Andy Beaulieu will explain you how to use TransformToVisual for custom XAML animation.
I recently had the need to dynamically draw a shape in XAML from a specific X,Y offset within another control. This is straightforward... unless the control is Rotated, Scaled, or otherwise transformed. Since the original X,Y position is no longer in the same spot after a transform, we need to use some method to calculate the new X,Y position within the control.