Convert webpage to image from ASP.NET

Question

I would like to create a function in C# that takes a specific webpage and coverts it to a JPG image from within ASP.NET. I don't want to do this via a third party or thumbnail service as I need the full image. I assume I would need to somehow leverage the webbrowser control from within ASP.NET but I just can't see where to get started. Does anyone have examples?

Answer 1

Ok, this was rather easy when I combined several different solutions:

These solutions gave me a thread-safe way to use the WebBrowser from ASP.NET:

http://www.beansoftware.com/ASP.NET-Tutorials/Get-Web-Site-Thumbnail-Image.aspx

http://www.eggheadcafe.com/tutorials/aspnet/b7cce396-e2b3-42d7-9571-cdc4eb38f3c1/build-a-selfcaching-asp.aspx

This solution gave me a way to convert BMP to JPG:

Bmp to jpg/png in C#

I simply adapted the code and put the following into a .cs:

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

public class WebsiteToImage
{
    private Bitmap m_Bitmap;
    private string m_Url;
    private string m_FileName = string.Empty;

    public WebsiteToImage(string url)
    {
        // Without file 
        m_Url = url;
    }

    public WebsiteToImage(string url, string fileName)
    {
        // With file 
        m_Url = url;
        m_FileName = fileName;
    }

    public Bitmap Generate()
    {
        // Thread 
        var m_thread = new Thread(_Generate);
        m_thread.SetApartmentState(ApartmentState.STA);
        m_thread.Start();
        m_thread.Join();
        return m_Bitmap;
    }

    private void _Generate()
    {
        var browser = new WebBrowser { ScrollBarsEnabled = false };
        browser.Navigate(m_Url);
        browser.DocumentCompleted += WebBrowser_DocumentCompleted;

        while (browser.ReadyState != WebBrowserReadyState.Complete)
        {
            Application.DoEvents();
        }

        browser.Dispose();
    }

    private void WebBrowser_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
    {
        // Capture 
        var browser = (WebBrowser)sender;
        browser.ClientSize = new Size(browser.Document.Body.ScrollRectangle.Width, browser.Document.Body.ScrollRectangle.Bottom);
        browser.ScrollBarsEnabled = false;
        m_Bitmap = new Bitmap(browser.Document.Body.ScrollRectangle.Width, browser.Document.Body.ScrollRectangle.Bottom);
        browser.BringToFront();
        browser.DrawToBitmap(m_Bitmap, browser.Bounds);

        // Save as file? 
        if (m_FileName.Length > 0)
        {
            // Save 
            m_Bitmap.SaveJPG100(m_FileName);
        }
    }
}

public static class BitmapExtensions
{
    public static void SaveJPG100(this Bitmap bmp, string filename)
    {
        var encoderParameters = new EncoderParameters(1);
        encoderParameters.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L);
        bmp.Save(filename, GetEncoder(ImageFormat.Jpeg), encoderParameters);
    }

    public static void SaveJPG100(this Bitmap bmp, Stream stream)
    {
        var encoderParameters = new EncoderParameters(1);
        encoderParameters.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, 100L);
        bmp.Save(stream, GetEncoder(ImageFormat.Jpeg), encoderParameters);
    }

    public static ImageCodecInfo GetEncoder(ImageFormat format)
    {
        var codecs = ImageCodecInfo.GetImageDecoders();

        foreach (var codec in codecs)
        {
            if (codec.FormatID == format.Guid)
            {
                return codec;
            }
        }

        // Return 
        return null;
    }
}

And can call it as follows:

WebsiteToImage websiteToImage = new WebsiteToImage( "http://www.cnn.com", @"C:\Some Folder\Test.jpg");
websiteToImage.Generate();

It works with both a file and a stream. Make sure you add a reference to System.Windows.Forms to your ASP.NET project. I hope this helps.

UPDATE: I've updated the code to include the ability to capture the full page and not require any special settings to capture only a part of it.

Answer 2

Good solution by Mr Cat Man Do.

I've needed to add a row to suppress some errors that came up in some webpages (with the help of an awesome colleague of mine)

private void _Generate()
{
    var browser = new WebBrowser { ScrollBarsEnabled = false };

    browser.ScriptErrorsSuppressed = true;        //           <--

    browser.Navigate(m_Url);
    browser.DocumentCompleted += WebBrowser_DocumentCompleted;
}

...

Thanks Mr Do

Answer 3

Here is my implementation using extension methods and task factory instead thread:

/// <summary>
    /// Convert url to bitmap byte array
    /// </summary>
    /// <param name="url">Url to browse</param>
    /// <param name="width">width of page (if page contains frame, you need to pass this params)</param>
    /// <param name="height">heigth of page (if page contains frame, you need to pass this params)</param>
    /// <param name="htmlToManipulate">function to manipulate dom</param>
    /// <param name="timeout">in milliseconds, how long can you wait for page response?</param>
    /// <returns>bitmap byte[]</returns>
    /// <example>
    /// byte[] img = new Uri("http://www.uol.com.br").ToImage();
    /// </example>
    public static byte[] ToImage(this Uri url, int? width = null, int? height = null, Action<HtmlDocument> htmlToManipulate = null, int timeout = -1)
    {
        byte[] toReturn = null;

        Task tsk = Task.Factory.StartNew(() =>
        {
            WebBrowser browser = new WebBrowser() { ScrollBarsEnabled = false };
            browser.Navigate(url);

            browser.DocumentCompleted += (s, e) =>
            {
                var browserSender = (WebBrowser)s;

                if (browserSender.ReadyState == WebBrowserReadyState.Complete)
                {
                    if (htmlToManipulate != null) htmlToManipulate(browserSender.Document);

                    browserSender.ClientSize = new Size(width ?? browser.Document.Body.ScrollRectangle.Width, height ?? browser.Document.Body.ScrollRectangle.Bottom);
                    browserSender.ScrollBarsEnabled = false;
                    browserSender.BringToFront();

                    using (Bitmap bmp = new Bitmap(browserSender.Document.Body.ScrollRectangle.Width, browserSender.Document.Body.ScrollRectangle.Bottom))
                    {
                        browserSender.DrawToBitmap(bmp, browserSender.Bounds);
                        toReturn = (byte[])new ImageConverter().ConvertTo(bmp, typeof(byte[]));
                    }
                }

            };

            while (browser.ReadyState != WebBrowserReadyState.Complete)
            {
                Application.DoEvents();
            }

            browser.Dispose();

        }, CancellationToken.None, TaskCreationOptions.None, TaskScheduler.FromCurrentSynchronizationContext());

        tsk.Wait(timeout);

        return toReturn;
    }

Answer 4

The solution is perfect, just needs a fixation in the line which sets the WIDTH of the image. For pages with a LARGE HEIGHT, it does not set the WIDTH appropriately:

    //browser.ClientSize = new Size(browser.Document.Body.ScrollRectangle.Width, browser.Document.Body.ScrollRectangle.Bottom);
    browser.ClientSize = new Size(1000, browser.Document.Body.ScrollRectangle.Bottom);

And for adding a reference to System.Windows.Forms, you should do it in .NET-tab of ADD REFERENCE instead of COM -tab.

Answer 5

There is a good article by Peter Bromberg on this subject here. His solution seems to do what you need...

Answer 6

You could use WatiN to open a new browser, then capture the screen and crop it appropriately.