Source for javax.swing.JScrollPane

   1: /* JScrollPane.java --
   2:    Copyright (C) 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 javax.swing;
  40: 
  41: import java.awt.Component;
  42: import java.awt.ComponentOrientation;
  43: import java.awt.Insets;
  44: import java.awt.LayoutManager;
  45: import java.awt.Rectangle;
  46: import java.beans.PropertyChangeEvent;
  47: import java.beans.PropertyChangeListener;
  48: 
  49: import javax.accessibility.Accessible;
  50: import javax.accessibility.AccessibleContext;
  51: import javax.swing.border.Border;
  52: import javax.swing.event.ChangeEvent;
  53: import javax.swing.event.ChangeListener;
  54: import javax.swing.plaf.ScrollPaneUI;
  55: import javax.swing.plaf.UIResource;
  56: 
  57: /**
  58:  * A component that embeds another component and enables it to be scrolled
  59:  * both in horizontal and vertical direction.
  60:  *
  61:  * <table>
  62:  * <tr><th>Property                    </th><th>Stored in       </th><th>Bound?</th></tr>
  63:  * <tr><td>columnHeader                </td><td>scrollPane      </td><td>yes   </td></tr>
  64:  * <tr><td>columnHeaderView            </td><td>columnHeader    </td><td>no    </td></tr>
  65:  * <tr><td>componentOrientation        </td><td>scrollPane      </td><td>yes   </td></tr>
  66:  * <tr><td>horizontalScrollBar         </td><td>scrollPane      </td><td>yes   </td></tr>
  67:  * <tr><td>horizontalScrollBarPolicy   </td><td>scrollPane      </td><td>yes   </td></tr>
  68:  * <tr><td>layout                      </td><td>scrollPane      </td><td>yes   </td></tr>
  69:  * <tr><td>rowHeader                   </td><td>scrollPane      </td><td>yes   </td></tr>
  70:  * <tr><td>rowHeaderView               </td><td>rowHeader       </td><td>no    </td></tr>
  71:  * <tr><td>validateRoot                </td><td>scrollPane      </td><td>no    </td></tr>
  72:  * <tr><td>verticalScrollBar           </td><td>scrollPane      </td><td>yes   </td></tr>
  73:  * <tr><td>verticalScrollBarPolicy     </td><td>scrollPane      </td><td>yes   </td></tr>
  74:  * <tr><td>viewport                    </td><td>scrollPane      </td><td>yes   </td></tr>
  75:  * <tr><td>viewportBorder              </td><td>scrollPane      </td><td>yes   </td></tr>
  76:  * <tr><td>viewportBorderBounds        </td><td>scrollPane      </td><td>no    </td></tr>
  77:  * <tr><td>viewportView                </td><td>viewport        </td><td>no    </td></tr>
  78:  * <tr><td>wheelScrollingEnabled       </td><td>scrollPane      </td><td>yes   </td></tr>
  79:  * </table>
  80:  */
  81: public class JScrollPane extends JComponent
  82:   implements Accessible, ScrollPaneConstants
  83: {
  84:   /**
  85:    * Provides accessibility support for the <code>JScrollPane</code>.
  86:    *
  87:    * @author Roman Kennke (kennke@aicas.com)
  88:    */
  89:   protected class AccessibleJScrollPane extends AccessibleJComponent
  90:     implements ChangeListener, PropertyChangeListener
  91:   {
  92: 
  93:     /**
  94:      * The viewport of the underlying scrollpane.
  95:      */
  96:     protected JViewport viewPort;
  97: 
  98:     /**
  99:      * Creates a new <code>AccessibleJScrollPane</code> object. This
 100:      * initializes the <code>viewport</code> field with the current viewport
 101:      * from the scrollpane associated with this
 102:      * <code>AccessibleJScrollPane</code>.
 103:      */
 104:     public AccessibleJScrollPane()
 105:     {
 106:       viewPort = getViewport();
 107:       viewPort.addChangeListener(this);
 108:       viewPort.addPropertyChangeListener(this);
 109:     }
 110: 
 111:     /**
 112:      * Receives notification when the state of the viewport changes.
 113:      *
 114:      * @param event the change event
 115:      */
 116:     public void stateChanged(ChangeEvent event)
 117:     {
 118:       // TODO: Figure out what should be done here, if anything.
 119:     }
 120: 
 121:     /**
 122:      * Receives notification if any of the viewport's bound properties changes.
