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