How To Retrieve the URL of a Web Page from an ActiveX Control
SUMMARY
This article demonstrates how an ActiveX control can retrieve the Uniform Resource Locator (URL) of the Web page (document) on which it is being hosted.
This may be useful for restricting usage of an ActiveX control to a particular domain/site or accessing files when supplied a relative path.
MORE INFORMATION
During the initialization of an embedded ActiveX control, Internet Explorer (IE) passes a pointer to its client site by calling IOleObject::SetClientSite(). This process can be used to either retrieve a moniker for the container or access the document object model to retrieve the URL for the hosting Web page.
This article demonstrates how to retrieve the current URL from the container moniker. For additional information about how to obtain the URL from the document object model, please see the following article in the Microsoft Knowledge Base:
172763 (http://support.microsoft.com/kb/172763/EN-US/) INFO: Accessing the Object Model from Within an ActiveX Control
Follow these steps to retrieve the current URL from the container moniker: 1. Obtain the client site (IOleClientSite) interface pointer. The container calls IOleObject::SetClientSite() to pass a pointer to the client site. Override this method to cache this pointer.
2. Obtain a moniker to the client site by calling IOleClientSite::GetMoniker().
3. Call IMoniker::GetDisplayName() to obtain the URL for the current document.
The following sample code demonstrates how to perform the above steps by overriding the IOleObject::SetClientSite() method in an Active Template Library (ATL) ActiveX control:
Sample Code
STDMETHOD(SetClientSite)(IOleClientSite *pClientSite)
{
if (pClientSite != NULL)
{
// Obtain URL from container moniker.
CComPtr<IMoniker> spmk;
LPOLESTR pszDisplayName;
if (SUCCEEDED(pClientSite->GetMoniker(
OLEGETMONIKER_TEMPFORUSER,
OLEWHICHMK_CONTAINER,
&spmk)))
{
if (SUCCEEDED(spmk->GetDisplayName(
NULL, NULL, &pszDisplayName)))
{
USES_CONVERSION;
CComBSTR bstrURL;
bstrURL = pszDisplayName;
ATLTRACE("The current URL is %s/n", OLE2T(bstrURL));
CoTaskMemFree((LPVOID)pszDisplayName);
}
}
}
return IOleObject_SetClientSite(pClientSite);
}
REFERENCES
For more information on the IOleObject, IoleClientSite, and IOleContainer interfaces, please refer to the Microsoft Visual C++ online help.
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