org.apache.batik.dom.events
Class EventSupport

java.lang.Object
  |
  +--org.apache.batik.dom.events.EventSupport

public class EventSupport

extends java.lang.Object

The class allows registration and removal of EventListeners on an NodeEventTarget and dispatch of events to that NodeEventTarget.

See Also:

NodeEventTarget

Field Summary

protected HashTable	bubblingListeners The bubbling listeners table.
protected HashTable	capturingListeners The capturing listeners table.

Constructor Summary

EventSupport()

Method Summary

void	addEventListener(java.lang.String type, EventListener listener, boolean useCapture) This method allows the registration of event listeners on the event target.
static boolean	dispatchEvent(NodeEventTarget target, Event e) This method allows the dispatch of events into the implementations event model.
EventListenerList	getEventListeners(java.lang.String type, boolean useCapture) Returns a list event listeners depending on the specified event type and phase.
void	removeEventListener(java.lang.String type, EventListener listener, boolean useCapture) This method allows the removal of event listeners from the event target.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

capturingListeners

protected HashTable capturingListeners

The capturing listeners table.

bubblingListeners

protected HashTable bubblingListeners

The bubbling listeners table.

Constructor Detail

EventSupport

public EventSupport()

Method Detail

addEventListener

public void addEventListener(java.lang.String type,
                             EventListener listener,
                             boolean useCapture)

This method allows the registration of event listeners on the event target. If an EventListener is added to an EventTarget which is currently processing an event the new listener will not be triggered by the current event.
If multiple identical EventListeners are registered on the same EventTarget with the same parameters the duplicate instances are discarded. They do not cause the EventListener to be called twice and since they are discarded they do not need to be removed with the removeEventListener method.

Parameters:

type - The event type for which the user is registering

listener - The listener parameter takes an interface implemented by the user which contains the methods to be called when the event occurs.

useCapture - If true, useCapture indicates that the user wishes to initiate capture. After initiating capture, all events of the specified type will be dispatched to the registered EventListener before being dispatched to any EventTargets beneath them in the tree. Events which are bubbling upward through the tree will not trigger an EventListener designated to use capture.

removeEventListener

public void removeEventListener(java.lang.String type,
                                EventListener listener,
                                boolean useCapture)

This method allows the removal of event listeners from the event target. If an EventListener is removed from an EventTarget while it is processing an event, it will complete its current actions but will not be triggered again during any later stages of event flow.
If an EventListener is removed from an EventTarget which is currently processing an event the removed listener will still be triggered by the current event.
Calling removeEventListener with arguments which do not identify any currently registered EventListener on the EventTarget has no effect.

Parameters:

type - Specifies the event type of the EventListener being removed.

listener - The EventListener parameter indicates the EventListener to be removed.

useCapture - Specifies whether the EventListener being removed was registered as a capturing listener or not. If a listener was registered twice, one with capture and one without, each must be removed separately. Removal of a capturing listener does not affect a non-capturing version of the same listener, and vice versa.

dispatchEvent

public static boolean dispatchEvent(NodeEventTarget target,
                                    Event e)
                             throws EventException

This method allows the dispatch of events into the implementations event model. Events dispatched in this manner will have the same capturing and bubbling behavior as events dispatched directly by the implementation. The target of the event is the EventTarget on which dispatchEvent is called.

Parameters:

target - the target node

evt - Specifies the event type, behavior, and contextual information to be used in processing the event.

Returns:

The return value of dispatchEvent indicates whether any of the listeners which handled the event called preventDefault. If preventDefault was called the value is false, else the value is true.

Throws:

EventException - UNSPECIFIED_EVENT_TYPE_ERR: Raised if the Event's type was not specified by initializing the event before dispatchEvent was called. Specification of the Event's type as null or an empty string will also trigger this exception.

getEventListeners

public EventListenerList getEventListeners(java.lang.String type,
                                           boolean useCapture)

Returns a list event listeners depending on the specified event type and phase.

Parameters:

type - the event type

useCapture -