svgeventqueue.java

一个用Java写的

/******************************************************************
 * Copyright (C) 2002-2006 Andrew Girow. All rights reserved.     *
 * ---------------------------------------------------------------*
 * This software is published under the terms of the TinyLine     *
 * License, a copy of which has been included with this           *
 * distribution in the TINYLINE_LICENSE.TXT file.                 *
 *                                                                *
 * For more information on the TinyLine,                          *
 * please see <http://www.tinyline.com/>.                         *
 *****************************************************************/

package com.tinyline.app;

import com.tinyline.svg.*;
import com.tinyline.tiny2d.*;

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



/**
 * The <tt>SVGEventQueue</tt> is a class that queues SVG events.
 *
 * <p>
 * @author Andrew Girow
 * @version 1.9
 * <p>
 */
public class SVGEventQueue
{

    private SVGEvent queue;

    /**
     * Creates a new SVGEventQueue object.
     */
    public SVGEventQueue()
    {
        queue = null;
    }

    /**
     * Resets the SVGEventQueue.
     */
    public synchronized void reset()
    {
        queue = null;
    }


    /**
     * Remove an event from the queue and return it.  This method will
     * block until an event has been posted by another thread.
     * @return the next SVGEvent
     * @exception InterruptedException
     *            if another thread has interrupted this thread.
     */
    public synchronized SVGEvent getNextEvent() throws InterruptedException
    {
        while (queue == null)
        {
            wait();
        }
        SVGEvent event = queue;
        queue = queue.next;
        return event;
    }

    /**
     * Dispatch an event to the eventHandler.
     *
     * @param theEvent an instance of SVGEvent, or a
     * subclass of it.
     */
    public void handleEvent(SVGEvent theEvent)
    {
        if(theEvent!=null)
        {
           EventTarget target = theEvent.getCurrentTarget();
           if(target!= null)
              target.dispatchEvent(theEvent);
        }
    }


    /**
     * Post an event to the EventQueue.
     *
     * @param theEvent an instance of SVGEvent, or a
     * subclass of it.
     */
    public synchronized void postEvent(SVGEvent theEvent)
    {
//System.out.println("postEvent! 0");
        // empty queue
        if (queue == null)
        {
           queue = theEvent;
        }
        // add to the end
        else
        {
           SVGEvent q = queue;
           for (;;)
           {
              if (q.id == theEvent.id)
              {
                  if(q.id == SVGEvent.EVENT_UPDATE)
                  {
                      ((TinyRect)q.data).union((TinyRect)theEvent.data);
                      return;
                  }
              }
              if (q.next != null)
              {
                  q = q.next;
              }
              else
              {
                  break;
              }
           } //for(;;)
           q.next = theEvent;
        } //else
        notifyAll();
//System.out.println("postEvent! 1");
    }

    /**
     * Return the first event without removing it.
     */
    public synchronized SVGEvent peekEvent()
    {
        return queue;
    }
}