Asp.Net给图片附加水印 - 黑马程序员技术交流社区

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Drawing;
using System.Drawing.Imaging;
using System.IO;
/// <summary>
///CoverHandler 的摘要说明
/// </summary>
public class CoverHandler:IHttpHandler
{
//所有需要添加水印图片的路径
public const string oldImageUrl = "~/admin/BookConvers/";
//水印图片
public const string waterUrl = "~/admin/images/WaterMark.jpg";
//默认图片
public const string DefaultImage = "~/admin/images/Default.jpg";
public CoverHandler()
{
//
//TODO: 在此处添加构造函数逻辑
//
}
public void ProcessRequest(HttpContext context)
{
//string path = context.Request.MapPath(oldImageUrl+context.Request.Params["ISBN"]+".jpg");
System.Drawing.Image Cover;
//判断请求的物理路径中，是否存在文件
if (File.Exists(context.Request.PhysicalPath))
{
//加载文件
//Cover= Image.FromFile(context.Request.PhysicalPath);
Cover = Image.FromFile(context.Request.PhysicalPath);
//加载水印图片
Image watermark = Image.FromFile(context.Request.MapPath(waterUrl));
//实例化画布
Graphics g = Graphics.FromImage(Cover);
//在Cover上绘制水印
g.DrawImage(watermark, new Point(Cover.Width - watermark.Width, Cover.Height - watermark.Height));
//释放画布
g.Dispose();
//释放水印图片
watermark.Dispose();
//保存输出流
Cover.Save(context.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
//结束输出
Cover.Dispose();
context.Response.End();
}
else
{
Cover = Image.FromFile(context.Request.MapPath(DefaultImage));
}
}
public bool IsReusable
{
get
{
return false;
}
}
}

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