www.pudn.com > Windows Game Programming Gurus Examp > demo5_1.cpp

// DEMO5_1.CPP - A ultra minimal working COM example 
// NOTE: not fully COM compliant 
 
// INCLUDES ////////////////////////////////////////////////////////////////////////////////// 
 
#include  
#include  
#include  
#include  // note: you must include this header it contains important constants 
                     // you must use in COM programs 
 
// GUIDS ///////////////////////////////////////////////////////////////////////////////////// 
 
// these were all generated with GUIDGEN.EXE 
 
// {B9B8ACE1-CE14-11d0-AE58-444553540000} 
const IID IID_IX =  
{ 0xb9b8ace1, 0xce14, 0x11d0, { 0xae, 0x58, 0x44, 0x45, 0x53, 0x54, 0x0, 0x0 } }; 
 
 
// {B9B8ACE2-CE14-11d0-AE58-444553540000} 
const IID IID_IY =  
{ 0xb9b8ace2, 0xce14, 0x11d0, { 0xae, 0x58, 0x44, 0x45, 0x53, 0x54, 0x0, 0x0 } }; 
 
// {B9B8ACE3-CE14-11d0-AE58-444553540000} 
const IID IID_IZ =  
{ 0xb9b8ace3, 0xce14, 0x11d0, { 0xae, 0x58, 0x44, 0x45, 0x53, 0x54, 0x0, 0x0 } }; 
 
 
// INTERFACES //////////////////////////////////////////////////////////////////////////////// 
 
// define the IX interface 
interface IX: IUnknown 
{ 
 
virtual void __stdcall fx(void)=0; 
 
};  
 
// define the IY interface 
interface IY: IUnknown 
{ 
 
virtual void __stdcall fy(void)=0; 
 
};  
 
 
// CLASSES AND COMPONENTS /////////////////////////////////////////////////////////////////// 
 
// define the COM object 
class CCOM_OBJECT :	public IX, 
                    public IY 
{ 
public: 
 
	CCOM_OBJECT() : ref_count(0) {} 
	~CCOM_OBJECT() {} 
 
private: 
 
virtual HRESULT __stdcall QueryInterface(const IID &iid, void **iface); 
virtual ULONG __stdcall AddRef(); 
virtual ULONG __stdcall Release(); 
 
virtual	void __stdcall fx(void) {cout << "Function fx has been called." << endl; } 
virtual void __stdcall fy(void) {cout << "Function fy has been called." << endl; } 
 
int ref_count; 
 
}; 
 
// CLASS METHODS //////////////////////////////////////////////////////////////////////////// 
 
HRESULT __stdcall CCOM_OBJECT::QueryInterface(const IID &iid, void **iface) 
{ 
// this function basically casts the this pointer or the Iunknown 
// pointer into the interface requested, notice the comparison with 
// the GUIDs generated and defined in the begining of the program 
 
// requesting the IUnknown base interface 
if (iid==IID_IUnknown) 
	{ 
	cout << "Requesting IUnknown interface" << endl; 
	*iface = (IX*)this; 
	 
	} // end if 
 
// maybe IX? 
if (iid==IID_IX) 
	{ 
	cout << "Requesting IX interface" << endl; 
	*iface = (IX*)this; 
 
	} // end if 
else  // maybe IY 
if (iid==IID_IY) 
	{ 
	cout << "Requesting IY interface" << endl; 
	*iface = (IY*)this; 
 
	} // end if 
else 
	{ // cant find it! 
	cout << "Requesting unknown interaface!" << endl; 
	*iface = NULL; 
	return(E_NOINTERFACE); 
	} // end else 
 
// if everything went well cast pointer to IUnknown and call addref() 
((IUnknown *)(*iface))->AddRef(); 
 
return(S_OK); 
 
} // end QueryInterface 
 
//////////////////////////////////////////////////////////////////////////////////////////////// 
 
ULONG __stdcall CCOM_OBJECT::AddRef() 
{ 
// increments reference count 
cout << "Adding a reference" << endl; 
return(++ref_count); 
 
} // end AddRef 
 
/////////////////////////////////////////////////////////////////////////////////////////////// 
 
ULONG __stdcall CCOM_OBJECT::Release() 
{ 
// decrements reference count 
cout << "Deleting a reference" << endl; 
if (--ref_count==0) 
	{ 
	delete this; 
	return(0); 
	} // end if 
else 
	return(ref_count); 
 
} // end Release 
 
/////////////////////////////////////////////////////////////////////////////////////////////// 
 
IUnknown *CoCreateInstance(void) 
{ 
// this is a very basic implementation of CoCreateInstance() 
// it creates an instance of the COM object, in this case 
// I decided to start with a pointer to IX -- IY would have 
// done just as well 
 
IUnknown *comm_obj = (IX *)new(CCOM_OBJECT); 
 
cout << "Creating Comm object" << endl; 
 
// update reference count 
comm_obj->AddRef(); 
 
return(comm_obj); 
 
} // end CoCreateInstance 
 
/////////////////////////////////////////////////////////////////////////////////////////////// 
 
void main(void) 
{ 
 
// create the main COM object 
IUnknown *punknown = CoCreateInstance(); 
 
// create two NULL pointers the the IX and IY interfaces 
IX *pix=NULL; 
IY *piy=NULL; 
 
// from the original COM object query for interface IX 
punknown->QueryInterface(IID_IX, (void **)&pix); 
 
// try some of the methods of IX 
pix->fx(); 
 
// release the interface 
pix->Release(); 
 
 
// now query for the IY interface 
punknown->QueryInterface(IID_IY, (void **)&piy); 
 
// try some of the methods 
piy->fy(); 
 
// release the interface 
piy->Release(); 
 
// release the COM object itself 
punknown->Release(); 
 
} // end main