src/org/apache/xerces/dom/events/EventImpl.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.xerces.dom.events;

import org.w3c.dom.events.Event;
import org.w3c.dom.events.EventTarget;

/**  
 * EventImpl is an implementation of the basic "generic" DOM Level 2 Event
 * object. It may be subclassed by more specialized event sets.
 * Note that in our implementation, events are re-dispatchable (dispatch
 * clears the stopPropagation and preventDefault flags before it starts);
 * I believe that is the DOM's intent but I don't see an explicit statement
 * to this effect.
 *   
 * @xerces.internal 
 *
 * @version $Id$
 */
public class EventImpl implements Event {
    
    public String type = null;
    public EventTarget target;
    public EventTarget currentTarget;
    public short eventPhase;
    public boolean initialized = false, bubbles = true, cancelable = false;
    public boolean stopPropagation = false, preventDefault = false;

    protected long timeStamp = System.currentTimeMillis();

    /** 
     * The DOM doesn't deal with constructors, so instead we have an
     * initializer call to set most of the read-only fields. The
     * others are set, and reset, by the event subsystem during dispatch.
     * <p>
     * Note that init() -- and the subclass-specific initWhatever() calls --
     * may be reinvoked. At least one initialization is required; repeated
     * initializations overwrite the event with new values of their
     * parameters.
     */
    public void initEvent(String eventTypeArg, boolean canBubbleArg, 
            boolean cancelableArg) {
        type = eventTypeArg;
        bubbles = canBubbleArg;
        cancelable = cancelableArg;
        initialized = true;
    }

    /** 
     * @return true iff this Event is of a class and type which supports
     * bubbling. In the generic case, this is True.
     */
    public boolean getBubbles() {
        return bubbles;
    }

    /** 
     * @return true iff this Event is of a class and type which (a) has a
     * Default Behavior in this DOM, and (b)allows cancellation (blocking)
     * of that behavior. In the generic case, this is False.
     */
    public boolean getCancelable() {
        return cancelable;
    }

    /** 
     * @return the Node (EventTarget) whose EventListeners are currently
     * being processed. During capture and bubble phases, this may not be
     * the target node. 
     */
    public EventTarget getCurrentTarget() {
        return currentTarget;
    }

    /** 
     * @return the current processing phase for this event -- 
     * CAPTURING_PHASE, AT_TARGET, BUBBLING_PHASE. (There may be
     * an internal DEFAULT_PHASE as well, but the users won't see it.) 
     */
    public short getEventPhase() {
        return eventPhase;
    }

    /** 
     * @return the EventTarget (Node) to which the event was originally
     * dispatched.
     */
    public EventTarget getTarget() {
        return target;
    }

    /** 
     * @return event name as a string
     */
    public String getType() {
        return type;
    }

    public long getTimeStamp() {
        return timeStamp;
    }

    /** 
     * Causes exit from in-progress event dispatch before the next
     * currentTarget is selected. Replaces the preventBubble() and 
     * preventCapture() methods which were present in early drafts; 
     * they may be reintroduced in future levels of the DOM. 
     */
    public void stopPropagation() {
        stopPropagation = true;
    }

    /** 
     * Prevents any default processing built into the target node from
     * occurring.
     */
    public void preventDefault() {
        preventDefault = true;
    }
}