Initial revision

From-SVN: r102074

libjava/classpath/javax/swing/Timer.java

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+/* Timer.java --
+   Copyright (C) 2002, 2004, 2005  Free Software Foundation, Inc.
+
+This file is part of GNU Classpath.
+
+GNU Classpath is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU Classpath is distributed in the hope that it will be useful, but
+WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU Classpath; see the file COPYING.  If not, write to the
+Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+02110-1301 USA.
+
+Linking this library statically or dynamically with other modules is
+making a combined work based on this library.  Thus, the terms and
+conditions of the GNU General Public License cover the whole
+combination.
+
+As a special exception, the copyright holders of this library give you
+permission to link this library with independent modules to produce an
+executable, regardless of the license terms of these independent
+modules, and to copy and distribute the resulting executable under
+terms of your choice, provided that you also meet, for each linked
+independent module, the terms and conditions of the license of that
+module.  An independent module is a module which is not derived from
+or based on this library.  If you modify this library, you may extend
+this exception to your version of the library, but you are not
+obligated to do so.  If you do not wish to do so, delete this
+exception statement from your version. */
+
+
+package javax.swing;
+
+import java.awt.event.ActionEvent;
+import java.awt.event.ActionListener;
+import java.io.Serializable;
+import java.util.EventListener;
+
+import javax.swing.event.EventListenerList;
+
+/**
+ * Fires one or more action events after the specified delay.
+ * @author Ronald Veldema
+ * @author Audrius Meskauskas (audriusa@Bionformatics.org) - bug fixes
+ * and documentation comments
+ */
+public class Timer
+  implements Serializable
+{
+  /**
+   * The timer thread
+   */
+  private class Waker
+    extends Thread
+  {
+    /**
+     * Fires events, pausing for required intervals.
+     */
+    public void run()
+    {
+      running = true;
+      try
+        {
+          sleep(initialDelay);
+
+          queueEvent();
+
+          while (running)
+            {
+              try
+                {
+                  sleep(delay);
+                }
+              catch (InterruptedException e)
+                {
+                  return;
+                }
+              queueEvent();
+
+              if (logTimers)
+                System.out.println("javax.swing.Timer -> clocktick");
+
+              if ( ! repeats)
+                break;
+            }
+          running = false;
+        }
+      catch (Exception e)
+        {
+          // The timer is no longer running.
+          running = false;
+        }
+    }
+  }
+
+  /**
+   * Use serialVersionUID for interoperability.
+   */
+  private static final long serialVersionUID = -1116180831621385484L;
+
+  /**
+   * The encloding class, used with {@link SwingUtilities#invokeLater}
+   * to invoke the {@link #drainEvents()}.
+   */
+  private Runnable drainer = new Runnable()
+    {
+      public void run()
+      {
+        drainEvents();
+      }
+    };
+
+  /**
+   * If <code>true</code>, the timer prints a message to
+   * {@link System#out} when firing each event.
+   */
+  static boolean logTimers;
+
+  /**
+   * A field to store all listeners who are listening to this timer.
+   */
+  protected EventListenerList listenerList = new EventListenerList();
+
+  /**
+   * <code>true</code> if the timer coalesces events.
+   */
+  boolean coalesce = true;
+
+  /**
+   * <code>true</code> if the timer is firing repetetive events.
+   */
+  boolean repeats = true;
+
+  /**
+   * <code>true</code> if the timer is currently active, firing events
+   * as scheduled.
+   */
+  boolean running;
+
+  /**
+   * The delay between subsequent repetetive events.
+   */
+  int delay;
+
+  /**
+   * The initial delay before the first event.
+   */
+  int initialDelay;
+
+  /**
+   * The number of events that have been already fired by this timer.
+   * This is used as a numeric identifier for the next event that would
+   * be fired.
+   */
+  int ticks;
+
+  /**
+   * Stores the thread that posts events to the queue at required time
+   * intervals.
