHint)
-	w.setStage(StagePaused)
 	w.processEvent(AndroidViewEvent{View: uintptr(view)})
 	return C.jlong(w.handle)
 }
@@ -528,7 +528,7 @@ func Java_org_gioui_GioView_onDestroyView(env *C.JNIEnv, class C.jclass, handle
 func Java_org_gioui_GioView_onStopView(env *C.JNIEnv, class C.jclass, handle C.jlong) {
 	w := cgo.Handle(handle).Value().(*window)
 	w.started = false
-	w.setStage(StagePaused)
+	w.visible = false
 }
 
 //export Java_org_gioui_GioView_onStartView
@@ -544,7 +544,7 @@ func Java_org_gioui_GioView_onStartView(env *C.JNIEnv, class C.jclass, handle C.
 func Java_org_gioui_GioView_onSurfaceDestroyed(env *C.JNIEnv, class C.jclass, handle C.jlong) {
 	w := cgo.Handle(handle).Value().(*window)
 	w.win = nil
-	w.setStage(StagePaused)
+	w.visible = false
 }
 
 //export Java_org_gioui_GioView_onSurfaceChanged
@@ -566,9 +566,7 @@ func Java_org_gioui_GioView_onLowMemory(env *C.JNIEnv, class C.jclass) {
 func Java_org_gioui_GioView_onConfigurationChanged(env *C.JNIEnv, class C.jclass, view C.jlong) {
 	w := cgo.Handle(view).Value().(*window)
 	w.loadConfig(env, class)
-	if w.stage >= StageInactive {
+	w.draw(env, true)
-		w.draw(env, true)
-	}
 }
 
 //export Java_org_gioui_GioView_onFrameCallback
@@ -577,10 +575,7 @@ func Java_org_gioui_GioView_onFrameCallback(env *C.JNIEnv, class C.jclass, view
 	if !exist {
 		return
 	}
-	if w.stage < StageInactive {
+	if w.visible && w.animating {
-		return
-	}
-	if w.animating {
 		w.draw(env, false)
 		callVoidMethod(env, w.view, gioView.postFrameCallback)
 	}
@@ -610,9 +605,7 @@ func Java_org_gioui_GioView_onWindowInsets(env *C.JNIEnv, class C.jclass, view C
 		left:   int(left),
 		right:  int(right),
 	}
-	if w.stage >= StageInactive {
+	w.draw(env, true)
-		w.draw(env, true)
-	}
 }
 
 //export Java_org_gioui_GioView_initializeAccessibilityNodeInfo
@@ -816,18 +809,10 @@ func (w *window) setVisible(env *C.JNIEnv) {
 	if width == 0 || height == 0 {
 		return
 	}
-	w.setStage(StageRunning)
+	w.visible = true
 	w.draw(env, true)
 }
 
-func (w *window) setStage(stage Stage) {
-	if stage == w.stage {
-		return
-	}
-	w.stage = stage
-	w.processEvent(StageEvent{stage})
-}
-
 func (w *window) setVisual(visID int) error {
 	if C.ANativeWindow_setBuffersGeometry(w.win, 0, 0, C.int32_t(visID)) != 0 {
 		return errors.New("ANativeWindow_setBuffersGeometry failed")
@@ -864,6 +849,9 @@ func (w *window) SetAnimating(anim bool) {
 }
 
 func (w *window) draw(env *C.JNIEnv, sync bool) {
+	if !w.visible {
+		return
+	}
 	size := image.Pt(int(C.ANativeWindow_getWidth(w.win)), int(C.ANativeWindow_getHeight(w.win)))
 	if size != w.config.Size {
 		w.config.Size = size

app/os_ios.go

@@ -138,7 +138,6 @@ func onCreate(view, controller C.CFTypeRef) {
 	w.displayLink = dl
 	C.gio_viewSetHandle(view, C.uintptr_t(cgo.NewHandle(w)))
 	w.Configure(wopts.options)
-	w.ProcessEvent(StageEvent{Stage: StageRunning})
 	w.ProcessEvent(UIKitViewEvent{ViewController: uintptr(controller)})
 }
 
@@ -189,14 +188,12 @@ func (w *window) draw(sync bool) {
 func onStop(h C.uintptr_t) {
 	w := viewFor(h)
 	w.hidden = true
-	w.ProcessEvent(StageEvent{Stage: StagePaused})
 }
 
