ActiveX

An ActiveX control is intended to be a lighter weight version of an OLE Custom Control. The only requirement of an ActiveX control is that it implements IUnknown, so technically every COM object is an ActiveX control.

This is not a useful definition. In practice, a ‘control’ is expected to support certain behaviors, i.e. implement certain interfaces. The best definition I’ve been able to come up with is, a control whose project was originally created by running the ActiveX AppWizard. There were 6 templates available in Visual Studio 97:

ActiveX Full Control and Lite Control
ActiveX Composite Control and Lite Composite Control
ActiveX HTML Control and Lite HTML Control

All of these are deprecated, except the HTML Control, which is very deprecated. In VS ‘22, the closest thing to be found is the ATL Control, which is lighter weight than any of the ‘Lite’ controls. (It’s basically a Lite Control without the persistence.) The punchline to the joke is that all of these, including the ATL Control, implement IOleObject.

For an idea of what these are like, here are their COM maps:

BEGIN_COM_MAP(CFullATLControl)
    COM_INTERFACE_ENTRY(IFullATLControl)
    COM_INTERFACE_ENTRY(IDispatch)
    COM_INTERFACE_ENTRY(IViewObjectEx)
    COM_INTERFACE_ENTRY(IViewObject2)
    COM_INTERFACE_ENTRY(IViewObject)
    COM_INTERFACE_ENTRY(IOleInPlaceObjectWindowless)
    COM_INTERFACE_ENTRY(IOleInPlaceObject)
    COM_INTERFACE_ENTRY2(IOleWindow, IOleInPlaceObjectWindowless)
    COM_INTERFACE_ENTRY(IOleInPlaceActiveObject)
    COM_INTERFACE_ENTRY(IOleControl)
    COM_INTERFACE_ENTRY(IOleObject)
    COM_INTERFACE_ENTRY(IPersistStreamInit)
    COM_INTERFACE_ENTRY2(IPersist, IPersistStreamInit)
    COM_INTERFACE_ENTRY(ISpecifyPropertyPages)
    COM_INTERFACE_ENTRY(IQuickActivate)
    COM_INTERFACE_ENTRY(IPersistStorage)
    COM_INTERFACE_ENTRY(IDataObject)
    COM_INTERFACE_ENTRY(IProvideClassInfo)
    COM_INTERFACE_ENTRY(IProvideClassInfo2)
END_COM_MAP()

BEGIN_COM_MAP(CLiteATLControl)
    COM_INTERFACE_ENTRY(ILiteATLControl)
    COM_INTERFACE_ENTRY(IDispatch)
    COM_INTERFACE_ENTRY(IViewObjectEx)
    COM_INTERFACE_ENTRY(IViewObject2)
    COM_INTERFACE_ENTRY(IViewObject)
    COM_INTERFACE_ENTRY(IOleInPlaceObjectWindowless)
    COM_INTERFACE_ENTRY(IOleInPlaceObject)
    COM_INTERFACE_ENTRY2(IOleWindow, IOleInPlaceObjectWindowless)
    COM_INTERFACE_ENTRY(IOleInPlaceActiveObject)
    COM_INTERFACE_ENTRY(IOleControl)
    COM_INTERFACE_ENTRY(IOleObject)
    COM_INTERFACE_ENTRY(IPersistStreamInit)
    COM_INTERFACE_ENTRY2(IPersist, IPersistStreamInit)
END_COM_MAP()


BEGIN_COM_MAP(CCompositeATLControl)
    COM_INTERFACE_ENTRY(ICompositeATLControl)
    COM_INTERFACE_ENTRY(IDispatch)
    COM_INTERFACE_ENTRY(IViewObjectEx)
    COM_INTERFACE_ENTRY(IViewObject2)
    COM_INTERFACE_ENTRY(IViewObject)
    COM_INTERFACE_ENTRY(IOleInPlaceObjectWindowless)
    COM_INTERFACE_ENTRY(IOleInPlaceObject)
    COM_INTERFACE_ENTRY2(IOleWindow, IOleInPlaceObjectWindowless)
    COM_INTERFACE_ENTRY(IOleInPlaceActiveObject)
    COM_INTERFACE_ENTRY(IOleControl)
    COM_INTERFACE_ENTRY(IOleObject)
    COM_INTERFACE_ENTRY(IPersistStreamInit)
    COM_INTERFACE_ENTRY2(IPersist, IPersistStreamInit)
    COM_INTERFACE_ENTRY(ISpecifyPropertyPages)
    COM_INTERFACE_ENTRY(IQuickActivate)
    COM_INTERFACE_ENTRY(IPersistStorage)
    COM_INTERFACE_ENTRY(IDataObject)
    COM_INTERFACE_ENTRY(IProvideClassInfo)
    COM_INTERFACE_ENTRY(IProvideClassInfo2)
END_COM_MAP()

BEGIN_COM_MAP(CLiteCompositeATLControl)
    COM_INTERFACE_ENTRY(ILiteCompositeATLControl)
    COM_INTERFACE_ENTRY(IDispatch)
    COM_INTERFACE_ENTRY(IViewObjectEx)
    COM_INTERFACE_ENTRY(IViewObject2)
    COM_INTERFACE_ENTRY(IViewObject)
    COM_INTERFACE_ENTRY(IOleInPlaceObjectWindowless)
    COM_INTERFACE_ENTRY(IOleInPlaceObject)
    COM_INTERFACE_ENTRY2(IOleWindow, IOleInPlaceObjectWindowless)
    COM_INTERFACE_ENTRY(IOleInPlaceActiveObject)
    COM_INTERFACE_ENTRY(IOleControl)
    COM_INTERFACE_ENTRY(IOleObject)
    COM_INTERFACE_ENTRY(IPersistStreamInit)
    COM_INTERFACE_ENTRY2(IPersist, IPersistStreamInit)
END_COM_MAP()

ActiveX

References