1 /*
   2  * Copyright (c) 2000, 2003, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 package java.awt;
  26 
  27 import java.util.List;
  28 import java.util.ArrayList;
  29 import sun.util.logging.PlatformLogger;
  30 
  31 /**
  32  * A FocusTraversalPolicy that determines traversal order based on the order
  33  * of child Components in a Container. From a particular focus cycle root, the
  34  * policy makes a pre-order traversal of the Component hierarchy, and traverses
  35  * a Container's children according to the ordering of the array returned by
  36  * <code>Container.getComponents()</code>. Portions of the hierarchy that are
  37  * not visible and displayable will not be searched.
  38  * <p>
  39  * By default, ContainerOrderFocusTraversalPolicy implicitly transfers focus
  40  * down-cycle. That is, during normal forward focus traversal, the Component
  41  * traversed after a focus cycle root will be the focus-cycle-root's default
  42  * Component to focus. This behavior can be disabled using the
  43  * <code>setImplicitDownCycleTraversal</code> method.
  44  * <p>
  45  * By default, methods of this class with return a Component only if it is
  46  * visible, displayable, enabled, and focusable. Subclasses can modify this
  47  * behavior by overriding the <code>accept</code> method.
  48  * <p>
  49  * This policy takes into account <a
  50  * href="doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus traversal
  51  * policy providers</a>.  When searching for first/last/next/previous Component,
  52  * if a focus traversal policy provider is encountered, its focus traversal
  53  * policy is used to perform the search operation.
  54  *
  55  * @author David Mendenhall
  56  *
  57  * @see Container#getComponents
  58  * @since 1.4
  59  */
  60 public class ContainerOrderFocusTraversalPolicy extends FocusTraversalPolicy
  61     implements java.io.Serializable
  62 {
  63     private static final PlatformLogger log = PlatformLogger.getLogger("java.awt.ContainerOrderFocusTraversalPolicy");
  64 
  65     final private int FORWARD_TRAVERSAL = 0;
  66     final private int BACKWARD_TRAVERSAL = 1;
  67 
  68     /*
  69      * JDK 1.4 serialVersionUID
  70      */
  71     private static final long serialVersionUID = 486933713763926351L;
  72 
  73     private boolean implicitDownCycleTraversal = true;
  74 
  75     /**
  76      * Used by getComponentAfter and getComponentBefore for efficiency. In
  77      * order to maintain compliance with the specification of
  78      * FocusTraversalPolicy, if traversal wraps, we should invoke
  79      * getFirstComponent or getLastComponent. These methods may be overriden in
  80      * subclasses to behave in a non-generic way. However, in the generic case,
  81      * these methods will simply return the first or last Components of the
  82      * sorted list, respectively. Since getComponentAfter and
  83      * getComponentBefore have already built the list before determining
  84      * that they need to invoke getFirstComponent or getLastComponent, the
  85      * list should be reused if possible.
  86      */
  87     transient private Container cachedRoot;
  88     transient private List cachedCycle;
  89 
  90     /*
  91      * We suppose to use getFocusTraversalCycle & getComponentIndex methods in order
  92      * to divide the policy into two parts:
  93      * 1) Making the focus traversal cycle.
  94      * 2) Traversing the cycle.
  95      * The 1st point assumes producing a list of components representing the focus
  96      * traversal cycle. The two methods mentioned above should implement this logic.
  97      * The 2nd point assumes implementing the common concepts of operating on the
  98      * cycle: traversing back and forth, retrieving the initial/default/first/last
  99      * component. These concepts are described in the AWT Focus Spec and they are
 100      * applied to the FocusTraversalPolicy in general.
 101      * Thus, a descendant of this policy may wish to not reimplement the logic of
 102      * the 2nd point but just override the implementation of the 1st one.
 103      * A striking example of such a descendant is the javax.swing.SortingFocusTraversalPolicy.
