C#实现在网页中根据url截图并输出到网页的方法

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Threading;
using System.Windows.Forms;
using System.Drawing;
using System.IO;
/// <summary>
/// This page show the way of generate a image in website
/// </summary>
public partial class Default2 : System.Web.UI.Page
{
  protected void Page_Load(object sender, EventArgs e)
  {
    Bitmap m_Bitmap = WebSiteThumbnail.GetWebSiteThumbnail("http://www.google.cn", 600, 600, 600, 600);
    MemoryStream ms = new MemoryStream();
    m_Bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Png);//JPG、GIF、PNG等均可  
    byte[] buff = ms.ToArray();
    Response.BinaryWrite(buff);
  }
}
public class WebSiteThumbnail
{
  Bitmap m_Bitmap;
  string m_Url;
  int m_BrowserWidth, m_BrowserHeight, m_ThumbnailWidth, m_ThumbnailHeight;
  public WebSiteThumbnail(string Url, int BrowserWidth, int BrowserHeight, int ThumbnailWidth, int ThumbnailHeight)
  {
    m_Url = Url;
    m_BrowserHeight = BrowserHeight;
    m_BrowserWidth = BrowserWidth;
    m_ThumbnailWidth = ThumbnailWidth;
    m_ThumbnailHeight = ThumbnailHeight;
  }
  public static Bitmap GetWebSiteThumbnail(string Url, int BrowserWidth, int BrowserHeight, int ThumbnailWidth, int ThumbnailHeight)
  {
    WebSiteThumbnail thumbnailGenerator = new WebSiteThumbnail(Url, BrowserWidth, BrowserHeight, ThumbnailWidth, ThumbnailHeight);
    return thumbnailGenerator.GenerateWebSiteThumbnailImage();
  }
  public Bitmap GenerateWebSiteThumbnailImage()
  {
    Thread m_thread = new Thread(new ThreadStart(_GenerateWebSiteThumbnailImage));
    m_thread.SetApartmentState(ApartmentState.STA);
    m_thread.Start();
    m_thread.Join();
    return m_Bitmap;
  }
  private void _GenerateWebSiteThumbnailImage()
  {
    WebBrowser m_WebBrowser = new WebBrowser();
    m_WebBrowser.ScrollBarsEnabled = false;
    m_WebBrowser.Navigate(m_Url);
    m_WebBrowser.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(WebBrowser_DocumentCompleted);
    while(m_WebBrowser.ReadyState != WebBrowserReadyState.Complete)
      Application.DoEvents();
    m_WebBrowser.Dispose();
  }
  private void WebBrowser_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
  {
    WebBrowser m_WebBrowser = (WebBrowser)sender;
    m_WebBrowser.ClientSize = new Size(this.m_BrowserWidth, this.m_BrowserHeight);
    m_WebBrowser.ScrollBarsEnabled = false;
    m_Bitmap = new Bitmap(m_WebBrowser.Bounds.Width, m_WebBrowser.Bounds.Height);
    m_WebBrowser.BringToFront();
    m_WebBrowser.DrawToBitmap(m_Bitmap, m_WebBrowser.Bounds);
    m_Bitmap = (Bitmap)m_Bitmap.GetThumbnailImage(m_ThumbnailWidth, m_ThumbnailHeight, null, IntPtr.Zero);
  }
}