MFPMediaItem_QueryInterface

Queries a COM object for a pointer to one of its interface; identifying the interface by a reference to its interface identifier (IID). If the COM object implements the interface, then it returns a pointer to that interface after calling IUnknown::AddRef on it.

MFPMediaItem_QueryInterface PROTO pMediaItem:DWORD, riid:DWORD, ppvObject:DWORD

Parameters

pMediaItem - A pointer to the Media Item (IMFPMediaItem) object.
riid - A reference to the interface identifier (IID) of the interface being queried for.
ppvObject - The address of a pointer to an interface with the IID specified in the riid parameter. Because you pass the address of an interface pointer the method can overwrite that address with the pointer to the interface being queried for. Upon successful return, ppvObject (the dereferenced address) contains a pointer to the requested interface. If the object doesn’t support the interface, the method sets ppvObject (the dereferenced address) to nullptr.

Returns

TRUE if successful or FALSE otherwise.

Notes

For any given COM object (also known as a COM component), a specific query for the IUnknown interface on any of the object’s interfaces must always return the same pointer value. This enables a client to determine whether two pointers point to the same component by calling QueryInterface with IID_IUnknown and comparing the results. It is specifically not the case that queries for interfaces other than IUnknown (even the same interface through the same pointer) must return the same pointer value.