 123:      *
 124:      * @param e the propery change event
 125:      */
 126:     public void propertyChange(PropertyChangeEvent e)
 127:     {
 128:       // TODO: Figure out what should be done here, if anything.
 129:     }
 130: 
 131:     /**
 132:      * Resets the <code>viewPort</code> field when the scrollpane's viewport
 133:      * changes. This method is called by
 134:      * {@link JScrollPane#setViewport(JViewport)} in order to update the
 135:      * <code>viewPort</code> field and set up the listeners on this viewport
 136:      * correctly.
 137:      */
 138:     public void resetViewPort()
 139:     {
 140:       viewPort.removeChangeListener(this);
 141:       viewPort.removePropertyChangeListener(this);
 142:       viewPort = getViewport();
 143:       viewPort.addChangeListener(this);
 144:       viewPort.addPropertyChangeListener(this);
 145:     }
 146:   }
 147: 
 148:   private static final long serialVersionUID = 5203525440012340014L;
 149: 
 150:   protected JViewport columnHeader;
 151:   protected JViewport rowHeader;
 152: 
 153:   protected Component lowerLeft;
 154:   protected Component lowerRight;
 155:   protected Component upperLeft;
 156:   protected Component upperRight;
 157: 
 158:   protected JScrollBar horizontalScrollBar;
 159:   protected int horizontalScrollBarPolicy;
 160:   protected JScrollBar verticalScrollBar;
 161:   protected int verticalScrollBarPolicy;
 162: 
 163:   protected JViewport viewport;
 164: 
 165:   private Border viewportBorder;
 166: 
 167:   private boolean wheelScrollingEnabled;
 168: 
 169:   public JViewport getColumnHeader()
 170:   {
 171:     return columnHeader;
 172:   }
 173: 
 174:   public Component getCorner(String key)
 175:   {
 176:     if (getComponentOrientation()
 177:         == ComponentOrientation.LEFT_TO_RIGHT)
 178:       {
 179:         if (key == LOWER_LEADING_CORNER)
 180:           key = LOWER_LEFT_CORNER;
 181:         else if (key == LOWER_TRAILING_CORNER)
 182:           key = LOWER_RIGHT_CORNER;
 183:         else if (key == UPPER_LEADING_CORNER)
 184:           key = UPPER_LEFT_CORNER;
 185:         else if (key == UPPER_TRAILING_CORNER)
 186:           key = UPPER_RIGHT_CORNER;
 187:       }
 188:     else if (getComponentOrientation()
 189:              == ComponentOrientation.RIGHT_TO_LEFT)
 190:       {
 191:         if (key == LOWER_LEADING_CORNER)
 192:           key = LOWER_RIGHT_CORNER;
 193:         else if (key == LOWER_TRAILING_CORNER)
 194:           key = LOWER_LEFT_CORNER;
 195:         else if (key == UPPER_LEADING_CORNER)
 196:           key = UPPER_RIGHT_CORNER;
 197:         else if (key == UPPER_TRAILING_CORNER)
 198:           key = UPPER_LEFT_CORNER;
 199:       }
 200: 
 201:     if (key == LOWER_RIGHT_CORNER)
 202:       return lowerRight;
 203:     else if (key == UPPER_RIGHT_CORNER)
 204:       return upperRight;
 205:     else if (key == LOWER_LEFT_CORNER)
 206:       return lowerLeft;
 207:     else if (key == UPPER_LEFT_CORNER)
 208:       return upperLeft;
 209:     return null;
 210:   }
 211: 
 212:   public JScrollBar getHorizontalScrollBar()
 213:   {
 214:     return horizontalScrollBar;
 215:   }
 216: 
 217:   public int getHorizontalScrollBarPolicy()
 218:   {
 219:     return horizontalScrollBarPolicy;
 220:   }
 221: 
 222:   public JViewport getRowHeader()
 223:   {
 224:     return rowHeader;
 225:   }
 226: 
 227:   public JScrollBar getVerticalScrollBar()
 228:   {
 229:     return verticalScrollBar;
 230:   }
 231: 
 232:   public int getVerticalScrollBarPolicy()
 233:   {
 234:     return verticalScrollBarPolicy;
 235:   }
