WPF相当于Silverlight“RootVisual”

Question

I am trying to port an application from silverlight to wpf. Unfortunatley I am new to both. Is there an equvivalent to the following Silverlight code in WPF?

        private static Canvas GetCanvas()
        {
            var uc = Application.Current.RootVisual as UserControl;
            if (uc == null)
            {
                return null;
            }
            return uc.FindName("ChoiceCanvas") as Canvas;
        }

Currently I am using

Application.Current.MainWindow.FindName("ChoiceCanvas") as Canvas;

But this doesn't work, perhaps because ChoiceCanvas is something located in a UserControl and not in the MainWindow?

Answer 1

There is no RootVisual property in WPF. As far as I understand, the "Window" is the "root". You can get the Window that any WPF (DO) object belongs to by running the static method Window myWindow = Window.GetWindow (myControl);

Answer 2

FindName won't work becuase the Canvas exists in the namescope of the UserControl, try using the LogicalTreeHelper instead.

 var canvas = LogicalTreeHelper.FindLogicalNode(
      Application.Current.MainWindow, "ChoiceCanvas") as Canvas; 

Answer 3

The current window is the root visual.

From MSDN WPF Graphics Rendering Overview :

The root visual is the top-most element in a visual tree hierarchy. In most applications, the base class of the root visual is either Window or NavigationWindow. However, if you were hosting visual objects in a Win32 application, the root visual would be the top-most visual you were hosting in the Win32 window. For more information, see Tutorial: Hosting Visual Objects in a Win32 Application.