<Window x:Class="WPFBrushes.ColorAndAlpha" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="Alpha Channel" Height="300" Width="300"> <Grid VerticalAlignment="Center" HorizontalAlignment="Center"> <Rectangle Height="200" Width="200"> <Rectangle.Fill> <DrawingBrush Viewport="0,0,10,10" ViewportUnits="Absolute" TileMode="Tile"> <DrawingBrush.Drawing> <DrawingGroup> <GeometryDrawing Brush="Black"> <GeometryDrawing.Geometry> <RectangleGeometry Rect="0,0,10,10" /> </GeometryDrawing.Geometry> </GeometryDrawing> <GeometryDrawing Brush="Red" Geometry="M0,10 L 0,0 10,0 10,1 1,1 1,10Z"> </GeometryDrawing> </DrawingGroup> </DrawingBrush.Drawing> </DrawingBrush> </Rectangle.Fill> </Rectangle> </Grid> </Window>