 236: 
 237:   public JViewport getViewport()
 238:   {
 239:     return viewport;
 240:   }
 241: 
 242:   public Border getViewportBorder()
 243:   {
 244:     return viewportBorder;
 245:   }
 246: 
 247:   public Rectangle getViewportBorderBounds()
 248:   {
 249:     if (viewportBorder == null)
 250:       {
 251:         if (getViewport() == null)
 252:           return new Rectangle(0, 0, 0, 0);
 253:         else
 254:           return getViewport().getBounds();
 255:       }
 256:     else
 257:       {
 258:         Insets i = viewportBorder.getBorderInsets(getViewport());
 259:         if (getViewport() == null)
 260:           return new Rectangle(0, 0, i.left + i.right, i.top + i.bottom);
 261:         else
 262:           {
 263:             Rectangle b = getViewport().getBounds();
 264:             return new Rectangle(b.x - i.left,
 265:                                  b.y - i.top,
 266:                                  b.width + i.left + i.right,
 267:                                  b.height + i.top + i.bottom);
 268:           }
 269:       }
 270:   }
 271: 
 272:   public boolean isWheelScrollingEnabled()
 273:   {
 274:     return wheelScrollingEnabled;
 275:   }
 276: 
 277: 
 278: 
 279:   private void sync()
 280:   {
 281:     LayoutManager m = super.getLayout();
 282:     if (m != null && m instanceof ScrollPaneLayout)
 283:       {
 284:         ScrollPaneLayout sl = (ScrollPaneLayout) m;
 285:         sl.syncWithScrollPane(this);
 286:       }
 287:   }
 288: 
 289:   private void removeNonNull(Component c)
 290:   {
 291:     if (c != null)
 292:       remove(c);
 293:   }
 294: 
 295:   private void addNonNull(Component c, Object constraints)
 296:   {
 297:     if (c != null)
 298:       add(c, constraints);
 299:   }
 300: 
 301:   public void setComponentOrientation(ComponentOrientation co)
 302:   {
 303:     ComponentOrientation old = super.getComponentOrientation();
 304:     super.setComponentOrientation(co);
 305:     firePropertyChange("componentOrientation", old, co);
 306:     sync();
 307:   }
 308: 
 309:   public void setColumnHeader(JViewport h)
 310:   {
 311:     if (columnHeader == h)
 312:       return;
 313: 
 314:     JViewport old = columnHeader;
 315:     removeNonNull(old);
 316:     columnHeader = h;
 317:     addNonNull(h, JScrollPane.COLUMN_HEADER);
 318:     firePropertyChange("columnHeader", old, h);
 319:     sync();
 320:   }
 321: 
 322:   public void setColumnHeaderView(Component c)
 323:   {
 324:     if (columnHeader == null)
 325:       setColumnHeader(createViewport());
 326:     columnHeader.setView(c);
 327:     sync();
 328:   }
 329: 
 330:   public void setCorner(String key, Component c)
 331:   {
 332:     if (getComponentOrientation()
 333:         == ComponentOrientation.LEFT_TO_RIGHT)
 334:       {
 335:         if (key == LOWER_LEADING_CORNER)
 336:           key = LOWER_LEFT_CORNER;
 337:         else if (key == LOWER_TRAILING_CORNER)
 338:           key = LOWER_RIGHT_CORNER;
 339:         else if (key == UPPER_LEADING_CORNER)
 340:           key = UPPER_LEFT_CORNER;
 341:         else if (key == UPPER_TRAILING_CORNER)
 342:           key = UPPER_RIGHT_CORNER;
 343:       }
 344:     else if (getComponentOrientation()
 345:              == ComponentOrientation.RIGHT_TO_LEFT)
 346:       {
 347:         if (key == LOWER_LEADING_CORNER)
 348:           key = LOWER_RIGHT_CORNER;
 349:         else if (key == LOWER_TRAILING_CORNER)
 350:           key = LOWER_LEFT_CORNER;
 351:         else if (key == UPPER_LEADING_CORNER)
 352:           key = UPPER_RIGHT_CORNER;
 353:         else if (key == UPPER_TRAILING_CORNER)
