libjava/java/awt/Button.java

   1 /* Button.java -- AWT button widget
   2    Copyright (C) 1999, 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., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 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 java.awt;
  40
  41 import java.awt.event.ActionEvent;
  42 import java.awt.event.ActionListener;
  43 import java.awt.peer.ButtonPeer;
  44 import java.lang.reflect.Array;
  45 import java.util.EventListener;
  46
  47 import javax.accessibility.Accessible;
  48 import javax.accessibility.AccessibleAction;
  49 import javax.accessibility.AccessibleContext;
  50 import javax.accessibility.AccessibleRole;
  51 import javax.accessibility.AccessibleValue;
  52
  53 /**
  54   * This class provides a button widget for the AWT.
  55   *
  56   * @author Aaron M. Renn (arenn@urbanophile.com)
  57   * @author Tom Tromey (tromey@cygnus.com)
  58   */
  59 public class Button extends Component
  60   implements java.io.Serializable, Accessible
  61 {
  62
  63 /*
  64  * Static Variables
  65  */
  66
  67 // FIXME: Need readObject/writeObject for serialization
  68
  69 // Serialization version constant
  70 private static final long serialVersionUID = -8774683716313001058L;
  71
  72 /*************************************************************************/
  73
  74 /*
  75  * Instance Variables
  76  */
  77
  78 /**
  79   * @serial The action command name for this button.
  80   */
  81 private String actionCommand;
  82
  83 /**
  84   * @serial The label for this button.
  85   */
  86 private String label;
  87
  88 // List of ActionListeners for this class.
  89 private transient ActionListener action_listeners;
  90
  91   /*
  92    * The number used to generate the name returned by getName.
  93    */
  94   private static transient long next_button_number;
  95
  96   protected class AccessibleAWTButton extends AccessibleAWTComponent
  97     implements AccessibleAction, AccessibleValue
  98   {
  99     protected AccessibleAWTButton()
 100     {
 101       // Do nothing here.
 102     }
 103
 104     /* (non-Javadoc)
 105      * @see javax.accessibility.AccessibleAction#getAccessibleActionCount()
 106      */
 107     public int getAccessibleActionCount()
 108     {
 109       // Only 1 action possible
 110       return 1;
 111     }
 112
 113     /* (non-Javadoc)
 114      * @see javax.accessibility.AccessibleAction#getAccessibleActionDescription(int)
 115      */
 116     public String getAccessibleActionDescription(int i)
 117     {
 118       // JDK 1.4.2 returns the string "click" for action 0.  However, the API
 119       // docs don't say what the string to be returned is, beyond being a
 120       // description of the action.  So we return the same thing for
 121       // compatibility with 1.4.2.
 122       if (i == 0)
 123         return "click";
 124       return null;
 125     }
 126
 127     /* (non-Javadoc)
 128      * @see javax.accessibility.AccessibleAction#doAccessibleAction(int)
 129      */
 130     public boolean doAccessibleAction(int i)
 131     {
 132       if (i != 0)
 133         return false;
 134       processActionEvent(new ActionEvent(this, ActionEvent.ACTION_PERFORMED, actionCommand));
 135       return true;
 136     }
 137
 138     public String getAccessibleName()
 139     {
 140       return label;
 141     }
 142
 143     public AccessibleAction getAccessibleAction()
 144     {
 145       return this;
 146     }
 147
 148     public AccessibleValue getAccessibleValue()
 149     {
 150       return this;
 151     }
 152
 153     /* (non-Javadoc)
 154      * @see javax.accessibility.AccessibleValue#getCurrentAccessibleValue()
 155      */
 156     public Number getCurrentAccessibleValue()
 157     {
 158       // Docs say return 1 if selected, but buttons can't be selected, right?
 159       return new Integer(0);
 160     }
 161
 162     /* (non-Javadoc)
 163      * @see javax.accessibility.AccessibleValue#setCurrentAccessibleValue(java.lang.Number)
 164      */
 165     public boolean setCurrentAccessibleValue(Number number)
 166     {
 167       // Since there's no selection with buttons, we're ignoring this.
