在web项目中使用WebBrowser类-----给网站抓图

最近做一个WEB项目，其中要求有个功能就是程序能网页抓图，举个例子：
在test.aspx页面上放一个TextBox和一个Button，TextBox用来输入要抓取的网页地址，然后按了Button之后，服务器要对前面输入的网址进行抓图，然后显示出来。我把抓图的业务逻辑做成一个类：

using System;
using System.Data;
using System.Windows.Forms;
using System.Drawing;

/// <summary>
/// WebSnap ：网页抓图对象
/// </summary>
public class WebSnap2
{

    public WebSnap2()
    {
        //
        // TODO: 在此处添加构造函数逻辑
        //
    }

    /// <summary>
    /// 开始一个抓图并返回图象
    /// </summary>
    /// <param name="Url">要抓取的网页地址</param>
    /// <returns></returns>
    public Bitmap StartSnap(string Url)
    {
        WebBrowser myWB = this.GetPage(Url);
        Bitmap returnValue = this.SnapWeb(myWB);
        myWB.Dispose();
        return returnValue;
    }

    private WebBrowser GetPage(string Url)
    {
        WebBrowser myWB = new WebBrowser();
        myWB.ScrollBarsEnabled = false;
        myWB.Navigate(Url);
        while (myWB.ReadyState != WebBrowserReadyState.Complete)
        {
            System.Windows.Forms.Application.DoEvents();
        }
        return myWB;
    }

    private Bitmap SnapWeb(WebBrowser wb)
    {
        HtmlDocument hd = wb.Document;
        int height = Convert.ToInt32(hd.Body.GetAttribute("scrollHeight")) + 10;
        int width = Convert.ToInt32(hd.Body.GetAttribute("scrollWidth")) + 10;
        wb.Height = height;
        wb.Width = width;
        Bitmap bmp = new Bitmap(width, height);
        Rectangle rec = new Rectangle();
        rec.Width = width;
        rec.Height = height;
        wb.DrawToBitmap(bmp, rec);
        return bmp;
    }

}

然后在test.asp的button_click事件里面调用：

        WebSnap ws = new WebSnap();
        Bitmap bmp= ws.StartSnap(TextBox1.Text);
        System.IO.MemoryStream ms = new System.IO.MemoryStream();
        bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
        Response.BinaryWrite(ms.GetBuffer());