libjava/classpath/javax/swing/Timer.java

   1 /* Timer.java --
   2    Copyright (C) 2002, 2004, 2005  Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19 02110-1301 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package javax.swing;
  40
  41 import java.awt.event.ActionEvent;
  42 import java.awt.event.ActionListener;
  43 import java.io.Serializable;
  44 import java.util.EventListener;
  45
  46 import javax.swing.event.EventListenerList;
  47
  48 /**
  49  * Fires one or more action events after the specified delay.  This is
  50  * a specialised version of <code>java.util.Timer</code> just for
  51  * firing <code>ActionEvent</code>s. All Timers share one (daemon)
  52  * Thread (or java.util.Timer). All events are fired from the event
  53  * queue.
  54  *
  55  * @author Ronald Veldema
  56  * @author Audrius Meskauskas (audriusa@Bionformatics.org) - bug fixes
  57  * and documentation comments
  58  */
  59 public class Timer
  60   implements Serializable
  61 {
  62   /**
  63    * Given to the shared java.util.Timer to (possibly repeatedly) call
  64    * queueEvent().
  65    */
  66   private class Task extends java.util.TimerTask
  67   {
  68     public void run()
  69     {
  70       if (logTimers)
  71         System.out.println("javax.swing.Timer -> queueEvent()");
  72       queueEvent();
  73
  74       if (!repeats)
  75         task = null;
  76     }
  77   }
  78
  79   /**
  80    * Use serialVersionUID for interoperability.
  81    */
  82   private static final long serialVersionUID = -1116180831621385484L;
  83
  84   /**
  85    * The encloding class, used with {@link SwingUtilities#invokeLater}
  86    * to invoke the {@link #drainEvents()}.
  87    */
  88   private Runnable drainer = new Runnable()
  89     {
  90       public void run()
  91       {
  92         drainEvents();
  93       }
  94     };
  95
  96   /**
  97    * The static java.util.Timer daemon which will be used to schedule
  98    * all javax.swing.Timer.Task objects. The daemon will always be
  99    * running, even if there's no task scheduled in it.
 100    */
 101   private static java.util.Timer timer = new java.util.Timer("swing.Timer",
 102                                                              true);
 103
 104   /**
 105    * If <code>true</code>, the timer prints a message to
 106    * {@link System#out} when firing each event.
 107    */
 108   static boolean logTimers;
 109
 110   /**
 111    * A field to store all listeners who are listening to this timer.
 112    */
 113   protected EventListenerList listenerList = new EventListenerList();
 114
 115   /**
 116    * <code>true</code> if the timer coalesces events.
 117    */
 118   boolean coalesce = true;
 119
 120   /**
 121    * <code>true</code> if the timer is firing repetetive events.
 122    */
 123   boolean repeats = true;
 124
 125   /**
 126    * The delay between subsequent repetetive events.
 127    */
 128   int delay;
 129
 130   /**
 131    * The initial delay before the first event.
 132    */
 133   int initialDelay;
 134
 135   /**
 136    * The number of events that have been already fired by this timer.
 137    * This is used as a numeric identifier for the next event that would
 138    * be fired.
 139    */
 140   int ticks;
 141
 142   /**
 143    * The task that calls queueEvent(). When null this Timer is stopped.
 144    * This is package private to avoid synthetic accessor method.
 145    */
 146   Task task;
 147
 148   /**
 149    * This object manages a "queue" of virtual actionEvents, maintained as a
 150    * simple long counter. When the timer expires, a new event is queued,
 151    * and a dispatcher object is pushed into the system event queue. When
 152    * the system thread runs the dispatcher, it will fire as many
 153    * ActionEvents as have been queued, unless the timer is set to
 154    * coalescing mode, in which case it will fire only one ActionEvent.
 155    */
 156   private long queue;
 157
 158   /**
 159    * <code>synchronized(queueLock)</code> replaces
 160    * <code>synchronized(queue)</code> that is not supported by this language.
 161    */
 162   private Object queueLock = new Object();
 163
 164   /**
 165    * Creates a new Timer object.