 104      */
 105     /*protected*/ private List<Component> getFocusTraversalCycle(Container aContainer) {
 106         List<Component> cycle = new ArrayList<Component>();
 107         enumerateCycle(aContainer, cycle);
 108         return cycle;
 109     }
 110     /*protected*/ private int getComponentIndex(List<Component> cycle, Component aComponent) {
 111         return cycle.indexOf(aComponent);
 112     }
 113 
 114     private void enumerateCycle(Container container, List cycle) {
 115         if (!(container.isVisible() && container.isDisplayable())) {
 116             return;
 117         }
 118 
 119         cycle.add(container);
 120 
 121         Component[] components = container.getComponents();
 122         for (int i = 0; i < components.length; i++) {
 123             Component comp = components[i];
 124             if (comp instanceof Container) {
 125                 Container cont = (Container)comp;
 126 
 127                 if (!cont.isFocusCycleRoot() && !cont.isFocusTraversalPolicyProvider()) {
 128                     enumerateCycle(cont, cycle);
 129                     continue;
 130                 }
 131             }
 132             cycle.add(comp);
 133         }
 134     }
 135 
 136     private Container getTopmostProvider(Container focusCycleRoot, Component aComponent) {
 137         Container aCont = aComponent.getParent();
 138         Container ftp = null;
 139         while (aCont  != focusCycleRoot && aCont != null) {
 140             if (aCont.isFocusTraversalPolicyProvider()) {
 141                 ftp = aCont;
 142             }
 143             aCont = aCont.getParent();
 144         }
 145         if (aCont == null) {
 146             return null;
 147         }
 148         return ftp;
 149     }
 150 
 151     /*
 152      * Checks if a new focus cycle takes place and returns a Component to traverse focus to.
 153      * @param comp a possible focus cycle root or policy provider
 154      * @param traversalDirection the direction of the traversal
 155      * @return a Component to traverse focus to if {@code comp} is a root or provider
 156      *         and implicit down-cycle is set, otherwise {@code null}
 157      */
 158     private Component getComponentDownCycle(Component comp, int traversalDirection) {
 159         Component retComp = null;
 160 
 161         if (comp instanceof Container) {
 162             Container cont = (Container)comp;
 163 
 164             if (cont.isFocusCycleRoot()) {
 165                 if (getImplicitDownCycleTraversal()) {
 166                     retComp = cont.getFocusTraversalPolicy().getDefaultComponent(cont);
 167 
 168                     if (retComp != null && log.isLoggable(PlatformLogger.FINE)) {
 169                         log.fine("### Transfered focus down-cycle to " + retComp +
 170                                  " in the focus cycle root " + cont);
 171                     }
 172                 } else {
 173                     return null;
 174                 }
 175             } else if (cont.isFocusTraversalPolicyProvider()) {
 176                 retComp = (traversalDirection == FORWARD_TRAVERSAL ?
 177                            cont.getFocusTraversalPolicy().getDefaultComponent(cont) :
 178                            cont.getFocusTraversalPolicy().getLastComponent(cont));
 179 
 180                 if (retComp != null && log.isLoggable(PlatformLogger.FINE)) {
 181                     log.fine("### Transfered focus to " + retComp + " in the FTP provider " + cont);
 182                 }
 183             }
 184         }
 185         return retComp;
 186     }
 187 
 188     /**
 189      * Returns the Component that should receive the focus after aComponent.
 190      * aContainer must be a focus cycle root of aComponent or a focus traversal policy provider.
 191      * <p>
 192      * By default, ContainerOrderFocusTraversalPolicy implicitly transfers
 193      * focus down-cycle. That is, during normal forward focus traversal, the
 194      * Component traversed after a focus cycle root will be the focus-cycle-
 195      * root's default Component to focus. This behavior can be disabled using
 196      * the <code>setImplicitDownCycleTraversal</code> method.
 197      * <p>
 198      * If aContainer is <a href="doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus
 199      * traversal policy provider</a>, the focus is always transferred down-cycle.
