258 lines
8.1 KiB
C
258 lines
8.1 KiB
C
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//==========================================================================;
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//
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// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY
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// KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR
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// PURPOSE.
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//
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// Copyright (c) 1992 - 1998 Microsoft Corporation. All Rights Reserved.
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//
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//--------------------------------------------------------------------------;
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// Base class hierachy for creating COM objects, December 1994
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/*
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a. Derive your COM object from CComBase
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b. Make a static CreateInstance function that takes an IUnknown* and an
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HRESULT*. The IUnknown* defines the object to delegate IUnknown calls
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to. The HRESULT * allows error codes to be passed around constructors.
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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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c. Have a constructor for your object that passes the IUnknown* and HRESULT*
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to the CComBase constructor. You can set the HRESULT if you have an error,
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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 CComClassTemplate 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 NDQueryInterface 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 CComBase::NDQueryInterface(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 CComBase
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2. Include DECLARE_IUNKNOWN in your class definition
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3. Override NDQueryInterface 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 CComBase::NDQueryInterface(riid, ppv);
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}
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4. Implement the member functions of ISomeInterface. Use \() 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 CComBase 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 NDQueryInterface with code like this:
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if (riid == IID_ISomeInterface) {
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return m_pImplFilter->
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NDQueryInterface(IID_ISomeInterface, ppv);
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} else {
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return CComBase::NDQueryInterface(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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#include <windows.h>
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#include <basetyps.h>
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#include <unknwn.h>
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extern int g_cActiveObjects;
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STDAPI CreateCLSIDRegKey(REFCLSID clsid, const char *szName);
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STDAPI RemoveCLSIDRegKey(REFCLSID clsid);
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#ifdef DEBUG
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// We chose a common name for our ASSERT macro, MFC also uses this name
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// So long as the implementation evaluates the condition and handles it
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// then we will be ok. Rather than override the behaviour expected we
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// will leave whatever first defines ASSERT as the handler (i.e. MFC)
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#ifndef ASSERT
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#define ASSERT(_x_) if (!(_x_)) \
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DbgAssert(TEXT(#_x_),TEXT(__FILE__),__LINE__)
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#endif
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#define EXECUTE_ASSERT(_x_) ASSERT(_x_)
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#define ValidateReadPtr(p,cb) \
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{if(IsBadReadPtr((PVOID)p,cb) == TRUE) \
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DbgBreak("Invalid read pointer");}
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#define ValidateWritePtr(p,cb) \
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{if(IsBadWritePtr((PVOID)p,cb) == TRUE) \
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DbgBreak("Invalid write pointer");}
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#define ValidateReadWritePtr(p,cb) \
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{ValidateReadPtr(p,cb) ValidateWritePtr(p,cb)}
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#else
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#ifndef ASSERT
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#define ASSERT(_x_) ((void)0)
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#endif
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#define EXECUTE_ASSERT(_x_) ((void)(_x_))
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#define ValidateReadPtr(p,cb) 0
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#define ValidateWritePtr(p,cb) 0
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#define ValidateReadWritePtr(p,cb) 0
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#endif
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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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/* 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 INDUNKNOWN_DEFINED
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DECLARE_INTERFACE(INDUnknown)
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{
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STDMETHOD(NDQueryInterface) (THIS_ REFIID, LPVOID *) PURE;
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STDMETHOD_(ULONG, NDAddRef)(THIS) PURE;
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STDMETHOD_(ULONG, NDRelease)(THIS) PURE;
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};
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#define INDUNKNOWN_DEFINED
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#endif
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class CBaseObject {
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public:
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CBaseObject() {g_cActiveObjects++;}
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~CBaseObject() {g_cActiveObjects--;}
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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 CComBase : public INDUnknown,
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CBaseObject
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{
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private:
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IUnknown* m_pUnknown; /* Owner of this object */
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protected: /* So we can override NDRelease() */
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volatile LONG m_cRef; /* Number of reference counts */
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public:
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CComBase(IUnknown* pUnk);
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virtual ~CComBase() {};
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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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CComBase(IUnknown* pUnk,HRESULT *phr);
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/* Return the owner of this object */
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IUnknown* 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 CComBase *CreateInstance(IUnknown*, HRESULT *) */
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/* Non delegating unknown implementation */
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STDMETHODIMP NDQueryInterface(REFIID, void **);
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STDMETHODIMP_(ULONG) NDAddRef();
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STDMETHODIMP_(ULONG) NDRelease();
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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(IUnknown* pUnk, void **ppv);
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/* A function that can create a new COM object */
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typedef CComBase *(CALLBACK *LPFNNewCOMObject)(IUnknown* pUnkOuter, 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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#define CheckPointer(p,ret) {if((p)==NULL) return (ret);}
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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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struct CComClassTemplate {
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const CLSID * m_ClsID;
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LPFNNewCOMObject m_lpfnNew;
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};
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/* You must override the (pure virtual) NDQueryInterface 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, 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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