TABLE OF CONTENTS We can make considerable progress in the development of our QuickTime applications just by setting properties and calling methods of the various objects in the QuickTime Object Model. However, modern object-oriented applications more often than not employ an event-driven model: something happens such as a mouse click and we have an event handler to respond to it. A QuickTime application is no different except that, in addition to responding to user interface events, we can respond to events that are triggered by the QuickTime objects themselves. We touched on this briefly in Chapter 2 when we looked at the SizeChanged event of the QuickTime Control, which is fired whenever the control changes size.
As it turns out, there are so many events that the QuickTime objects can potentially notify us about that it would be impractical, not to mention grossly inefficient, for our application to receive and handle them all willy-nilly. So in order to be notified of events by an instance of a QuickTime object we must first specify the particular event(s) we are interested in. We do this by adding those events about which we want to be notified to the EventListeners collection of the object. Each type of event is specified by two constants: the event class and the event ID, as defined by two enumerations: QTEventClassesEnum and QTEventIDsEnum. By adding an event of a particular class and ID to the EventListeners collection, we are said...
