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324 lines
8.8 KiB
Java
324 lines
8.8 KiB
Java
/* Copyright (C) 1999, 2000, 2001, 2002 Free Software Foundation
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.awt;
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import java.awt.event.*;
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import java.util.EmptyStackException;
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import java.lang.reflect.InvocationTargetException;
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/* Written using on-line Java 2 Platform Standard Edition v1.3 API
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* Specification, as well as "The Java Class Libraries", 2nd edition
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* (Addison-Wesley, 1998).
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* Status: Believed complete, but untested. Check FIXME's.
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*/
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/**
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* This class manages a queue of <code>AWTEvent</code> objects that
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* are posted to it. The AWT system uses only one event queue for all
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* events.
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*
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* @author Bryce McKinlay
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* @author Aaron M. Renn (arenn@urbanophile.com)
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*/
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public class EventQueue
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{
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private static final int INITIAL_QUEUE_DEPTH = 8;
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private AWTEvent[] queue = new AWTEvent[INITIAL_QUEUE_DEPTH];
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private int next_in = 0; // Index where next event will be added to queue
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private int next_out = 0; // Index of next event to be removed from queue
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private EventQueue next;
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private EventQueue prev;
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private EventDispatchThread dispatchThread = new EventDispatchThread(this);
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/**
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* Initializes a new instance of <code>EventQueue</code>.
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*/
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public EventQueue()
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{
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}
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/**
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* Returns the next event in the queue. This method will block until
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* an event is available or until the thread is interrupted.
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*
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* @return The next event in the queue.
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*
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* @exception InterruptedException If this thread is interrupted while
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* waiting for an event to be posted to the queue.
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*/
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public synchronized AWTEvent getNextEvent()
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throws InterruptedException
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{
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if (next != null)
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return next.getNextEvent();
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while (next_in == next_out)
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wait();
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AWTEvent res = queue[next_out];
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if (++next_out == queue.length)
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next_out = 0;
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return res;
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}
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/**
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* Returns the next event in the queue without removing it from the queue.
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* This method will block until an event is available or until the thread
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* is interrupted.
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*
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* @return The next event in the queue.
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* @specnote Does not block. Returns null if there are no events on the
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* queue.
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*/
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public synchronized AWTEvent peekEvent()
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{
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if (next != null)
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return next.peekEvent();
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if (next_in != next_out)
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return queue[next_out];
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else return null;
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}
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/**
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* Returns the next event in the queue that has the specified id
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* without removing it from the queue.
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* This method will block until an event is available or until the thread
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* is interrupted.
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*
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* @param id The event id to return.
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*
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* @return The next event in the queue.
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*
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* @specnote Does not block. Returns null if there are no matching events
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* on the queue.
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*/
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public synchronized AWTEvent peekEvent(int id)
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{
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if (next != null)
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return next.peekEvent(id);
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int i = next_out;
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while (i != next_in)
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{
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AWTEvent qevt = queue[i];
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if (qevt.id == id)
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return qevt;
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}
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return null;
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}
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/**
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* Posts a new event to the queue.
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*
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* @param event The event to post to the queue.
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*/
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public synchronized void postEvent(AWTEvent evt)
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{
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if (next != null)
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{
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next.postEvent(evt);
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return;
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}
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// FIXME: Security checks?
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/* Check for any events already on the queue with the same source
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and ID. */
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int i = next_out;
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while (i != next_in)
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{
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AWTEvent qevt = queue[i];
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Object src;
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if (qevt.id == evt.id
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&& (src = qevt.getSource()) == evt.getSource()
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&& src instanceof Component)
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{
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/* If there are, call coalesceEvents on the source component
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to see if they can be combined. */
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Component srccmp = (Component) src;
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AWTEvent coalesced_evt = srccmp.coalesceEvents(qevt, evt);
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if (coalesced_evt != null)
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{
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/* Yes. Replace the existing event with the combined event. */
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queue[i] = coalesced_evt;
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return;
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}
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break;
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}
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if (++i == queue.length)
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i = 0;
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}
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queue[next_in] = evt;
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if (++next_in == queue.length)
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next_in = 0;
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if (next_in == next_out)
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{
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/* Queue is full. Extend it. */
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AWTEvent[] oldQueue = queue;
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queue = new AWTEvent[queue.length * 2];
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int len = oldQueue.length - next_out;
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System.arraycopy(oldQueue, next_out, queue, 0, len);
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if (next_out != 0)
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System.arraycopy(oldQueue, 0, queue, len, next_out);
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next_out = 0;
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next_in = oldQueue.length;
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}
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notify();
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}
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/** @since JDK1.2 */
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public static void invokeAndWait(Runnable runnable)
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throws InterruptedException, InvocationTargetException
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{
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EventQueue eq = Toolkit.getDefaultToolkit().getSystemEventQueue();
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Thread current = Thread.currentThread();
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if (current == eq.dispatchThread)
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throw new Error("Can't call invokeAndWait from event dispatch thread");
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InvocationEvent ie =
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new InvocationEvent(eq, runnable, current, true);
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synchronized (current)
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{
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eq.postEvent(ie);
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current.wait();
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}
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Exception exception;
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if ((exception = ie.getException()) != null)
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throw new InvocationTargetException(exception);
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}
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/** @since JDK1.2 */
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public static void invokeLater(Runnable runnable)
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{
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EventQueue eq = Toolkit.getDefaultToolkit().getSystemEventQueue();
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InvocationEvent ie =
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new InvocationEvent(eq, runnable, null, false);
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eq.postEvent(ie);
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}
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public static boolean isDispatchThread()
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{
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EventQueue eq = Toolkit.getDefaultToolkit().getSystemEventQueue();
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return (Thread.currentThread() == eq.dispatchThread);
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}
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/** Allows a custom EventQueue implementation to replace this one.
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* All pending events are transferred to the new queue. Calls to postEvent,
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* getNextEvent, and peekEvent are forwarded to the pushed queue until it
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* is removed with a pop().
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*/
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public synchronized void push(EventQueue newEventQueue)
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{
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int i = next_out;
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while (i != next_in)
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{
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newEventQueue.postEvent(queue[i]);
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next_out = i;
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if (++i == queue.length)
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i = 0;
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}
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next = newEventQueue;
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newEventQueue.prev = this;
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}
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/** Transfer any pending events from this queue back to the parent queue that
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* was previously push()ed. Event dispatch from this queue is suspended. */
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protected void pop() throws EmptyStackException
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{
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if (prev == null)
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throw new EmptyStackException();
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// Don't synchronize both this and prev at the same time, or deadlock could
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// occur.
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synchronized (prev)
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{
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prev.next = null;
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}
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synchronized (this)
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{
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int i = next_out;
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while (i != next_in)
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{
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prev.postEvent(queue[i]);
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next_out = i;
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if (++i == queue.length)
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i = 0;
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}
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}
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}
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protected void dispatchEvent(AWTEvent evt)
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{
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if (evt instanceof ActiveEvent)
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{
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ActiveEvent active_evt = (ActiveEvent) evt;
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active_evt.dispatch();
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}
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else
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{
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Object source = evt.getSource();
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if (source instanceof Component)
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{
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Component srccmp = (Component) source;
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srccmp.dispatchEvent(evt);
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}
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else if (source instanceof MenuComponent)
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{
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MenuComponent srccmp = (MenuComponent) source;
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srccmp.dispatchEvent(evt);
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}
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}
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}
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}
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