 168       // TODO someone who knows shoulw check this.
 169       return false;
 170     }
 171
 172     /* (non-Javadoc)
 173      * @see javax.accessibility.AccessibleValue#getMinimumAccessibleValue()
 174      */
 175     public Number getMinimumAccessibleValue()
 176     {
 177       return new Integer(0);
 178     }
 179
 180     /* (non-Javadoc)
 181      * @see javax.accessibility.AccessibleValue#getMaximumAccessibleValue()
 182      */
 183     public Number getMaximumAccessibleValue()
 184     {
 185       return new Integer(0);
 186     }
 187
 188     public AccessibleRole getAccessibleRole()
 189     {
 190       return AccessibleRole.PUSH_BUTTON;
 191     }
 192   }
 193
 194 /*************************************************************************/
 195
 196 /*
 197  * Constructors
 198  */
 199
 200 /**
 201   * Initializes a new instance of <code>Button</code> with no label.
 202   *
 203   * @exception HeadlessException If GraphicsEnvironment.isHeadless()
 204   * returns true
 205   */
 206 public
 207 Button()
 208 {
 209   this("");
 210 }
 211
 212 /*************************************************************************/
 213
 214 /**
 215   * Initializes a new instance of <code>Button</code> with the specified
 216   * label.  The action command name is also initialized to this value.
 217   *
 218   * @param label The label to display on the button.
 219   *
 220   * @exception HeadlessException If GraphicsEnvironment.isHeadless()
 221   * returns true
 222   */
 223 public
 224 Button(String label)
 225 {
 226   this.label = label;
 227   actionCommand = label;
 228
 229   if (GraphicsEnvironment.isHeadless ())
 230     throw new HeadlessException ();
 231 }
 232
 233 /*************************************************************************/
 234
 235 /*
 236  * Instance Variables
 237  */
 238
 239 /**
 240   * Returns the label for this button.
 241   *
 242   * @return The label for this button.
 243   */
 244 public String
 245 getLabel()
 246 {
 247   return(label);
 248 }
 249
 250 /*************************************************************************/
 251
 252 /**
 253   * Sets the label for this button to the specified value.
 254   *
 255   * @param label The new label for this button.
 256   */
 257 public synchronized void
 258 setLabel(String label)
 259 {
 260   this.label = label;
 261   actionCommand = label;
 262   if (peer != null)
 263     {
 264       ButtonPeer bp = (ButtonPeer) peer;
 265       bp.setLabel (label);
 266     }
 267 }
 268
 269 /*************************************************************************/
 270
 271 /**
 272   * Returns the action command name for this button.
 273   *
 274   * @return The action command name for this button.
 275   */
 276 public String
 277 getActionCommand()
 278 {
 279   return(actionCommand);
 280 }
 281
 282 /*************************************************************************/
 283
 284 /**
 285   * Sets the action command name for this button to the specified value.
 286   *
 287   * @param actionCommand The new action command name.
 288   */
 289 public void
 290 setActionCommand(String actionCommand)
 291 {
 292   this.actionCommand = actionCommand == null ? label : actionCommand;
 293 }
 294
 295 /*************************************************************************/
 296
 297 /**
 298   * Adds a new entry to the list of listeners that will receive
 299   * action events from this button.
 300   *
 301   * @param listener The listener to add.
 302   */
 303 public synchronized void
 304 addActionListener(ActionListener listener)
 305 {
 306   action_listeners = AWTEventMulticaster.add(action_listeners, listener);
 307 }
 308
 309 /*************************************************************************/
 310
 311 /**
 312   * Removes the specified listener from the list of listeners that will
 313   * receive action events from this button.
 314   *
 315   * @param listener The listener to remove.
 316   */
 317 public synchronized void
 318 removeActionListener(ActionListener listener)
 319 {
 320   action_listeners = AWTEventMulticaster.remove(action_listeners, listener);
 321 }
 322
 323   /**
 324    * Returns all added <code>ActionListener</code> objects.
