ebiten: add RunGameOptions.X11ClassName and X11InstanceName

Closes #2904

examples/windowsize/main.go

@@ -475,6 +475,8 @@ func main() {
 	}
 	op.InitUnfocused = !*flagInitFocused
 	op.ScreenTransparent = *flagTransparent
+	op.X11ClassName = "Window-Size"
+	op.X11InstanceName = "window-size"
 
 	const title = "Window Size (Ebitengine Demo)"
 	ww := int(float64(g.width) * initScreenScale)

internal/glfw/const.go

@@ -110,6 +110,8 @@ const (
 	Stereo                 = Hint(0x0002100C)
 	TransparentFramebuffer = Hint(0x0002000A)
 	Visible                = Hint(0x00020004)
+	X11ClassName           = Hint(0x00024001)
+	X11InstanceName        = Hint(0x00024002)
 )
 
 const (

internal/glfw/window_unix.go

@@ -225,10 +225,14 @@ func WindowHint(target Hint, hint int) error {
 // Setting these hints requires no platform specific headers or functions.
 //
 // This function must only be called from the main thread.
-func WindowHintString(hint Hint, value string) {
+func WindowHintString(hint Hint, value string) error {
 	str := C.CString(value)
 	defer C.free(unsafe.Pointer(str))
 	C.glfwWindowHintString(C.int(hint), str)
+	if err := fetchErrorIgnoringPlatformError(); err != nil {
+		return err
+	}
+	return nil
 }
 
 // CreateWindow creates a window and its associated context. Most of the options

internal/glfw/window_windows.go

@@ -284,6 +284,10 @@ func WindowHint(hint Hint, value int) error {
 }
 
 // WindowHintString is not implemented.
+func WindowHintString(hint Hint, value string) error {
+	// Do nothing.
+	return nil
+}
 
 func (w *Window) Destroy() error {
 	if !_glfw.initialized {

internal/ui/ui.go

@@ -144,6 +144,8 @@ type RunOptions struct {
 	ScreenTransparent bool
 	SkipTaskbar       bool
 	SingleThread      bool
+	X11ClassName      string
+	X11InstanceName   string
 }
 
 // InitialWindowPosition returns the position for centering the given second width/height pair within the first width/height pair.

internal/ui/ui_glfw.go

@@ -1083,6 +1083,14 @@ func (u *UserInterface) initOnMainThread(options *RunOptions) error {
 		return err
 	}
 
+	if err := glfw.WindowHintString(glfw.X11ClassName, options.X11ClassName); err != nil {
+		return err
+	}
+
+	if err := glfw.WindowHintString(glfw.X11InstanceName, options.X11InstanceName); err != nil {
+		return err
+	}
+
 	// On macOS, window decoration should be initialized once after buffers are swapped (#2600).
 	if runtime.GOOS != "darwin" {
 		decorated := glfw.False

run.go

@@ -267,6 +267,12 @@ type RunGameOptions struct {
 	//
 	// The default (zero) value is false, which means that the single thread mode is disabled.
 	SingleThread bool
+
+	// X11DisplayName is a class name in the ICCCM WM_CLASS window property.
+	X11ClassName string
+
+	// X11InstanceName is an instance name in the ICCCM WM_CLASS window property.
+	X11InstanceName string
 }
 
 // RunGameWithOptions starts the main loop and runs the game with the specified options.
@@ -675,18 +681,34 @@ func SetInitFocused(focused bool) {
 var initUnfocused int32 = 0
 
 func toUIRunOptions(options *RunGameOptions) *ui.RunOptions {
+	const (
+		defaultX11ClassName    = "Ebitengine-Application"
+		defaultX11InstanceName = "ebitengine-application"
+	)
+
 	if options == nil {
 		return &ui.RunOptions{
 			InitUnfocused:     atomic.LoadInt32(&initUnfocused) != 0,
 			ScreenTransparent: atomic.LoadInt32(&screenTransparent) != 0,
+			X11ClassName:      defaultX11ClassName,
+			X11InstanceName:   defaultX11InstanceName,
 		}
 	}
+
+	if options.X11ClassName == "" {
+		options.X11ClassName = defaultX11ClassName
+	}
+	if options.X11InstanceName == "" {
+		options.X11InstanceName = defaultX11InstanceName
+	}
 	return &ui.RunOptions{
 		GraphicsLibrary:   ui.GraphicsLibrary(options.GraphicsLibrary),
 		InitUnfocused:     options.InitUnfocused,
 		ScreenTransparent: options.ScreenTransparent,
 		SkipTaskbar:       options.SkipTaskbar,
 		SingleThread:      options.SingleThread,
+		X11ClassName:      options.X11ClassName,
+		X11InstanceName:   options.X11InstanceName,
 	}
 }