public static void RenderBlurred(this DrawingContext dc, int width, int height, Rect targetRect, double blurRadius, Action <DrawingContext> action)
{
Rect elementRect = new Rect(0, 0, width, height);
Placeholder element = new Placeholder(action)
{
Width = width,
Height = height,
Effect = new BlurEffect()
{
Radius = blurRadius
}
};
element.Arrange(elementRect);
RenderTargetBitmap rtb = new RenderTargetBitmap(width, height, 96, 96, PixelFormats.Default);
rtb.Render(element);
dc.DrawImage(rtb, targetRect);
}