 200      *
 201      * @param aContainer a focus cycle root of aComponent or a focus traversal policy provider
 202      * @param aComponent a (possibly indirect) child of aContainer, or
 203      *        aContainer itself
 204      * @return the Component that should receive the focus after aComponent, or
 205      *         null if no suitable Component can be found
 206      * @throws IllegalArgumentException if aContainer is not a focus cycle
 207      *         root of aComponent or focus traversal policy provider, or if either aContainer or
 208      *         aComponent is null
 209      */
 210     public Component getComponentAfter(Container aContainer, Component aComponent) {
 211         if (log.isLoggable(PlatformLogger.FINE)) {
 212             log.fine("### Searching in " + aContainer + " for component after " + aComponent);
 213         }
 214 
 215         if (aContainer == null || aComponent == null) {
 216             throw new IllegalArgumentException("aContainer and aComponent cannot be null");
 217         }
 218         if (!aContainer.isFocusTraversalPolicyProvider() && !aContainer.isFocusCycleRoot()) {
 219             throw new IllegalArgumentException("aContainer should be focus cycle root or focus traversal policy provider");
 220 
 221         } else if (aContainer.isFocusCycleRoot() && !aComponent.isFocusCycleRoot(aContainer)) {
 222             throw new IllegalArgumentException("aContainer is not a focus cycle root of aComponent");
 223         }
 224 
 225         synchronized(aContainer.getTreeLock()) {
 226 
 227             if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
 228                 return null;
 229             }
 230 
 231             // Before all the ckecks below we first see if it's an FTP provider or a focus cycle root.
 232             // If it's the case just go down cycle (if it's set to "implicit").
 233             Component comp = getComponentDownCycle(aComponent, FORWARD_TRAVERSAL);
 234             if (comp != null) {
 235                 return comp;
 236             }
 237 
 238             // See if the component is inside of policy provider.
 239             Container provider = getTopmostProvider(aContainer, aComponent);
 240             if (provider != null) {
 241                 if (log.isLoggable(PlatformLogger.FINE)) {
 242                     log.fine("### Asking FTP " + provider + " for component after " + aComponent);
 243                 }
 244 
 245                 // FTP knows how to find component after the given. We don't.
 246                 FocusTraversalPolicy policy = provider.getFocusTraversalPolicy();
 247                 Component afterComp = policy.getComponentAfter(provider, aComponent);
 248 
 249                 // Null result means that we overstepped the limit of the FTP's cycle.
 250                 // In that case we must quit the cycle, otherwise return the component found.
 251                 if (afterComp != null) {
 252                     if (log.isLoggable(PlatformLogger.FINE)) {
 253                         log.fine("### FTP returned " + afterComp);
 254                     }
 255                     return afterComp;
 256                 }
 257                 aComponent = provider;
 258             }
 259 
 260             List<Component> cycle = getFocusTraversalCycle(aContainer);
 261 
 262             if (log.isLoggable(PlatformLogger.FINE)) {
 263                 log.fine("### Cycle is " + cycle + ", component is " + aComponent);
 264             }
 265 
 266             int index = getComponentIndex(cycle, aComponent);
 267 
 268             if (index < 0) {
 269                 if (log.isLoggable(PlatformLogger.FINE)) {
 270                     log.fine("### Didn't find component " + aComponent + " in a cycle " + aContainer);
 271                 }
 272                 return getFirstComponent(aContainer);
 273             }
 274 
 275             for (index++; index < cycle.size(); index++) {
 276                 comp = cycle.get(index);
 277                 if (accept(comp)) {
 278                     return comp;
 279                 } else if ((comp = getComponentDownCycle(comp, FORWARD_TRAVERSAL)) != null) {
 280                     return comp;
 281                 }
 282             }
 283 
 284             if (aContainer.isFocusCycleRoot()) {
 285                 this.cachedRoot = aContainer;
 286                 this.cachedCycle = cycle;
 287 
 288                 comp = getFirstComponent(aContainer);
 289 
 290                 this.cachedRoot = null;
 291                 this.cachedCycle = null;
 292 
 293                 return comp;
 294             }
 295         }
 296         return null;
 297     }
 298 
 299     /**
 300      * Returns the Component that should receive the focus before aComponent.
