Get ASP.NET C# 2.0 Website Thumbnail Screenshot

• Download source code - 80.3 KB

Introduction

This sample code/website gets the thumbnail/screenshot for a specific URL, giving the browser dimensions and the thumbnail dimensions you want.

Background

Well, tired of search for a method for giving me the screenshot of a URL, and just finding examples of Windows.Forms, with the simple method DrawToBitmap, I just realized that in ASP.NET, that does not work like that, because of Single Thread and Multi Thread; so I used .SetApartmentState(ApartmentState.STA) to make it single threaded.

Using the Code

Just call the method that you want to associate with the ImageUrl of an ASP.NET Image control.

Server-side

Calling with the IHttpHandler Method

ImageBox.ImageUrl = "~/HandlerWSThumb.ashx?url=" + 
   Server.UrlEncode(txtURL.Text).ToLower().ToString() + "&bw=" + 
   txtBW.Text + "&bh=" + txtBH.Text + "&tw=" + 
   txtTW.Text + "&th=" + txtTH.Text;

Calling with the Class Method

Bitmap bmp = ClassWSThumb.GetWebSiteThumbnail(txtURL.Text, Int32.Parse(txtBW.Text), 
             Int32.Parse(txtBH.Text), Int32.Parse(txtTW.Text), 
             Int32.Parse(txtTH.Text));
bmp.Save(Server.MapPath("~") + "/thumbnail.bmp");
ImageBox.ImageUrl = "~/thumbnail.bmp";

//**if Jpeg is the image format you need just replace the 2 lines above for:
//
//bmp.Save(Server.MapPath("~") + "/thumbnail.jpg", ImageFormat.Jpeg);
//ImageBox.ImageUrl = "~/thumbnail.jpg";

//** but don't forget to add the reference
//   to the class in the page 'Default.aspx'(code behind):
//using System.Drawing.Imaging;

Here is the class method code:

using System;
using System.Drawing;
using System.Windows.Forms;
using System.Threading;
using System.IO;

namespace GetWebSiteThumb
{
    public class ClassWSThumb
    {
        public static Bitmap GetWebSiteThumbnail(string Url, int BrowserWidth, 
               int BrowserHeight, int ThumbnailWidth, int ThumbnailHeight)
        {
            return new WSThumb(Url, BrowserWidth, BrowserHeight, 
                   ThumbnailWidth, ThumbnailHeight).GetWSThumb();
        }

        private class WSThumb
        {
            public WSThumb(string Url, int BW, int BH, int TW, int TH) {
                __Url = Url;
                __BrowserWidth = BW;
                __BrowserHeight = BH;
                __ThumbnailWidth = TW;
                __ThumbnailHeight = TH;
            }

            private Bitmap __Bitmap = null;            
            private string __Url = null;
            private int __ThumbnailWidth;
            private int __ThumbnailHeight;
            private int __BrowserWidth;
            private int __BrowserHeight;

            public string Url            {
                get{return __Url;}
                set{__Url = value;}
            }
            
            public Bitmap ThumbnailImage            {
                get{return __Bitmap;}
            }

            public int ThumbnailWidth            {
                get{return __ThumbnailWidth;}
                set{__ThumbnailWidth = value;}
            }

            public int ThumbnailHeight            {
                get {return __ThumbnailHeight;}
                set {__ThumbnailHeight = value;}
            }

            public int BrowserWidth            {
                get{return __BrowserWidth;}
                set{__BrowserWidth = value;}
            }

            public int BrowserHeight            {
                get{return __BrowserHeight;}
                set{__BrowserHeight = value;}
            }

            public Bitmap GetWSThumb()            {
                ThreadStart __threadStart = new ThreadStart(_GenerateWSThumb);
                Thread __thread = new Thread(__threadStart);

                __thread.SetApartmentState(ApartmentState.STA);
                __thread.Start();
                __thread.Join();
                return __Bitmap;
            }

            private void _GenerateWSThumb()            {
                WebBrowser __WebBrowser = new WebBrowser();
                __WebBrowser.ScrollBarsEnabled = false;
                __WebBrowser.Navigate(__Url);
                __WebBrowser.DocumentCompleted += 
                  new WebBrowserDocumentCompletedEventHandler(WebBrowser_DocumentCompleted);
                while (__WebBrowser.ReadyState != WebBrowserReadyState.Complete)
                    Application.DoEvents();
                __WebBrowser.Dispose();
            }

