connection point event is not fire from com component

"Jenny" <>
20 Sep 2006 19:11:53 -0700

I have a com component and fire event to an MFC application using
connection point. But the wizard generated helper function in the event
procxy class does not fire event since the the m_vec is empty. I
suspect the ATLadvise has some problem, but the return result is OK.
can anyone tell me the possible cause? I have the following code.

//in component

//appwizard generated code. m_vec is empty

template <class T>
class CProxyIExtractEvent : public IConnectionPointImpl<T,
&IID_IExtractEvent, CComDynamicUnkArray>
    //Warning this class may be recreated by the wizard.
    HRESULT Fire_OnExtractImage()
        HRESULT ret;
        T* pT = static_cast<T*>(this);
        int nConnectionIndex;
        int nConnections = m_vec.GetSize();

        for (nConnectionIndex = 0; nConnectionIndex < nConnections;
            CComPtr<IUnknown> sp = m_vec.GetAt(nConnectionIndex);
            IExtractEvent* pIExtractEvent =
            if (pIExtractEvent != NULL)
                ret = pIExtractEvent->OnExtractImage();
        } return ret;



HRESULT CScribbleExtractor::Extract(HBITMAP* phBmpThumbnail)

    Fire_OnExtractImage( );

//client code
class CTstConnect :
   public IDispatchImpl<IExtractEvent, &IID_IExtractEvent,
    public CComObjectRoot
    CTstConnect() {}


      //This method will be called when DoTest() is called, if this
      // has connected to the COM DLL (AtlAdvise)
      return S_OK;


BOOL CScribbleDoc::OnSaveDocument(LPCTSTR lpszPathName)
    // TODO: Add your specialized code here and/or call the base class
    HRESULT hRes = CoInitialize( NULL );

       //Initialize global CComModule
   _Module.Init( NULL, AfxGetInstanceHandle() );

    //Pointer to the interface defined in the COM DLL
    IScribbleExtractor *pM;

    //Create an instance of the interface defined in the COM DLL
    HRESULT theResult = CoCreateInstance( CLSID_ScribbleExtractor,

    if ( theResult != S_OK ) {
        std::ostringstream os;
        _com_error err(theResult);
        os << "CoCreateInstance() failed: " << err.ErrorMessage();


   //Create the COM object (client) that is to connect to the COM DLL
   CComObject<CTstConnect> *pTstConnect;

   //Create an instance of the client object

      //Variable for the connection point cookie
    DWORD dwAdvise = 0;

      //AtlAdvise, connect connection point
   hRes = AtlAdvise( pM,

    BOOL result = CDocument::OnSaveDocument(lpszPathName);

    AtlUnadvise(pM, IID_IExtractEvent, dwAdvise);

       //Finished with the server

      //Uninitialize to match CoInitialize

    return result;

//.idl file
import "oaidl.idl";
import "ocidl.idl";

        helpstring("IIconExtractor Interface"),
    interface IScribbleExtractor : IDispatch

    helpstring("ConnectDemo 1.0 Type Library")
    interface IExtractEvent : IDispatch
        [helpstring("method OnExtractImage")] HRESULT OnExtractImage();

    helpstring("ThumbScb 1.0 Type Library")
library THUMBSCBLib

        helpstring("IconExtractor Class")
    coclass ScribbleExtractor
        [default] interface IScribbleExtractor;
        [default, source] interface IExtractEvent;

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