 301      * aContainer must be a focus cycle root of aComponent or a <a
 302      * href="doc-files/FocusSpec.html#FocusTraversalPolicyProviders">focus traversal policy
 303      * provider</a>.
 304      *
 305      * @param aContainer a focus cycle root of aComponent or focus traversal policy provider
 306      * @param aComponent a (possibly indirect) child of aContainer, or
 307      *        aContainer itself
 308      * @return the Component that should receive the focus before aComponent,
 309      *         or null if no suitable Component can be found
 310      * @throws IllegalArgumentException if aContainer is not a focus cycle
 311      *         root of aComponent or focus traversal policy provider, or if either aContainer or
 312      *         aComponent is null
 313      */
 314     public Component getComponentBefore(Container aContainer, Component aComponent) {
 315         if (aContainer == null || aComponent == null) {
 316             throw new IllegalArgumentException("aContainer and aComponent cannot be null");
 317         }
 318         if (!aContainer.isFocusTraversalPolicyProvider() && !aContainer.isFocusCycleRoot()) {
 319             throw new IllegalArgumentException("aContainer should be focus cycle root or focus traversal policy provider");
 320 
 321         } else if (aContainer.isFocusCycleRoot() && !aComponent.isFocusCycleRoot(aContainer)) {
 322             throw new IllegalArgumentException("aContainer is not a focus cycle root of aComponent");
 323         }
 324 
 325         synchronized(aContainer.getTreeLock()) {
 326 
 327             if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
 328                 return null;
 329             }
 330 
 331             // See if the component is inside of policy provider.
 332             Container provider = getTopmostProvider(aContainer, aComponent);
 333             if (provider != null) {
 334                 if (log.isLoggable(PlatformLogger.FINE)) {
 335                     log.fine("### Asking FTP " + provider + " for component after " + aComponent);
 336                 }
 337 
 338                 // FTP knows how to find component after the given. We don't.
 339                 FocusTraversalPolicy policy = provider.getFocusTraversalPolicy();
 340                 Component beforeComp = policy.getComponentBefore(provider, aComponent);
 341 
 342                 // Null result means that we overstepped the limit of the FTP's cycle.
 343                 // In that case we must quit the cycle, otherwise return the component found.
 344                 if (beforeComp != null) {
 345                     if (log.isLoggable(PlatformLogger.FINE)) {
 346                         log.fine("### FTP returned " + beforeComp);
 347                     }
 348                     return beforeComp;
 349                 }
 350                 aComponent = provider;
 351 
 352                 // If the provider is traversable it's returned.
 353                 if (accept(aComponent)) {
 354                     return aComponent;
 355                 }
 356             }
 357 
 358             List<Component> cycle = getFocusTraversalCycle(aContainer);
 359 
 360             if (log.isLoggable(PlatformLogger.FINE)) {
 361                 log.fine("### Cycle is " + cycle + ", component is " + aComponent);
 362             }
 363 
 364             int index = getComponentIndex(cycle, aComponent);
 365 
 366             if (index < 0) {
 367                 if (log.isLoggable(PlatformLogger.FINE)) {
 368                     log.fine("### Didn't find component " + aComponent + " in a cycle " + aContainer);
 369                 }
 370                 return getLastComponent(aContainer);
 371             }
 372 
 373             Component comp = null;
 374             Component tryComp = null;
 375 
 376             for (index--; index>=0; index--) {
 377                 comp = cycle.get(index);
 378                 if (comp != aContainer && (tryComp = getComponentDownCycle(comp, BACKWARD_TRAVERSAL)) != null) {
 379                     return tryComp;
 380                 } else if (accept(comp)) {
 381                     return comp;
 382                 }
 383             }
 384 
 385             if (aContainer.isFocusCycleRoot()) {
 386                 this.cachedRoot = aContainer;
 387                 this.cachedCycle = cycle;
 388 
 389                 comp = getLastComponent(aContainer);
 390 
 391                 this.cachedRoot = null;
 392                 this.cachedCycle = null;
 393 
 394                 return comp;
 395             }
 396         }
 397         return null;
 398     }
 399 
 400     /**
 401      * Returns the first Component in the traversal cycle. This method is used
 402      * to determine the next Component to focus when traversal wraps in the
 403      * forward direction.