 354:           key = UPPER_LEFT_CORNER;
 355:       }
 356: 
 357:     if (key == LOWER_RIGHT_CORNER)
 358:       {
 359:         removeNonNull(lowerRight);
 360:         lowerRight = c;
 361:         addNonNull(c, JScrollPane.LOWER_RIGHT_CORNER);
 362:       }
 363:     else if (key == UPPER_RIGHT_CORNER)
 364:       {
 365:         removeNonNull(upperRight);
 366:         upperRight = c;
 367:         addNonNull(c, JScrollPane.UPPER_RIGHT_CORNER);
 368:       }
 369:     else if (key == LOWER_LEFT_CORNER)
 370:       {
 371:         removeNonNull(lowerLeft);
 372:         lowerLeft = c;
 373:         addNonNull(c, JScrollPane.LOWER_LEFT_CORNER);
 374:       }
 375:     else if (key == UPPER_LEFT_CORNER)
 376:       {
 377:         removeNonNull(upperLeft);
 378:         upperLeft = c;
 379:         addNonNull(c, JScrollPane.UPPER_LEFT_CORNER);
 380:       }
 381:     else
 382:       throw new IllegalArgumentException("unknown corner " + key);
 383:     sync();
 384:   }
 385: 
 386:   public void setHorizontalScrollBar(JScrollBar h)
 387:   {
 388:     if (horizontalScrollBar == h)
 389:       return;
 390: 
 391:     JScrollBar old = horizontalScrollBar;
 392:     removeNonNull(old);
 393:     horizontalScrollBar = h;
 394:     addNonNull(h, JScrollPane.HORIZONTAL_SCROLLBAR);
 395:     firePropertyChange("horizontalScrollBar", old, h);
 396:     sync();
 397: 
 398:   }
 399: 
 400:   public void setHorizontalScrollBarPolicy(int h)
 401:   {
 402:     if (horizontalScrollBarPolicy == h)
 403:       return;
 404: 
 405:     if (h != HORIZONTAL_SCROLLBAR_AS_NEEDED
 406:         && h != HORIZONTAL_SCROLLBAR_NEVER
 407:         && h != HORIZONTAL_SCROLLBAR_ALWAYS)
 408:       throw new IllegalArgumentException("unknown horizontal scrollbar policy");
 409: 
 410:     int old = horizontalScrollBarPolicy;
 411:     horizontalScrollBarPolicy = h;
 412:     firePropertyChange("horizontalScrollBarPolicy", old, h);
 413:     sync();
 414:     revalidate();
 415:   }
 416: 
 417:   public void setLayout(LayoutManager l)
 418:   {
 419:     LayoutManager old = super.getLayout();
 420:     ScrollPaneLayout tmp = (ScrollPaneLayout) l;
 421:     super.setLayout(l);
 422:     tmp.syncWithScrollPane(this);
 423:     firePropertyChange("layout", old, l);
 424:     sync();
 425:   }
 426: 
 427:   public void setRowHeader(JViewport v)
 428:   {
 429:     if (rowHeader == v)
 430:       return;
 431: 
 432:     JViewport old = rowHeader;
 433:     removeNonNull(old);
 434:     rowHeader = v;
 435:     addNonNull(v, JScrollPane.ROW_HEADER);
 436:     firePropertyChange("rowHeader", old, v);
 437:     sync();
 438:   }
 439: 
 440:   public void setRowHeaderView(Component c)
 441:   {
 442:     if (rowHeader == null)
 443:       setRowHeader(createViewport());
 444:     rowHeader.setView(c);
 445:     sync();
 446:   }
 447: 
 448:   public void setVerticalScrollBar(JScrollBar v)
 449:   {
 450:     if (verticalScrollBar == v)
 451:       return;
 452: 
 453:     JScrollBar old = verticalScrollBar;
 454:     removeNonNull(old);
 455:     verticalScrollBar = v;
 456:     addNonNull(v, JScrollPane.VERTICAL_SCROLLBAR);
 457:     firePropertyChange("verticalScrollBar", old, v);
 458:     sync();
 459:   }
 460: 
 461:   public void setVerticalScrollBarPolicy(int v)
 462:   {
 463:     if (verticalScrollBarPolicy == v)
 464:       return;
 465: 
 466:     if (v != VERTICAL_SCROLLBAR_AS_NEEDED
 467:         && v != VERTICAL_SCROLLBAR_NEVER
 468:         && v != VERTICAL_SCROLLBAR_ALWAYS)
 469:       throw new IllegalArgumentException("unknown vertical scrollbar policy");
