Capturing webpage as image in c#, ensuring javascript rendered elements are visible

Question

I am trying to capture the following page using standard c# .net code. I've searched around for people's various methods, most of which involve instantiating a browser object and using a draw to bitmap method. However, none of these pick up the contents of the chart on this page:

http://www.highcharts.com/demo/combo-dual-axes

Perhaps the javascript doesn't have time to run, but adding Thread.Sleep(x) hasn't assisted.

This commercial component captures it correctly, but I'd rather avoid requiring an additional dependency in my project and paying $150 when the other solutions are sooo close!.

Anyone find their solution renders this correctly?

Answer 1

You have possibly tried IECapt. I think it is the right way to go. I created a modified version of it and use a timer instead of Thread.Sleep it captures your site as expected.

------EDIT------

Here is the ugly source. Just Add a reference to Microsoft HTML Object Library.

And this is the usage:

HtmlCapture capture = new HtmlCapture(@"c:\temp\myimg.png");
capture.HtmlImageCapture += new HtmlCapture.HtmlCaptureEvent(capture_HtmlImageCapture);
capture.Create("http://www.highcharts.com/demo/combo-dual-axes");

void capture_HtmlImageCapture(object sender, Uri url)
{
    this.Close();
}

File1

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.IO;


namespace MyIECapt
{
    public class HtmlCapture
    {
        private WebBrowser web;
        private Timer tready;
        private Rectangle screen;
        private Size? imgsize = null;

        //an event that triggers when the html document is captured
        public delegate void HtmlCaptureEvent(object sender, Uri url);

        public event HtmlCaptureEvent HtmlImageCapture;

        string fileName = "";

        //class constructor
        public HtmlCapture(string fileName)
        {
            this.fileName = fileName;

            //initialise the webbrowser and the timer
            web = new WebBrowser();
            tready = new Timer();
            tready.Interval = 2000;
            screen = Screen.PrimaryScreen.Bounds;
            //set the webbrowser width and hight
            web.Width = 1024; //screen.Width;
            web.Height = 768; // screen.Height;
            //suppress script errors and hide scroll bars
            web.ScriptErrorsSuppressed = true;
            web.ScrollBarsEnabled = false;
            //attached events
            web.Navigating +=
              new WebBrowserNavigatingEventHandler(web_Navigating);
            web.DocumentCompleted += new
              WebBrowserDocumentCompletedEventHandler(web_DocumentCompleted);
            tready.Tick += new EventHandler(tready_Tick);
        }


        public void Create(string url)
        {
            imgsize = null;
            web.Navigate(url);
        }

        public void Create(string url, Size imgsz)
        {
            this.imgsize = imgsz;
            web.Navigate(url);
        }



        void web_DocumentCompleted(object sender,
                 WebBrowserDocumentCompletedEventArgs e)
        {
            //start the timer
            tready.Start();
        }

        void web_Navigating(object sender, WebBrowserNavigatingEventArgs e)
        {
            //stop the timer   
            tready.Stop();
        }



        void tready_Tick(object sender, EventArgs e)
        {
            try
            {
                //stop the timer
                tready.Stop();

                mshtml.IHTMLDocument2 docs2 = (mshtml.IHTMLDocument2)web.Document.DomDocument;
                mshtml.IHTMLDocument3 docs3 = (mshtml.IHTMLDocument3)web.Document.DomDocument;
                mshtml.IHTMLElement2 body2 = (mshtml.IHTMLElement2)docs2.body;
                mshtml.IHTMLElement2 root2 = (mshtml.IHTMLElement2)docs3.documentElement;

                // Determine dimensions for the image; we could add minWidth here
                // to ensure that we get closer to the minimal width (the width
                // computed might be a few pixels less than what we want).
                int width = Math.Max(body2.scrollWidth, root2.scrollWidth);
                int height = Math.Max(root2.scrollHeight, body2.scrollHeight);

                //get the size of the document's body
                Rectangle docRectangle = new Rectangle(0, 0, width, height);

                web.Width = docRectangle.Width;
                web.Height = docRectangle.Height;