 325    *
 326    * @return an array of listeners
 327    *
 328    * @since 1.4
 329    */
 330   public synchronized ActionListener[] getActionListeners()
 331   {
 332     return (ActionListener[])
 333       AWTEventMulticaster.getListeners(action_listeners,
 334                                        ActionListener.class);
 335   }
 336
 337 /**
 338  * Returns all registered EventListers of the given listenerType.
 339  * listenerType must be a subclass of EventListener, or a
 340  * ClassClassException is thrown.
 341  *
 342  * @param listenerType the listener type to return
 343  *
 344  * @return an array of listeners
 345  *
 346  * @exception ClassCastException If listenerType doesn't specify a class or
 347  * interface that implements @see java.util.EventListener.
 348  *
 349  * @since 1.3
 350  */
 351   public EventListener[] getListeners(Class listenerType)
 352   {
 353     if (listenerType == ActionListener.class)
 354       return getActionListeners();
 355     return (EventListener[]) Array.newInstance(listenerType, 0);
 356   }
 357
 358 /*************************************************************************/
 359
 360 /**
 361   * Notifies this button that it should create its native peer object.
 362   */
 363 public void
 364 addNotify()
 365 {
 366   if (peer == null)
 367     peer = getToolkit ().createButton (this);
 368   super.addNotify();
 369 }
 370
 371 /*************************************************************************/
 372
 373 /**
 374   * Processes an event for this button.  If the specified event is an
 375   * instance of <code>ActionEvent</code>, then the
 376   * <code>processActionEvent()</code> method is called to dispatch it
 377   * to any registered listeners.  Otherwise, the superclass method
 378   * will be invoked.  Note that this method will not be called at all
 379   * unless <code>ActionEvent</code>'s are enabled.  This will be done
 380   * implicitly if any listeners are added.
 381   *
 382   * @param event The event to process.
 383   */
 384 protected void
 385 processEvent(AWTEvent event)
 386 {
 387   if (event instanceof ActionEvent)
 388     processActionEvent((ActionEvent)event);
 389   else
 390     super.processEvent(event);
 391 }
 392
 393 /*************************************************************************/
 394
 395 /**
 396   * This method dispatches an action event for this button to any
 397   * registered listeners.
 398   *
 399   * @param event The event to process.
 400   */
 401 protected void
 402 processActionEvent(ActionEvent event)
 403 {
 404   if (action_listeners != null)
 405     action_listeners.actionPerformed(event);
 406 }
 407
 408 void
 409 dispatchEventImpl(AWTEvent e)
 410 {
 411   if (e.id <= ActionEvent.ACTION_LAST
 412       && e.id >= ActionEvent.ACTION_FIRST
 413       && (action_listeners != null
 414           || (eventMask & AWTEvent.ACTION_EVENT_MASK) != 0))
 415     processEvent(e);
 416   else
 417     super.dispatchEventImpl(e);
 418 }
 419
 420 /*************************************************************************/
 421
 422 /**
 423   * Returns a debugging string for this button.
 424   *
 425   * @return A debugging string for this button.
 426   */
 427 protected String
 428 paramString()
 429 {
 430   return getName () + "," + getX () + "," + getY () + ","
 431     + getWidth () + "x" + getHeight () + ",label=" + getLabel ();
 432 }
 433
 434 /**
 435  * Gets the AccessibleContext associated with this <code>Button</code>.
 436  * The context is created, if necessary.
 437  *
 438  * @return the associated context
 439  */
 440 public AccessibleContext getAccessibleContext()
 441 {
 442   /* Create the context if this is the first request */
 443   if (accessibleContext == null)
 444     accessibleContext = new AccessibleAWTButton();
 445   return accessibleContext;
 446 }
 447
 448   /**
 449    * Generate a unique name for this button.
 450    *
 451    * @return A unique name for this button.
 452    */
 453   String generateName ()
 454   {
 455     return "button" + getUniqueLong ();
 456   }
 457
 458   private static synchronized long getUniqueLong ()
 459   {
 460     return next_button_number++;
 461   }
 462
 463 } // class Button
 464