用C#简单在DOTNET中完成缩略图

');
   foreach(string filetype in aExt)
   {
    if(filetype.ToLower()==sExt)
    {
     flag = true;
     break;
    }
   }   
   return flag;
  }

  /// <summary>
  /// 保存图片
  /// </summary>
  /// <param name="image">Image 对象</param>
  /// <param name="savePath">保存路径</param>
  /// <param name="ici">指定格式的编解码参数</param>
  void SaveImage(System.Drawing.Image image,string savePath,ImageCodecInfo ici)
  {
   //设置 原图片 对象的 EncoderParameters 对象
   EncoderParameters parameters = new EncoderParameters(1);
   parameters.Param[0] = new EncoderParameter(Encoder.Quality, ((long) 90));
   image.Save(savePath, ici, parameters);
   parameters.Dispose();
  }
  #endregion

  #region Methods

  /// <summary>
  /// 生成缩略图
  /// </summary>
  /// <param name="sourceImagePath">原图片路径(相对路径)</param>
  /// <param name="thumbnailImagePath">生成的缩略图路径,如果为空则保存为原图片路径(相对路径)</param>
  /// <param name="thumbnailImageWidth">缩略图的宽度（高度与按源图片比例自动生成）</param>
  public void ToThumbnailImages(string sourceImagePath,string thumbnailImagePath,int thumbnailImageWidth)
  {
   string SourceImagePath = sourceImagePath;
   string ThumbnailImagePath = thumbnailImagePath;
   int ThumbnailImageWidth = thumbnailImageWidth;
   string sExt = SourceImagePath.Substring(SourceImagePath.LastIndexOf(".")).ToLower();
   if(SourceImagePath.ToString()==System.String.Empty) throw new NullReferenceException("SourceImagePath

is null!");
   if(!CheckValidExt(sExt))
   {
    throw new ArgumentException("原图片文件格式不正确,支持的格式有[ "+ AllowExt +"

]","SourceImagePath");
   }
   //从 原图片 创建 Image 对象
   System.Drawing.Image image = System.Drawing.Image.FromFile(HttpContext.Current.Server.MapPath

(SourceImagePath));  
   int num = ((ThumbnailImageWidth / 4) * 3);
   int width = image.Width;
   int height = image.Height;
   //计算图片的比例
   if ((((double) width) / ((double) height)) >= 1.3333333333333333f)
   {
    num = ((height * ThumbnailImageWidth) / width);
   }
   else
   {
    ThumbnailImageWidth = ((width * num) / height);
   }
   if ((ThumbnailImageWidth < 1)

关键词：用C#简单在DOTNET中完成缩略图