C# 代码生成缩略图

        /// <summary>
        /// 返回缩略图
        /// </summary>
        /// <param name="path"></param>
        public void MakeThumbnail(string path)
        {
            if (!path.StartsWith("/"))
            {
                path = "/" + path;
            }
            try
            {
                int W = 0;
                int H = 0;
                path = path.ToLower();
                Regex reg = new Regex("_\\d+(x\\d+)?");
                Match m = reg.Match(path);
                string size = m.Groups[0].ToString().Replace("_", "");
                var arr = size.Split('x');
                if (arr.Length == 1)
                {
                    W = arr[0].ToInt32();
                    H = W;
                }
                else
                {
                    W = arr[0].ToInt32();
                    H = arr[1].ToInt32();
                }
                path = reg.Replace(path, ""); //去掉裁剪格式

                MakeThumbnail(path, W, H, "Cut");
            }
            catch (Exception ex)
            {
                Response.Write("The file is not exists");
            }

        }

        #region 私有方法
        ///<summary>
        /// 生成缩略图
        /// </summary>
        /// <param name="originalImagePath">源图路径（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>    
        private void MakeThumbnail(string originalImagePath, int width, int height, string mode)
        {
            try
            {
                string ext = originalImagePath.Substring(originalImagePath.LastIndexOf('.')).ToLower();
                System.Drawing.Image originalImage = System.Drawing.Image.FromFile(Server.MapPath(originalImagePath), true);

                int towidth = width;
                int toheight = height;

                int x = 0;
                int y = 0;
                int ow = originalImage.Width;