001 /* Button.java -- AWT button widget 002 Copyright (C) 1999, 2002, 2004, 2005 Free Software Foundation, Inc. 003 004 This file is part of GNU Classpath. 005 006 GNU Classpath is free software; you can redistribute it and/or modify 007 it under the terms of the GNU General Public License as published by 008 the Free Software Foundation; either version 2, or (at your option) 009 any later version. 010 011 GNU Classpath is distributed in the hope that it will be useful, but 012 WITHOUT ANY WARRANTY; without even the implied warranty of 013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014 General Public License for more details. 015 016 You should have received a copy of the GNU General Public License 017 along with GNU Classpath; see the file COPYING. If not, write to the 018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 019 02110-1301 USA. 020 021 Linking this library statically or dynamically with other modules is 022 making a combined work based on this library. Thus, the terms and 023 conditions of the GNU General Public License cover the whole 024 combination. 025 026 As a special exception, the copyright holders of this library give you 027 permission to link this library with independent modules to produce an 028 executable, regardless of the license terms of these independent 029 modules, and to copy and distribute the resulting executable under 030 terms of your choice, provided that you also meet, for each linked 031 independent module, the terms and conditions of the license of that 032 module. An independent module is a module which is not derived from 033 or based on this library. If you modify this library, you may extend 034 this exception to your version of the library, but you are not 035 obligated to do so. If you do not wish to do so, delete this 036 exception statement from your version. */ 037 038 039 package java.awt; 040 041 import java.awt.event.ActionEvent; 042 import java.awt.event.ActionListener; 043 import java.awt.peer.ButtonPeer; 044 import java.lang.reflect.Array; 045 import java.util.EventListener; 046 047 import javax.accessibility.Accessible; 048 import javax.accessibility.AccessibleAction; 049 import javax.accessibility.AccessibleContext; 050 import javax.accessibility.AccessibleRole; 051 import javax.accessibility.AccessibleValue; 052 053 /** 054 * This class provides a button widget for the AWT. 055 * 056 * @author Aaron M. Renn (arenn@urbanophile.com) 057 * @author Tom Tromey (tromey@cygnus.com) 058 */ 059 public class Button extends Component 060 implements java.io.Serializable, Accessible 061 { 062 063 /* 064 * Static Variables 065 */ 066 067 // FIXME: Need readObject/writeObject for serialization 068 069 // Serialization version constant 070 private static final long serialVersionUID = -8774683716313001058L; 071 072 /*************************************************************************/ 073 074 /* 075 * Instance Variables 076 */ 077 078 /** 079 * @serial The action command name for this button. 080 * This is package-private to avoid an accessor method. 081 */ 082 String actionCommand; 083 084 /** 085 * @serial The label for this button. 086 * This is package-private to avoid an accessor method. 087 */ 088 String label; 089 090 // List of ActionListeners for this class. 091 private transient ActionListener action_listeners; 092 093 /* 094 * The number used to generate the name returned by getName. 095 */ 096 private static transient long next_button_number; 097 098 protected class AccessibleAWTButton extends AccessibleAWTComponent 099 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 468