Code：
#region CreateThumbnail
/// <summary>
/// 生成缩略图
/// </summary>
/// <param name="uploadObject">上传的HttpPostedFile或图片物理路径</param>
/// <param name="uploaddir">上传文件夹相对路径</param>
/// <param name="ext">后缀（如：.jpg）</param>
/// <param name="t_width">缩略图宽</param>
/// <param name="t_height">缩略图高</param>
/// <param name="filename">文件夹，不含路径和后缀</param>
/// <param name="tm">枚举类-缩略图的样式</param>
/// <returns>返回生成图片的路径</returns>
public static string CreateThumbnail(object uploadObject, string uploaddir, string ext, int t_width, int t_height, string filename, ThumbModel tm)
{
System.Drawing.Image thumbnail_image = null;
System.Drawing.Image original_image = null;
System.Drawing.Bitmap final_image = null;
System.Drawing.Graphics graphic = null;
MemoryStream ms = null;