asp.net生成缩略图、文字图片水印

        /// <summary>
         /// 会产生graphics异常的PixelFormat
         /// </summary>
         private static PixelFormat[] indexedPixelFormats = { PixelFormat.Undefined, PixelFormat.DontCare,
 PixelFormat.Format16bppArgb1555, PixelFormat.Format1bppIndexed, PixelFormat.Format4bppIndexed,
 PixelFormat.Format8bppIndexed
     };

         /// <summary>
         /// 判断图片的PixelFormat 是否在 引发异常的 PixelFormat 之中
         /// </summary>
         /// <param name="imgPixelFormat">原图片的PixelFormat</param>
         /// <returns></returns>
         private static bool IsPixelFormatIndexed(PixelFormat imgPixelFormat)
         {
             foreach (PixelFormat pf in indexedPixelFormats)
             {
                 if (pf.Equals(imgPixelFormat)) return true;
             }

             return false;
         }

        /// <summary>
         /// 在图片上生成图片水印
         /// </summary>
         /// <param name="Path">原服务器图片路径</param>
         /// <param name="Path_syp">生成的带图片水印的图片路径</param>
         /// <param name="Path_sypf">水印图片路径</param>
         public static void AddShuiYinPic(string Path, string Path_syp, string Path_sypf)
         {
             System.Drawing.Image image = System.Drawing.Image.FromFile(Path);
             System.Drawing.Image copyImage = System.Drawing.Image.FromFile(Path_sypf);
             System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(image);
             g.DrawImage(copyImage, new System.Drawing.Rectangle(image.Width - copyImage.Width, image.Height - copyImage.Height, copyImage.Width, copyImage.Height), , , copyImage.Width, copyImage.Height, System.Drawing.GraphicsUnit.Pixel);
             g.Dispose();

             image.Save(Path_syp);
             image.Dispose();
         }
         /// <summary>
         /// 在图片上增加文字水印
         /// </summary>
         /// <param name="Path">原服务器图片路径</param>
         /// <param name="Path_sy">生成的带文字水印的图片路径</param>
         public static void AddShuiYinWord(string Path, string Path_sy)
         {

             using (System.Drawing.Image img = System.Drawing.Image.FromFile(Path))
             {
                 //如果原图片是索引像素格式之列的，则需要转换
                 if (IsPixelFormatIndexed(img.PixelFormat))
                 {
                     Bitmap bmp = new Bitmap(img.Width, img.Height, PixelFormat.Format32bppArgb);
                     using (Graphics g = Graphics.FromImage(bmp))
                     {
                         g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                         g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                         g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
                         g.DrawImage(img, , );

                         System.Drawing.Font f = new System.Drawing.Font("Verdana", );
                         System.Drawing.Brush b = new System.Drawing.SolidBrush(System.Drawing.Color.Red);
                         g.DrawString("爱智旮旯", f, b, , );

                     }
                     bmp.Save(Path_sy);
                     bmp.Dispose();

                 }
                 else //否则直接操作
                 {
                     string addText = "爱智旮旯";
                     System.Drawing.Image image = System.Drawing.Image.FromFile(Path);
                     System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(image);
                     g.DrawImage(image, , , image.Width, image.Height);
                     System.Drawing.Font f = new System.Drawing.Font("Verdana", );
                     System.Drawing.Brush b = new System.Drawing.SolidBrush(System.Drawing.Color.Blue);

                     g.DrawString(addText, f, b, , );
                     g.Dispose();

                     image.Save(Path_sy);
                     image.Dispose();
                 }
             } 

