: Interface Notifier
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quicktime.app.actions
Interface Notifier
All Known Implementing Classes: QTImageDrawer
public interface Notifier
The Notifier and NotifyListener interfaces provide a way for objects
to deal with some state that is not available immediately but can
be acquired. The Notifier represents the class that is waiting for
some condition to be set or established. When this condition is met
it notifies its listener that the state is established.
The kind of classes that interact this way generally have some interdependence
and so the NotifyListener will generally expect its Notifier to be a
a particular type of object.
When a NotifyListener is added to a Notifier if the NotifyListener and Notifier
are compatible the addNotifyListener returns true, at that point the Notifier
can notify its Listener when the condition it is awaiting is fulfilled.
For instance, the QTImageDrawer is a Notifier and the TwoDSprite is a NotifyListener.
A TwoDSprite requires valid image data before it can present an image in a SWCompositor.
A QTImageDrawer does not have valid image data until it has been added to a java.awt.Component.
Thus the QTImageDrawer has a need to notify its TwoDSprite when its image data is complete
and valid. The TwoDSprite is a NotifyListener that expects its Notifiers to also implement
the ImageSpec interface. When the QTImageDrawer has valid image data it notifies its
TwoDSprite listener and the TwoDSprite can retrieve that image data and present it
within the context of its Compositor.
This type of pairing can be used in other situations where some deferral of resources
is an issue. For example a class could be defined that downloads image data through a
network connection. When the image data is completely retrieved this type of Notifier
could then notify a TwoDSprite (for instance) that its image data is now complete.
See Also: QTImageDrawer,
TwoDSprite
Method Summary
boolean
addNotifyListener(NotifyListener nl)
This method is called at some point when a relationship between a Notifier
and a listener is required.
Method Detail
addNotifyListener
public boolean addNotifyListener(NotifyListener nl)
This method is called at some point when a relationship between a Notifier
and a listener is required.
Parameters:nl - the NotifyListener that is interested in something from this NotifierReturns:true if the Notifer is an appropriate Notifier for the Listener
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