001 /*
002 * Copyright (c) 2000 World Wide Web Consortium,
003 * (Massachusetts Institute of Technology, Institut National de
004 * Recherche en Informatique et en Automatique, Keio University). All
005 * Rights Reserved. This program is distributed under the W3C's Software
006 * Intellectual Property License. This program is distributed in the
007 * hope that it will be useful, but WITHOUT ANY WARRANTY; without even
008 * the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
009 * PURPOSE.
010 * See W3C License http://www.w3.org/Consortium/Legal/ for more details.
011 */
012
013 package org.w3c.dom.events;
014
015 /**
016 * The <code>EventTarget</code> interface is implemented by all
017 * <code>Nodes</code> in an implementation which supports the DOM Event
018 * Model. Therefore, this interface can be obtained by using
019 * binding-specific casting methods on an instance of the <code>Node</code>
020 * interface. The interface allows registration and removal of
021 * <code>EventListeners</code> on an <code>EventTarget</code> and dispatch
022 * of events to that <code>EventTarget</code>.
023 * <p>See also the <a href='http://www.w3.org/TR/2000/REC-DOM-Level-2-Events-20001113'>Document Object Model (DOM) Level 2 Events Specification</a>.
024 * @since DOM Level 2
025 */
026 public interface EventTarget {
027 /**
028 * This method allows the registration of event listeners on the event
029 * target. If an <code>EventListener</code> is added to an
030 * <code>EventTarget</code> while it is processing an event, it will not
031 * be triggered by the current actions but may be triggered during a
032 * later stage of event flow, such as the bubbling phase.
033 * <br> If multiple identical <code>EventListener</code>s are registered
034 * on the same <code>EventTarget</code> with the same parameters the
035 * duplicate instances are discarded. They do not cause the
036 * <code>EventListener</code> to be called twice and since they are
037 * discarded they do not need to be removed with the
038 * <code>removeEventListener</code> method.
039 * @param type The event type for which the user is registering
040 * @param listener The <code>listener</code> parameter takes an interface
041 * implemented by the user which contains the methods to be called
042 * when the event occurs.
043 * @param useCapture If true, <code>useCapture</code> indicates that the
044 * user wishes to initiate capture. After initiating capture, all
045 * events of the specified type will be dispatched to the registered
046 * <code>EventListener</code> before being dispatched to any
047 * <code>EventTargets</code> beneath them in the tree. Events which
048 * are bubbling upward through the tree will not trigger an
049 * <code>EventListener</code> designated to use capture.
050 */
051 public void addEventListener(String type,
052 EventListener listener,
053 boolean useCapture);
054
055 /**
056 * This method allows the removal of event listeners from the event
057 * target. If an <code>EventListener</code> is removed from an
058 * <code>EventTarget</code> while it is processing an event, it will not
059 * be triggered by the current actions. <code>EventListener</code>s can
060 * never be invoked after being removed.
061 * <br>Calling <code>removeEventListener</code> with arguments which do
062 * not identify any currently registered <code>EventListener</code> on
063 * the <code>EventTarget</code> has no effect.
064 * @param type Specifies the event type of the <code>EventListener</code>
065 * being removed.
066 * @param listener The <code>EventListener</code> parameter indicates the
067 * <code>EventListener </code> to be removed.
068 * @param useCapture Specifies whether the <code>EventListener</code>
069 * being removed was registered as a capturing listener or not. If a
070 * listener was registered twice, one with capture and one without,
071 * each must be removed separately. Removal of a capturing listener
072 * does not affect a non-capturing version of the same listener, and
073 * vice versa.
074 */
075 public void removeEventListener(String type,
076 EventListener listener,
077 boolean useCapture);
078
079 /**
080 * This method allows the dispatch of events into the implementations
081 * event model. Events dispatched in this manner will have the same
082 * capturing and bubbling behavior as events dispatched directly by the
083 * implementation. The target of the event is the
084 * <code> EventTarget</code> on which <code>dispatchEvent</code> is
085 * called.
086 * @param evt Specifies the event type, behavior, and contextual
087 * information to be used in processing the event.
088 * @return The return value of <code>dispatchEvent</code> indicates
089 * whether any of the listeners which handled the event called
090 * <code>preventDefault</code>. If <code>preventDefault</code> was
091 * called the value is false, else the value is true.
092 * @exception EventException
093 * UNSPECIFIED_EVENT_TYPE_ERR: Raised if the <code>Event</code>'s type
094 * was not specified by initializing the event before
095 * <code>dispatchEvent</code> was called. Specification of the
096 * <code>Event</code>'s type as <code>null</code> or an empty string
097 * will also trigger this exception.
098 */
099 public boolean dispatchEvent(Event evt)
100 throws EventException;
101
102 }