1 /* 2 * Copyright (c) 1997, 2008, 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 javax.swing; 26 27 import java.awt.Component; 28 import java.util.ArrayList; 29 import java.util.Hashtable; 30 import java.awt.Color; 31 import java.awt.Graphics; 32 import java.awt.Rectangle; 33 import sun.awt.SunToolkit; 34 35 import javax.accessibility.*; 36 37 /** 38 * <code>JLayeredPane</code> adds depth to a JFC/Swing container, 39 * allowing components to overlap each other when needed. 40 * An <code>Integer</code> object specifies each component's depth in the 41 * container, where higher-numbered components sit "on top" of other 42 * components. 43 * For task-oriented documentation and examples of using layered panes see 44 * <a href="http://java.sun.com/docs/books/tutorial/uiswing/components/layeredpane.html">How to Use a Layered Pane</a>, 45 * a section in <em>The Java Tutorial</em>. 46 * <P> 47 * <TABLE ALIGN="RIGHT" BORDER="0" SUMMARY="layout"> 48 * <TR> 49 * <TD ALIGN="CENTER"> 50 * <P ALIGN="CENTER"><IMG SRC="doc-files/JLayeredPane-1.gif" 51 * alt="The following text describes this image." 52 * WIDTH="269" HEIGHT="264" ALIGN="BOTTOM" BORDER="0"> 53 * </TD> 54 * </TR> 55 * </TABLE> 56 * For convenience, <code>JLayeredPane</code> divides the depth-range 57 * into several different layers. Putting a component into one of those 58 * layers makes it easy to ensure that components overlap properly, 59 * without having to worry about specifying numbers for specific depths: 60 * <DL> 61 * <DT><FONT SIZE="2">DEFAULT_LAYER</FONT></DT> 62 * <DD>The standard layer, where most components go. This the bottommost 63 * layer. 64 * <DT><FONT SIZE="2">PALETTE_LAYER</FONT></DT> 65 * <DD>The palette layer sits over the default layer. Useful for floating 66 * toolbars and palettes, so they can be positioned above other components. 67 * <DT><FONT SIZE="2">MODAL_LAYER</FONT></DT> 68 * <DD>The layer used for modal dialogs. They will appear on top of any 69 * toolbars, palettes, or standard components in the container. 70 * <DT><FONT SIZE="2">POPUP_LAYER</FONT></DT> 71 * <DD>The popup layer displays above dialogs. That way, the popup windows 72 * associated with combo boxes, tooltips, and other help text will appear 73 * above the component, palette, or dialog that generated them. 74 * <DT><FONT SIZE="2">DRAG_LAYER</FONT></DT> 75 * <DD>When dragging a component, reassigning it to the drag layer ensures 76 * that it is positioned over every other component in the container. When 77 * finished dragging, it can be reassigned to its normal layer. 78 * </DL> 79 * The <code>JLayeredPane</code> methods <code>moveToFront(Component)</code>, 80 * <code>moveToBack(Component)</code> and <code>setPosition</code> can be used 81 * to reposition a component within its layer. The <code>setLayer</code> method 82 * can also be used to change the component's current layer. 83 * 84 * <h2>Details</h2> 85 * <code>JLayeredPane</code> manages its list of children like 86 * <code>Container</code>, but allows for the definition of a several 87 * layers within itself. Children in the same layer are managed exactly 88 * like the normal <code>Container</code> object, 89 * with the added feature that when children components overlap, children 90 * in higher layers display above the children in lower layers. 91 * <p> 92 * Each layer is a distinct integer number. The layer attribute can be set 93 * on a <code>Component</code> by passing an <code>Integer</code> 94 * object during the add call.<br> For example: 95 * <PRE> 96 * layeredPane.add(child, JLayeredPane.DEFAULT_LAYER); 97 * or 98 * layeredPane.add(child, new Integer(10)); 99 * </PRE> 100 * The layer attribute can also be set on a Component by calling<PRE> 101 * layeredPaneParent.setLayer(child, 10)</PRE> 102 * on the <code>JLayeredPane</code> that is the parent of component. The layer 103 * should be set <i>before</i> adding the child to the parent. 104 * <p> 105 * Higher number layers display above lower number layers. So, using 106 * numbers for the layers and letters for individual components, a 107 * representative list order would look like this:<PRE> 108 * 5a, 5b, 5c, 2a, 2b, 2c, 1a </PRE> 109 * where the leftmost components are closest to the top of the display. 110 * <p> 111 * A component can be moved to the top or bottom position within its 112 * layer by calling <code>moveToFront</code> or <code>moveToBack</code>. 113 * <p> 114 * The position of a component within a layer can also be specified directly. 115 * Valid positions range from 0 up to one less than the number of 116 * components in that layer. A value of -1 indicates the bottommost 117 * position. A value of 0 indicates the topmost position. Unlike layer 118 * numbers, higher position values are <i>lower</i> in the display. 119 * <blockquote> 120 * <b>Note:</b> This sequence (defined by java.awt.Container) is the reverse 121 * of the layer numbering sequence. Usually though, you will use <code>moveToFront</code>, 122 * <code>moveToBack</code>, and <code>setLayer</code>. 123 * </blockquote> 124 * Here are some examples using the method add(Component, layer, position): 125 * Calling add(5x, 5, -1) results in:<PRE> 126 * 5a, 5b, 5c, 5x, 2a, 2b, 2c, 1a </PRE> 127 * 128 * Calling add(5z, 5, 2) results in:<PRE> 129 * 5a, 5b, 5z, 5c, 5x, 2a, 2b, 2c, 1a </PRE> 130 * 131 * Calling add(3a, 3, 7) results in:<PRE> 132 * 5a, 5b, 5z, 5c, 5x, 3a, 2a, 2b, 2c, 1a </PRE> 133 * 134 * Using normal paint/event mechanics results in 1a appearing at the bottom 135 * and 5a being above all other components. 