 166    *
 167    * @param d the default value for both initial and between event delay, in
 168    * milliseconds.
 169    * @param listener the first action listener, can be <code>null</code>.
 170    */
 171   public Timer(int d, ActionListener listener)
 172   {
 173     delay = d;
 174     initialDelay = d;
 175
 176     if (listener != null)
 177       addActionListener(listener);
 178   }
 179
 180   /**
 181    * Get the array of action listeners.
 182    *
 183    * @return the array of action listeners that are listening for the events,
 184    * fired by this timer
 185    *
 186    * @since 1.4
 187    */
 188   public ActionListener[] getActionListeners()
 189   {
 190     return (ActionListener[]) listenerList.getListeners(ActionListener.class);
 191   }
 192
 193   /**
 194    * Sets whether the Timer coalesces multiple pending event firings.
 195    * If the coalescing is enabled, the multiple events that have not been
 196    * fired on time are replaced by the single event. The events may not
 197    * be fired on time if the application is busy.
 198    *
 199    * @param c <code>true</code> (default) to enable the event coalescing,
 200    * <code>false</code> otherwise
 201    */
 202   public void setCoalesce(boolean c)
 203   {
 204     coalesce = c;
 205   }
 206
 207   /**
 208    * Checks if the Timer coalesces multiple pending event firings.
 209    * If the coalescing is enabled, the multiple events that have not been
 210    * fired on time are replaced by the single event. The events may not
 211    * be fired on time if the application is busy.
 212    *
 213    * @return <code>true</code> if the coalescing is enabled,
 214    * <code>false</code> otherwise
 215    */
 216   public boolean isCoalesce()
 217   {
 218     return coalesce;
 219   }
 220
 221   /**
 222    * Get the event listeners of the given type that are listening for the
 223    * events, fired by this timer.
 224    *
 225    * @param listenerType the listener type (for example, ActionListener.class)
 226    *
 227    * @return the array of event listeners that are listening for the events,
 228    * fired by this timer
 229    * @since 1.3
 230    */
 231   public EventListener[] getListeners(Class listenerType)
 232   {
 233     return listenerList.getListeners(listenerType);
 234   }
 235
 236   /**
 237    * Set the timer logging state. If it is set to <code>true</code>, the
 238    * timer prints a message to {@link System#out} when firing each
 239    * action event.
 240    *
 241    * @param lt <code>true</code> if logging is enabled, <code>false</code>
 242    * (default value) otherwise
 243    */
 244   public static void setLogTimers(boolean lt)
 245   {
 246     logTimers = lt;
 247   }
 248
 249   /**
 250    * Return the logging state.
 251    *
 252    * @return <code>true</code> if the timer is printing a message to
 253    * {@link System#out}
 254    * when firing each action event
 255    */
 256   public static boolean getLogTimers()
 257   {
 258     return logTimers;
 259   }
 260
 261   /**
 262    * Set the delay between firing the subsequent events.
 263    * This parameter does not change the value of the initial delay before
 264    * firing the first event.
 265    *
 266    * @param d The time gap between the subsequent events, in milliseconds
 267    */
 268   public void setDelay(int d)
 269   {
 270     delay = d;
 271   }
 272
 273   /**
 274    * Get the delay between firing the subsequent events.
 275    *
 276    * @return The delay between subsequent events, in milliseconds
 277    */
 278   public int getDelay()
 279   {
 280     return delay;
 281   }
 282
 283   /**
 284    * Set the intial delay before firing the first event since calling
 285    * the {@link #start()} method. If the initial delay has not been
 286    * set, it is assumed having the same value as the delay between the
 287    * subsequent events.
 288    *
 289    * @param i the initial delay, in milliseconds
 290    */
 291   public void setInitialDelay(int i)
 292   {
 293     initialDelay = i;
 294   }
 295
 296   /**
 297    * Get the intial delay before firing the first event since calling
 298    * the {@link #start()} method. If the initial delay has not been
 299    * set, returns the same value as {@link #getDelay()}.
 300    *
 301    * @return the initial delay before firing the first action event.
