C# Internet Explorer DOM using ObjectFromLresult.


Senior Contributor
Oct 1, 2002
Ashby, Leicestershire.
Howdo, I've been working on this for a couple of days, I did a VB.NET example of this on a forum a few years ago, but C# presented me with a new challenge & it took a while to figure out.
The Idea is to get hold of an open instance of IE ( IE7 in this case ) & grab hold of it's IHTMLDocument2 Interface, giving the ability to manipulate that external Internet Explorer window / grab it's url address, it's html, make it navigate elsewhere, etc...
when this code is added to a project, you must make a reference to Microsoft.mshtml
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Diagnostics;
using System.Drawing;
using System.Runtime.InteropServices;
using System.Text;
using System.Windows.Forms;
using mshtml;
namespace HookBrowser
    public partial class Form1 : Form
        public Form1()
        #region API CALLS
        [DllImport("user32.dll", EntryPoint = "GetClassNameA")]
        public static extern int GetClassName(IntPtr hwnd, StringBuilder lpClassName, int nMaxCount);
        /*delegate to handle EnumChildWindows*/
        public delegate int EnumProc(IntPtr hWnd, ref IntPtr lParam);
        public static extern int EnumChildWindows(IntPtr hWndParent, EnumProc lpEnumFunc, ref  IntPtr lParam);
        [DllImport("user32.dll", EntryPoint = "RegisterWindowMessageA")]
        public static extern int RegisterWindowMessage(string lpString);
        [DllImport("user32.dll", EntryPoint = "SendMessageTimeoutA")]
        public static extern int SendMessageTimeout(IntPtr hwnd, int msg, int wParam, int lParam, int fuFlags, int uTimeout, out int lpdwResult);
        public static extern int ObjectFromLresult(int lResult, ref Guid riid, int wParam, ref IHTMLDocument2 ppvObject);
        public const int SMTO_ABORTIFHUNG = 0x2;
        public Guid IID_IHTMLDocument = new Guid("626FC520-A41E-11CF-A731-00A0C9082637");
        public IHTMLDocument2 document;
        private void button1_Click(object sender, EventArgs e)
            document = documentFromDOM();
            /// check that we have hold of the IHTMLDocument2...
            if (!(bool)(document == null))
                this.Text = document.url;
        private IHTMLDocument2 documentFromDOM()
            Process[] processes = Process.GetProcessesByName("iexplore");
            if (processes.Length > 0)
                IntPtr hWnd = processes[0].MainWindowHandle;
                int lngMsg = 0;
                int lRes;
                EnumProc proc = new EnumProc(EnumWindows);
                EnumChildWindows(hWnd, proc, ref hWnd);
                if (!hWnd.Equals(IntPtr.Zero))
                    lngMsg = RegisterWindowMessage("WM_HTML_GETOBJECT");
                    if (lngMsg != 0)
                        SendMessageTimeout(hWnd, lngMsg, 0, 0, SMTO_ABORTIFHUNG, 1000, out lRes);
                        if (!(bool)(lRes == 0))
                            int hr = ObjectFromLresult(lRes, ref IID_IHTMLDocument, 0, ref document);
                            if ((bool)(document == null))
                                MessageBox.Show("No IHTMLDocument Found!", "Warning");
            return document;
        private int EnumWindows(IntPtr hWnd, ref IntPtr lParam)
            int retVal = 1;
            StringBuilder classname = new StringBuilder(128);
            GetClassName(hWnd, classname, classname.Capacity);
            /// check if the instance we have found is Internet Explorer_Server
            if ((bool)(string.Compare(classname.ToString(), "Internet Explorer_Server") == 0))
                lParam = hWnd;
                retVal = 0;
            return retVal;
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