// Converts a IHTMLWindow2 object to a IHTMLDocument2. Returns NULL in case of failure.

// It takes into account accessing the DOM across frames loaded from different domains.

CComQIPtr<IHTMLDocument2> HtmlWindowToHtmlDocument(CComQIPtr<IHTMLWindow2> spWindow)

{

ATLASSERT(spWindow != NULL);

CComQIPtr<IHTMLDocument2> spDocument;

HRESULT hRes = spWindow->get_document(&spDocument);

if ((S_OK == hRes) && (spDocument != NULL))

{

// The html document was properly retrieved.

return spDocument;

}

// hRes could be E_ACCESSDENIED that means a security restriction that

// prevents scripting across frames that loads documents from different internet domains.

CComQIPtr<IWebBrowser2> spBrws = HtmlWindowToHtmlWebBrowser(spWindow);

if (spBrws == NULL)

{

return CComQIPtr<IHTMLDocument2>();

}

// Get the document object from the IWebBrowser2 object.

CComQIPtr<IDispatch> spDisp;

hRes = spBrws->get_Document(&spDisp);

spDocument = spDisp;

return spDocument;

}

// Converts a IHTMLWindow2 object to a IWebBrowser2. Returns NULL in case of failure.

CComQIPtr<IWebBrowser2> HtmlWindowToHtmlWebBrowser(CComQIPtr<IHTMLWindow2> spWindow)

{

	ATLASSERT(spWindow != NULL);

	CComQIPtr<IServiceProvider>   spServiceProvider = spWindow;

	if (spServiceProvider == NULL)

	{

		return CComQIPtr<IWebBrowser2>();

	}

	CComQIPtr<IWebBrowser2> spWebBrws;

	HRESULT hRes = spServiceProvider->QueryService(IID_IWebBrowserApp, IID_IWebBrowser2, (void**)&spWebBrws);

	if (hRes != S_OK)

	{

		return CComQIPtr<IWebBrowser2>();

	}

	return spWebBrws;

}

附:

IE(控件/接口)中主要有4个部分, Browser, Document, Frame/IFrame, Element , 其对应接口分别是

Browser          -     IWebBrowser2

Document       -     IHTMLDocument2

Frame/IFrame-     IHTMLWindow2

Element          -     IHTMLElement

可以通过下面方法互相获取

browser      -> document        IWebBrowser2::get_Document

document     -> frame           IHTMLDocument2::get_parentWindow

frame        -> document        IHTMLWindow2::get_document

frame        -> parent frame    IHTMLWindow2::get_parent

frame        -> children frames IHTMLWindow2::get_frames

element     -> Frame              IHTMLElement->QI(IHTMLFrameBase2) -> IHTMLFrameBase2->get_contentWindow -> IHTMLWindow2 ->

HtmlWindowToHtmlWebBrowser -> IWebBrowser2