Add callbacks for resize and move

screen/screen.go

@@ -57,8 +57,12 @@ type ScreenHandler interface {
 }
 
 type Screen struct {
+	fyne.CanvasObject
 	rootElement   *Element
 	screenHandler ScreenHandler
+
+	resizeCallbacks []func(fyne.Size)
+	moveCallbacks   []func(fyne.Position)
 }
 
 func New(
@@ -107,13 +111,44 @@ func NewTemplate(
 }
 
 func (s *Screen) Initialize() (obj fyne.CanvasObject, err error) {
-	if obj, err = s.rootElement.BuildUI(s.screenHandler); err != nil {
+	if s.CanvasObject, err = s.rootElement.BuildUI(s.screenHandler); err != nil {
 		err = fmt.Errorf("failed to build screen: %w", err)
 		return
 	}
+	obj = s
 	return
 }
 
+func (s *Screen) Move(p fyne.Position) {
+	s.CanvasObject.Move(p)
+	for _, cb := range s.moveCallbacks {
+		cb(p)
+	}
+}
+
+func (s *Screen) Resize(sz fyne.Size) {
+	s.CanvasObject.Resize(sz)
+	for _, cb := range s.resizeCallbacks {
+		cb(sz)
+	}
+}
+
+func (s *Screen) CreateRenderer() fyne.WidgetRenderer {
+	return widget.NewSimpleRenderer(s.CanvasObject)
+}
+
+func (s *Screen) RegisterResizeCallback(cb func(fyne.Size)) {
+	s.resizeCallbacks = append(s.resizeCallbacks, cb)
+}
+
+func (s *Screen) RegisterMoveCallback(cb func(fyne.Position)) {
+	s.moveCallbacks = append(s.moveCallbacks, cb)
+}
+
+func (s *Screen) AsContainer() *fyne.Container {
+	return s.CanvasObject.(*fyne.Container)
+}
+
 type TemplateScreenHandler struct {
 	localizer   *i18n.Localizer
 	elementsMap map[string]*UIElement