306 lines
10 KiB
C
306 lines
10 KiB
C
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//------------------------------------------------------------------------------
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// File: ComBase.h
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//
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// Desc: DirectShow base classes - defines a class hierarchy for creating
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// COM objects.
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//
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// Copyright (c) 1992-2001 Microsoft Corporation. All rights reserved.
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//------------------------------------------------------------------------------
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/*
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a. Derive your COM object from CUnknown
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b. Make a static CreateInstance function that takes an LPUNKNOWN, an HRESULT *
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and a TCHAR *. The LPUNKNOWN defines the object to delegate IUnknown calls
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to. The HRESULT * allows error codes to be passed around constructors and
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the TCHAR * is a descriptive name that can be printed on the debugger.
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It is important that constructors only change the HRESULT * if they have
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to set an ERROR code, if it was successful then leave it alone or you may
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overwrite an error code from an object previously created.
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When you call a constructor the descriptive name should be in static store
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as we do not copy the string. To stop large amounts of memory being used
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in retail builds by all these static strings use the NAME macro,
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CMyFilter = new CImplFilter(NAME("My filter"),pUnknown,phr);
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if (FAILED(hr)) {
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return hr;
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}
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In retail builds NAME(_x_) compiles to NULL, the base CBaseObject class
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knows not to do anything with objects that don't have a name.
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c. Have a constructor for your object that passes the LPUNKNOWN, HRESULT * and
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TCHAR * to the CUnknown constructor. You can set the HRESULT if you have an
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error, or just simply pass it through to the constructor.
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The object creation will fail in the class factory if the HRESULT indicates
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an error (ie FAILED(HRESULT) == TRUE)
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d. Create a FactoryTemplate with your object's class id and CreateInstance
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function.
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Then (for each interface) either
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Multiple inheritance
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1. Also derive it from ISomeInterface
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2. Include DECLARE_IUNKNOWN in your class definition to declare
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implementations of QueryInterface, AddRef and Release that
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call the outer unknown
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3. Override NonDelegatingQueryInterface to expose ISomeInterface by
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code something like
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if (riid == IID_ISomeInterface) {
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return GetInterface((ISomeInterface *) this, ppv);
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} else {
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return CUnknown::NonDelegatingQueryInterface(riid, ppv);
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}
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4. Declare and implement the member functions of ISomeInterface.
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or: Nested interfaces
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1. Declare a class derived from CUnknown
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2. Include DECLARE_IUNKNOWN in your class definition
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3. Override NonDelegatingQueryInterface to expose ISomeInterface by
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code something like
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if (riid == IID_ISomeInterface) {
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return GetInterface((ISomeInterface *) this, ppv);
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} else {
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return CUnknown::NonDelegatingQueryInterface(riid, ppv);
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}
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4. Implement the member functions of ISomeInterface. Use GetOwner() to
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access the COM object class.
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And in your COM object class:
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5. Make the nested class a friend of the COM object class, and declare
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an instance of the nested class as a member of the COM object class.
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NOTE that because you must always pass the outer unknown and an hResult
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to the CUnknown constructor you cannot use a default constructor, in
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other words you will have to make the member variable a pointer to the
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class and make a NEW call in your constructor to actually create it.
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6. override the NonDelegatingQueryInterface with code like this:
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if (riid == IID_ISomeInterface) {
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return m_pImplFilter->
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NonDelegatingQueryInterface(IID_ISomeInterface, ppv);
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} else {
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return CUnknown::NonDelegatingQueryInterface(riid, ppv);
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}
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You can have mixed classes which support some interfaces via multiple
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inheritance and some via nested classes
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*/
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#ifndef __COMBASE__
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#define __COMBASE__
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// Filter Setup data structures no defined in axextend.idl
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typedef REGPINTYPES
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AMOVIESETUP_MEDIATYPE, * PAMOVIESETUP_MEDIATYPE, * FAR LPAMOVIESETUP_MEDIATYPE;
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typedef REGFILTERPINS
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AMOVIESETUP_PIN, * PAMOVIESETUP_PIN, * FAR LPAMOVIESETUP_PIN;
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typedef struct _AMOVIESETUP_FILTER
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{
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const CLSID * clsID;
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const WCHAR * strName;
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DWORD dwMerit;
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UINT nPins;
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const AMOVIESETUP_PIN * lpPin;
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}
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AMOVIESETUP_FILTER, * PAMOVIESETUP_FILTER, * FAR LPAMOVIESETUP_FILTER;
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/* The DLLENTRY module initialises the module handle on loading */
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extern HINSTANCE g_hInst;
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/* On DLL load remember which platform we are running on */
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extern DWORD g_amPlatform;
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extern OSVERSIONINFO g_osInfo; // Filled in by GetVersionEx
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/* Version of IUnknown that is renamed to allow a class to support both
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non delegating and delegating IUnknowns in the same COM object */
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#ifndef INONDELEGATINGUNKNOWN_DEFINED
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DECLARE_INTERFACE(INonDelegatingUnknown)
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{
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STDMETHOD(NonDelegatingQueryInterface) (THIS_ REFIID, LPVOID *) PURE;
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STDMETHOD_(ULONG, NonDelegatingAddRef)(THIS) PURE;
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STDMETHOD_(ULONG, NonDelegatingRelease)(THIS) PURE;
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};
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#define INONDELEGATINGUNKNOWN_DEFINED
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#endif
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typedef INonDelegatingUnknown *PNDUNKNOWN;
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/* This is the base object class that supports active object counting. As
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part of the debug facilities we trace every time a C++ object is created
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or destroyed. The name of the object has to be passed up through the class
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derivation list during construction as you cannot call virtual functions
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in the constructor. The downside of all this is that every single object
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constructor has to take an object name parameter that describes it */
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class CBaseObject
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{
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private:
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// Disable the copy constructor and assignment by default so you will get
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// compiler errors instead of unexpected behaviour if you pass objects
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// by value or assign objects.
