ui: Add SetInitFocused

Updates #769

examples/windowsize/main.go

@@ -58,6 +58,7 @@ var (
 	flagWindowPosition    = flag.String("windowposition", "", "window position (e.g., 100,200)")
 	flagScreenTransparent = flag.Bool("screentransparent", false, "screen transparent")
 	flagAutoAdjusting     = flag.Bool("autoadjusting", false, "make the game screen auto-adjusting")
+	flagInitFocused       = flag.Bool("initfocused", true, "whether the window is focused on start")
 )
 
 func init() {
@@ -370,6 +371,11 @@ func main() {
 		ebiten.SetWindowResizable(true)
 	}
 
+	ebiten.SetInitFocused(*flagInitFocused)
+	if !*flagInitFocused {
+		ebiten.SetRunnableInBackground(true)
+	}
+
 	const title = "Window Size (Ebiten Demo)"
 	if *flagLegacy {
 		if err := ebiten.Run(g.Update, g.width, g.height, initScreenScale, title); err != nil {

internal/driver/ui.go

@@ -49,6 +49,7 @@ type UI interface {
 	SetRunnableInBackground(runnableInBackground bool)
 	SetVsyncEnabled(enabled bool)
 	SetScreenTransparent(transparent bool)
+	SetInitFocused(focused bool)
 
 	Input() Input
 	Window() Window

internal/glfw/const.go

@@ -78,6 +78,7 @@ const (
 	ContextVersionMinor    = Hint(0x00022003)
 	Decorated              = Hint(0x00020005)
 	Focused                = Hint(0x00020001)
+	FocusOnShow            = Hint(0x0002000C)
 	Resizable              = Hint(0x00020003)
 	TransparentFramebuffer = Hint(0x0002000A)
 	Visible                = Hint(0x00020004)

internal/uidriver/glfw/ui.go

@@ -68,6 +68,7 @@ type UserInterface struct {
 	initWindowHeightInDP     int
 	initScreenTransparent    bool
 	initIconImages           []image.Image
+	initFocused              bool
 
 	reqWidth  int
 	reqHeight int
@@ -95,6 +96,7 @@ var (
 		initWindowPositionYInDP: invalidPos,
 		initWindowWidthInDP:     640,
 		initWindowHeightInDP:    480,
+		initFocused:             true,
 		vsync:                   true,
 	}
 )
@@ -334,6 +336,19 @@ func (u *UserInterface) setInitWindowSize(width, height int) {
 	u.m.Unlock()
 }
 
+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()
+}
+
 // toDeviceIndependentPixel must be called from the main thread.
 func (u *UserInterface) toDeviceIndependentPixel(x float64) float64 {
 	return x / u.glfwScale()
@@ -628,6 +643,12 @@ func (u *UserInterface) run(context driver.UIContext) error {
 		}
 		glfw.WindowHint(glfw.Resizable, resizable)
 
+		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)
@@ -1015,6 +1036,13 @@ func (u *UserInterface) MonitorPosition() (int, int) {
 	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()

internal/uidriver/js/ui.go

@@ -33,6 +33,7 @@ type UserInterface struct {
 	runnableInBackground bool
 	vsync                bool
 	running              bool
+	initFocused          bool
 
 	sizeChanged bool
 	contextLost bool
@@ -46,6 +47,7 @@ type UserInterface struct {
 var theUI = &UserInterface{
 	sizeChanged: true,
 	vsync:       true,
+	initFocused: true,
 }
 
 func init() {
@@ -405,7 +407,9 @@ 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) MonitorPosition() (int, int) {
 	return 0, 0
 }
 
+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

@@ -420,6 +420,10 @@ func (u *UserInterface) MonitorPosition() (int, int) {
 	return 0, 0
 }
 
+func (u *UserInterface) SetInitFocused(focused bool) {
+	// Do nothing
+}
+
 func (u *UserInterface) Input() driver.Input {
 	return &u.input
 }

run.go

@@ -486,3 +486,17 @@ 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)
+}