Method RegisterForSystemEvent

Core/ClientSML/src/sml_ClientKernel.cpp:1901–1932

* @brief Register for a "SystemEvent". * Multiple handlers can be registered for the same event. * @param smlEventId The event we're interested in (see the list below for valid values) * @param handler A function that will be called when the event happens * @param pUserData Arbitrary data that will be passed back to the handler function when the event happens. * @param addTo

* @returns Unique ID for this callback.  Required when unregistering this callback.
*************************************************************/
int Kernel::RegisterForSystemEvent(smlSystemEventId id, SystemEventHandler handler, void* pUserData, bool addToBack)
{
    // Start by checking if this id, handler, pUSerData combination has already been registered
    TestSystemCallbackFull test(id, handler, pUserData) ;
    
    // See if this handler is already registered
    SystemEventHandlerPlusData plus(0, 0, 0, 0) ;
    bool found = m_SystemEventMap.findFirstValueByTest(&test, &plus) ;
    
    if (found && plus.m_Handler != 0)
    {
        return plus.getCallbackID() ;
    }
    
    // If we have no handlers registered with the kernel, then we need
    // to register for this event.  No need to do this multiple times.
    if (m_SystemEventMap.getListSize(id) == 0)
    {
        RegisterForEventWithKernel(id, NULL) ;
    }
    
    // Record the handler
    // We use a struct rather than a pointer to a struct, so there's no need to new/delete
    // everything as the objects are added and deleted.
    m_CallbackIDCounter++ ;
    
    SystemEventHandlerPlusData handlerPlus(id, handler, pUserData, m_CallbackIDCounter) ;
    m_SystemEventMap.add(id, handlerPlus, addToBack) ;
    
    // Return the ID.  We use this later to unregister the callback
    return m_CallbackIDCounter ;
}

/*************************************************************
* @brief Register for an "UpdateEvent".