Source for java.awt.Button

   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., 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 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:   * This is package-private to avoid an accessor method.
  81:   */
  82: String actionCommand;
  83: 
  84: /**
  85:   * @serial The label for this button.
  86:   * This is package-private to avoid an accessor method.
  87:   */
  88: String label;
  89: 
  90: // List of ActionListeners for this class.
  91: private transient ActionListener action_listeners;
  92: 
  93:   /*
  94:    * The number used to generate the name returned by getName.
  95:    */
  96:   private static transient long next_button_number;
  97:   
  98:   protected class AccessibleAWTButton extends AccessibleAWTComponent
  99:     implements AccessibleAction, AccessibleValue
 100:   {
 101:     private static final long serialVersionUID = -5932203980244017102L;
 102: 
 103:     protected AccessibleAWTButton()
 104:     {
 105:       // Do nothing here.
 106:     }
 107: 
 108:     /* (non-Javadoc)
 109:      * @see javax.accessibility.AccessibleAction#getAccessibleActionCount()
 110:      */
 111:     public int getAccessibleActionCount()
 112:     {
 113:       // Only 1 action possible
 114:       return 1;
 115:     }
 116: 
 117:     /* (non-Javadoc)
 118:      * @see javax.accessibility.AccessibleAction#getAccessibleActionDescription(int)
 119:      */
 120:     public String getAccessibleActionDescription(int i)
 121:     {
 122:       // JDK 1.4.2 returns the string "click" for action 0.  However, the API
 123:       // docs don't say what the string to be returned is, beyond being a
 124:       // description of the action.  So we return the same thing for
 125:       // compatibility with 1.4.2.
 126:       if (i == 0)
 127:         return "click";
 128:       return null;
 129:     }
 130: 
 131:     /* (non-Javadoc)
 132:      * @see javax.accessibility.AccessibleAction#doAccessibleAction(int)
 133:      */
 134:     public boolean doAccessibleAction(int i)
 135:     {
 136:       if (i != 0)
 137:         return false;
 138:       processActionEvent(new ActionEvent(this, ActionEvent.ACTION_PERFORMED, actionCommand));
 139:       return true;
 140:     }
 141:     
 142:     public String getAccessibleName()
 143:     {
 144:       return label;
 145:     }
 146:     
 147:     public AccessibleAction getAccessibleAction()
 148:     {
 149:       return this;
 150:     }
 151:     
 152:     public AccessibleValue getAccessibleValue()
 153:     {
 154:       return this;
 155:     }
 156: 
 157:     /* (non-Javadoc)
 158:      * @see javax.accessibility.AccessibleValue#getCurrentAccessibleValue()
 159:      */
 160:     public Number getCurrentAccessibleValue()
 161:     {
 162:       // Docs say return 1 if selected, but buttons can't be selected, right?
 163:       return new Integer(0);
 164:     }
 165: 
 166:     /* (non-Javadoc)
 167:      * @see javax.accessibility.AccessibleValue#setCurrentAccessibleValue(java.lang.Number)
 168:      */
 169:     public boolean setCurrentAccessibleValue(Number number)
 170:     {
 171:       // Since there's no selection with buttons, we're ignoring this.
 172:       // TODO someone who knows shoulw check this.
 173:       return false;
 174:     }
 175: 
 176:     /* (non-Javadoc)
 177:      * @see javax.accessibility.AccessibleValue#getMinimumAccessibleValue()
 178:      */
 179:     public Number getMinimumAccessibleValue()
 180:     {
 181:       return new Integer(0);
 182:     }
 183: 
 184:     /* (non-Javadoc)
 185:      * @see javax.accessibility.AccessibleValue#getMaximumAccessibleValue()
 186:      */
 187:     public Number getMaximumAccessibleValue()
 188:     {
 189:       return new Integer(0);
 190:     }
 191:     
 192:     public AccessibleRole getAccessibleRole()
 193:     {
 194:       return AccessibleRole.PUSH_BUTTON;
 195:     }
 196:   }
 197: 
 198: /*************************************************************************/
 199: 
 200: /*
 201:  * Constructors
 202:  */
 203: 
 204: /**
 205:   * Initializes a new instance of <code>Button</code> with no label.
