IMFCollection::GetElement Method
Retrieves an object in the collection.
Syntax
HRESULT GetElement(
[in] DWORD dwElementIndex,
[out] IUnknown **ppUnkElement
);
Parameter
dwElementIndex [in]
Zero-based index of the object to retrieve. Objects are indexed in the order in which they were added to the collection.ppUnkElement [out]
Receives a pointer to the object's IUnknown interface. The caller must release the interface. The retrieved pointer value might be NULL.
Rückgabewert
Ist Methode erfolgreich, wird "S_OK" zurückgegeben. Andernfalls wird ein HRESULT-Fehlercode zurückgegeben.
Hinweise
This method does not remove the object from the collection. To remove an object, call IMFCollection::RemoveElement.
Beispiele
// Gets an interface pointer from a collection (IMFCollection).
//
// Q: Interface type
template <class Q>
HRESULT GetCollectionObject(IMFCollection *pCollection,
DWORD dwIndex, Q **ppObject)
{
*ppObject = NULL; // zero output
IUnknown *pUnk = NULL;
HRESULT hr = pCollection->GetElement(dwIndex, &pUnk);
if (SUCCEEDED(hr))
{
hr = pUnk->QueryInterface(IID_PPV_ARGS(ppObject));
pUnk->Release();
}
return hr;
}
Anforderungen
Mindestens unterstützter Client |
Windows Vista |
Mindestens unterstützter Server |
Windows Server 2008 |
Header |
Mfobjects.h (include Mfidl.h) |
Bibliothek |
Mfuuid.lib |