 470: 
 471:     int old = verticalScrollBarPolicy;
 472:     verticalScrollBarPolicy = v;
 473:     firePropertyChange("verticalScrollBarPolicy", old, v);
 474:     sync();
 475:     revalidate();
 476:   }
 477: 
 478:   public void setWheelScrollingEnabled(boolean b)
 479:   {
 480:     if (wheelScrollingEnabled == b)
 481:       return;
 482: 
 483:     boolean old = wheelScrollingEnabled;
 484:     wheelScrollingEnabled = b;
 485:     firePropertyChange("wheelScrollingEnabled", old, b);
 486:     sync();
 487:   }
 488: 
 489:   public void setViewport(JViewport v)
 490:   {
 491:     if (viewport == v)
 492:       return;
 493: 
 494:     JViewport old = viewport;
 495:     removeNonNull(old);
 496:     viewport = v;
 497:     addNonNull(v, JScrollPane.VIEWPORT);
 498:     revalidate();
 499:     repaint();
 500:     firePropertyChange("viewport", old, v);
 501:     sync();
 502:     if (accessibleContext != null)
 503:       {
 504:         AccessibleJScrollPane asp = (AccessibleJScrollPane) accessibleContext;
 505:         asp.resetViewPort();
 506:       }
 507:   }
 508: 
 509:   public void setViewportBorder(Border b)
 510:   {
 511:     if (viewportBorder == b)
 512:       return;
 513: 
 514:     Border old = viewportBorder;
 515:     viewportBorder = b;
 516:     firePropertyChange("viewportBorder", old, b);
 517:     sync();
 518:   }
 519: 
 520:   public void setViewportView(Component view)
 521:   {
 522:     if (getViewport() == null)
 523:       {
 524:         setViewport(createViewport());
 525:       }
 526: 
 527:     if (view != null)
 528:       {
 529:         getViewport().setView(view);
 530:       }
 531:     sync();
 532:   }
 533: 
 534:   public boolean isValidateRoot()
 535:   {
 536:     return true;
 537:   }
 538: 
 539:   /**
 540:    * Creates a new <code>JScrollPane</code> without a view. The scrollbar
 541:    * policy is set to {@link #VERTICAL_SCROLLBAR_AS_NEEDED} and
 542:    * {@link #HORIZONTAL_SCROLLBAR_AS_NEEDED}.
 543:    */
 544:   public JScrollPane()
 545:   {
 546:     this(null);
 547:   }
 548: 
 549:   /**
 550:    * Creates a new <code>JScrollPane</code> that embeds the specified
 551:    * <code>view</code> component, displaying vertical and horizontal scrollbars
 552:    * as needed.
 553:    *
 554:    * @param view the component that is embedded inside the JScrollPane
 555:    */
 556:   public JScrollPane(Component view)
 557:   {
 558:     this(view,
 559:          VERTICAL_SCROLLBAR_AS_NEEDED,
 560:          HORIZONTAL_SCROLLBAR_AS_NEEDED);
 561:   }
 562: 
 563:   /**
 564:    * Creates a new <code>JScrollPane</code> without a view; The scrollbar
 565:    * policies are set to <code>vsbPolicy</code> and <code>hsbPolicy</code>.
 566:    *
 567:    * @param vsbPolicy the vertical scrollbar policy to set
 568:    * @param hsbPolicy the vertical scrollbar policy to set
 569:    *
 570:    * @see ScrollPaneConstants#HORIZONTAL_SCROLLBAR_ALWAYS
 571:    * @see ScrollPaneConstants#HORIZONTAL_SCROLLBAR_AS_NEEDED
 572:    * @see ScrollPaneConstants#HORIZONTAL_SCROLLBAR_NEVER
 573:    * @see ScrollPaneConstants#VERTICAL_SCROLLBAR_ALWAYS
 574:    * @see ScrollPaneConstants#VERTICAL_SCROLLBAR_AS_NEEDED
 575:    * @see ScrollPaneConstants#VERTICAL_SCROLLBAR_NEVER
 576:    */
 577:   public JScrollPane(int vsbPolicy, int hsbPolicy)
 578:   {
 579:     this(null, vsbPolicy, hsbPolicy);
 580:   }
 581: 
 582:   /**
 583:    * Creates a new <code>JScrollPane</code> that embeds the specified
 584:    * <code>view</code> component; The scrollbar
 585:    * policies are set to <code>vsbPolicy</code> and <code>hsbPolicy</code>.