 206:   *
 207:   * @exception HeadlessException If GraphicsEnvironment.isHeadless()
 208:   * returns true
 209:   */
 210: public
 211: Button()
 212: {
 213:   this("");
 214: }
 215: 
 216: /*************************************************************************/
 217: 
 218: /**
 219:   * Initializes a new instance of <code>Button</code> with the specified
 220:   * label.  The action command name is also initialized to this value.
 221:   *
 222:   * @param label The label to display on the button.
 223:   *
 224:   * @exception HeadlessException If GraphicsEnvironment.isHeadless()
 225:   * returns true
 226:   */
 227: public
 228: Button(String label)
 229: {
 230:   this.label = label;
 231:   actionCommand = label;
 232: 
 233:   if (GraphicsEnvironment.isHeadless ())
 234:     throw new HeadlessException ();
 235: }
 236: 
 237: /*************************************************************************/
 238: 
 239: /*
 240:  * Instance Variables
 241:  */
 242: 
 243: /**
 244:   * Returns the label for this button.
 245:   *
 246:   * @return The label for this button.
 247:   */
 248: public String
 249: getLabel()
 250: {
 251:   return(label);
 252: }
 253: 
 254: /*************************************************************************/
 255: 
 256: /**
 257:   * Sets the label for this button to the specified value.
 258:   *
 259:   * @param label The new label for this button.
 260:   */
 261: public synchronized void
 262: setLabel(String label)
 263: {
 264:   this.label = label;
 265:   actionCommand = label;
 266:   if (peer != null)
 267:     {
 268:       ButtonPeer bp = (ButtonPeer) peer;
 269:       bp.setLabel (label);
 270:     }
 271: }
 272: 
 273: /*************************************************************************/
 274: 
 275: /**
 276:   * Returns the action command name for this button.
 277:   *
 278:   * @return The action command name for this button.
 279:   */
 280: public String
 281: getActionCommand()
 282: {
 283:   return(actionCommand);
 284: }
 285: 
 286: /*************************************************************************/
 287: 
 288: /**
 289:   * Sets the action command name for this button to the specified value.
 290:   *
 291:   * @param actionCommand The new action command name.
 292:   */
 293: public void
 294: setActionCommand(String actionCommand)
 295: {
 296:   this.actionCommand = actionCommand == null ? label : actionCommand;
 297: }
 298: 
 299: /*************************************************************************/
 300: 
 301: /**
 302:   * Adds a new entry to the list of listeners that will receive
 303:   * action events from this button.
 304:   *
 305:   * @param listener The listener to add.
 306:   */
 307: public synchronized void
 308: addActionListener(ActionListener listener)
 309: {
 310:   action_listeners = AWTEventMulticaster.add(action_listeners, listener);
 311: }
 312: 
 313: /*************************************************************************/
 314: 
 315: /**
 316:   * Removes the specified listener from the list of listeners that will
 317:   * receive action events from this button.
 318:   * 
 319:   * @param listener The listener to remove.
 320:   */
 321: public synchronized void
 322: removeActionListener(ActionListener listener)
 323: {
 324:   action_listeners = AWTEventMulticaster.remove(action_listeners, listener);
 325: }
 326: 
 327:   /**
 328:    * Returns all added <code>ActionListener</code> objects.
 329:    *
 330:    * @return an array of listeners
 331:    *
 332:    * @since 1.4
 333:    */
 334:   public synchronized ActionListener[] getActionListeners()
 335:   {
 336:     return (ActionListener[])
 337:       AWTEventMulticaster.getListeners(action_listeners,
 338:                                        ActionListener.class);
 339:   }
 340: 
 341: /**
 342:  * Returns all registered EventListers of the given listenerType. 