 //export onStart
 func onStart(h C.uintptr_t) {
 	w := viewFor(h)
 	w.hidden = false
-	w.ProcessEvent(StageEvent{Stage: StageRunning})
 	w.draw(true)
 }
 

app/os_js.go

@@ -115,7 +115,6 @@ func newWindow(win *callbacks, options []Option) {
 	w.Configure(options)
 	w.blur()
 	w.processEvent(JSViewEvent{Element: cont})
-	w.processEvent(StageEvent{Stage: StageRunning})
 	w.resize()
 	w.draw(true)
 }
@@ -195,17 +194,6 @@ func (w *window) addEventListeners() {
 		}
 		return w.browserHistory.Call("back")
 	})
-	w.addEventListener(w.document, "visibilitychange", func(this js.Value, args []js.Value) interface{} {
-		ev := StageEvent{}
-		switch w.document.Get("visibilityState").String() {
-		case "hidden", "prerender", "unloaded":
-			ev.Stage = StagePaused
-		default:
-			ev.Stage = StageRunning
-		}
-		w.processEvent(ev)
-		return nil
-	})
 	w.addEventListener(w.cnv, "mousemove", func(this js.Value, args []js.Value) interface{} {
 		w.pointerEvent(pointer.Move, 0, 0, args[0])
 		return nil

app/os_macos.go

@@ -309,7 +309,8 @@ type AppKitViewEvent struct {
 type window struct {
 	view        C.CFTypeRef
 	w           *callbacks
-	stage       Stage
+	anim        bool
+	visible     bool
 	displayLink *displayLink
 	// redraw is a single entry channel for making sure only one
 	// display link redraw request is in flight.
@@ -507,7 +508,8 @@ func (w *window) ShowTextInput(show bool) {}
 func (w *window) SetInputHint(_ key.InputHint) {}
 
 func (w *window) SetAnimating(anim bool) {
-	if anim {
+	w.anim = anim
+	if w.anim && w.visible {
 		w.displayLink.Start()
 	} else {
 		w.displayLink.Stop()
@@ -524,14 +526,6 @@ func (w *window) runOnMain(f func()) {
 	})
 }
 
-func (w *window) setStage(stage Stage) {
-	if stage == w.stage {
-		return
-	}
-	w.stage = stage
-	w.ProcessEvent(StageEvent{Stage: stage})
-}
-
 //export gio_onKeys
 func gio_onKeys(h C.uintptr_t, cstr C.CFTypeRef, ti C.double, mods C.NSUInteger, keyDown C.bool) {
 	str := nsstringToString(cstr)
@@ -619,13 +613,6 @@ func gio_onDraw(h C.uintptr_t) {
 func gio_onFocus(h C.uintptr_t, focus C.int) {
 	w := windowFor(h)
 	w.ProcessEvent(key.FocusEvent{Focus: focus == 1})
-	if w.stage >= StageInactive {
-		if focus == 0 {
-			w.setStage(StageInactive)
-		} else {
-			w.setStage(StageRunning)
-		}
-	}
 	w.SetCursor(w.cursor)
 }
 
@@ -804,6 +791,10 @@ func (w *window) draw() {
 	case <-w.redraw:
 	default:
 	}
+	w.visible = true
+	if w.anim {
+		w.SetAnimating(w.anim)
+	}
 	w.scale = float32(C.getViewBackingScale(w.view))
 	wf, hf := float32(C.viewWidth(w.view)), float32(C.viewHeight(w.view))
 	sz := image.Point{
@@ -818,7 +809,6 @@ func (w *window) draw() {
 		return
 	}
 	cfg := configFor(w.scale)
-	w.setStage(StageRunning)
 	w.ProcessEvent(frameEvent{
 		FrameEvent: FrameEvent{
 			Now:    time.Now(),
@@ -865,7 +855,8 @@ func gio_onAttached(h C.uintptr_t, attached C.int) {
 		w.ProcessEvent(AppKitViewEvent{View: uintptr(w.view), Layer: uintptr(layer)})
 	} else {
 		w.ProcessEvent(AppKitViewEvent{})
-		w.setStage(StagePaused)
+		w.visible = false
+		w.SetAnimating(w.anim)
 	}
 }
 
@@ -882,13 +873,14 @@ func gio_onDestroy(h C.uintptr_t) {
 //export gio_onHide
 func gio_onHide(h C.uintptr_t) {
 	w := windowFor(h)
-	w.setStage(StagePaused)
+	w.visible = false
+	w.SetAnimating(w.anim)
 }
 
 //export gio_onShow
 func gio_onShow(h C.uintptr_t) {
 	w := windowFor(h)
-	w.setStage(StageRunning)
+	w.draw()
 }
 
