如何：裁剪图像
更新：2007 年 11 月
本示例演示如何使用 CroppedBitmap 裁剪图像。
CroppedBitmap 主要在对图像的裁剪版本进行编码以保存到文件时使用。若要出于显示目的而裁剪图像，请参见如何：创建剪辑区域主题。
示例
下面的可扩展应用程序标记语言 (XAML) 定义在下面的示例中使用的资源。
<Page.Resources>
<!-- Define some image resources, for use as the image element source. -->
<BitmapImage x:Key="masterImage" UriSource="/sampleImages/gecko.jpg" />
<CroppedBitmap x:Key="croppedImage"
Source="{StaticResource masterImage}" SourceRect="30 20 105 50"/>
</Page.Resources>
<Page.Resources>
<!-- Define some image resources, for use as the image element source. -->
<BitmapImage x:Key="masterImage" UriSource="/sampleImages/gecko.jpg" />
<CroppedBitmap x:Key="croppedImage"
Source="{StaticResource masterImage}" SourceRect="30 20 105 50"/>
</Page.Resources>
下面的示例使用 CroppedBitmap 作为源来创建图像。
<!-- Use the cropped image resource as the images source -->
<Image Width="200" Source="{StaticResource croppedImage}"
Margin="5" Grid.Column="0" Grid.Row="1" />
<!-- Use the cropped image resource as the images source -->
<Image Width="200" Source="{StaticResource croppedImage}"
Margin="5" Grid.Column="0" Grid.Row="1" />
' Create an Image element.
Dim croppedImage As New Image()
croppedImage.Width = 200
croppedImage.Margin = New Thickness(5)
' Create a CroppedBitmap based off of a xaml defined resource.
Dim cb As New CroppedBitmap(CType(Me.Resources("masterImage"), BitmapSource), New Int32Rect(30, 20, 105, 50))
'select region rect
croppedImage.Source = cb 'set image source to cropped
// Create an Image element.
Image croppedImage = new Image();
croppedImage.Width = 200;
croppedImage.Margin = new Thickness(5);
// Create a CroppedBitmap based off of a xaml defined resource.
CroppedBitmap cb = new CroppedBitmap(
(BitmapSource)this.Resources["masterImage"],
new Int32Rect(30, 20, 105, 50)); //select region rect
croppedImage.Source = cb; //set image source to cropped
CroppedBitmap 还可以用作另一个 CroppedBitmap 的源，从而链接裁剪内容。请注意，SourceRect 使用相对于源裁剪位图的值，而不是使用相对于初始图像的值。
<!-- Chain a cropped bitmap off a previosly defined cropped image -->
<Image Width="200" Grid.Column="0" Grid.Row="3" Margin="5">
<Image.Source>
<CroppedBitmap Source="{StaticResource croppedImage}"
SourceRect="30 0 75 50"/>
</Image.Source>
</Image>
<!-- Chain a cropped bitmap off a previosly defined cropped image -->
<Image Width="200" Grid.Column="0" Grid.Row="3" Margin="5">
<Image.Source>
<CroppedBitmap Source="{StaticResource croppedImage}"
SourceRect="30 0 75 50"/>
</Image.Source>
</Image>
' Create an Image element.
Dim chainImage As New Image()
chainImage.Width = 200
chainImage.Margin = New Thickness(5)
' Create the cropped image based on previous CroppedBitmap.
Dim chained As New CroppedBitmap(cb, New Int32Rect(30, 0, CType(cb.Width, Integer) - 30, CType(cb.Height, Integer)))
' Set the image's source.
chainImage.Source = chained
// Create an Image element.
Image chainImage = new Image();
chainImage.Width = 200;
chainImage.Margin = new Thickness(5);
// Create the cropped image based on previous CroppedBitmap.
CroppedBitmap chained = new CroppedBitmap(cb,
new Int32Rect(30, 0, (int)cb.Width-30, (int)cb.Height));
// Set the image's source.
chainImage.Source = chained;
有关完整示例，请参见 Image 元素示例。