 343:  * listenerType must be a subclass of EventListener, or a 
 344:  * ClassClassException is thrown.
 345:  *
 346:  * @param listenerType the listener type to return
 347:  *
 348:  * @return an array of listeners
 349:  * 
 350:  * @exception ClassCastException If listenerType doesn't specify a class or
 351:  * interface that implements @see java.util.EventListener.
 352:  *
 353:  * @since 1.3 
 354:  */
 355:   public <T extends EventListener> T[] getListeners(Class<T> listenerType)
 356:   {
 357:     if (listenerType == ActionListener.class)
 358:       return (T[]) getActionListeners();
 359:     return (T[]) Array.newInstance(listenerType, 0);
 360:   }
 361: 
 362: /*************************************************************************/
 363: 
 364: /**
 365:   * Notifies this button that it should create its native peer object.
 366:   */
 367: public void
 368: addNotify()
 369: {
 370:   if (peer == null)
 371:     peer = getToolkit ().createButton (this);
 372:   super.addNotify();
 373: }
 374: 
 375: /*************************************************************************/
 376: 
 377: /**
 378:   * Processes an event for this button.  If the specified event is an
 379:   * instance of <code>ActionEvent</code>, then the
 380:   * <code>processActionEvent()</code> method is called to dispatch it
 381:   * to any registered listeners.  Otherwise, the superclass method
 382:   * will be invoked.  Note that this method will not be called at all
 383:   * unless <code>ActionEvent</code>'s are enabled.  This will be done
 384:   * implicitly if any listeners are added.
 385:   *
 386:   * @param event The event to process.
 387:   */
 388: protected void
 389: processEvent(AWTEvent event)
 390: {
 391:   if (event instanceof ActionEvent)
 392:     processActionEvent((ActionEvent)event);
 393:   else
 394:     super.processEvent(event);
 395: }
 396: 
 397: /*************************************************************************/
 398: 
 399: /**
 400:   * This method dispatches an action event for this button to any
 401:   * registered listeners.
 402:   *
 403:   * @param event The event to process.
 404:   */
 405: protected void
 406: processActionEvent(ActionEvent event)
 407: {
 408:   if (action_listeners != null)
 409:     action_listeners.actionPerformed(event);
 410: }
 411: 
 412: void
 413: dispatchEventImpl(AWTEvent e)
 414: {
 415:   if (e.id <= ActionEvent.ACTION_LAST 
 416:       && e.id >= ActionEvent.ACTION_FIRST
 417:       && (action_listeners != null 
 418:       || (eventMask & AWTEvent.ACTION_EVENT_MASK) != 0))
 419:     processEvent(e);
 420:   else
 421:     super.dispatchEventImpl(e);
 422: }
 423: 
 424: /*************************************************************************/
 425: 
 426: /**
 427:   * Returns a debugging string for this button.
 428:   *
 429:   * @return A debugging string for this button.
 430:   */
 431: protected String
 432: paramString()
 433: {
 434:   return getName () + "," + getX () + "," + getY () + ","
 435:     + getWidth () + "x" + getHeight () + ",label=" + getLabel ();
 436: }
 437: 
 438: /**
 439:  * Gets the AccessibleContext associated with this <code>Button</code>.
 440:  * The context is created, if necessary.
 441:  *
 442:  * @return the associated context
 443:  */
 444: public AccessibleContext getAccessibleContext()
 445: {
 446:   /* Create the context if this is the first request */
 447:   if (accessibleContext == null)
 448:     accessibleContext = new AccessibleAWTButton();
 449:   return accessibleContext;
 450: }
 451: 
 452:   /**
 453:    * Generate a unique name for this button.
 454:    *
 455:    * @return A unique name for this button.
 456:    */
 457:   String generateName ()
 458:   {
 459:     return "button" + getUniqueLong ();
 460:   }
 461: 
 462:   private static synchronized long getUniqueLong ()
 463:   {
 464:     return next_button_number++;
 465:   }
 466: 
 467: } // class Button