 //export gio_onFullscreen
@@ -956,7 +948,9 @@ func (w *window) init() error {
 			return
 		}
 		w.runOnMain(func() {
-			C.setNeedsDisplay(w.view)
+			if w.visible {
+				C.setNeedsDisplay(w.view)
+			}
 		})
 	})
 	w.displayLink = dl

app/os_wayland.go

@@ -199,7 +199,7 @@ type window struct {
 		dir            f32.Point
 	}
 
-	stage             Stage
+	configured        bool
 	lastFrameCallback *C.struct_wl_callback
 
 	animating bool
@@ -549,7 +549,7 @@ func gio_onXdgSurfaceConfigure(data unsafe.Pointer, wmSurf *C.struct_xdg_surface
 	w := callbackLoad(data).(*window)
 	w.serial = serial
 	C.xdg_surface_ack_configure(wmSurf, serial)
-	w.setStage(StageRunning)
+	w.configured = true
 	w.draw(true)
 }
 
@@ -1738,10 +1738,7 @@ func (w *window) updateOutputs() {
 		C.wl_surface_set_buffer_scale(w.surf, C.int32_t(w.scale))
 		w.draw(true)
 	}
-	if !found {
+	if found {
-		w.setStage(StagePaused)
-	} else {
-		w.setStage(StageRunning)
 		w.draw(true)
 	}
 }
@@ -1755,6 +1752,9 @@ func (w *window) getConfig() (image.Point, unit.Metric) {
 }
 
 func (w *window) draw(sync bool) {
+	if !w.configured {
+		return
+	}
 	w.flushScroll()
 	size, cfg := w.getConfig()
 	if cfg == (unit.Metric{}) {
@@ -1785,14 +1785,6 @@ func (w *window) draw(sync bool) {
 	})
 }
 
-func (w *window) setStage(s Stage) {
-	if s == w.stage {
-		return
-	}
-	w.stage = s
-	w.ProcessEvent(StageEvent{Stage: s})
-}
-
 func (w *window) display() *C.struct_wl_display {
 	return w.disp.disp
 }

app/os_windows.go

@@ -39,7 +39,6 @@ type window struct {
 	hwnd        syscall.Handle
 	hdc         syscall.Handle
 	w           *callbacks
-	stage       Stage
 	pointerBtns pointer.Buttons
 
 	// cursorIn tracks whether the cursor was inside the window according
@@ -275,14 +274,6 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 	case windows.WM_KILLFOCUS:
 		w.focused = false
 		w.ProcessEvent(key.FocusEvent{Focus: false})
-	case windows.WM_NCACTIVATE:
-		if w.stage >= StageInactive {
-			if wParam == windows.TRUE {
-				w.setStage(StageRunning)
-			} else {
-				w.setStage(StageInactive)
-			}
-		}
 	case windows.WM_NCHITTEST:
 		if w.config.Decorated {
 			// Let the system handle it.
@@ -348,15 +339,12 @@ func windowProc(hwnd syscall.Handle, msg uint32, wParam, lParam uintptr) uintptr
 		switch wParam {
 		case windows.SIZE_MINIMIZED:
 			w.config.Mode = Minimized
-			w.setStage(StagePaused)
 		case windows.SIZE_MAXIMIZED:
 			w.config.Mode = Maximized
-			w.setStage(StageRunning)
 		case windows.SIZE_RESTORED:
 			if w.config.Mode != Fullscreen {
 				w.config.Mode = Windowed
 			}
-			w.setStage(StageRunning)
 		}
 	case windows.WM_GETMINMAXINFO:
 		mm := (*windows.MinMaxInfo)(unsafe.Pointer(lParam))
@@ -645,13 +633,6 @@ func (w *window) wakeup() {
 	}
 }
 
-func (w *window) setStage(s Stage) {
-	if s != w.stage {
-		w.stage = s
-		w.ProcessEvent(StageEvent{Stage: s})
-	}
-}
-
 func (w *window) draw(sync bool) {
 	if w.config.Size.X == 0 || w.config.Size.Y == 0 {
 		return

app/os_x11.go

@@ -95,7 +95,6 @@ type x11Window struct {
 		// _NET_WM_STATE_MAXIMIZED_VERT
 		wmStateMaximizedVert C.Atom
 	}
-	stage  Stage
 	metric unit.Metric
 	notify struct {
 		read, write int
@@ -437,14 +436,6 @@ func (w *x11Window) window() (C.Window, int, int) {
 	return w.xw, w.config.Size.X, w.config.Size.Y
 }
 
