Add option to prevent application shutdown

This update allows the application shutdown to be cancelled. It implements the shouldQuit function, which can prevent the application from quitting if it returns false. Additional checks have been added to ensure cleanup and quit processes are performed only if required. The darwin delegate and linux and windows applications were modified to include this new functionality.

v3/examples/window/main.go

@@ -21,7 +21,7 @@ func main() {
 		Description: "A demo of the WebviewWindow API",
 		Assets:      application.AlphaAssets,
 		Mac: application.MacOptions{
-			ApplicationShouldTerminateAfterLastWindowClosed: false,
+			ApplicationShouldTerminateAfterLastWindowClosed: true,
 		},
 	})
 	app.On(events.Mac.ApplicationDidFinishLaunching, func(event *application.Event) {
@@ -40,8 +40,11 @@ func main() {
 
 	// Create a custom menu
 	menu := app.NewMenu()
-	menu.AddRole(application.AppMenu)
-
+	if runtime.GOOS == "darwin" {
+		menu.AddRole(application.AppMenu)
+	} else {
+		menu.AddRole(application.FileMenu)
+	}
 	windowCounter := 1
 
 	// Let's make a "Demo" menu

v3/pkg/application/application.go

@@ -297,6 +297,7 @@ type App struct {
 
 	// Shutdown
 	performingShutdown bool
+
 	// Shutdown tasks are run when the application is shutting down.
 	// They are run in the order they are added and run on the main thread.
 	// The application option `OnShutdown` is run first.
@@ -617,12 +618,11 @@ func (a *App) OnShutdown(f func()) {
 	a.shutdownTasks = append(a.shutdownTasks, f)
 }
 
-func (a *App) Quit() {
+func (a *App) cleanup() {
 	if a.performingShutdown {
 		return
 	}
 	a.performingShutdown = true
-	// Run the shutdown tasks
 	for _, shutdownTask := range a.shutdownTasks {
 		InvokeSync(shutdownTask)
 	}
@@ -639,13 +639,15 @@ func (a *App) Quit() {
 		}
 		a.systemTrays = nil
 		a.systemTraysLock.Unlock()
-		if a.impl != nil {
-			a.impl.destroy()
-			a.impl = nil
-		}
 	})
 }
 
+func (a *App) Quit() {
+	if a.impl != nil {
+		InvokeSync(a.impl.destroy)
+	}
+}
+
 func (a *App) SetIcon(icon []byte) {
 	if a.impl != nil {
 		a.impl.setIcon(icon)
@@ -867,3 +869,10 @@ func (a *App) Environment() EnvironmentInfo {
 		Debug: a.isDebugMode,
 	}
 }
+
+func (a *App) shouldQuit() bool {
+	if a.options.ShouldQuit != nil {
+		return a.options.ShouldQuit()
+	}
+	return true
+}

v3/pkg/application/application_darwin.go

@@ -334,9 +334,15 @@ func processMenuItemClick(menuID C.uint) {
 	menuItemClicked <- uint(menuID)
 }
 
-//export quitApplication
-func quitApplication() {
-	globalApplication.Quit()
+//export shouldQuitApplication
+func shouldQuitApplication() C.bool {
+	// TODO: This should be configurable
+	return C.bool(globalApplication.shouldQuit())
+}
+
+//export cleanup
+func cleanup() {
+	globalApplication.cleanup()
 }
 
 func (a *App) logPlatformInfo() {

v3/pkg/application/application_darwin_delegate.h

@@ -7,6 +7,7 @@
 
 @interface AppDelegate : NSObject <NSApplicationDelegate>
 @property bool shouldTerminateWhenLastWindowClosed;
+@property bool shuttingDown;
 - (BOOL)applicationSupportsSecureRestorableState:(NSApplication *)app;
 @end
 

v3/pkg/application/application_darwin_delegate.m

@@ -2,7 +2,8 @@
 #import "application_darwin_delegate.h"
 #import "../events/events_darwin.h"
 extern bool hasListeners(unsigned int);
-extern void quitApplication();
+extern bool shouldQuitApplication();
+extern void cleanup();
 
 @implementation AppDelegate
 - (void)dealloc
@@ -20,8 +21,14 @@ extern void quitApplication();
     }
 }
 - (NSApplicationTerminateReply)applicationShouldTerminate:(NSApplication *)sender {
-    quitApplication();
-    return NSTerminateCancel;
+    if( ! shouldQuitApplication() ) {
+        return NSTerminateCancel;
+    }
+    if( !self.shuttingDown ) {
+        self.shuttingDown = true;
+        cleanup();
+    }
+    return NSTerminateNow;
 }
 - (BOOL)applicationSupportsSecureRestorableState:(NSApplication *)app
 {

v3/pkg/application/application_linux.go

@@ -116,6 +116,10 @@ func (m *linuxApp) run() error {
 }
 
 func (m *linuxApp) destroy() {
+	if !globalApplication.shouldQuit() {
+		return
+	}
+	globalApplication.cleanup()
 	appDestroy(m.application)
 }
 

v3/pkg/application/application_windows.go

@@ -192,6 +192,10 @@ func (m *windowsApp) run() error {
 }
 
 func (m *windowsApp) destroy() {
+	if !globalApplication.shouldQuit() {
+		return
+	}
+	globalApplication.cleanup()
 	// Post a quit message to the main thread
 	w32.PostQuitMessage(0)
 }

v3/pkg/application/menuitem_windows.go

@@ -190,8 +190,10 @@ func newDeleteMenuItem() *MenuItem {
 }
 
 func newQuitMenuItem() *MenuItem {
-	panic("implement me")
-
+	return newMenuItem("Quit").
+		OnClick(func(ctx *Context) {
+			globalApplication.Quit()
+		})
 }
 
 func newSelectAllMenuItem() *MenuItem {

v3/pkg/application/options_application.go

@@ -52,10 +52,15 @@ type Options struct {
 	// KeyBindings is a map of key bindings to functions
 	KeyBindings map[string]func(window *WebviewWindow)
 
-	// OnShutdown is called when the application is about to quit.
+	// OnShutdown is called when the application is about to terminate.
 	// This is useful for cleanup tasks.
 	// The shutdown process blocks until this function returns
 	OnShutdown func()
+
+	// ShouldQuit is a function that is called when the user tries to quit the application.
+	// If the function returns true, the application will quit.
+	// If the function returns false, the application will not quit.
+	ShouldQuit func() bool
 }
 
 // AssetOptions defines the configuration of the AssetServer.

v3/pkg/application/webview_window_darwin.go

@@ -956,7 +956,14 @@ func (w *macosWebviewWindow) setEnabled(enabled bool) {
 }
 
 func (w *macosWebviewWindow) execJS(js string) {
+
 	InvokeAsync(func() {
+		if globalApplication.performingShutdown {
+			return
+		}
+		if w.nsWindow == nil {
+			return
+		}
 		C.windowExecJS(w.nsWindow, C.CString(js))
 	})
 }