GDI+ 图像剪切

  Dim  SourceImg  As  System.Drawing.Image  =  System.Drawing.Image.FromStream( Me .FileUpload1.PostedFile.InputStream)
         Dim  SourceImgWidth  As   Integer   =  SourceImg.Width  ' 图片的原始Width 
         Dim  SourceImgHeight  As   Integer   =  SourceImg.Height  ' 图片的原始Height 

         Dim  bit  As   New  Bitmap(SourceImg)


         Dim  rec  As   New  Rectangle()  ' 构造一个Rectangle类,一个矩形 
        rec.Width  =   100   ' ConfigHelper.UserFaceWidth
        rec.Height  =   100   ' ConfigHelper.UserFaceHeight

         If  SourceImgWidth  >  rec.Width  Then
            rec.X  =   20   ' (SourceImgWidth - rec.Width) / 2
         Else
            rec.X  =   0
            rec.Width  =  SourceImg.Width
         End   If

         If  SourceImgHeight  >  rec.Height  Then
            rec.Y  =   20   ' (SourceImgHeight - rec.Height) / 2
         Else
            rec.Y  =   0
            rec.Height  =  SourceImg.Height
         End   If

         Try
             ' 这里就是把从上传过程中构造的bitmap克隆一份,并按定义好的矩形裁剪 
            bit.Clone(rec, PixelFormat.DontCare).Save(Response.OutputStream, ImageFormat.Jpeg)

         Catch  ex  As  Exception
            Context.Response.Write(ex.Message)
             Exit Sub
         Finally
            bit.Dispose()
            SourceImg.Dispose()
         End   Try