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QAxWidget get pointer to my activeX control

  • Hi guys simple question ..maybe :)

    How can I achieve this in Qt:

    // in MFC VC++ project
    CWnd *pdfControl = GetDlgItem( IDC_PDFCREACTIVEX1 );
     ASSERT( pdfControl );
     LPUNKNOWN lpUnknown = pdfControl->GetControlUnknown();
     ASSERT( lpUnknown );

    I find this


    but its return only QString I need LPUNKOWN

    It's really important for me to get pointer to my ActiveX control somehow.

    Thanks in advance

  • Hi, #include "windows.h" and #include "QUuid" and try

    LPUNKNOWN lpUnknown;
    ui.myAxWidget.queryInterface(QUuid(IID_IUnknown),(LPVOID*) &lpUnknown);

    Then, to check to really got the correct LPUNKNOWN for your ActiveX control, you can try something like this: (it parties on the LPUNKNOWN above to retrieve some documentation for that ActiveX control)

    LPDISPATCH pDispatch;
    lpUnknown->QueryInterface(IID_IDispatch, (LPVOID*) &pDispatch);
    LPTYPEINFO pTypeInfo;
    LPTYPELIB pTypeLib;
    UINT uTypeInfoIndex;
    BSTR bstrName,bstrDocString;
    QString sName((QChar*)bstrName,::SysStringLen(bstrName));
    QString sDocString((QChar*)bstrDocString,::SysStringLen(bstrDocString));
    // show what we've got
    qDebug() << sName << sDocString;

  • Thanks @hskoglund for reply.
    When I type it like this:

    	LPUNKNOWN lpUnknown;
    	long lo = ui.axWidget->queryInterface(QUuid(ui.axWidget->control()), (LPVOID*)&lpUnknown);

    lpUknown is null.

    Thanks in advance!

  • Well that's because ->queryInterface() expects an Interface-flavored UUID, for example IID_IUnknown or IID_IDispatch etc. These are stored in the registry in the HKEY_CLASSES_ROOT\Interface part. You can use either IID_IUnknown as in my example above, or use its string representation like this:
    long lo = ui.axWidget->queryInterface(QUuid("{00000000-0000-0000-c000-000000000046}"), (LPVOID*)&lpUnknown);

    But using a CLSID-flavored UUID, like in your ...ui.axWidget->control())... example above, will fail and return the HRESULT 0x80004002 (No such interface supported)

    Yeah, so there are many types of different UUIDs used in COM, you can read more here

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