xaml中资源在cs中调用

xaml中有如下资源

    <UserControl.Resources>
        <VisualBrush x:Key="HatchBrush"
                     TileMode="Tile"
                     Viewport="0,0,10,10"
                     ViewportUnits="Absolute"
                     Viewbox="0,0,10,10"
                     ViewboxUnits="Absolute">
            <VisualBrush.Visual>
                <Canvas>
                    <Rectangle Fill="Azure"
                               Width="10"
                               Height="10" />
                    <Path Stroke="Purple"
                          Data="M 0 0 l 10 10" />
                </Canvas>
            </VisualBrush.Visual>
        </VisualBrush>

    </UserControl.Resources>

cs中调用：

            var brush = this.Resources["HatchBrush"] as VisualBrush;