 404      *
 405      * @param aContainer the focus cycle root or focus traversal policy provider whose first
 406      *        Component is to be returned
 407      * @return the first Component in the traversal cycle of aContainer,
 408      *         or null if no suitable Component can be found
 409      * @throws IllegalArgumentException if aContainer is null
 410      */
 411     public Component getFirstComponent(Container aContainer) {
 412         List<Component> cycle;
 413 
 414         if (log.isLoggable(PlatformLogger.FINE)) {
 415             log.fine("### Getting first component in " + aContainer);
 416         }
 417         if (aContainer == null) {
 418             throw new IllegalArgumentException("aContainer cannot be null");
 419 
 420         }
 421 
 422         synchronized(aContainer.getTreeLock()) {
 423 
 424             if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
 425                 return null;
 426             }
 427 
 428             if (this.cachedRoot == aContainer) {
 429                 cycle = this.cachedCycle;
 430             } else {
 431                 cycle = getFocusTraversalCycle(aContainer);
 432             }
 433 
 434             if (cycle.size() == 0) {
 435                 if (log.isLoggable(PlatformLogger.FINE)) {
 436                     log.fine("### Cycle is empty");
 437                 }
 438                 return null;
 439             }
 440             if (log.isLoggable(PlatformLogger.FINE)) {
 441                 log.fine("### Cycle is " + cycle);
 442             }
 443 
 444             for (Component comp : cycle) {
 445                 if (accept(comp)) {
 446                     return comp;
 447                 } else if (comp != aContainer &&
 448                            (comp = getComponentDownCycle(comp, FORWARD_TRAVERSAL)) != null)
 449                 {
 450                     return comp;
 451                 }
 452             }
 453         }
 454         return null;
 455     }
 456 
 457     /**
 458      * Returns the last Component in the traversal cycle. This method is used
 459      * to determine the next Component to focus when traversal wraps in the
 460      * reverse direction.
 461      *
 462      * @param aContainer the focus cycle root or focus traversal policy provider whose last
 463      *        Component is to be returned
 464      * @return the last Component in the traversal cycle of aContainer,
 465      *         or null if no suitable Component can be found
 466      * @throws IllegalArgumentException if aContainer is null
 467      */
 468     public Component getLastComponent(Container aContainer) {
 469         List<Component> cycle;
 470         if (log.isLoggable(PlatformLogger.FINE)) {
 471             log.fine("### Getting last component in " + aContainer);
 472         }
 473 
 474         if (aContainer == null) {
 475             throw new IllegalArgumentException("aContainer cannot be null");
 476         }
 477 
 478         synchronized(aContainer.getTreeLock()) {
 479 
 480             if (!(aContainer.isVisible() && aContainer.isDisplayable())) {
 481                 return null;
 482             }
 483 
 484             if (this.cachedRoot == aContainer) {
 485                 cycle = this.cachedCycle;
 486             } else {
 487                 cycle = getFocusTraversalCycle(aContainer);
 488             }
 489 
 490             if (cycle.size() == 0) {
 491                 if (log.isLoggable(PlatformLogger.FINE)) {
 492                     log.fine("### Cycle is empty");
 493                 }
 494                 return null;
 495             }
 496             if (log.isLoggable(PlatformLogger.FINE)) {
 497                 log.fine("### Cycle is " + cycle);
 498             }
 499 
 500             for (int i= cycle.size() - 1; i >= 0; i--) {
 501                 Component comp = cycle.get(i);
 502                 if (accept(comp)) {
 503                     return comp;
 504                 } else if (comp instanceof Container && comp != aContainer) {
 505                     Container cont = (Container)comp;
 506                     if (cont.isFocusTraversalPolicyProvider()) {
 507                         return cont.getFocusTraversalPolicy().getLastComponent(cont);
 508                     }
 509                 }
 510             }
 511         }
 512         return null;
 513     }
 514 
 515     /**
 516      * Returns the default Component to focus. This Component will be the first
 517      * to receive focus when traversing down into a new focus traversal cycle
 518      * rooted at aContainer. The default implementation of this method
 519      * returns the same Component as <code>getFirstComponent</code>.
