I am trying to call my BHO method from the javascript. The problem is same as stated in the the following posts:
- Call BHO from Javascript function
- http://social.msdn.microsoft.com/Forums/en-US/ieextensiondevelopment/thread/91d4076e-4795-4d9e-9b07-5b9c9eca62fb/
- Calling C++ function from JavaScript script running in a web browser control
Third link is another SO post talking about it, but I did not understand the need and code. Also the shared working sample keeps crashing on windows 7 with ie 8 and windows vista with ie 7.
If it helps my BHO is written in C++ using ATL.
What I have tried:
I have written a very basic BHO and tried the approach as mentioned here by Igor Tandetnik. There is no exception generated but when I open the following html file in IE then it says object undefined.
<html>
<head>
<script language='javascript'>
function call_external(){
try{
alert(window.external.TestScript);
//JQueryTest.HelloJquery('a');
}catch(err){
alert(err.description );
}
}
</script>
</head>
<body id='bodyid' onload="call_external();">
<center><div><span>Hello jQuery!!</span></div></center>
</boay>
</html>
Question:
- Please clarify whether is it possible to expose and call BHO method from javascript or do i have to expose it using an activex (as answered by jeffdav in [2] )? If yes then how to do it.
- Basically i want to extend the
window.externalbut the way shown in the above link [2] usesvar x = new ActiveXObject("MySampleATL.MyClass");; Is both the calling conventions are same or different?
Note:
- There is a related post on SO which gives hint that it is possible through inserting this
[id(1), helpstring("method DoSomething")] HRESULT DoSomething();in the BHO IDL file. I am not sure how it was done and couldn't find any supporting resource through google. - I am aware of this post calling-into-your-bho-from-a-client-script, but haven't tried it as it is solving the problem using ActiveX.
- My reason to avoid ActiveX is primarily due to the security restrictions.
Edit 1
It seems there is a way to extend the
window.external. Check this. Specially the section titled IDocHostUIHandler::GetExternal: Extending the DOM.Now assuming our IDispatch interface is on the same object that implements IDocHostUIHandler. Then we can do something like this:
HRESULT CBrowserHost::GetExternal(IDispatch **ppDispatch)
{
*ppDispatch = this;
return S_OK;
}
The problem with this approach is that it won't append to the existing windows methods, but rather replace them. Please tell if I am wrong.
Edit 2
The BHO Class:
class ATL_NO_VTABLE CTestScript :
public CComObjectRootEx<CComSingleThreadModel>,
public CComCoClass<CTestScript, &CLSID_TestScript>,
public IObjectWithSiteImpl<CTestScript>,
public IDispatchImpl<ITestScript, &IID_ITestScript, &LIBID_TestBHOLib, /*wMajor =*/ 1, /*wMinor =*/ 0>,
public IDispEventImpl<1, CTestScript, &DIID_DWebBrowserEvents2, &LIBID_SHDocVw, 1, 1>
{
public:
CTestScript()
{
}
DECLARE_REGISTRY_RESOURCEID(IDR_TESTSCRIPT)
DECLARE_NOT_AGGREGATABLE(CTestScript)
BEGIN_COM_MAP(CTestScript)
COM_INTERFACE_ENTRY(ITestScript)
COM_INTERFACE_ENTRY(IDispatch)
COM_INTERFACE_ENTRY(IObjectWithSite)
END_COM_MAP()
DECLARE_PROTECT_FINAL_CONSTRUCT()
HRESULT FinalConstruct()
{
return S_OK;
}
void FinalRelease()
{
}
public:
BEGIN_SINK_MAP(CTestScript)
SINK_ENTRY_EX(1, DIID_DWebBrowserEvents2, DISPID_DOCUMENTCOMPLETE, OnDocumentComplete)
//SINK_ENTRY_EX(1, DIID_DWebBrowserEvents2, DISPID_NAVIGATECOMPLETE2, OnNavigationComplete)
END_SINK_MAP()
void STDMETHODCALLTYPE OnDocumentComplete(IDispatch *pDisp, VARIANT *pvarURL);
//void STDMETHODCALLTYPE OnNavigationComplete(IDispatch *pDisp, VARIANT *pvarURL);
STDMETHOD(SetSite)(IUnknown *pUnkSite);
HRESULT STDMETHODCALLTYPE DoSomething(){
::MessageBox(NULL, L"Hello", L"World", MB_OK);
return S_OK;
}
public:
//private:
// InstallBHOMethod();
private:
CComPtr<IWebBrowser2> m_spWebBrowser;
BOOL m_fAdvised;
};
// TestScript.cpp : Implementation of CTestScript
#include "stdafx.h"
#include "TestScript.h"
// CTestScript
STDMETHODIMP CTestScript::SetSite(IUnknown* pUnkSite)
{
if (pUnkSite != NULL)
{
HRESULT hr = pUnkSite->QueryInterface(IID_IWebBrowser2, (void **)&m_spWebBrowser);
if (SUCCEEDED(hr))
{
hr = DispEventAdvise(m_spWebBrowser);
if (SUCCEEDED(hr))
{
m_fAdvised = TRUE;
}
}
}else
{
if (m_fAdvised)
{
DispEventUnadvise(m_spWebBrowser);
m_fAdvised = FALSE;
}
m_spWebBrowser.Release();
}
return IObjectWithSiteImpl<CTestScript>::SetSite(pUnkSite);
}
void STDMETHODCALLTYPE CTestScript::OnDocumentComplete(IDispatch *pDisp, VARIANT *pvarURL)
{
CComPtr<IDispatch> dispDoc;
CComPtr<IHTMLDocument2> ifDoc;
CComPtr<IHTMLWindow2> ifWnd;
CComPtr<IDispatchEx> dispxWnd;
HRESULT hr = m_spWebBrowser->get_Document( &dispDoc );
hr = dispDoc.QueryInterface( &ifDoc );
hr = ifDoc->get_parentWindow( &ifWnd );
hr = ifWnd.QueryInterface( &dispxWnd );
// now ... be careful. Do exactly as described here. Very easy to make mistakes
CComBSTR propName( L"myBho" );
DISPID dispid;
hr = dispxWnd->GetDispID( propName, fdexNameEnsure, &dispid );
CComVariant varMyBho( (IDispatch*)this );
DISPPARAMS params;
params.cArgs = 1;
params.cNamedArgs = 0;
params.rgvarg = &varMyBho;
params.rgdispidNamedArgs = NULL;
hr = dispxWnd->Invoke( dispid, IID_NULL, LOCALE_USER_DEFAULT, DISPATCH_PROPERTYPUT,
¶ms, NULL, NULL, NULL );
}
The Javascript:
<script language='javascript'>
function call_external(){
try{
alert(window.ITestScript);
}catch(err){
alert(err.description );
}
}
</script>
Edit 3
After spending three days on this, I think I should take the ActiveX path. Writing a basic activex is just way to easy, written one and tested on all major IE releases. I am leaving this question as open, please see comments in Uri's answer (many thanks to him). I have tried most of his suggestions (except for 4 and 5).
I will also suggest you to see the MSDN IDispatcEx sample. If you find a solution then please post, if I find a solution then I will definitely update here.
Edit 4
See my last comment in URI's post. Issue Resolved.