                //if the imgsize is null, the size of the image will 
                //be the same as the size of webbrowser object
                //otherwise  set the image size to imgsize
                Rectangle imgRectangle;
                if (imgsize == null) imgRectangle = docRectangle;
                else imgRectangle = new Rectangle() { Location = new Point(0, 0), Size = imgsize.Value };

                //create a bitmap object 
                Bitmap bitmap = new Bitmap(imgRectangle.Width, imgRectangle.Height);
                //get the viewobject of the WebBrowser
                IViewObject ivo = web.Document.DomDocument as IViewObject;

                using (Graphics g = Graphics.FromImage(bitmap))
                {
                    //get the handle to the device context and draw
                    IntPtr hdc = g.GetHdc();
                    ivo.Draw(1, -1, IntPtr.Zero, IntPtr.Zero,
                             IntPtr.Zero, hdc, ref imgRectangle,
                             ref docRectangle, IntPtr.Zero, 0);
                    g.ReleaseHdc(hdc);
                }
                //invoke the HtmlImageCapture event
                bitmap.Save(fileName);
                bitmap.Dispose();
            }
            catch 
            {
                //System.Diagnostics.Process.GetCurrentProcess().Kill();
            }
            if(HtmlImageCapture!=null) HtmlImageCapture(this, web.Url);
        }
    }
}

and File2

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Drawing;
using System.Runtime.InteropServices;

namespace MyIECapt
{
    [ComVisible(true), ComImport()]
    [GuidAttribute("0000010d-0000-0000-C000-000000000046")]
    [InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)]
    public interface IViewObject
    {
        [return: MarshalAs(UnmanagedType.I4)]
        [PreserveSig]
        int Draw(
            [MarshalAs(UnmanagedType.U4)] UInt32 dwDrawAspect,
            int lindex,
            IntPtr pvAspect,
            [In] IntPtr ptd,
            IntPtr hdcTargetDev,
            IntPtr hdcDraw,
            [MarshalAs(UnmanagedType.Struct)] ref Rectangle lprcBounds,
            [MarshalAs(UnmanagedType.Struct)] ref Rectangle lprcWBounds,
            IntPtr pfnContinue,
            [MarshalAs(UnmanagedType.U4)] UInt32 dwContinue);
        [PreserveSig]
        int GetColorSet([In, MarshalAs(UnmanagedType.U4)] int dwDrawAspect,
           int lindex, IntPtr pvAspect, [In] IntPtr ptd,
            IntPtr hicTargetDev, [Out] IntPtr ppColorSet);
        [PreserveSig]
        int Freeze([In, MarshalAs(UnmanagedType.U4)] int dwDrawAspect,
                        int lindex, IntPtr pvAspect, [Out] IntPtr pdwFreeze);
        [PreserveSig]
        int Unfreeze([In, MarshalAs(UnmanagedType.U4)] int dwFreeze);
    }
}

Answer 2

Thread.Sleep will simply suspend the thread your web browser is running on - how do you expect it to render anything when it is suspended? :)

Instead, you need to allow the thread to process work. You can achieve this with a combination of Thread.Sleep(0) and Application.DoEvents(), with something like the following:

DateTime finish = DateTime.Now.AddSeconds(3);
while (DateTime.Now < finish) {
    Application.DoEvents();
    Thread.Sleep(0);
}

Answer 3

@L.B , thank you for the help!

Just an FYI for anyone wanting to run it in a class library, WebBrowser needs to Single Threaded Apartment, so do something like this:

  var t = new Thread(InitAndDo); //InitAndDo would have your code creating the webbrowser object etc...
  t.SetApartmentState(ApartmentState.STA);
  t.Start();

Then the Gotcha, after the navigate call is done, add this line of code so that you get the completed navigation event:

    web.Navigate(Url);
    Application.Run();

Answer 4

I created a nuget package for this purpose https://github.com/dcumin39/RenderHighCharts/wiki