ATL Control Embedded in JSP Page 2003-07-30 - By Chanian, Raj
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Hi,
Hi All,
I have my ATL control working in a full browser window, embedded in a HTML
page.
However when I embed it into HTML HEAD of JSP page the control works fine,
provides Print Preview but then the screen freezes and then I can do nothing
with the browser.
What extra interfaces do I need to add to my control so that it integrates
perfectly with JSP/HTML without crashing the browser.
Our solution targets IE5.5 browser hence the ATL control to tap into IE's
native COM interfaces for implementing Print Preview.
Regards,
Raj Chanian
-- --Original Message-- --
From: Chanian, Raj
Sent: 29 July 2003 12:21
To: 'Discussion related to the Active Template Library and COM development'
Subject: RE: [ATL] Debug Assertion failed in atlbase.h Line 474
Thanks Maxine,
I think it was because the code below which WORKS in a normal browser
window, does not work in a modal dialog window. It threw the assert between
the following two lines of code
//QueryService for WebBrowser
hresult= spIServiceProvider->QueryService(SID_SWebBrowserApp,
IID_IWebBrowser, (void**)&spIWebBrowser2);
//Errs here! Possibly due to null value on constructor for spIWebBrowser2
//Get IDispatch Interface for Document
hresult= spIWebBrowser2->get_Document(&spIDispatch);
I got it to work by using window.open instead of window.showModalDialog in
my javascript. And grabbed arguments to opened window by using
window.document.getelementbyid("openedwindowelement")=
window.opener.document.getelementbyid("openerwindowelement");
The question I have is what com interfaces are not supported in the dialog
window compared to full browser window. And what tweak on this function can
be made to make it work in a dialog window?
Below is the function that encapsulates this behaviour.
STDMETHODIMP CPreviewer::PreviewDefault()
{
HRESULT hresult=S_OK;
try
{
//Smart Pointer Declarations
CComPtr<IOleContainer> spIOleContainer;
CComPtr<IServiceProvider> spIServiceProvider;
CComPtr<IWebBrowser2> spIWebBrowser2;
CComPtr<IDispatch> spIDispatch;
CComPtr<IHTMLDocument2> spIHTMLDocument2;
CComPtr<IOleCommandTarget> spIOleCommandTarget;
//Member of CComControlBase::m_spClientSite
//A pointer to the control's client site within the container
//CComPtr<IOleClientSite> m_spClientSite;
//Get IOleContainer
hresult= m_spClientSite->GetContainer(&spIOleContainer);
//QueryInterface for IServiceProvider
hresult= spIOleContainer->QueryInterface(IID_IServiceProvider,
(void**)&spIServiceProvider);
//QueryService for WebBrowser
hresult= spIServiceProvider->QueryService(SID_SWebBrowserApp,
IID_IWebBrowser, (void**)&spIWebBrowser2);
//Get IDispatch Interface for Document
hresult= spIWebBrowser2->get_Document(&spIDispatch);
//QueryInterface for IHTMLDocument2
hresult= spIDispatch->QueryInterface(IID_IHTMLDocument2,
(void**)&spIHTMLDocument2);
//QueryInterface for IOleCommandTarget
hresult= spIHTMLDocument2->QueryInterface(IID_IOleCommandTarget,
(void**)&spIOleCommandTarget);
//Do not pass a custom template as we are using default template
//Invoke PrintPreview
hresult= spIOleCommandTarget->Exec(&CGID_MSHTML, IDM_PRINTPREVIEW,
NULL, NULL, NULL);
//If No Errors Return Default Status
return S_OK;
}
catch(...)
{
//Need to Expand Here
//return E_FAIL;
//HRESULT May Differ Here
ATLASSERT(0);
return hresult;
}
}
-- --Original Message-- --
From: LABELLE, Maxime [mailto:mlabelle@(protected)]
Sent: 28 July 2003 13:17
To: ATL@(protected)
Subject: Re: [ATL] Debug Assertion failed in atlbase.h Line 474
Oops!
> He already has. :-)
That's my mistake. Sorry. I overlooked the subject.
OK, well, here's what I've got at the specified line:
472: _NoAddRefReleaseOnCComPtr<T>* operator->() const
473: {
474: ATLASSERT(p!=NULL);
475: return (_NoAddRefReleaseOnCComPtr<T>*)p;
476: }
That seems pretty clear to me. It is illegal to dereference
a null pointer. So the question is why is the smart pointer
containing a null pointer ?
I see several options:
1. the p member has never been assigned a value other than the default
(431).
2. .Release() has already been called on the smart pointer (452).
3. .operator &() has been called by passing the smart-pointer in one of the
returned arguments of ::CoCreateInstance, but the ::CoCreateInstance call
failed for some reason. Lookup the resulting HRESULT (470).
4. .Attach() has been called with a null pointer (516).
5. .Detach() has been explicitely called (521).
6. .CoCreateInstance() failed. Lookup the resulting HRESULT (705).
Cheers.
Maxime.
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