            private void WebBrowser_DocumentCompleted(object sender, 
                         WebBrowserDocumentCompletedEventArgs e)            {
                WebBrowser __WebBrowser = (WebBrowser)sender;
                __WebBrowser.ClientSize = new Size(this.__BrowserWidth, this.__BrowserHeight);
                __WebBrowser.ScrollBarsEnabled = false;
                __Bitmap = new Bitmap(__WebBrowser.Bounds.Width, __WebBrowser.Bounds.Height);
                __WebBrowser.BringToFront();
                __WebBrowser.DrawToBitmap(__Bitmap, __WebBrowser.Bounds);
                
                if (__ThumbnailHeight != 0 && __ThumbnailWidth !=0)
                __Bitmap = (Bitmap)__Bitmap.GetThumbnailImage(
                    __ThumbnailWidth, __ThumbnailHeight, null, IntPtr.Zero);                
            }
        }
    }
}

Here is the IHTTPHandler method code:

using System;
using System.Data;
using System.Web;
using System.Collections;
using System.Web.Services;
using System.Web.Services.Protocols;
using System.Drawing;
using System.Drawing.Imaging;
using System.Windows.Forms;
using System.Threading;
using System.IO;
using System.Reflection;

namespace GetWebSiteThumb
{
    /// <summary>
    /// Summary description for $codebehindclassname$
    /// </summary>
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    public class HandlerWSThumb : IHttpHandler
    {
        public void ProcessRequest(HttpContext context)
        {
            Bitmap thumb = null;
            string url = null;
            int bw = 800; //valor por defeito
            int bh = 600; //valor por defeito
            int tw = 0;    // sem thumbnail 
            int th = 0;

            context.Response.ContentType = "image/jpeg";
            if (context.Request["url"] != null)
            {
                if (context.Request["url"].ToString().ToLower().Contains("http://") || 
                       context.Request["url"].ToString().ToLower().Contains("https://"))
                    url = context.Request["url"].ToString();
                else
                    url = "http://" + context.Request["url"].ToString();
            }

            if (context.Request["bw"] != null)
                bw = Int32.Parse(context.Request["bw"].ToString());

            if (context.Request["bh"] != null)
                bh = Int32.Parse(context.Request["bh"].ToString());

            if (context.Request["tw"] != null)
                tw = Int32.Parse(context.Request["tw"].ToString());

            if (context.Request["th"] != null)
                th = Int32.Parse(context.Request["th"].ToString());

            // return context bitmap
            thumb = GetWebSiteThumbnail(url, bw, bh);

            if (tw != 0 && th != 0)
                thumb.GetThumbnailImage(tw, th, null, IntPtr.Zero).Save(
                           context.Response.OutputStream, ImageFormat.Jpeg);
            else
                thumb.Save(context.Response.OutputStream, ImageFormat.Jpeg);

            thumb.Dispose();
        }

        public static Bitmap GetWebSiteThumbnail(string Url, 
                      int BrowserWidth, int BrowserHeight)
        {
            WebsiteThumbnailImage thumbnailGenerator = 
              new WebsiteThumbnailImage(Url, BrowserWidth, BrowserHeight);
            return thumbnailGenerator.GenerateWebSiteThumbnailImage();
        }

        private class WebsiteThumbnailImage
        {
            public WebsiteThumbnailImage(string Url, 
                   int BrowserWidth, int BrowserHeight)
            {
                this.m_Url = Url;
                this.m_BrowserWidth = BrowserWidth;
                this.m_BrowserHeight = BrowserHeight;
            }

            private string m_Url = null;
            public string Url
            {
                get { return m_Url; }
                set { m_Url = value; }
            }

            private Bitmap m_Bitmap = null;
            public Bitmap ThumbnailImage
            {
                get { return m_Bitmap; }
            }

            private int m_BrowserWidth;
            public int BrowserWidth
            {
                get { return m_BrowserWidth; }
                set { m_BrowserWidth = value; }
            }

            private int m_BrowserHeight;
            public int BrowserHeight
            {
                get { return m_BrowserHeight; }
                set { m_BrowserHeight = value; }
            }

            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);
            }
        }

        // Resusable flag
        public bool IsReusable
        {
            get { return false; }
        }
    }
}

Points of Interest

I learn that there are always three ways to do things: the right way, the wrong way, and the best way. I tried to cover the 3 of them ;) As an add-on, you could build a WebService method for returning the thumbnail. Maybe I will edit this article in the near future and put some code in the sample to accomplish it.

History

• Version 1.0: Upgrades and tips are welcome.
• Version 1.1: Just added a comment about converting the resulting BMP in the class method to JPEG, after a user asked me to do that.