public void Invalidate()
{
var g = new FastGraphics(Canvas, _typedChildren);
Canvas.Clip = new RectangleGeometry()
{
Rect = new Rect(0, 0, Canvas.ActualWidth, Canvas.ActualHeight)
};
GraphCanvas.Paint(g, (int)Canvas.ActualWidth, (int)Canvas.ActualHeight);
g.FinalizeGraphics();
}