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), 0, 0, 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, 0, 0);

                        System.Drawing.Font f = new System.Drawing.Font("Verdana", 16);
                        System.Drawing.Brush b = new System.Drawing.SolidBrush(System.Drawing.Color.Red);
                        g.DrawString("爱智旮旯", f, b, 15, 15);
                     

                    }
                    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, 0, 0, image.Width, image.Height);
                    System.Drawing.Font f = new System.Drawing.Font("Verdana", 16);
                    System.Drawing.Brush b = new System.Drawing.SolidBrush(System.Drawing.Color.Blue);

                    g.DrawString(addText, f, b, 15, 15);
                    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 = 0;
            int y = 0;
            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 = 0;
                        x = (originalImage.Width - ow) / 2;
                    }
                    else
                    {
                        ow = originalImage.Width;
                        oh = originalImage.Width * height / towidth;
                        x = 0;
                        y = (originalImage.Height - oh) / 2;
                    }
                    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(0, 0, 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, 130, 130, "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";
                }

            }
        }