ASP.NET入门教程 14.1.1 对象处理[3]

内部的Try/Catch块则包围在targetImage外部根据SourceImage使用利用新高度和宽度的GetThumbnailImage生成TargetImage这可以创建基于新尺寸的新图像一旦生成targetlmage则作为GIF图像被保存为文件

通过调用Dispose方法每个Try/Catch的Finally块在处理Image对象前检查该对象 是否存在

使用Using语句进行处理

Using语句可简化前面的代码具体如下所示

Public Shared Sub GenerateThumbnail(ByVal SourceImagePath As String ByVal TargetImagePath As String)

Dim newHeight As Short

Dim newWidth As Short

Using sourceImage As Image = ImageFromFile(SourceImagePath)

newHeight = CShort(sourceImageHeight * )

newWidth = CShort(sourceImageWidth * )

Dim cb As New ImageGetThumbnailImageAbort(AddressOf ThumbnailCallback)

Using targetImage As Image = sourceImageGetThumbnailImage(newWidth newHeight cb IntPtrZero)

targetImageSave(TargetImagePath ImagingImageFormatGif)

End Using

End Using

End Sub

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