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:
<UserControl xmlns="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