         }

         /// <summary>
         /// 生成缩略图
         /// </summary>
         /// <param name="originalImagePath">源图路径（物理路径）</param>
         /// <param name="thumbnailPath">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 static void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode)
         {
             System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath);

             int towidth = width;
             int toheight = height;

             int x = ;
             int y = ;
             int ow = originalImage.Width;
             int oh = originalImage.Height;

             switch (mode)
             {
                 case "HW"://指定高宽缩放（可能变形）
                     break;
                 case "W"://指定宽，高按比例
                     toheight = originalImage.Height * width / originalImage.Width;
                     break;
                 case "H"://指定高，宽按比例
                     towidth = originalImage.Width * height / originalImage.Height;
                     break;
                 case "Cut"://指定高宽裁减（不变形）
                     if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight)
                     {
                         oh = originalImage.Height;
                         ow = originalImage.Height * towidth / toheight;
                         y = ;
                         x = (originalImage.Width - ow) / ;
                     }
                     else
                     {
                         ow = originalImage.Width;
                         oh = originalImage.Width * height / towidth;
                         x = ;
                         y = (originalImage.Height - oh) / ;
                     }
                     break;
                 default:
                     break;
             }

             //新建一个bmp图片
             System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);

             //新建一个画板
             System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);

             //设置高质量插值法
             g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

             //设置高质量,低速度呈现平滑程度
             g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

             //清空画布并以透明背景色填充
             g.Clear(System.Drawing.Color.Transparent);

             //在指定位置并且按指定大小绘制原图片的指定部分
             g.DrawImage(originalImage, new System.Drawing.Rectangle(, , towidth, toheight),
             new System.Drawing.Rectangle(x, y, ow, oh),
             System.Drawing.GraphicsUnit.Pixel);

             try
             {
                 //以jpg格式保存缩略图
                 bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
             }
             catch (System.Exception e)
             {
                 throw e;
             }
             finally
             {
                 originalImage.Dispose();
                 bitmap.Dispose();
                 g.Dispose();
             }
         }

       protected void Button1_Click(object sender, EventArgs e)
         {
             if (FileUpload1.HasFile)
             {
                 string fileContentType = FileUpload1.PostedFile.ContentType;
                 if (fileContentType == "image/bmp" || fileContentType == "image/gif" || fileContentType == "image/pjpeg" || fileContentType == "image/jpg")
                 {
                     string name = FileUpload1.PostedFile.FileName; // 客户端文件路径

                     FileInfo file = new FileInfo(name);
                     string fileName = file.Name; // 文件名称
                     string fileName_s = "s_" + file.Name; // 缩略图文件名称
                     string fileName_sy = "sy_" + file.Name; // 水印图文件名称（文字）
                     string fileName_syp = "syp_" + file.Name; // 水印图文件名称（图片）
                     //以下路径可以根据情况进行修改
                     string webFilePath = Server.MapPath("file/" + fileName); // 服务器端文件路径
                     string webFilePath_s = Server.MapPath("file/" + fileName_s);　　// 服务器端缩略图路径
                     string webFilePath_sy = Server.MapPath("file/" + fileName_sy);　// 服务器端带水印图路径(文字)
                     string webFilePath_syp = Server.MapPath("file/" + fileName_syp);　// 服务器端带水印图路径(图片)
                     //以下为水印图片的路径一定要先准备一张水印图片！
                     string webFilePath_sypf = Server.MapPath("file/shuiyin.jpg");　// 服务器端水印图路径(图片)

                     if (!File.Exists(webFilePath))
                     {
                         try
                         {
                             FileUpload1.SaveAs(webFilePath); // 使用 SaveAs 方法保存文件
                             AddShuiYinWord(webFilePath, webFilePath_sy);
                             //AddShuiYinPic(webFilePath, webFilePath_syp, webFilePath_sypf);
                             MakeThumbnail(webFilePath, webFilePath_s, , , "Cut"); // 生成缩略图方法
                             Label1.Text = "提示：文件“" + fileName + "”成功上传，并生成“" + fileName_s + "”缩略图，文件类型为：" + FileUpload1.PostedFile.ContentType + "，文件大小为：" + FileUpload1.PostedFile.ContentLength + "B";
                         }
                         catch (Exception ex)
                         {
                             Label1.Text = "提示：文件上传失败，失败原因：" + ex.Message;
                         }
                     }
                     else
                     {
                         Label1.Text = "提示：文件已经存在，请重命名后上传";
                     }
                 }
                 else
                 {
                     Label1.Text = "提示：文件类型不符";
                 }

             }
         }