When Lucy is starting up or shutting down, several events are fired to notify registered listeners of the progress.
These events can be used, for instance, to display a splash screen when Lucy is starting, or to ask the user to save data
when Lucy is about to close.
To receive notifications of these events, you must register an
ILcyLucyEnvListener with the Lucy back-end using the methods
You can remove it using the method
You can get the active state of Lucy with the method
The listeners are notified of the Lucy events with the method
lucyEnvStatusChanged, which takes a
TLcyLucyEnvEvent as parameter. This object has an ID, which is one of the following:
Indicates that Lucy is starting the initialization process. You can use this event to pop up a splash screen, for instance.
Indicates that Lucy has finished its initialization process and is ready for use. You could use this to hide the splash screen, for instance.
Indicates that Lucy is starting the closing process. You can use this event to ask the users if they want to save some unsaved changes, for instance.
Indicates that Lucy had finished the closing process.
Indicates that Lucy is starting the disposal process.
Indicates that Lucy has finished the disposal process.
An important aspect of the
lucyEnvStatusChanged method is that it can throw a
TLcyVetoException. If a listener decides that it cannot allow Lucy to change its state to the state specified by the ID of the event, that
listener can throw a
TLcyVetoException to prevent this change from completing. The most obvious use for this is to prevent the closing of Lucy when something has
not been saved yet. If a listener throws a
TLcyVetoException, all listeners that were already notified of the changed state, are notified of the reverse state change. For instance, when
a certain listener throws a
TLcyVetoException on an event with ID
TLcyLucyEnvEvent.CLOSING, all listeners that were already notified before that listener will receive an event with ID
TLcyLucyEnvEvent.INITIALIZED, which was the previous state.
The events are always fired in the order in which they are listed here. The only exception is when a listener throws a
TLcyVetoException, at which point all listeners that had already been notified of the state change are notified of the reverse state change
as noted above.