 302    */
 303   public int getInitialDelay()
 304   {
 305     return initialDelay;
 306   }
 307
 308   /**
 309    * Enable firing the repetetive events.
 310    *
 311    * @param r <code>true</code> (default value) to fire repetetive events.
 312    * <code>false</code> to fire
 313    * only one event after the initial delay
 314    */
 315   public void setRepeats(boolean r)
 316   {
 317     repeats = r;
 318   }
 319
 320   /**
 321    * Check is this timer fires repetetive events.
 322    *
 323    * @return <code>true</code> if the timer fires repetetive events,
 324    * <code>false</code> if it fires
 325    * only one event after the initial delay
 326    */
 327   public boolean isRepeats()
 328   {
 329     return repeats;
 330   }
 331
 332   /**
 333    * Get the timer state.
 334    *
 335    * @return <code>true</code> if the timer has been started and is firing
 336    * the action events as scheduled. <code>false</code>
 337    * if the timer is inactive.
 338    */
 339   public boolean isRunning()
 340   {
 341     return task != null;
 342   }
 343
 344   /**
 345    * Add the action listener
 346    *
 347    * @param listener the action listener to add
 348    */
 349   public void addActionListener(ActionListener listener)
 350   {
 351     listenerList.add(ActionListener.class, listener);
 352   }
 353
 354   /**
 355    * Remove the action listener.
 356    *
 357    * @param listener the action listener to remove
 358    */
 359   public void removeActionListener(ActionListener listener)
 360   {
 361     listenerList.remove(ActionListener.class, listener);
 362   }
 363
 364   /**
 365    * Cancel all pending tasks and fire the first event after the initial
 366    * delay.
 367    */
 368   public void restart()
 369   {
 370     stop();
 371     start();
 372   }
 373
 374   /**
 375    * Start firing the action events.
 376    */
 377   public void start()
 378   {
 379     Task t = task;
 380     if (t == null)
 381       {
 382         t = new Task();
 383         if (isRepeats())
 384           timer.schedule(t, getInitialDelay(), getDelay());
 385         else
 386           timer.schedule(t, getInitialDelay());
 387         task = t;
 388       }
 389   }
 390
 391   /**
 392    * Stop firing the action events.
 393    */
 394   public void stop()
 395   {
 396     Task t = task;
 397     if (t != null)
 398       {
 399         t.cancel();
 400         task = null;
 401       }
 402   }
 403
 404   /**
 405    * Fire the given action event to the action listeners.
 406    *
 407    * @param event the event to fire
 408    */
 409   protected void fireActionPerformed(ActionEvent event)
 410   {
 411     ActionListener[] listeners = getActionListeners();
 412
 413     for (int i = 0; i < listeners.length; i++)
 414       listeners [ i ].actionPerformed(event);
 415   }
 416
 417   /**
 418    * Fire the action event, named "Timer" and having the numeric
 419    * identifier, equal to the numer of events that have been
 420    * already fired before.
 421    */
 422   void fireActionPerformed()
 423   {
 424     fireActionPerformed(new ActionEvent(this, ticks++, "Timer"));
 425   }
 426
 427   /**
 428    * Fire the queued action events.
 429    * In the coalescing mode, a single event is fired as a replacement
 430    * for all queued events. In non coalescing mode, a series of
 431    * all queued events is fired.
 432    * This is package-private to avoid an accessor method.
 433    */
 434   void drainEvents()
 435   {
 436     synchronized (queueLock)
 437       {
 438         if (isCoalesce())
 439           {
 440             if (queue > 0)
 441               fireActionPerformed();
 442           }
 443         else
 444           {
 445             while (queue > 0)
 446               {
 447                 fireActionPerformed();
 448                 queue--;
 449               }
 450           }
 451         queue = 0;
 452       }
 453   }
 454
 455   /**
 456   * Post a scheduled event to the event queue.
 457   * Package-private to avoid an accessor method.
 458   */
 459   void queueEvent()
 460   {
 461     synchronized(queueLock)
 462       {
 463         queue++;
 464         if (queue == 1)
 465           SwingUtilities.invokeLater(drainer);
 466       }
 467   }
 468 }