WPF 用Clip属性实现蒙板特效

上一篇，已简单介绍Clip属性的用法，这一篇用它来实现简单蒙板功能，很简单，直接上代码

<Window x:Class="擦除效果.MainWindow"
? ? ? ? xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
? ? ? ? xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
? ? ? ? Title="MainWindow" Height="537" Width="866" MouseMove="canvas_MouseMove" MouseDown="Window_MouseDown" MouseUp="Window_MouseUp">
? ? <Grid>


? ? ? ? <Rectangle Height="100" HorizontalAlignment="Left" Margin="164,92,0,0" Name="rectangle1" Stroke="Black" VerticalAlignment="Top" Width="200" Fill="Lime" />
? ? ? ? <Button Content="Button" Height="83" HorizontalAlignment="Left" Margin="526,109,0,0" Name="button1" VerticalAlignment="Top" Width="115" Click="button1_Click" />
? ? ? ? <Grid x:Name="grid" ?Background="#88FFFFFF" ></Grid>
? ? </Grid>


? ? <Window.Background>
? ? ? ? <ImageBrush ImageSource="/擦除效果;component/Images/s01.jpg" />
? ? </Window.Background>
</Window>

后台：

? ? public partial class MainWindow : Window
? ? {
? ? ? ? private bool isDown = false;
? ? ? ? public MainWindow()
? ? ? ? {
? ? ? ? ? ? InitializeComponent();
? ? ? ? ? ? RectangleGeometry rg = new RectangleGeometry();
? ? ? ? ? ? rg.Rect = new Rect(0, 0, this.Width, this.Height);
? ? ? ? ? ? gridGeometry = Geometry.Combine(gridGeometry, rg, GeometryCombineMode.Union, null);
? ? ? ? ? ? grid.Clip = gridGeometry;
? ? ? ? }
? ? ? ? PathGeometry gridGeometry = new PathGeometry();
? ? ? ? private void canvas_MouseMove(object sender, MouseEventArgs e)
? ? ? ? {
? ? ? ? ? ? if (isDown)
? ? ? ? ? ? {
? ? ? ? ? ? ? ? EllipseGeometry rg = new EllipseGeometry();
? ? ? ? ? ? ? ? rg.Center = e.GetPosition(this);
? ? ? ? ? ? ? ? rg.RadiusX = 50;
? ? ? ? ? ? ? ? rg.RadiusY = 50;
? ? ? ? ? ? ? ? //排除几何图形
? ? ? ? ? ? ? ? gridGeometry = Geometry.Combine(gridGeometry, rg, GeometryCombineMode.Exclude, null);
? ? ? ? ? ? ? ? grid.Clip = gridGeometry;
? ? ? ? ? ? }
? ? ? ? }


? ? ? ? private void button1_Click(object sender, RoutedEventArgs e)
? ? ? ? {
? ? ? ? ? ? MessageBox.Show("OK!");
? ? ? ? }


? ? ? ? private void Window_MouseDown(object sender, MouseButtonEventArgs e)
? ? ? ? {
? ? ? ? ? ? isDown = true;
? ? ? ? }


? ? ? ? private void Window_MouseUp(object sender, MouseButtonEventArgs e)
? ? ? ? {
? ? ? ? ? ? isDown = false;
? ? ? ? }
? ? }

效果如下：

源码