C#裁剪照片并保存

/// <summary>
    ///
    /// </summary>
    /// <summary>
    /// 生成缩略图
    /// </summary>
    /// <param name="sSavePath">源图路径（物理路径）</param>
    /// <param name="sThumbExtension">缩略图路径（物理路径）</param>
    /// <param name="width">缩略图宽度</param>
    /// <param name="height">缩略图高度</param>
    /// <param name="mode">生成缩略图的方式</param>   
    public string UpLoadImage(HtmlInputFile upImage, string sSavePath, string sThumbExtension, int intThumbWidth, int intThumbHeight)   
   {   
       string sThumbFile = "";   
       string sFilename = "";           
 
       if (upImage.PostedFile != null)   
       {   
           HttpPostedFile myFile = upImage.PostedFile;   
           int nFileLen = myFile.ContentLength;   
           if (nFileLen == 0)   
              return "没有选择上传图片";               
 
           //获取upImage选择文件的扩展名   
           string extendName = System.IO.Path.GetExtension(myFile.FileName).ToLower();   
          //判断是否为图片格式   
          if (extendName != ".jpg" && extendName != ".jpge" && extendName != ".gif" && extendName != ".bmp" && extendName != ".png")   
             return "图片格式不正确";   
             
 
          byte[] myData = new Byte[nFileLen];   
           myFile.InputStream.Read(myData, 0, nFileLen);   
 
          sFilename = System.IO.Path.GetFileName(myFile.FileName);   
          int file_append = 0;   
           //检查当前文件夹下是否有同名图片,有则在文件名+1   
          while (System.IO.File.Exists(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename)))   
           {   
               file_append++;   
              sFilename = System.IO.Path.GetFileNameWithoutExtension(myFile.FileName)   
                   + file_append.ToString() + extendName;   
           }   
          System.IO.FileStream newFile   
              = new System.IO.FileStream(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename),   
               System.IO.FileMode.Create, System.IO.FileAccess.Write);   
                newFile.Write(myData, 0, myData.Length);   
            newFile.Close();   
 
          //以上为上传原图   
 
           try   
           {   
               //原图加载   
               using (System.Drawing.Image sourceImage = System.Drawing.Image.FromFile(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename)))   
               {   
                   //原图宽度和高度   
                   int width = sourceImage.Width;   
                   int height = sourceImage.Height;   
                   int smallWidth;   
                  int smallHeight;   
 
                  //获取第一张绘制图的大小,(比较 原图的宽/缩略图的宽  和 原图的高/缩略图的高)   
                   if (((decimal)width) / height <= ((decimal)intThumbWidth) / intThumbHeight)   
                   {   
                       smallWidth = intThumbWidth;   
                       smallHeight = intThumbWidth * height / width;   
                   }   
                   else   
                   {   
                       smallWidth = intThumbHeight * width / height;   
                       smallHeight = intThumbHeight;   
                   }   
                //判断缩略图在当前文件夹下是否同名称文件存在   
                 file_append = 0;   
                  sThumbFile = sThumbExtension + System.IO.Path.GetFileNameWithoutExtension(myFile.FileName) + extendName;   
 
                   while (System.IO.File.Exists(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sThumbFile)))   
                   {   
                         file_append++;   
                       sThumbFile = sThumbExtension + System.IO.Path.GetFileNameWithoutExtension(myFile.FileName) +   
                           file_append.ToString() + extendName;   
                   }   
                   //缩略图保存的绝对路径   
                   string smallImagePath = System.Web.HttpContext.Current.Server.MapPath(sSavePath) + sThumbFile;   
 
                   //新建一个图板,以最小等比例压缩大小绘制原图   
                   using (System.Drawing.Image bitmap = new System.Drawing.Bitmap(smallWidth, smallHeight))   
                   {   
                       //绘制中间图   
                       using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap))   
                       {   
                           //高清,平滑   
                           g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;   
                           g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;   
                           g.Clear(Color.Black);   
                           g.DrawImage(                              sourceImage,   
                           new System.Drawing.Rectangle(0, 0, smallWidth, smallHeight),   
                           new System.Drawing.Rectangle(0, 0, width, height),   
                          System.Drawing.GraphicsUnit.Pixel   
                           );   
                      }   
                       //新建一个图板,以缩略图大小绘制中间图   
                       using (System.Drawing.Image bitmap1 = new System.Drawing.Bitmap(intThumbWidth, intThumbHeight))   
                      {   
                          //绘制缩略图   
                          using (System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap1))   
                           {   
                               //高清,平滑   
                               g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;   
                              g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;   
                              g.Clear(Color.Black);   
                               int lwidth = (smallWidth - intThumbWidth) / 2;   
                               int bheight = (smallHeight - intThumbHeight) / 2;   
                                g.DrawImage(bitmap, new Rectangle(0, 0, intThumbWidth, intThumbHeight), lwidth, bheight, intThumbWidth, intThumbHeight, GraphicsUnit.Pixel);   
                               g.Dispose();   
                               bitmap1.Save(smallImagePath, System.Drawing.Imaging.ImageFormat.Jpeg);   
                          }   
                       }   
                 }   
             }   
       }   
           catch   
          {   
              //出错则删除   
             System.IO.File.Delete(System.Web.HttpContext.Current.Server.MapPath(sSavePath + sFilename));                  return "图片格式不正确";   
          }   
           //返回缩略图名称   
           return sThumbFile;   
       }   
       return "没有选择图片";   
   }