-func (w *x11Window) setStage(s Stage) {
-	if s == w.stage {
-		return
-	}
-	w.stage = s
-	w.ProcessEvent(StageEvent{Stage: s})
-}
-
 func (w *x11Window) dispatch() {
 	if w.x == nil {
 		// Only Invalidate can wake us up.
@@ -879,7 +870,6 @@ func newX11Window(gioWin *callbacks, options []Option) error {
 	C.XMapWindow(dpy, win)
 	w.Configure(options)
 	w.ProcessEvent(X11ViewEvent{Display: unsafe.Pointer(dpy), Window: uintptr(win)})
-	w.setStage(StageRunning)
 	return nil
 }
 

app/system.go

@@ -10,40 +10,4 @@ type DestroyEvent struct {
 	Err error
 }
 
-// A StageEvent is generated whenever the stage of a
-// Window changes.
-type StageEvent struct {
-	Stage Stage
-}
-
-// Stage of a Window.
-type Stage uint8
-
-const (
-	// StagePaused is the stage for windows that have no on-screen representation.
-	// Paused windows don't receive frames.
-	StagePaused Stage = iota
-	// StageInactive is the stage for windows that are visible, but not active.
-	// Inactive windows receive frames.
-	StageInactive
-	// StageRunning is for active and visible Windows.
-	// Running windows receive frames.
-	StageRunning
-)
-
-// String implements fmt.Stringer.
-func (l Stage) String() string {
-	switch l {
-	case StagePaused:
-		return "StagePaused"
-	case StageInactive:
-		return "StageInactive"
-	case StageRunning:
-		return "StageRunning"
-	default:
-		panic("unexpected Stage value")
-	}
-}
-
-func (StageEvent) ImplementsEvent()   {}
 func (DestroyEvent) ImplementsEvent() {}

app/window.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"image"
 	"image/color"
+	"reflect"
 	"runtime"
 	"sync"
 	"time"
@@ -53,7 +54,6 @@ type Window struct {
 		update chan time.Time
 	}
 
-	stage        Stage
 	animating    bool
 	hasNextFrame bool
 	nextFrame    time.Time
@@ -109,7 +109,6 @@ type eventSummary struct {
 	cfg     *ConfigEvent
 	view    *ViewEvent
 	frame   *frameEvent
-	stage   *StageEvent
 	destroy *DestroyEvent
 }
 
@@ -328,7 +327,7 @@ func (w *Window) updateAnimation() {
 		return
 	}
 	animate := false
-	if w.stage >= StageInactive && w.hasNextFrame {
+	if w.hasNextFrame {
 		if dt := time.Until(w.nextFrame); dt <= 0 {
 			animate = true
 		} else {
@@ -566,10 +565,6 @@ func (c *callbacks) nextEvent() (event.Event, bool) {
 		e := *s.cfg
 		s.cfg = nil
 		return e, true
-	case s.stage != nil:
-		e := *s.stage
-		s.stage = nil
-		return e, true
 	case s.frame != nil:
 		e := *s.frame
 		s.frame = nil
@@ -582,28 +577,12 @@ func (c *callbacks) nextEvent() (event.Event, bool) {
 
 func (w *Window) processEvent(e event.Event) bool {
 	switch e2 := e.(type) {
-	case StageEvent:
-		if e2.Stage < StageInactive {
-			if w.gpu != nil {
-				w.ctx.Lock()
-				w.gpu.Release()
-				w.gpu = nil
-				w.ctx.Unlock()
-			}
-		}
-		w.stage = e2.Stage
-		w.updateAnimation()
-		w.coalesced.stage = &e2
 	case wakeupEvent:
 		w.coalesced.wakeup = true
 	case frameEvent:
 		if e2.Size == (image.Point{}) {
 			panic(errors.New("internal error: zero-sized Draw"))
 		}
-		if w.stage < StageInactive {
-			// No drawing if not visible.
-			break
-		}
 		w.metric = e2.Metric
 		w.hasNextFrame = false
 		e2.Frame = w.driver.Frame
@@ -643,6 +622,12 @@ func (w *Window) processEvent(e event.Event) bool {
 		}
 		w.coalesced.destroy = &e2
 	case ViewEvent:
+		if reflect.ValueOf(e2).IsZero() && w.gpu != nil {
+			w.ctx.Lock()
+			w.gpu.Release()
+			w.gpu = nil
+			w.ctx.Unlock()
+		}
 		w.coalesced.view = &e2
 	case ConfigEvent:
 		w.decorations.Config = e2.Config