Implementation Details

The first step to using the Direct Annotation feature of the Dynamic Annotation API is to create an [IAccPropServices][] object using either the CoCreateInstance function or CoCreateInstanceEx function. Then you can use either the IAccPropServices::SetHwndProp method or the IAccPropServices::SetHwndPropStr method.

The following sample from Using Direct Annotation demonstrates the technique.

HRESULT CMyTextControl::SetAccessibleProperties()
{
    // COM is assumed to be initialized...
    IAccPropServices* pAccPropServices = NULL;
    HRESULT hr = CoCreateInstance(
        CLSID_AccPropServices, nullptr,
        CLSCTX_SERVER, IID_IAccPropServices, 
        reinterpret_cast<void**>(&pAccPropServices));
    if (SUCCEEDED(hr))
    {
        // Annotating the Role of this object to be STATICTEXT
        VARIANT var;
        var.vt = VT_I4;
        var.lVal = ROLE_SYSTEM_STATICTEXT;
        hr = pAccPropServices->SetHwndProp(
            _hwnd, OBJID_CLIENT, CHILDID_SELF,
            PROPID_ACC_ROLE, var);
        pAccPropServices->Release();
    }
    return hr;
}

More complete examples can be found in the following locations.

• WndWithCustomizedAccessibleInfo.cpp and WndWithCustomizedAccessibleInfo.h

  Implements the CWndWithCustomizedAccessibleInfo class, a ATL/MFC class that uses Direct Annotation to customize the accessible info of a window.

• DirectAnnotation.cpp and DirectAnnotation.h

  Implements the DirectAnnotation class, a Window API class that uses Direct Annotation to customize the accessible info of a window.

Note that using the IAccPropServices::SetHwndProp method or the IAccPropServices::SetHwndPropStr method will not send WinEvents. It is your responsibility to send appropriate events by calling the NotifyWinEvent function after the IAccPropServices::SetHwndProp method or the IAccPropServices::SetHwndPropStr method has been called.

For example, if you use IAccPropServices::SetHwndPropStr method to set the Name property of an element, send an EVENT_OBJECT_NAMECHANGE event for that object after SetHwndPropStr returns.

The CWndWithCustomizedAccessibleInfo class and DirectAnnotation class both make the necessary calls to the NotifyWinEvent function for you.