上传附件加水印

/// <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
    };

public string Upload()
        {
            Response.ContentType = "text/plain";
            string str1 = Request.Form["str1"];
            string str2 = Request.Form["str2"];
            string filetype = Request.Form["filetype"];

            var obj = RoadFlow.Cache.IO.Opation.Get(str1 ?? "");
            if (str1.IsNullOrEmpty() || str2.IsNullOrEmpty() || obj == null || obj.ToString() != str2)
            {
                return "您不能上传文件";
            }

            //接收上传后的文件
            HttpPostedFileBase file = Request.Files["Filedata"];

            if (filetype.IsNullOrEmpty())
            {
                if (!RoadFlow.Utility.Config.UploadFileType.Contains(Path.GetExtension(file.FileName).TrimStart(‘.‘), StringComparison.CurrentCultureIgnoreCase))
                {
                    return "您上传的文件类型不被允许";
                }
            }
            else
            {

                if (!filetype.Contains(Path.GetExtension(file.FileName).TrimStart(‘.‘), StringComparison.CurrentCultureIgnoreCase))
                {
                    return "您上传的文件类型不被允许";
                }
            }
            var reg = new Regex(@"^/w+$");
            var fname = file.FileName.Split(‘.‘)[0];
            if (!reg.IsMatch(fname) && !new Regex(@"^[a-zA-Z0-9_\u4e00-\u9fa5]+$").IsMatch(fname) && !new Regex(@"^[u4e00-u9fa5]+$").IsMatch(fname))
                return "上传的文件名只能由数字字母汉字或者下划线组成";

            //获取文件的保存路径
            string uploadPath;
            string uploadFullPath = Server.MapPath(getFilePath(out uploadPath));

            //判断上传的文件是否为空
            if (file != null)
            {
                if (!Directory.Exists(uploadFullPath))
                {
                    Directory.CreateDirectory(uploadFullPath);
                }

                //保存文件
                string newFileName = getFileName(uploadFullPath, file.FileName);
                string newFileFullPath = uploadFullPath + newFileName;
                try
                {
                    int fileLength = file.ContentLength;
                    //添加水印
                    var str = "jpg,png,gif,bmp";
                    if (str.Contains(Path.GetExtension(file.FileName).TrimStart(‘.‘)))
                    {

                        System.Drawing.Image image = System.Drawing.Image.FromStream(file.InputStream);
                        System.Drawing.Graphics g;
                        System.Drawing.Font f = new System.Drawing.Font("宋体", 15, System.Drawing.FontStyle.Bold);

                        if (IsPixelFormatIndexed(image.PixelFormat))
                        {
                            Bitmap bmp = new Bitmap(image.Width, image.Height, PixelFormat.Format32bppArgb);
                            using (g = Graphics.FromImage(bmp))
                            {
                                g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                                g.SmoothingMode = SmoothingMode.AntiAlias;
                                g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
                                g.DrawImage(image, 0, 0, image.Width, image.Height);
                                System.Drawing.Brush b = new System.Drawing.SolidBrush(System.Drawing.Color.Red);
                                PointF pointF = new PointF(image.Width - (RoadFlow.Platform.Users.CurrentUserName.Length * f.Size + 30), image.Height - 30);
                                SizeF sizeF = g.MeasureString(RoadFlow.Platform.Users.CurrentUserName, f);
                                g.FillRectangle(Brushes.Gray, new RectangleF(pointF, sizeF));
                                g.DrawString(RoadFlow.Platform.Users.CurrentUserName, f, Brushes.Red, pointF);
                                g.DrawString(RoadFlow.Platform.Users.CurrentUserName, f, b, image.Width - (RoadFlow.Platform.Users.CurrentUserName.Length * f.Size + 30), image.Height - 30);

                            }
                            bmp.Save(uploadFullPath + "ShuiYin_" + newFileName);
                            bmp.Dispose();
                        }
                        else
                        {
                            //g = Graphics.FromImage(image);
                            g = System.Drawing.Graphics.FromImage(image);
                            g.DrawImage(image, 0, 0, image.Width, image.Height);

                            System.Drawing.Brush b = new System.Drawing.SolidBrush(System.Drawing.Color.Red);
                            PointF pointF = new PointF(image.Width - (RoadFlow.Platform.Users.CurrentUserName.Length * f.Size + 30), image.Height - 30);
                            SizeF sizeF = g.MeasureString(RoadFlow.Platform.Users.CurrentUserName, f);
                            g.FillRectangle(Brushes.Gray, new RectangleF(pointF, sizeF));
                            g.DrawString(RoadFlow.Platform.Users.CurrentUserName, f, Brushes.Red, pointF);
                            g.DrawString(RoadFlow.Platform.Users.CurrentUserName, f, b, image.Width - (RoadFlow.Platform.Users.CurrentUserName.Length * f.Size + 30), image.Height - 30);
                            g.Dispose();
                            image.Save(uploadFullPath + "ShuiYin_" + newFileName);
                            image.Dispose();
                        }

                        //保存原图
                        file.SaveAs(newFileFullPath);
                        return "1|" + (uploadPath + "ShuiYin_" + newFileName) + "|" + (fileLength / 1000).ToString("###,###") + "|" + "ShuiYin_" + newFileName;
                    }
                    else
                    {

                        file.SaveAs(newFileFullPath);
                        return "1|" + (uploadPath + newFileName) + "|" + (fileLength / 1000).ToString("###,###") + "|" + newFileName;
                    }

                    file.SaveAs(newFileFullPath);
                    return "1|" + (uploadPath + newFileName) + "|" + (fileLength / 1000).ToString("###,###") + "|" + newFileName;
                }
                catch
                {
                    return "上传文件发生了错误";
                }
            }
            else
            {
                return "上传文件为空";
            }
        }

        /// <summary>
        /// 得到上传文件名
        /// </summary>
        /// <param name="fileName"></param>
        /// <returns></returns>
        private string getFileName(string filePath, string fileName)
        {
            while (System.IO.File.Exists(filePath + fileName))
            {
                fileName = Path.GetFileNameWithoutExtension(fileName) + "_" + RoadFlow.Utility.Tools.GetRandomString() + Path.GetExtension(fileName);
            }
            return fileName;
        }

        /// <summary>
        /// 得到文件保存路径
        /// </summary>
        /// <returns></returns>
        private string getFilePath(out string path1)
        {
            DateTime date = RoadFlow.Utility.DateTimeNew.Now;
            path1 = Url.Content("~/Content/UploadFiles/" + date.ToString("yyyyMM") + "/" + date.ToString("dd") + "/");
            return path1;
        }

        private static bool IsPixelFormatIndexed(PixelFormat imgPixelFormat)
        {
            foreach (PixelFormat pf in indexedPixelFormats)
            {
                if (pf.Equals(imgPixelFormat)) return true;
            }

            return false;
        }

说明：

1.有时候上传会出现无法添加水印的情况，需要，图片下载下来生成bmp格式的图片才可以添加。