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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * published by the Free Software Foundation.  Oracle designates this
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
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package javafx.event;

// PENDING_DOC_REVIEW
/**
 * An {@code EventDispatcher} represents an event dispatching and processing
 * entity. It is used when an {@code Event} needs to be dispatched to the
 * associated {@code EventTarget} through the {@code EventDispatchChain}
 * specified by the target. Each {@code EventDispatcher} in the chain can
 * influence the event path and the event itself. One {@code EventDispatcher}
 * can appear in multiple chains.
 * 

* The system defines two successive phases of event delivery. The first * phase is called capturing phase and happens when when an event travels from * the first element of the {@code EventDispatchChain} associated with the event * target to its last element. If the event target is part of some hierarchy, * the direction of the event in this phase usually corresponds with the * direction from the root element of the hierarchy to the target. The second * phase is called bubbling phase and happens in the reverse order to the first * phase. So the event is returning back from the last element of the * {@code EventDispatchChain} to its first element in this phase. Usually that * corresponds to the direction from the event target back to the root in the * event target's hierarchy. *

* Each {@code EventDispatcher} in an {@code EventDispatchChain} is responsible * for forwarding the event to the rest of the chain during event dispatching. * This forwarding happens in the {@code dispatchEvent} method and forms a chain * of nested calls which allows one {@code EventDispatcher} to see the event * during both dispatching phases in a single {@code dispatchEvent} call. *

* Template for {@code dispatchEvent} implementation.

public Event dispatchEvent(Event event, EventDispatchChain tail) {
    // capturing phase, can handle / modify / substitute / divert the event

    if (notHandledYet) {
        // forward the event to the rest of the chain
        event = tail.dispatchEvent(event);

        if (event != null) {
            // bubbling phase, can handle / modify / substitute / divert
            // the event
        }
    }

    return notHandledYet ? event : null;
} * @since JavaFX 2.0 */ public interface EventDispatcher { /** * Dispatches the specified event by this {@code EventDispatcher}. Does * any required event processing. Both the event and its further path can * be modified in this method. If the event is not handled / consumed during * the capturing phase, it should be dispatched to the rest of the chain * ({@code event = tail.dispatch(event);}). * * @param event the event do dispatch * @param tail the rest of the chain to dispatch event to * @return the return event or {@code null} if the event has been handled / * consumed */ Event dispatchEvent(Event event, EventDispatchChain tail); }




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