ui: Add SetInitFocused

Fixes #769

examples/windowsize/main.go

@@ -61,6 +61,7 @@ var (
 	flagFloating          = flag.Bool("floating", false, "make the window floating")
 	flagMaximize          = flag.Bool("maximize", false, "maximize the window")
 	flagVsync             = flag.Bool("vsync", true, "enable vsync")
+	flagInitFocused       = flag.Bool("initfocused", true, "whether the window is focused on start")
 )
 
 func init() {
@@ -420,6 +421,11 @@ func main() {
 		ebiten.SetWindowResizable(true)
 	}
 
+	ebiten.SetInitFocused(*flagInitFocused)
+	if !*flagInitFocused {
+		ebiten.SetRunnableOnUnfocused(true)
+	}
+
 	const title = "Window Size (Ebiten Demo)"
 	if *flagLegacy {
 		update := func(screen *ebiten.Image) error {

internal/driver/ui.go

@@ -54,6 +54,7 @@ type UI interface {
 
 	IsScreenTransparent() bool
 	SetScreenTransparent(transparent bool)
+	SetInitFocused(focused bool)
 
 	Input() Input
 	Window() Window

internal/glfw/const.go

@@ -79,6 +79,7 @@ const (
 	Decorated              = Hint(0x00020005)
 	Floating               = Hint(0x00020007)
 	Focused                = Hint(0x00020001)
+	FocusOnShow            = Hint(0x0002000C)
 	Iconified              = Hint(0x00020002)
 	Maximized              = Hint(0x00020008)
 	Resizable              = Hint(0x00020003)

internal/uidriver/glfw/ui.go

@@ -72,6 +72,7 @@ type UserInterface struct {
 	initWindowMaximized      bool
 	initScreenTransparent    bool
 	initIconImages           []image.Image
+	initFocused              bool
 
 	vsyncInited bool
 
@@ -102,6 +103,8 @@ var (
 		initWindowPositionYInDP: invalidPos,
 		initWindowWidthInDP:     640,
 		initWindowHeightInDP:    480,
+		initFocused:             true,
+		vsync:                   true,
 	}
 )
 
@@ -371,6 +374,18 @@ func (u *UserInterface) isInitWindowMaximized() bool {
 func (u *UserInterface) setInitWindowMaximized(floating bool) {
 	u.m.Lock()
 	u.initWindowMaximized = floating
+}
+
+func (u *UserInterface) isInitFocused() bool {
+	u.m.Lock()
+	v := u.initFocused
+	u.m.Unlock()
+	return v
+}
+
+func (u *UserInterface) setInitFocused(focused bool) {
+	u.m.Lock()
+	u.initFocused = focused
 	u.m.Unlock()
 }
 
@@ -693,6 +708,12 @@ func (u *UserInterface) run() error {
 		}
 		glfw.WindowHint(glfw.Floating, floating)
 
+		focused := glfw.False
+		if u.isInitFocused() {
+			focused = glfw.True
+		}
+		glfw.WindowHint(glfw.FocusOnShow, focused)
+
 		// Set the window visible explicitly or the application freezes on Wayland (#974).
 		if os.Getenv("WAYLAND_DISPLAY") != "" {
 			glfw.WindowHint(glfw.Visible, glfw.True)
@@ -1109,6 +1130,30 @@ func (u *UserInterface) ResetForFrame() {
 	u.input.resetForFrame()
 }
 
+func (u *UserInterface) MonitorPosition() (int, int) {
+	if !u.isRunning() {
+		return u.monitorPosition()
+	}
+	var mx, my int
+	_ = u.t.Call(func() error {
+		mx, my = u.monitorPosition()
+		return nil
+	})
+	return mx, my
+}
+
+func (u *UserInterface) SetInitFocused(focused bool) {
+	if u.isRunning() {
+		panic("ui: SetInitFocused must be called before the main loop")
+	}
+	u.setInitFocused(focused)
+}
+
+func (u *UserInterface) monitorPosition() (int, int) {
+	// TODO: toDeviceIndependentPixel might be required.
+	return u.currentMonitor().GetPos()
+}
+
 func (u *UserInterface) Input() driver.Input {
 	return &u.input
 }

internal/uidriver/js/ui.go

@@ -34,6 +34,7 @@ type UserInterface struct {
 	runnableOnUnfocused bool
 	vsync               bool
 	running             bool
+	initFocused         bool
 
 	sizeChanged bool
 	contextLost bool
@@ -47,6 +48,7 @@ type UserInterface struct {
 var theUI = &UserInterface{
 	sizeChanged: true,
 	vsync:       true,
+	initFocused: true,
 }
 
 func init() {
@@ -404,7 +406,9 @@ func init() {
 }
 
 func (u *UserInterface) Run(context driver.UIContext) error {
-	canvas.Call("focus")
+	if u.initFocused {
+		canvas.Call("focus")
+	}
 	u.running = true
 	ch := u.loop(context)
 	if runtime.GOARCH == "wasm" {
@@ -460,6 +464,13 @@ func (u *UserInterface) ResetForFrame() {
 	u.input.resetForFrame()
 }
 
+func (u *UserInterface) SetInitFocused(focused bool) {
+	if u.running {
+		panic("ui: SetInitFocused must be called before the main loop")
+	}
+	u.initFocused = focused
+}
+
 func (u *UserInterface) Input() driver.Input {
 	return &u.input
 }

internal/uidriver/mobile/ui.go

@@ -441,6 +441,10 @@ func (u *UserInterface) ResetForFrame() {
 	u.input.resetForFrame()
 }
 
+func (u *UserInterface) SetInitFocused(focused bool) {
+	// Do nothing
+}
+
 func (u *UserInterface) Input() driver.Input {
 	return &u.input
 }

run.go

@@ -618,3 +618,17 @@ func IsScreenTransparent() bool {
 func SetScreenTransparent(transparent bool) {
 	uiDriver().SetScreenTransparent(transparent)
 }
+
+// SetInitFocused sets whether the application is focused on show.
+// The default value is true, i.e., the application is focused.
+// Note that the application does not proceed if this is not focused by default.
+// This behavior can be changed by SetRunnableInBackground.
+//
+// SetInitFocused does nothing on mobile.
+//
+// SetInitFocused panics if this is called after the main loop.
+//
+// SetInitFocused is cuncurrent-safe.
+func SetInitFocused(focused bool) {
+	uiDriver().SetInitFocused(focused)
+}