 586:    *
 587:    * @param vsbPolicy the vertical scrollbar policy to set
 588:    * @param hsbPolicy the vertical scrollbar policy to set
 589:    *
 590:    * @see ScrollPaneConstants#HORIZONTAL_SCROLLBAR_ALWAYS
 591:    * @see ScrollPaneConstants#HORIZONTAL_SCROLLBAR_AS_NEEDED
 592:    * @see ScrollPaneConstants#HORIZONTAL_SCROLLBAR_NEVER
 593:    * @see ScrollPaneConstants#VERTICAL_SCROLLBAR_ALWAYS
 594:    * @see ScrollPaneConstants#VERTICAL_SCROLLBAR_AS_NEEDED
 595:    * @see ScrollPaneConstants#VERTICAL_SCROLLBAR_NEVER
 596:    */
 597:   public JScrollPane(Component view, int vsbPolicy, int hsbPolicy)
 598:   {
 599:     wheelScrollingEnabled = true;
 600:     setVerticalScrollBarPolicy(vsbPolicy);
 601:     setVerticalScrollBar(createVerticalScrollBar());
 602:     setHorizontalScrollBarPolicy(hsbPolicy);
 603:     setHorizontalScrollBar(createHorizontalScrollBar());
 604:     viewport = createViewport();
 605:     if (view != null)
 606:       getViewport().setView(view);
 607:     add(viewport,0);
 608:     setLayout(new ScrollPaneLayout());
 609:     setOpaque(false);
 610:     updateUI();
 611:   }
 612: 
 613: 
 614:   public JScrollBar createHorizontalScrollBar()
 615:   {
 616:     return new ScrollBar(SwingConstants.HORIZONTAL);
 617:   }
 618: 
 619:   public JScrollBar createVerticalScrollBar()
 620:   {
 621:     return new ScrollBar(SwingConstants.VERTICAL);
 622:   }
 623: 
 624:   protected JViewport createViewport()
 625:   {
 626:     return new JViewport();
 627:   }
 628: 
 629:   public String getUIClassID()
 630:   {
 631:     return "ScrollPaneUI";
 632:   }
 633: 
 634:   public void updateUI()
 635:   {
 636:     setUI((ScrollPaneUI) UIManager.getUI(this));
 637:   }
 638: 
 639:   /**
 640:    * This method returns the scrollpane's UI delegate.
 641:    *
 642:    * @return The scrollpane's UI delegate.
 643:    */
 644:   public ScrollPaneUI getUI()
 645:   {
 646:     return (ScrollPaneUI) ui;
 647:   }
 648: 
 649:   /**
 650:    * This method sets the scrollpane's UI delegate.
 651:    *
 652:    * @param ui The scrollpane's UI delegate.
 653:    */
 654:   public void setUI(ScrollPaneUI ui)
 655:   {
 656:     super.setUI(ui);
 657:   }
 658: 
 659:   protected class ScrollBar
 660:     extends JScrollBar
 661:     implements UIResource
 662:   {
 663:     private static final long serialVersionUID = -42032395320987283L;
 664: 
 665:     public ScrollBar(int orientation)
 666:     {
 667:       super(orientation);
 668:     }
 669: 
 670:     public int getBlockIncrement(int direction)
 671:     {
 672:       Component view = JScrollPane.this.getViewport().getView();
 673:       if (view == null || (! (view instanceof Scrollable)))
 674:         return super.getBlockIncrement(direction);
 675:       else
 676:         {
 677:           Scrollable s = (Scrollable) view;
 678:           return s.getScrollableBlockIncrement(JScrollPane.this.getViewport().getViewRect(),
 679:                                                this.getOrientation(),
 680:                                                direction);
 681:         }
 682:     }
 683: 
 684:     public int getUnitIncrement(int direction)
 685:     {
 686:       Component view = JScrollPane.this.getViewport().getView();
 687:       if (view == null || (! (view instanceof Scrollable)))
 688:         return super.getUnitIncrement(direction);
 689:       else
 690:         {
 691:           Scrollable s = (Scrollable) view;
 692:           return s.getScrollableUnitIncrement(JScrollPane.this.getViewport().getViewRect(),
 693:                                               this.getOrientation(),
 694:                                               direction);
 695:         }
 696:     }
 697:   }
 698: 
 699:   /**
 700:    * Returns the accessible context associated with this
 701:    * <code>JScrollPane</code>.
 702:    *
 703:    * @return the accessible context associated with this
 704:    *         <code>JScrollPane</code>
 705:    */
 706:   public AccessibleContext getAccessibleContext()
 707:   {
 708:     if (accessibleContext == null)
 709:       accessibleContext = new AccessibleJScrollPane();
 710:     return accessibleContext;
 711:   }
 712: }