 520      *
 521      * @param aContainer the focus cycle root or focus traversal policy provider whose default
 522      *        Component is to be returned
 523      * @return the default Component in the traversal cycle of aContainer,
 524      *         or null if no suitable Component can be found
 525      * @see #getFirstComponent
 526      * @throws IllegalArgumentException if aContainer is null
 527      */
 528     public Component getDefaultComponent(Container aContainer) {
 529         return getFirstComponent(aContainer);
 530     }
 531 
 532     /**
 533      * Sets whether this ContainerOrderFocusTraversalPolicy transfers focus
 534      * down-cycle implicitly. If <code>true</code>, during normal forward focus
 535      * traversal, the Component traversed after a focus cycle root will be the
 536      * focus-cycle-root's default Component to focus. If <code>false</code>,
 537      * the next Component in the focus traversal cycle rooted at the specified
 538      * focus cycle root will be traversed instead. The default value for this
 539      * property is <code>true</code>.
 540      *
 541      * @param implicitDownCycleTraversal whether this
 542      *        ContainerOrderFocusTraversalPolicy transfers focus down-cycle
 543      *        implicitly
 544      * @see #getImplicitDownCycleTraversal
 545      * @see #getFirstComponent
 546      */
 547     public void setImplicitDownCycleTraversal(boolean implicitDownCycleTraversal) {
 548         this.implicitDownCycleTraversal = implicitDownCycleTraversal;
 549     }
 550 
 551     /**
 552      * Returns whether this ContainerOrderFocusTraversalPolicy transfers focus
 553      * down-cycle implicitly. If <code>true</code>, during normal forward focus
 554      * traversal, the Component traversed after a focus cycle root will be the
 555      * focus-cycle-root's default Component to focus. If <code>false</code>,
 556      * the next Component in the focus traversal cycle rooted at the specified
 557      * focus cycle root will be traversed instead.
 558      *
 559      * @return whether this ContainerOrderFocusTraversalPolicy transfers focus
 560      *         down-cycle implicitly
 561      * @see #setImplicitDownCycleTraversal
 562      * @see #getFirstComponent
 563      */
 564     public boolean getImplicitDownCycleTraversal() {
 565         return implicitDownCycleTraversal;
 566     }
 567 
 568     /**
 569      * Determines whether a Component is an acceptable choice as the new
 570      * focus owner. By default, this method will accept a Component if and
 571      * only if it is visible, displayable, enabled, and focusable.
 572      *
 573      * @param aComponent the Component whose fitness as a focus owner is to
 574      *        be tested
 575      * @return <code>true</code> if aComponent is visible, displayable,
 576      *         enabled, and focusable; <code>false</code> otherwise
 577      */
 578     protected boolean accept(Component aComponent) {
 579         if (!aComponent.canBeFocusOwner()) {
 580             return false;
 581         }
 582 
 583         // Verify that the Component is recursively enabled. Disabling a
 584         // heavyweight Container disables its children, whereas disabling
 585         // a lightweight Container does not.
 586         if (!(aComponent instanceof Window)) {
 587             for (Container enableTest = aComponent.getParent();
 588                  enableTest != null;
 589                  enableTest = enableTest.getParent())
 590             {
 591                 if (!(enableTest.isEnabled() || enableTest.isLightweight())) {
 592                     return false;
 593                 }
 594                 if (enableTest instanceof Window) {
 595                     break;
 596                 }
 597             }
 598         }
 599 
 600         return true;
 601     }
 602 }
--- EOF ---