javafx.event.EventTarget Maven / Gradle / Ivy
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package javafx.event;
// PENDING_DOC_REVIEW
/**
* Represents an event target.
* @since JavaFX 2.0
*/
public interface EventTarget {
/**
* Construct an event dispatch chain for this target. The event dispatch
* chain contains event dispatchers which might be interested in processing
* of events targeted at this {@code EventTarget}. This event target is
* not automatically added to the chain, so if it wants to process events,
* it needs to add an {@code EventDispatcher} for itself to the chain.
*
* In the case the event target is part of some hierarchy, the chain for it
* is usually built from event dispatchers collected from the root of the
* hierarchy to the event target.
*
* The event dispatch chain is constructed by modifications to the provided
* initial event dispatch chain. The returned chain should have the initial
* chain at its end so the dispatchers should be prepended to the initial
* chain.
*
* The caller shouldn't assume that the initial chain remains unchanged nor
* that the returned value will reference a different chain.
*
* @param tail the initial chain to build from
* @return the resulting event dispatch chain for this target
*/
EventDispatchChain buildEventDispatchChain(EventDispatchChain tail);
/**
* Registers an event handler for this target.
*
* The handler is called when the target receives an {@link Event} of the specified
* type during the bubbling phase of event delivery.
*
* @param the event class of the handler
* @param eventType the type of the events received by the handler
* @param eventHandler the event handler
* @throws NullPointerException if {@code eventType} or {@code eventHandler} is {@code null}
* @throws UnsupportedOperationException if this target does not support event handlers
* @implSpec The default implementation of this method throws {@code UnsupportedOperationException}.
* @since 21
*/
default void addEventHandler(EventType eventType, EventHandler eventHandler) {
throw new UnsupportedOperationException();
}
/**
* Unregisters a previously registered event handler from this target.
*
* Since it is possible to register a single {@link EventHandler} instance for different event types,
* the caller needs to specify the event type from which the handler should be unregistered.
*
* @param the event class of the handler
* @param eventType the event type from which to unregister
* @param eventHandler the event handler
* @throws NullPointerException if {@code eventType} or {@code eventHandler} is {@code null}
* @throws UnsupportedOperationException if this target does not support event handlers
* @implSpec The default implementation of this method throws {@code UnsupportedOperationException}.
* @since 21
*/
default void removeEventHandler(EventType eventType, EventHandler eventHandler) {
throw new UnsupportedOperationException();
}
/**
* Registers an event filter for this target.
*
* The filter is called when the target receives an {@link Event} of the specified
* type during the capturing phase of event delivery.
*
* @param the event class of the filter
* @param eventType the type of the events received by the filter
* @param eventFilter the event filter
* @throws NullPointerException if {@code eventType} or {@code eventFilter} is {@code null}
* @throws UnsupportedOperationException if this target does not support event filters
* @implSpec The default implementation of this method throws {@code UnsupportedOperationException}.
* @since 21
*/
default void addEventFilter(EventType eventType, EventHandler eventFilter) {
throw new UnsupportedOperationException();
}
/**
* Unregisters a previously registered event filter from this target.
*
* Since it is possible to register a single {@link EventHandler} instance for different event types,
* the caller needs to specify the event type from which the filter should be unregistered.
*
* @param the event class of the filter
* @param eventType the event type from which to unregister
* @param eventFilter the event filter
* @throws NullPointerException if {@code eventType} or {@code eventFilter} is {@code null}
* @throws UnsupportedOperationException if this target does not support event filters
* @implSpec The default implementation of this method throws {@code UnsupportedOperationException}.
* @since 21
*/
default void removeEventFilter(EventType eventType, EventHandler eventFilter) {
throw new UnsupportedOperationException();
}
}