C++/VB - Custom interface in source filter

Asked By Tomy

10-Apr-07 08:14 AM

Hi

I`ve qestion about implement custom interface in source filter
class myclass : public CSource
{
.
.
STDMETHODIMP NonDelegatingQueryInterface(REFIID riid, void ** ppv);
.
.
};

class CVCamStream :public custom_class, public CSourceStream, public
IAMStreamConfig, public IKsPropertySet
{
public:
.
.
STDMETHODIMP my_custom_function(void)
{
return NOERROR;
}

.
.
};
compilation OK

I tried to implement STDMETHODIMP my_custom_function(void) in myclass

class myclass :public custom_class, public CSource
{
.
.
STDMETHODIMP NonDelegatingQueryInterface(REFIID riid, void ** ppv);
STDMETHODIMP my_custom_function(void)
{
return NOERROR;
}


.
.
};

but It can`t compile properly:

error C2259: 'myclass' : cannot instantiate abstract class
due to following members:
'ULONG IUnknown::AddRef(void)' : is abstract
c:\Program Files\Microsoft Platform SDK for Windows Server 2003
R2\include\unknwn.h(117) : see declaration of 'IUnknown::AddRef'
'ULONG IUnknown::Release(void)' : is abstract
c:\Program Files\Microsoft Platform SDK for Windows Server 2003
R2\include\unknwn.h(119) : see declaration of 'IUnknown::Release'

I've qestion about location of  my_custom_function(void);. Is it correct
implementation in CVCamStream ?

my custom_interface implementation is in my_custom.h flie

my_custom.h

extern "C" {

DEFINE_GUID(IID_custom_class)
0x5022190a, 0x65d9, 0x4a06, 0xb8, 0x0a, 0x28, 0xb4, 0xe7, 0x8f, 0x44,
0xa6);

DECLARE_INTERFACE_(custom_class, IUnknown)
{
STDMETHOD(my_custom_function) (THIS_
void)PURE;
};
}

I`ve problem with call to this function "my_custom_function()" from windows
application (C++ visual studio 2005 .net)

include "my_custom.h"

IBaseFilter *pVideoInputFilter;
CComQIPtr<custom_class> my_pointer(pVideoInputFilter);// pVideoInputFilter
that has already been created with CoCreateInstance
if (!my_pointer)
{
return hr;
}
my_pointer->my_custom_function();

I can`t compile my windows application. I have compiler error :

P1.cpp
C:\Program Files\Microsoft Visual Studio
8\VC\atlmfc\include\atlcomcli.h(474) : error C2787: 'custom_class' : no GUID
has been associated with this object
AssemblyInfo.cpp
Generating Code...
Build log was saved at "file://d:\filters\new1\P1\P1\Debug\BuildLog.htm"
P1 - 1 error(s), 0 warning(s)
========== Rebuild All: 0 succeeded, 1 failed, 0 skipped ==========


Please clue me something !

10-Apr-07 09:59 AM

You are missing the DECLARE_IUNKNOWN macro in myclass. This is why
_AddRef, _Release are seen as not implemented.

Re  "'custom_class' : no GUID ", the code seems OK. Did you include
initguid.h? Try using QueryInterface on your pVideoInputFilter
interface to retrieve the custom_class pointer (using
IID_custom_class).

12-Apr-07 04:34 AM

Hi
All "myclass" looks like:

class myclass : public CSource
{
static CUnknown * WINAPI CreateInstance(LPUNKNOWN lpunk, HRESULT *phr);
STDMETHODIMP NonDelegatingQueryInterface(REFIID riid, void ** ppv);
STDMETHODIMP QueryInterface(REFIID riid, void **ppv);
IFilterGraph *GetGraph() {return m_pGraph;}
};


What do you mind DECLARE_IUNKNOWN macro in myclass ?

Yes in my windows application I included initguid.h.
I Tried using QueryInterface on my pVideoInputFilter
interface to retrieve the custom_class pointer (using
IID_custom_class).

include "my_custom.h"
IBaseFilter *pVideoInputFilter;// my source filter
custom_class *custom_class pointer; // The custom pointer on the filter

hr = pVideoInputFilter->QueryInterface(IID_custom_class, (void **)
&custom_class pointer);//  return OK

but call:

hr=custom_class pointer->my_custom_function(); ;
make message : System.AccessViolationException

What is wrong ?