WPF有CroppedBitmap类，能够很方便的裁剪图片，可是SilverLight里面没有。这可麻烦了用SilverLight做游戏的同仁们。

虽然可以用一个Border包着一个Image来解决，但程序员往往喜欢用更简单的方法。

这里给出一个用转换器实现的裁剪案例

代码只保证SilverLight 4.0测试通过，其他版本未测试

    public class CroppedBitmapConverter : IValueConverter{public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture){BitmapImage bi = value as BitmapImage;if (bi == null) return null;Rect rect;if (parameter is Rect){rect = (Rect)parameter;}else{try{string[] s = parameter.ToString().Split(',');rect = new Rect(double.Parse(s[0]), double.Parse(s[1]), double.Parse(s[2]), double.Parse(s[3]));}catch{rect = new Rect(0, 0, bi.PixelWidth, bi.PixelHeight);}}Image image = new Image();image.Stretch = Stretch.None;image.RenderTransform = new TranslateTransform { X = -rect.X, Y = -rect.Y };image.Source = bi;Canvas canvas = new Canvas();canvas.Width = rect.Width;canvas.Height = rect.Height;canvas.Children.Add(image);return new WriteableBitmap(canvas, null);}public object ConvertBack(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture){throw new NotSupportedException();}}

相应的前台代码:

<UserControlxmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"xmlns:local="clr-namespace:SilverlightApplication1"x:Class="SilverlightApplication1.MainPage"Width="640" Height="480"><UserControl.Resources><local:CroppedBitmapConverter x:Key="CroppedBitmapConverter"/></UserControl.Resources><Grid x:Name="LayoutRoot" Background="#FF959595"><Image x:Name="image" Source="未命名.jpg" VerticalAlignment="Top" HorizontalAlignment="Left" Stretch="None" /><Image DataContext="{Binding Source, ElementName=image}"Source="{Binding ConverterParameter=180\,0\,130\,100, Converter={StaticResource CroppedBitmapConverter}, Mode=OneWay}"VerticalAlignment="Bottom" HorizontalAlignment="Left" Stretch="None" /></Grid>
</UserControl>

最终的效果