How to get IHTMLDocument2 from a HWND

http://support.microsoft.com/kb/249232

 

This article shows how to get the IHTMLDocument2 interface from a HWND. If Microsoft Active Accessibility (MSAA) is installed, you can send the WM_HTML_GETOBJECT message to the document's window (with the window class "Internet Explorer_Server") and then pass the result from SendMessage to an MSAA function, ObjectFromLresult, to get a fully marshaled IHTMLDocument2 pointer.

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You must have Active Accessibility components installed on the system for the c...

The following code demonstrates how to allow multiple instances of the Internet Explorer to be registered in the ROT using item moniker.

/////////////////////////////////////////////////////////////////////////////  IEHELPER.H
#ifndef __IEHELPER_H_
#define __IEHELPER_H_

#include "resource.h"       // main symbols

/////////////////////////////////////////////////////////////////////////////
// CIEHelper
class CIEHelper : 
        public CComObjectRootEx<CComSingleThreadModel>,
        public CComCoClass<CIEHelper, &CLSID_IEHelper>,
        public IObjectWithSiteImpl<CIEHelper>,
        public IIEHelper
{
public:
        CIEHelper()
        {
                m_dwROTID = 0;
        }

       ~CIEHelper()
        {
        }

        // IObjectWithSite interface
        STDMETHOD(SetSite)(IUnknown* pUnkSite);

DECLARE_REGISTRY_RESOURCEID(IDR_IEHELPER)

BEGIN_COM_MAP(CIEHelper)
        COM_INTERFACE_ENTRY(IIEHelper)
        COM_INTERFACE_ENTRY(IObjectWithSite)
END_COM_MAP()

// IIEHelper
public:
        void SetROTID(DWORD dwValue)
        {
                m_dwROTID = dwValue;
        }
private:
        DWORD m_dwROTID;
        void ROT_UnRegister();
        void ROT_Register();
};

#endif //__IEHELPER_H_

/////////////////////////////////////////////////////////////////// IEHELPER.CPP
// IEHelper.cpp : Implementation of CIEHelper

#include "stdafx.h"
#include "IE.h"
#include "IEHelper.h"

#include <initguid.h>
#include <exdisp.h>        // the IID_IWebBrowser is located over there
#include <stdio.h>

/////////////////////////////////////////////////////////////////////////////
// CIEHelper
//

// CObjectWithSite Methods
//

STDMETHODIMP CIEHelper::SetSite(IUnknown* pUnkSite)
{
        USES_CONVERSION;

        // remove previously registered object from the table
        ROT_UnRegister();

        // neccessary initialization
        HRESULT hResult = IObjectWithSiteImpl<CIEHelper>::SetSite(pUnkSite);

        // register helper object in the running object table
        ROT_Register();

        return hResult;
}

///////////////////////////////////////////////////////////////////////////
//

//
// Private Section
//

const static TCHAR* szMonikerTemplateName = _T("Browser Helper Object");

//
// register the object in the running object table 
//

void CIEHelper::ROT_Register()
{
        CComPtr<IRunningObjectTable> pTable;
        if(GetRunningObjectTable(0, &pTable) == S_OK)
        {
                CComBSTR bstrItemName;
                CComPtr<IMoniker> pMoniker;
                TCHAR szBuffer[1024];

                sprintf(szBuffer, "%s | %d", szMonikerTemplateName, m_spUnkSite);
                bstrItemName = szBuffer;
                if(CreateItemMoniker(NULL, bstrItemName, &pMoniker) == S_OK)
                {
                        DWORD dwRegister;
                        if(pTable->Register(1, (IUnknown*)this, pMoniker, &dwRegister) == S_OK)
                        {
                                SetROTID(dwRegister);
                                ATLTRACE("IIEHelper: the moniker %s has been registered successfully/n", szBuffer);
                        }
                        else
                        {
                                ATLTRACE("IIEHelper: failed to register moniker % s in the ROT/n", szBuffer);
                        }
                }
                else
                {
                        ATLTRACE("IIEHelper: failed to create moniker %s/n", szBuffer);
                }
        }
        else
        {
                ATLTRACE("IIEHelper: Could not retrieve the ROT pointer/n");
        }
}

void CIEHelper::ROT_UnRegister()
{
        CComPtr<IRunningObjectTable> pTable;
        if(GetRunningObjectTable(0, &pTable) == S_OK)
        {
                HRESULT hRes = pTable->Revoke(m_dwROTID);
                ATLTRACE("IIEHelper: ID = %d, result code %x/n", m_dwROTID, hRes);
        }
        SetROTID(0);
}

////////////////////////////////////////////////////////////////////// IEHELPER.RGS
// The following lines should be included into the self-registration portion of 
// COM application.

...

HKLM
{
        SOFTWARE
        {
                Microsoft
                {
                        Windows
                        {
                                CurrentVersion
                                {
                                        Explorer
                                        {
                                                'Browser Helper Objects'
                                                {
                                                        <CLSID>
                                                }
                                        }
                                }
                        }
                }
        }
}

Having implemented and registered the Browser Helper, an application can now obtain the pointer to a running instance of IE by traversing the ROT.

The following example shows the rough method I used to list the instances of IE:

IRunningObjectTable* pTable;

if(!FAILED(GetRunningObjectTable(0, &pTable)))
{
        IEnumMoniker* pEnum;
        if(!FAILED(pTable->EnumRunning(&pEnum)))
        {
                IUnknown* pUnknown;
                IMoniker* pCurMoniker = NULL;
                LPMALLOC pMalloc;
                while (pEnum->Next(1, &pCurMoniker, NULL) == S_OK) 
                {
                        if(!FAILED(pTable->GetObject(pCurMoniker, &pUnknown)))
                        {
                                IObjectWithSite* pSite;
                                if(!FAILED(pUnknown->QueryInterface(IID_IObjectWithSite, (void**)&pSite)))
                                {
                                        IDispatch* pDispatch;
                                        if(pSite->GetSite(IID_IDispatch, (void**)&pDispatch) == S_OK)
                                        {
                                                CWebBrowserApp browser;
                                             
                                                browser.AttachDispatch(pDispatch);
                                                TRACE("LocationURL: %s/n", browser.GetLocationURL());
                                                        TRACE("LocationName: %s/n", browser.GetLocationName());
                                                browser.DetachDispatch();
                                                pDispatch->Release();
                                        }
                                        pSite->Release();
                                }
                                pUnknown->Release();
                        }
                        pCurMoniker->Release();
                }
                pEnum->Release();
        }
        pTable->Release();
}

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The following file is available for download from the Microsoft Software Library: