silverlight - Canvas 内 Silverlight 中的动态裁剪宽度

Question

为什么这会引发错误，我该如何解决...我需要将裁剪矩形设置为动态。

    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="42"/>
        <ColumnDefinition x:Name="ListBoxContainer" Width="*"/>
        <ColumnDefinition Width="42"/>
    </Grid.ColumnDefinitions>


    <Canvas>
        <Button x:Name="btnGalleryLeft" 
                Click="btnGalleryLeftClick" 
                Style="{StaticResource GalleryNavigationLeft}"
                Canvas.Left="7"
                Canvas.Top="50" />
    </Canvas>
    <Canvas Grid.Column="1" x:Name="ListboxWrapper">
        <Canvas.Clip>
            <RectangleGeometry>
                <RectangleGeometry.Rect>
                    <Rect X="0" Y="0" 
                          Width="{Binding ElementName=ListBoxContainer, Path=Width}"
                          Height="{Binding ElementName=ListBoxContainer, Path=Height}"/>
                </RectangleGeometry.Rect>
            </RectangleGeometry>
        </Canvas.Clip>
        <ListBox x:Name="ListBox1" 
                 Margin="15, 18, 15, 0"  
                 Style="{StaticResource GalleryListBoxStyle}" 
                 ItemsSource="{Binding DocItemCollection}" 
                 SelectionChanged="ListBox_SelectionChanged" 
                 MouseLeftButtonUp="ListBox_MouseLeftButtonUp" 
                 Canvas.Top="0"
                 Canvas.Left="0"
               />
    </Canvas>
    <Canvas Grid.Column="2">
        <Button x:Name="btnGalleryRight"                     
                Click="btnGalleryRightClick" 
                Style="{StaticResource GalleryNavigationRight}"
                Margin="0, 0, 7, 0"
                Canvas.Top="50" />         

Answer 1

您仍然可以使用 RectangleGeometry作为剪切区域。只需订阅 Loaded事件，并在其中创建一个新的 RectangleGeometry

void control_Loaded(object sender, RoutedEventArgs e)
        {
            LayoutRoot.DataContext = this;

            Rect rect = new Rect(0, 0, yourWidth, yourHeight);
            RectangleGeometry reo = new RectangleGeometry();
            reo.Rect = rect;
            this.canvas.Clip = reo;
        }

只是补充一点信息

In addition, opacity and clip property settings are handled by the composition thread. However, if an Opacity mask or non-rectangular clip is used on the animated object, these operations will be passed to the UI Thread. This means that even if the clip region is a rectangular shape but uses the PathGeometry the operations will be passed to the UI thread. So make sure to always use the RectangleGeometry for clipping paths if possible.