CUnknown Class

The CUnknown object implements the IUnknown interface. Most Component Object Model (COM) objects in Microsoft® DirectShow® derive from CUnknown.

If you implement a COM object, you might want to derive it from CUnknown. Deriving from CUknown provides a thread-safe implementation, and saves you the trouble of implementing IUnknown.

For a detailed discussion of how to use this base class, see How to Implement IUnknown. What follows is a brief summary:

• Include the DECLARE_IUNKNOWN macro in the public section of your class definition. This macro declares the three methods of the IUnknown interface.
• Override the NonDelegatingQueryInterface method to support interfaces other than IUnknown. Within this method, call the GetInterface function to retrieve interface pointers.
• In your class constructor, invoke the CUnknown constructor method.

Requirements

Header: Declared in Combase.h; include Streams.h.

Library: Use Strmbase.lib (retail builds) or Strmbasd.lib (debug builds).

• Protected Member Variables
  m_cRef	Reference count.
  Public Methods
  CUnknown	Constructor method.
  ~CUnknown	Destructor method. Virtual.
  GetOwner	Retrieves a pointer to the controlling IUnknown.
  INonDelegatingUnknown Methods
  NonDelegatingAddRef	Increments the reference count.
  NonDelegatingQueryInterface	Retrieves an interface pointer and increments the reference count.
  NonDelegatingRelease	Decrements the reference count.