+   */
+  private Waker waker;
+
+  /**
+   * This object manages a "queue" of virtual actionEvents, maintained as a
+   * simple long counter. When the timer expires, a new event is queued,
+   * and a dispatcher object is pushed into the system event queue. When
+   * the system thread runs the dispatcher, it will fire as many
+   * ActionEvents as have been queued, unless the timer is set to
+   * coalescing mode, in which case it will fire only one ActionEvent.
+   */
+  private long queue;
+
+  /**
+   * <code>synchronized(queueLock)</code> replaces
+   * <code>synchronized(queue)</code> that is not supported by this language.
+   */
+  private Object queueLock = new Object();
+
+  /**
+   * Creates a new Timer object.
+   *
+   * @param d the default value for both initial and between event delay, in
+   * milliseconds.
+   * @param listener the first action listener, can be <code>null</code>.
+   */
+  public Timer(int d, ActionListener listener)
+  {
+    delay = d;
+    initialDelay = d;
+
+    if (listener != null)
+      addActionListener(listener);
+  }
+
+  /**
+   * Get the array of action listeners.
+   *
+   * @return the array of action listeners that are listening for the events,
+   * fired by this timer
+   *
+   * @since 1.4
+   */
+  public ActionListener[] getActionListeners()
+  {
+    return (ActionListener[]) listenerList.getListeners(ActionListener.class);
+  }
+
+  /**
+   * Sets whether the Timer coalesces multiple pending event firings.
+   * If the coalescing is enabled, the multiple events that have not been
+   * fired on time are replaced by the single event. The events may not
+   * be fired on time if the application is busy.
+   *
+   * @param c <code>true</code> (default) to enable the event coalescing,
+   * <code>false</code> otherwise
+   */
+  public void setCoalesce(boolean c)
+  {
+    coalesce = c;
+  }
+
+  /**
+   * Checks if the Timer coalesces multiple pending event firings.
+   * If the coalescing is enabled, the multiple events that have not been
+   * fired on time are replaced by the single event. The events may not
+   * be fired on time if the application is busy.
+   *
+   * @return <code>true</code> if the coalescing is enabled,
+   * <code>false</code> otherwise
+   */
+  public boolean isCoalesce()
+  {
+    return coalesce;
+  }
+
+  /**
+   * Get the event listeners of the given type that are listening for the
+   * events, fired by this timer.
+   *
+   * @param listenerType the listener type (for example, ActionListener.class)
+   *
+   * @return the array of event listeners that are listening for the events,
+   * fired by this timer
+   * @since 1.3
+   */
+  public EventListener[] getListeners(Class listenerType)
+  {
+    return listenerList.getListeners(listenerType);
+  }
+
+  /**
+   * Set the timer logging state. If it is set to <code>true</code>, the
+   * timer prints a message to {@link System#out} when firing each
+   * action event.
+   *
+   * @param lt <code>true</code> if logging is enabled, <code>false</code>
+   * (default value) otherwise
+   */
+  public static void setLogTimers(boolean lt)
+  {
+    logTimers = lt;
+  }
+
+  /**
+   * Return the logging state.
+   *
+   * @return <code>true</code> if the timer is printing a message to
+   * {@link System#out}
+   * when firing each action event
+   */
+  public static boolean getLogTimers()
+  {
+    return logTimers;
+  }
+
+  /**
+   * Set the delay between firing the subsequent events.
+   * This parameter does not change the value of the initial delay before
+   * firing the first event.
+   *
+   * @param d The time gap between the subsequent events, in milliseconds
+   */
+  public void setDelay(int d)
+  {
+    delay = d;
+  }
+
+  /**
+   * Get the delay between firing the subsequent events.
+   *
+   * @return The delay between subsequent events, in milliseconds
+   */
+  public int getDelay()
+  {
+    return delay;
+  }
+
+  /**
+   * Set the intial delay before firing the first event since calling
+   * the {@link #start()} method. If the initial delay has not been
+   * set, it is assumed having the same value as the delay between the
+   * subsequent events.
