Programming Flex 3

Handling State Events

Four events are associated with state changes:

• When a state change is requested, the application or component containing the state dispatches a currentStateChanging event. The event occurs before the state actually changes.

• Once the state has changed, the application or component dispatches a currentStateChanged event. Both events are of type mx.events.StateChangeEvent (use the constants CURRENT_STATE_CHANGING and CURRENT_STATE_CHANGED to add listeners). Neither event is cancelable, which means you cannot prevent a state change from occurring by canceling a currentStateChanging event, for example. Rather, both events are used primarily by the transitions framework to detect when a transition should occur.

• The enterState and exitState events occur when the state starts and stops:

  • The enterState event occurs as soon as the state has started but before it is applied to the view.

  • The exitState event occurs as soon as the state is about to stop.

    Both events are of type mx.events.FlexEvent (use the constants ENTER_STATE and EXIT_STATE to add listeners).

• The enterState event is dispatched by a State object when the state starts, and by an application or component when returning to the base state. The exitState event is dispatched by a State object when the state stops, and by an application or component when exiting the base state.