Convert to VB.NET

  • 13 years ago


    Please help me to convert the belowing code to VB.NET.

    Design event object

    The event object will have a custom interface, since that is what WinFIOL uses to call the object. The base class IWFEvent is defined in "wfoleaut.h" and "wfoleaut.tlb":

        class CWFEvent : public IWFEvent
            int          iCount;
            IWFChannel * pIWFChannel;
            DWORD        dwThreadID;
            void         ReadPrintout(void);
            CWFEvent(IWFChannel *chnl);
            virtual ~CWFEvent() { }
            STDMETHOD(QueryInterface)(REFIID iid, void ** ppvObject);
            STDMETHOD_(ULONG, AddRef)(void);
            STDMETHOD_(ULONG, Release)(void);
            STDMETHOD(Notify)(INT event, BSTR eventstr);


    Most of the code below is standard and can be found in many books about COM. The constructor takes a pointer to IWFChannel to be able to call methods in this interface.

        CWFEvent::CWFEvent(IWFChannel *chnl)
            iCount = 0;
            pIWFChannel = chnl;
            dwThreadID = GetCurrentThreadId();

        STDMETHODIMP CWFEvent::QueryInterface(REFIID riid, void ** ppv)
            if ( riid == IID_IUnknown )
                *ppv = (IUnknown *) this;
            else if ( riid == IID_IWFEvent )
                *ppv = (IWFEvent *) this;
                *ppv = NULL;
                return E_NOINTERFACE;
            ((IUnknown *) *ppv)->AddRef();
            return S_OK;

        STDMETHODIMP_(ULONG) CWFEvent::AddRef(void)
            return ++iCount;

        STDMETHODIMP_(ULONG) CWFEvent::Release(void)
            if ( iCount == 1 )
                // make sure message loop is terminated:
                PostThreadMessage(dwThreadID, WM_QUIT, 0, 0);
                delete this;
                return 0;
            return --iCount;

        STDMETHODIMP CWFEvent::Notify(INT event, BSTR eventstr)
            if ( event == WFEVENT_PRINTOUT )
            return S_OK;

    Getting printout

    The function CWFEvent::ReadPrintout( ) is called from CWFEvent::Notify( ) when the WFEVENT_PRINTOUT is received from WinFIOL. This function calls IWFChannel::GetPrintoutArray( ). You can also call IWFChannel::GetPrintoutBuffer( ). For simplicity, this example uses the UNICODE version of printf( ) to print a BSTR. If the printout does not originate from the command that the COM client sent, the application needs to wait for the next printout. Otherwise, the WM_QUIT message is sent to the message loop in the send MML command example.

        void CWFEvent::ReadPrintout(void)
            BOOL bQuit = TRUE;
            SAFEARRAY *sa = NULL;
            int flags = 0, faultcode = 0;
            BSTR command = NULL;

            HRESULT hr = pIWFChannel->GetPrintoutArray(&flags, &faultcode, &command, &sa);
            if ( SUCCEEDED(hr) )
                BSTR *bstr;
                SafeArrayAccessData(sa, (void **) &bstr);
                int nLines = sa->rgsabound->cElements;    // number of lines
                for ( int i = sa->rgsabound->lLbound; i < nLines; i++ )
                    wprintf(L"%s", bstr[i]);
                if ( !command[0] )     // if command is empty, do not quit yet...
                    bQuit = FALSE;
            if ( bQuit )
                PostThreadMessage(dwThreadID, WM_QUIT, 0, 0);

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