图片加水印和生成缩略图

一： 图片加水印处理

         //获得图片的名称
        string name = context.Request["name"];
        string filePath = context.Server.MapPath("Upload/" + name);
        //首先获得要进行水印处理的图片
        if (!string.IsNullOrEmpty(name))
        {
            using (Image image = Bitmap.FromFile(filePath))
            {
                //准备一个画笔来在图片上作画
                using (Graphics g = Graphics.FromImage(image))
                {
                    //作画
                    g.DrawString("str", new Font("微软雅黑", 20), Brushes.Red, new PointF(1, 1));
                    image.Save(context.Response.OutputStream, ImageFormat.Jpeg);
                }
            }
        }

二：生成缩略图

        

 HttpPostedFile hpFile= context.Request.Files[0];
        if (hpFile.ContentLength > 0)
        {
            string filePath = context.Server.MapPath("Upload/" + hpFile.FileName);
            //判断文件是否为图片文件
            if (hpFile.ContentType.IndexOf("image") > -1)
            {
                //从输入流中获得图片数据
                using (Image img = Image.FromStream(hpFile.InputStream))
                {
                    //准备一张画板来存储小图
                    using (Bitmap thumbImg = new Bitmap(120, 80))
                    {
                        //利用画笔将大图绘制在小图中
                        using (Graphics g = Graphics.FromImage(thumbImg))
                        {                     //用于指定最终画的图的大小
                            g.DrawImage(img, new Rectangle(0, 0, thumbImg.Width, thumbImg.Height),
                                new Rectangle(0, 0, img.Width, img.Height), GraphicsUnit.Pixel);
                            //用于指定画大图中的那一部分

                            //将小图也保存在相应的路径中
                            thumbImg.Save(context.Server.MapPath("Upload/thumb_" + hpFile.FileName));
                            context.Response.Write("保存成功！");
                        }
                    }
                }
            }
           
           
            //保存大图
            hpFile.SaveAs(filePath);
        }