asp.net(c#)用httphandler加水印

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Drawing;

/// <summary>
/// Handler 的摘要说明
/// </summary>
public class Handler:IHttpHandler
{
public Handler()
{
//
// TODO: 在此处添加构造函数逻辑
//
}

    #region IHttpHandler 成员

    public bool IsReusable
    {
        get { return false; }
    }