图片加水印

       string newfilename="";
        string fullname = FileUpload1.FileName.ToString();
        string fn = DateTime.Now.ToString("yyyyMMddHHmmss") + fullname;
        string typ2 = fullname.Substring(fullname.LastIndexOf(".") + 1);
        if (typ2 == "gif" || typ2 == "jpg" || typ2 == "bmp" || typ2 == "png")
        {
            FileUpload1.SaveAs(Server.MapPath("../photo") + "//" + fn);          //将文件保存在跟目录的UP文件夹下
            System.Drawing.Image image = System.Drawing.Image.FromFile(Server.MapPath("../photo") + "//" + fn);   //加文字水印，注意，这里的代码和以下加图片水印的代码不能共存
            Graphics g = Graphics.FromImage(image);
            g.DrawImage(image, 0, 0, image.Width, image.Height);
            Font f = new Font("Verdana",12);
            Brush b = new SolidBrush(Color.Red);
            string addText = "自己随便加个什么字都行";
            g.DrawString(addText, f, b, 5, 5);
            g.Dispose();

            newfilename="new_"+fn;
            image.Save(Server.MapPath("../photo") + "//" + newfilename);
            image.Dispose();
            //生成新图片后删除上传时的图片
            System.IO.File.Delete(Server.MapPath("../photo/"+fn));
        }
        else
        {
            JScript.JScript.Alert("文件类型不支持");
        }