ebiten: add IsWindowAspectRatioFixed

This also updates examples/windowsize.

Closes #1804

examples/windowsize/main.go

@@ -60,7 +60,7 @@ func init() {
 
 const (
 	initScreenWidth  = 480
-	initScreenHeight = 360
+	initScreenHeight = 480
 	initScreenScale  = 1
 )
 
@@ -291,6 +291,10 @@ func (g *game) Update() error {
 		ebiten.SetWindowIcon([]image.Image{createRandomIconImage()})
 	}
 
+	if inpututil.IsKeyJustPressed(ebiten.KeyA) {
+		ebiten.SetWindowAspectRatioFixed(!ebiten.IsWindowAspectRatioFixed())
+	}
+
 	g.count++
 	return nil
 }
@@ -344,6 +348,7 @@ func (g *game) Draw(screen *ebiten.Image) {
 [D] Switch the window decoration (only for desktops)
 [L] Switch the window floating state (only for desktops)
 [W] Switch whether to skip clearing the screen
+[A] Switch whether to fix window aspect ratio (only for desktops)
 %s
 IsFocused?: %s
 Window Position: (%d, %d)

internal/ui/window_glfw.go

@@ -231,6 +231,10 @@ func (w *Window) SetAspectRatioFixed(fixed bool) {
 	w.ui.setWindowAspectRatioFixed(fixed)
 }
 
+func (w *Window) IsAspectRatioFixed() bool {
+	return w.ui.isWindowAspectRatioFixed()
+}
+
 func (w *Window) SetIcon(iconImages []image.Image) {
 	// The icons are actually set at (*UserInterface).loop.
 	w.ui.setIconImages(iconImages)

internal/ui/window_null.go

@@ -82,6 +82,10 @@ func (*Window) IsMinimized() bool {
 func (*Window) SetAspectRatioFixed(fixed bool) {
 }
 
+func (*Window) IsAspectRatioFixed() bool {
+	return false
+}
+
 func (*Window) SetIcon(iconImages []image.Image) {
 }
 

window.go

@@ -73,10 +73,19 @@ func SetWindowResizable(resizable bool) {
 }
 
 // SetWindowAspectRatioFixed sets whether the window should keep its aspect ratio while resizing.
+//
+// SetWindowAspectRatioFixed is concurrent-safe.
 func SetWindowAspectRatioFixed(fixed bool) {
 	ui.Get().Window().SetAspectRatioFixed(fixed)
 }
 
+// IsWindowAspectRatioFixed reports whether the window should keep its aspect ratio while resizing.
+//
+// IsWindowAspectRatioFixed is concurrent-safe.
+func IsWindowAspectRatioFixed() bool {
+	return ui.Get().Window().IsAspectRatioFixed()
+}
+
 // SetWindowTitle sets the title of the window.
 //
 // SetWindowTitle does nothing on browsers or mobiles.