Workaround BeforeNavigate2 not being fired in WPF .NET

Question

I need to send headers with every request I transmit using the System.Windows.Controls.WebBrowser control. Using C# with .Net, due to a bug described here, the BeforeNavigat

Answer 1

Here is another approach, it uses the low-level COM connection point container interfaces to attach to the underlying DWebBrowserEvents2 source interface directly.

Grab the full project source code from here. I don't have VS2010, so it's a VS2012 project, but it targets .NET 4.0. A compiled app is included in the Debug folder, if you're ready to try it as is.

Here is the relevant code. It's a quick proof of concept which still may have bugs:

using System;
using System.Reflection;
using System.Runtime.InteropServices;
using System.Windows;

namespace WpfWebBrowserEvents
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            this.Loaded += (s, e) =>
            {
                var sink = new WebBrowserEventSink();
                sink.Connect(this.webBrowser);

                this.webBrowser.Navigate("http://example.com");
            };
        }
    }

    /// <summary>
    /// Handling WebBrowser ActiveX events directly
    /// by Noseratio - http://stackoverflow.com/q/20838264/1768303
    /// </summary>

    [ComVisible(true)]
    [ClassInterface(ClassInterfaceType.None)]
    [ComDefaultInterface(typeof(SHDocVw.DWebBrowserEvents2))]
    public class WebBrowserEventSink : SHDocVw.DWebBrowserEvents2
    {
        System.Runtime.InteropServices.ComTypes.IConnectionPoint _sinkCP = null;
        int _sinkCookie = int.MaxValue;

        public void Connect(System.Windows.Controls.WebBrowser webBrowser)
        {
            if (_sinkCookie != int.MaxValue)
                throw new InvalidOperationException();

            var activeXInstance = webBrowser.GetType().InvokeMember("ActiveXInstance",
                BindingFlags.GetProperty | BindingFlags.Instance | BindingFlags.NonPublic,
                null, webBrowser, new object[] { }) as SHDocVw.WebBrowser;

            var cpc = (System.Runtime.InteropServices.ComTypes.IConnectionPointContainer)activeXInstance;
            var guid = typeof(SHDocVw.DWebBrowserEvents2).GUID;
            System.Runtime.InteropServices.ComTypes.IConnectionPoint _sinkCP;
            cpc.FindConnectionPoint(ref guid, out _sinkCP);
            _sinkCP.Advise(this, out _sinkCookie);
        }

        public void Disconnect()
        {
            if (_sinkCookie == int.MaxValue)
                throw new InvalidOperationException();
            _sinkCP.Unadvise(_sinkCookie);
            _sinkCookie = int.MaxValue;
            _sinkCP = null;
        }

        #region SHDocVw.DWebBrowserEvents2

        public void StatusTextChange(string Text)
        {
        }

        public void ProgressChange(int Progress, int ProgressMax)
        {
        }

        public void CommandStateChange(int Command, bool Enable)
        {
        }

        public void DownloadBegin()
        {
        }

        public void DownloadComplete()
        {
        }

        public void TitleChange(string Text)
        {
        }

        public void PropertyChange(string szProperty)
        {
        }

        public void BeforeNavigate2(object pDisp, ref object URL, ref object Flags, ref object TargetFrameName, ref object PostData, ref object Headers, ref bool Cancel)
        {
            MessageBox.Show("BeforeNavigate2: " + URL.ToString());
        }

        public void NewWindow2(ref object ppDisp, ref bool Cancel)
        {
        }

        public void NavigateComplete2(object pDisp, ref object URL)
        {
        }

        public void DocumentComplete(object pDisp, ref object URL)
        {
        }

        public void OnQuit()
        {
        }

        public void OnVisible(bool Visible)
        {
        }

        public void OnToolBar(bool ToolBar)
        {
        }

        public void OnMenuBar(bool MenuBar)
        {
        }

        public void OnStatusBar(bool StatusBar)
        {
        }

        public void OnFullScreen(bool FullScreen)
        {
        }

        public void OnTheaterMode(bool TheaterMode)
        {
        }

        public void WindowSetResizable(bool Resizable)
        {
        }

        public void WindowSetLeft(int Left)
        {
        }

        public void WindowSetTop(int Top)
        {
        }

        public void WindowSetWidth(int Width)
        {
        }

        public void WindowSetHeight(int Height)
        {
        }

        public void WindowClosing(bool IsChildWindow, ref bool Cancel)
        {
        }

        public void ClientToHostWindow(ref int CX, ref int CY)
        {
        }

        public void SetSecureLockIcon(int SecureLockIcon)
        {
        }

        public void FileDownload(bool ActiveDocument, ref bool Cancel)
        {
        }

        public void NavigateError(object pDisp, ref object URL, ref object Frame, ref object StatusCode, ref bool Cancel)
        {
        }

        public void PrintTemplateInstantiation(object pDisp)
        {
        }

        public void PrintTemplateTeardown(object pDisp)
        {
        }

        public void UpdatePageStatus(object pDisp, ref object nPage, ref object fDone)
        {
        }

        public void PrivacyImpactedStateChange(bool bImpacted)
        {
        }

        public void NewWindow3(ref object ppDisp, ref bool Cancel, uint dwFlags, string bstrUrlContext, string bstrUrl)
        {
        }

        public void SetPhishingFilterStatus(int PhishingFilterStatus)
        {
        }

        public void WindowStateChanged(uint dwWindowStateFlags, uint dwValidFlagsMask)
        {
        }

        public void NewProcess(int lCauseFlag, object pWB2, ref bool Cancel)
        {
        }

        public void ThirdPartyUrlBlocked(ref object URL, uint dwCount)
        {
        }

        public void RedirectXDomainBlocked(object pDisp, ref object StartURL, ref object RedirectURL, ref object Frame, ref object StatusCode)
        {
        }

        public void BeforeScriptExecute(object pDispWindow)
        {
        }

        public void WebWorkerStarted(uint dwUniqueID, string bstrWorkerLabel)
        {
        }

        public void WebWorkerFinsihed(uint dwUniqueID)
        {
        }

        #endregion
    }

}