[v3 Windows] Add WebviewWindow.Flash()

v3/examples/window/main.go

@@ -321,6 +321,15 @@ func main() {
 		})
 	})
 
+	if runtime.GOOS == "windows" {
+		stateMenu.Add("Flash Start").OnClick(func(ctx *application.Context) {
+			currentWindow(func(w *application.WebviewWindow) {
+				time.Sleep(2 * time.Second)
+				w.Flash(true)
+			})
+		})
+	}
+
 	printMenu := menu.AddSubmenu("Print")
 	printMenu.Add("Print").OnClick(func(ctx *application.Context) {
 		currentWindow(func(w *application.WebviewWindow) {

v3/pkg/application/webview_window.go

@@ -70,6 +70,7 @@ type (
 		setEnabled(enabled bool)
 		absolutePosition() (int, int)
 		setAbsolutePosition(x int, y int)
+		flash(enabled bool)
 	}
 )
 
@@ -418,6 +419,16 @@ func (w *WebviewWindow) SetFullscreenButtonEnabled(enabled bool) *WebviewWindow
 	return w
 }
 
+// Flash flashes the window's taskbar button/icon. Windows only.
+func (w *WebviewWindow) Flash(enabled bool) {
+	if w.impl == nil {
+		return
+	}
+	invokeSync(func() {
+		w.impl.flash(enabled)
+	})
+}
+
 // IsMinimised returns true if the window is minimised
 func (w *WebviewWindow) IsMinimised() bool {
 	if w.impl == nil {

v3/pkg/application/webview_window_darwin.go

@@ -944,6 +944,10 @@ func (w *macosWebviewWindow) setTitle(title string) {
 	}
 }
 
+func (w *macosWebviewWindow) flash(enabled bool) {
+	// Not supported on macOS
+}
+
 func (w *macosWebviewWindow) setSize(width, height int) {
 	C.windowSetSize(w.nsWindow, C.int(width), C.int(height))
 }

v3/pkg/application/webview_window_linux.go

@@ -179,6 +179,10 @@ func (w *linuxWebviewWindow) minimise() {
 	windowMinimize(w.window)
 }
 
+func (w *linuxWebviewWindow) flash(enabled bool) {
+	// Not supported on linux
+}
+
 func (w *linuxWebviewWindow) on(eventID uint) {
 	// Don't think this is correct!
 	// GTK Events are strings

v3/pkg/application/webview_window_windows.go

@@ -1464,6 +1464,10 @@ func (w *windowsWebviewWindow) setupChromium() {
 
 }
 
+func (w *windowsWebviewWindow) flash(enabled bool) {
+	w32.FlashWindow(w.hwnd, enabled)
+}
+
 func (w *windowsWebviewWindow) navigationCompleted(sender *edge.ICoreWebView2, args *edge.ICoreWebView2NavigationCompletedEventArgs) {
 
 	// Emit DomReady Event

v3/pkg/w32/constants.go

@@ -915,6 +915,15 @@ const (
 	SS_ELLIPSISMASK    = 0x0000C000
 )
 
+const (
+	FLASHW_STOP      = 0  // Stop flashing. The system restores the window to its original state.
+	FLASHW_CAPTION   = 1  // Flash the window caption.
+	FLASHW_TRAY      = 2  // Flash the taskbar button.
+	FLASHW_ALL       = 3  // Flash both the window caption and taskbar button. This is equivalent to setting the FLASHW_CAPTION | FLASHW_TRAY flags.
+	FLASHW_TIMER     = 4  // Flash continuously, until the FLASHW_STOP flag is set.
+	FLASHW_TIMERNOFG = 12 // Flash continuously until the window comes to the foreground.
+)
+
 // Edit styles
 const (
 	ES_LEFT        = 0x0000

v3/pkg/w32/typedef.go

@@ -1133,3 +1133,11 @@ type SCROLLINFO struct {
 	NPos      int32
 	NTrackPos int32
 }
+
+type FLASHWINFO struct {
+	CbSize    uint32
+	Hwnd      HWND
+	DwFlags   DWORD
+	UCount    uint32
+	DwTimeout DWORD
+}

v3/pkg/w32/user32.go

@@ -166,6 +166,8 @@ var (
 	procGetScrollInfo = moduser32.NewProc("GetScrollInfo")
 	procSetScrollInfo = moduser32.NewProc("SetScrollInfo")
 
+	procFlashWindowEx = moduser32.NewProc("FlashWindowEx")
+
 	mainThread HANDLE
 )
 

v3/pkg/w32/window.go

@@ -234,3 +234,15 @@ func RegisterWindow(name string, proc WindowProc) (HINSTANCE, error) {
 
 	return applicationInstance, nil
 }
+
+func FlashWindow(hwnd HWND, enabled bool) {
+	var flashInfo FLASHWINFO
+	flashInfo.CbSize = uint32(unsafe.Sizeof(flashInfo))
+	flashInfo.Hwnd = hwnd
+	if enabled {
+		flashInfo.DwFlags = FLASHW_ALL | FLASHW_TIMERNOFG
+	} else {
+		flashInfo.DwFlags = FLASHW_STOP
+	}
+	_, _, _ = procFlashWindowEx.Call(uintptr(unsafe.Pointer(&flashInfo)))
+}