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CBaseObject(const CBaseObject& objectSrc); // no implementation
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void operator=(const CBaseObject& objectSrc); // no implementation
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private:
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static LONG m_cObjects; /* Total number of objects active */
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protected:
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#ifdef DEBUG
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DWORD m_dwCookie; /* Cookie identifying this object */
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#endif
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public:
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/* These increment and decrement the number of active objects */
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CBaseObject(__in_opt LPCTSTR pName);
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#ifdef UNICODE
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CBaseObject(__in_opt LPCSTR pName);
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#endif
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~CBaseObject();
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/* Call this to find if there are any CUnknown derived objects active */
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static LONG ObjectsActive() {
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return m_cObjects;
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};
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};
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/* An object that supports one or more COM interfaces will be based on
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this class. It supports counting of total objects for DLLCanUnloadNow
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support, and an implementation of the core non delegating IUnknown */
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class AM_NOVTABLE CUnknown : public INonDelegatingUnknown,
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public CBaseObject
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{
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private:
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const LPUNKNOWN m_pUnknown; /* Owner of this object */
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protected: /* So we can override NonDelegatingRelease() */
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volatile LONG m_cRef; /* Number of reference counts */
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public:
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CUnknown(__in_opt LPCTSTR pName, __in_opt LPUNKNOWN pUnk);
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virtual ~CUnknown() {};
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// This is redundant, just use the other constructor
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// as we never touch the HRESULT in this anyway
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CUnknown(__in_opt LPCTSTR Name, __in_opt LPUNKNOWN pUnk, __inout_opt HRESULT *phr);
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#ifdef UNICODE
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CUnknown(__in_opt LPCSTR pName, __in_opt LPUNKNOWN pUnk);
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CUnknown(__in_opt LPCSTR pName, __in_opt LPUNKNOWN pUnk,__inout_opt HRESULT *phr);
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#endif
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/* Return the owner of this object */
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LPUNKNOWN GetOwner() const {
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return m_pUnknown;
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};
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/* Called from the class factory to create a new instance, it is
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pure virtual so it must be overriden in your derived class */
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/* static CUnknown *CreateInstance(LPUNKNOWN, HRESULT *) */
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/* Non delegating unknown implementation */
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STDMETHODIMP NonDelegatingQueryInterface(REFIID, __deref_out void **);
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STDMETHODIMP_(ULONG) NonDelegatingAddRef();
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STDMETHODIMP_(ULONG) NonDelegatingRelease();
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};
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/* Return an interface pointer to a requesting client
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performing a thread safe AddRef as necessary */
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STDAPI GetInterface(LPUNKNOWN pUnk, __out void **ppv);
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/* A function that can create a new COM object */
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typedef CUnknown *(CALLBACK *LPFNNewCOMObject)(__in_opt LPUNKNOWN pUnkOuter, __inout_opt HRESULT *phr);
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/* A function (can be NULL) which is called from the DLL entrypoint
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routine for each factory template:
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bLoading - TRUE on DLL load, FALSE on DLL unload
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rclsid - the m_ClsID of the entry
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*/
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typedef void (CALLBACK *LPFNInitRoutine)(BOOL bLoading, const CLSID *rclsid);
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/* Create one of these per object class in an array so that
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the default class factory code can create new instances */
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class CFactoryTemplate {
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public:
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const WCHAR * m_Name;
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const CLSID * m_ClsID;
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LPFNNewCOMObject m_lpfnNew;
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LPFNInitRoutine m_lpfnInit;
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const AMOVIESETUP_FILTER * m_pAMovieSetup_Filter;
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BOOL IsClassID(REFCLSID rclsid) const {
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return (IsEqualCLSID(*m_ClsID,rclsid));
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};
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CUnknown *CreateInstance(__inout_opt LPUNKNOWN pUnk, __inout_opt HRESULT *phr) const {
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CheckPointer(phr,NULL);
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return m_lpfnNew(pUnk, phr);
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};
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};
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/* You must override the (pure virtual) NonDelegatingQueryInterface to return
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interface pointers (using GetInterface) to the interfaces your derived
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class supports (the default implementation only supports IUnknown) */
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#define DECLARE_IUNKNOWN \
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STDMETHODIMP QueryInterface(REFIID riid, __deref_out void **ppv) { \
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return GetOwner()->QueryInterface(riid,ppv); \
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}; \
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STDMETHODIMP_(ULONG) AddRef() { \
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return GetOwner()->AddRef(); \
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}; \
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STDMETHODIMP_(ULONG) Release() { \
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return GetOwner()->Release(); \
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};
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HINSTANCE LoadOLEAut32();
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#endif /* __COMBASE__ */
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