Add playback controls to dock menu on MacOS

ui/app_delegate_darwin.go

@@ -3,11 +3,20 @@
 package ui
 
 /*
+#include <stdlib.h>
 void installReopenDelegate();
+void dockMenuBegin();
+void dockMenuAddItem(const char* title, int index);
+void dockMenuAddSeparator();
+void dockMenuCommit();
 */
 import "C"
 
-import "fyne.io/fyne/v2"
+import (
+	"unsafe"
+
+	"fyne.io/fyne/v2"
+)
 
 var darwinAppDelegateReopenWindow fyne.Window
 
@@ -38,3 +47,35 @@ func appReopened() {
 func appShouldTerminate() {
 	darwinQuitting = true
 }
+
+// darwinDockMenuCallbacks is indexed by the NSMenuItem tag set in
+// dockMenuAddItem, dispatched back to Go via dockMenuItemClicked.
+var darwinDockMenuCallbacks []func()
+
+func installDockMenu(menu *fyne.Menu) {
+	darwinDockMenuCallbacks = darwinDockMenuCallbacks[:0]
+
+	C.dockMenuBegin()
+	for _, item := range menu.Items {
+		if item.IsSeparator {
+			C.dockMenuAddSeparator()
+			continue
+		}
+		cTitle := C.CString(item.Label)
+		C.dockMenuAddItem(cTitle, C.int(len(darwinDockMenuCallbacks)))
+		C.free(unsafe.Pointer(cTitle))
+		darwinDockMenuCallbacks = append(darwinDockMenuCallbacks, item.Action)
+	}
+	C.dockMenuCommit()
+}
+
+//export dockMenuItemClicked
+func dockMenuItemClicked(index C.int) {
+	i := int(index)
+	if i < 0 || i >= len(darwinDockMenuCallbacks) {
+		return
+	}
+	if cb := darwinDockMenuCallbacks[i]; cb != nil {
+		go func() { fyne.Do(cb) }()
+	}
+}