Graph Events

The event-system is used by the Graph to inform the user about changes to the graph structure.

GraphEventPublisher

The GraphEventPublisher manages the subscribers and provides methods to notify subscribers about events. Every class that wants to publish events needs to extend GraphEventPublisher

GraphEventSubscriber

In order to receive events a class needs to extend GraphEventSubscriber and override the notifyGraphEvent() method. Three convenience classes already exist, that do this and simplify the usage of the event-system. Thus there is usually no need to derive from GraphEventSubscriber directly:

• The GraphEventDispatcher handles all events and provides virtual methods for each event. Thus a subscriber can simply extend the dispatcher and override the methods that it cares about.

• The GraphEventQueue buffers all events in a queue. If flush() is called, all events are processed at once. The user needs to override the process() method to process the events. The queue detects contradicting events and removes them from the queue. E.g. if a frame is added and removed before flush() is called, neither the added- nor the removed-event is processed.

• The GraphItemEventDispatcher<T> is a special dispatcher that is used to receive typed item events. To receive only item events for a certain item type, the user should derive from GraphItemEventDispatcher<T> where T is the item type that he cares about.

Tree Events

The TreeView does not use the above event system. Instead it provides simple events using boost signals.