+   *
+   * @param i the initial delay, in milliseconds
+   */
+  public void setInitialDelay(int i)
+  {
+    initialDelay = i;
+  }
+
+  /**
+   * Get the intial delay before firing the first event since calling
+   * the {@link #start()} method. If the initial delay has not been
+   * set, returns the same value as {@link #getDelay()}.
+   *
+   * @return the initial delay before firing the first action event.
+   */
+  public int getInitialDelay()
+  {
+    return initialDelay;
+  }
+
+  /**
+   * Enable firing the repetetive events.
+   *
+   * @param r <code>true</code> (default value) to fire repetetive events.
+   * <code>false</code> to fire
+   * only one event after the initial delay
+   */
+  public void setRepeats(boolean r)
+  {
+    repeats = r;
+  }
+
+  /**
+   * Check is this timer fires repetetive events.
+   *
+   * @return <code>true</code> if the timer fires repetetive events,
+   * <code>false</code> if it fires
+   * only one event after the initial delay
+   */
+  public boolean isRepeats()
+  {
+    return repeats;
+  }
+
+  /**
+   * Get the timer state.
+   *
+   * @return <code>true</code> if the timer has been started and is firing
+   * the action events as scheduled. <code>false</code>
+   * if the timer is inactive.
+   */
+  public boolean isRunning()
+  {
+    return running;
+  }
+
+  /**
+   * Add the action listener
+   *
+   * @param listener the action listener to add
+   */
+  public void addActionListener(ActionListener listener)
+  {
+    listenerList.add(ActionListener.class, listener);
+  }
+
+  /**
+   * Remove the action listener.
+   *
+   * @param listener the action listener to remove
+   */
+  public void removeActionListener(ActionListener listener)
+  {
+    listenerList.remove(ActionListener.class, listener);
+  }
+
+  /**
+   * Cancel all pending tasks and fire the first event after the initial
+   * delay.
+   */
+  public void restart()
+  {
+    stop();
+    start();
+  }
+
+  /**
+   * Start firing the action events.
+   */
+  public void start()
+  {
+    if (isRunning())
+      return;
+    waker = new Waker();
+    waker.start();
+  }
+
+  /**
+   * Stop firing the action events.
+   */
+  public void stop()
+  {
+    running = false;
+    if (waker != null)
+      waker.interrupt();
+    synchronized (queueLock)
+      {
+        queue = 0;
+      }
+  }
+
+  /**
+   * Fire the given action event to the action listeners.
+   *
+   * @param event the event to fire
+   */
+  protected void fireActionPerformed(ActionEvent event)
+  {
+    ActionListener[] listeners = getActionListeners();
+
+    for (int i = 0; i < listeners.length; i++)
+      listeners [ i ].actionPerformed(event);
+  }
+
+  /**
+   * Fire the action event, named "Timer" and having the numeric
+   * identifier, equal to the numer of events that have been
+   * already fired before.
+   */
+  void fireActionPerformed()
+  {
+    fireActionPerformed(new ActionEvent(this, ticks++, "Timer"));
+  }
+
+  /**
+   * Fire the queued action events.
+   * In the coalescing mode, a single event is fired as a replacement
+   * for all queued events. In non coalescing mode, a series of
+   * all queued events is fired.
+   * This is package-private to avoid an accessor method.
+   */
+  void drainEvents()
+  {
+    synchronized (queueLock)
+      {
+        if (isCoalesce())
+          {
+            if (queue > 0)
+              fireActionPerformed();
+          }
+        else
+          {
+            while (queue > 0)
+              {
+                fireActionPerformed();
+                queue--;
+              }
+          }
+        queue = 0;
+      }
+  }
+
+  /**
+  * Post a scheduled event to the event queue.
+  * Package-private to avoid an accessor method.
+  */
+  void queueEvent()
+  {
+    synchronized (queueLock)
+      {
+        queue++;
+        if (queue == 1)
+          SwingUtilities.invokeLater(drainer);
+      }
+  }
+}