ebiten: add RequestAttention

Closes #2998

examples/requestattention/main.go

@@ -0,0 +1,70 @@
+// Copyright 2024 The Ebitengine Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"fmt"
+	"math"
+
+	"github.com/hajimehoshi/ebiten/v2"
+	"github.com/hajimehoshi/ebiten/v2/ebitenutil"
+)
+
+const (
+	screenWidth  = 640
+	screenHeight = 480
+)
+
+type Game struct {
+	count int
+}
+
+func (g *Game) Update() error {
+	if g.count > 0 {
+		g.count--
+		if g.count == 0 {
+			ebiten.RequestAttention()
+		}
+	}
+	if ebiten.IsKeyPressed(ebiten.KeyR) {
+		g.count = ebiten.TPS() * 3
+	}
+	return nil
+}
+
+func (g *Game) Draw(screen *ebiten.Image) {
+	if g.count > 0 {
+		c := int(math.Ceil(float64(g.count) / float64(ebiten.TPS())))
+		msg := fmt.Sprintf("Requesting attention in %d seconds...", c)
+		if ebiten.IsFocused() {
+			msg += "\nPlease unfocus this window to see the effect."
+		}
+		ebitenutil.DebugPrint(screen, msg)
+		return
+	}
+	ebitenutil.DebugPrint(screen, "Press R to request attention after 3 seconds.")
+}
+
+func (g *Game) Layout(outsideWidth, outsideHeight int) (int, int) {
+	return screenWidth, screenHeight
+}
+
+func main() {
+	ebiten.SetWindowSize(screenWidth, screenHeight)
+	ebiten.SetWindowTitle("Request Attention (Ebitengine Demo)")
+	if err := ebiten.RunGame(&Game{}); err != nil {
+		panic(err)
+	}
+}

internal/glfw/window_unix.go

@@ -546,8 +546,9 @@ func (w *Window) SetOpacity(opacity float32) {
 // application, the system will end the request automatically.
 //
 // This function must only be called from the main thread.
-func (w *Window) RequestAttention() {
+func (w *Window) RequestAttention() error {
 	C.glfwRequestWindowAttention(w.data)
+	return nil
 }
 
 // Focus brings the specified window to front and sets input focus.

internal/ui/window.go

@@ -43,6 +43,7 @@ type Window interface {
 	IsClosingHandled() bool
 	SetMousePassthrough(enabled bool)
 	IsMousePassthrough() bool
+	RequestAttention()
 }
 
 type nullWindow struct{}
@@ -128,3 +129,6 @@ func (*nullWindow) SetMousePassthrough(enabled bool) {
 func (*nullWindow) IsMousePassthrough() bool {
 	return false
 }
+
+func (*nullWindow) RequestAttention() {
+}

internal/ui/window_glfw.go

@@ -506,3 +506,22 @@ func (w *glfwWindow) IsMousePassthrough() bool {
 	})
 	return v
 }
+
+func (w *glfwWindow) RequestAttention() {
+	if w.ui.isTerminated() {
+		return
+	}
+	if !w.ui.isRunning() {
+		// Do nothing
+		return
+	}
+	w.ui.mainThread.Call(func() {
+		if w.ui.isTerminated() {
+			return
+		}
+		if err := w.ui.window.RequestAttention(); err != nil {
+			w.ui.setError(err)
+			return
+		}
+	})
+}

window.go

@@ -341,3 +341,13 @@ func SetWindowMousePassthrough(enabled bool) {
 func IsWindowMousePassthrough() bool {
 	return ui.Get().Window().IsMousePassthrough()
 }
+
+// RequestAttention requests user attention to the current window and/or the current application.
+//
+// RequestAttention works only on desktops.
+// RequestAttention does nothing if the platform is not a desktop.
+//
+// RequestAttention is concurrent-safe.
+func RequestAttention() {
+	ui.Get().Window().RequestAttention()
+}