基本上我正在寻找一种方法来清除绘图上下文并再次调用OnRender.什么是最好的方法,还是有更好的方法？

public class MyAdorner : Adorner
{
    private Brush brush = Brushes.Red;

    public DragArrowAdorner(UIElement adornedElement) : base(adornedElement)
    {}

    public void RedrawWithBrush(Brush newBrush)
    {
        brush = newBrush;

        // redraw..?
    }

    protected override void OnRender(System.Windows.Media.DrawingContext drawingContext)
    {
        // some drawing code...
        drawingContext.DrawRectangle(
            brush,null,new Rect(AdornedElement.DesiredSize));
    }
}