Adding to Canvas Programmatically

Question

I've got code that adds a custom usercontrol to a canvas. I originally had it in the MouseRightButtonDown event of the Canvas but have since moved it to a collection changed event that fires off in a ViewModel. When I call the exact same method from the CollectionChanged event, the UI does not update to reflect the UserControl on the canvas. However, when I use the exact same code from a mouse event on the canvas, it works beautifully as intended.

I have done some digging and tried the following to fix things to no avail:

1. Calling the UpdateLayout method of the Canvas

2. Toggling Visibility properties to try to update the UI.

3. Invoking it using the UserControl's Dispatcher to invoke an anonymous delegate: Dispatcher.BeginInvoke(()=> code);

Here is an example of the code that I am using:

        CustomUserControl stub = new CustomUserControl();
        stub.Width = 10;
        stub.Height = 10;
        stub.SetValue(Canvas.LeftProperty, xCurrent);
        stub.SetValue(Canvas.TopProperty, yCurrent);

        stub.MouseLeftButtonDown += this.Element_MouseLeftButtonDown;
        stub.MouseMove += this.Element_MouseMove;
        stub.MouseLeftButtonUp += this.Element_MouseLeftButtonUp;

        this.Dispatcher.BeginInvoke(() =>
        {
            drawCanvas.Children.Add(stub);
            drawCanvas.Visibility = Visibility.Visible;
            this.Visibility = Visibility.Visible;
        });

Answer 1

It is possible that the collectonChanged event is happening before the canvas has been initalized. Try added stuff to the collection after the usercontrol that the canvas lives in has been loaded.