136 * <p> 137 * <b>Note:</b> that these layers are simply a logical construct and LayoutManagers 138 * will affect all child components of this container without regard for 139 * layer settings. 140 * <p> 141 * <strong>Warning:</strong> Swing is not thread safe. For more 142 * information see <a 143 * href="package-summary.html#threading">Swing's Threading 144 * Policy</a>. 145 * <p> 146 * <strong>Warning:</strong> 147 * Serialized objects of this class will not be compatible with 148 * future Swing releases. The current serialization support is 149 * appropriate for short term storage or RMI between applications running 150 * the same version of Swing. As of 1.4, support for long term storage 151 * of all JavaBeans<sup><font size="-2">TM</font></sup> 152 * has been added to the <code>java.beans</code> package. 153 * Please see {@link java.beans.XMLEncoder}. 154 * 155 * @author David Kloba 156 */ 157 @SuppressWarnings("serial") 158 public class JLayeredPane extends JComponent implements Accessible { 159 /// Watch the values in getObjectForLayer() 160 /** Convenience object defining the Default layer. Equivalent to new Integer(0).*/ 161 public final static Integer DEFAULT_LAYER = new Integer(0); 162 /** Convenience object defining the Palette layer. Equivalent to new Integer(100).*/ 163 public final static Integer PALETTE_LAYER = new Integer(100); 164 /** Convenience object defining the Modal layer. Equivalent to new Integer(200).*/ 165 public final static Integer MODAL_LAYER = new Integer(200); 166 /** Convenience object defining the Popup layer. Equivalent to new Integer(300).*/ 167 public final static Integer POPUP_LAYER = new Integer(300); 168 /** Convenience object defining the Drag layer. Equivalent to new Integer(400).*/ 169 public final static Integer DRAG_LAYER = new Integer(400); 170 /** Convenience object defining the Frame Content layer. 171 * This layer is normally only use to positon the contentPane and menuBar 172 * components of JFrame. 173 * Equivalent to new Integer(-30000). 174 * @see JFrame 175 */ 176 public final static Integer FRAME_CONTENT_LAYER = new Integer(-30000); 177 178 /** Bound property */ 179 public final static String LAYER_PROPERTY = "layeredContainerLayer"; 180 // Hashtable to store layer values for non-JComponent components 181 private Hashtable<Component,Integer> componentToLayer; 182 private boolean optimizedDrawingPossible = true; 183 184 185 ////////////////////////////////////////////////////////////////////////////// 186 //// Container Override methods 187 ////////////////////////////////////////////////////////////////////////////// 188 /** Create a new JLayeredPane */ 189 public JLayeredPane() { 190 setLayout(null); 191 } 192 193 private void validateOptimizedDrawing() { 194 boolean layeredComponentFound = false; 195 synchronized(getTreeLock()) { 196 Integer layer; 197 198 for (Component c : getComponents()) { 199 layer = null; 200 201 if(SunToolkit.isInstanceOf(c, "javax.swing.JInternalFrame") || 202 (c instanceof JComponent && 203 (layer = (Integer)((JComponent)c). 204 getClientProperty(LAYER_PROPERTY)) != null)) 205 { 206 if(layer != null && layer.equals(FRAME_CONTENT_LAYER)) 207 continue; 208 layeredComponentFound = true; 209 break; 210 } 211 } 212 } 213 214 if(layeredComponentFound) 215 optimizedDrawingPossible = false; 216 else 217 optimizedDrawingPossible = true; 218 } 219 220 protected void addImpl(Component comp, Object constraints, int index) { 221 int layer; 222 int pos; 223 224 if(constraints instanceof Integer) { 225 layer = ((Integer)constraints).intValue(); 226 setLayer(comp, layer); 227 } else 228 layer = getLayer(comp); 229 230 pos = insertIndexForLayer(layer, index); 231 super.addImpl(comp, constraints, pos); 232 comp.validate(); 233 comp.repaint(); 234 validateOptimizedDrawing(); 235 } 236 237 /** 238 * Remove the indexed component from this pane. 239 * This is the absolute index, ignoring layers. 240 * 241 * @param index an int specifying the component to remove 242 * @see #getIndexOf 243 */ 244 public void remove(int index) { 245 Component c = getComponent(index); 246 super.remove(index); 247 if (c != null && !(c instanceof JComponent)) { 248 getComponentToLayer().remove(c); 249 } 250 validateOptimizedDrawing(); 251 } 252 253 /** 254 * Removes all the components from this container. 255 * 256 * @since 1.5 257 */ 258 public void removeAll() { 259 Component[] children = getComponents(); 260 Hashtable<Component, Integer> cToL = getComponentToLayer(); 261 for (int counter = children.length - 1; counter >= 0; counter--) { 262 Component c = children[counter]; 263 if (c != null && !(c instanceof JComponent)) { 264 cToL.remove(c); 265 } 266 } 267 super.removeAll(); 268 } 269 270 /** 271 * Returns false if components in the pane can overlap, which makes 272 * optimized drawing impossible. Otherwise, returns true. 273 * 274 * @return false if components can overlap, else true 275 * @see JComponent#isOptimizedDrawingEnabled 276 */ 277 public boolean isOptimizedDrawingEnabled() { 278 return optimizedDrawingPossible; 279 } 280 281 282 ////////////////////////////////////////////////////////////////////////////// 283 //// New methods for managing layers 284 ////////////////////////////////////////////////////////////////////////////// 285 /** Sets the layer property on a JComponent. This method does not cause 286 * any side effects like setLayer() (painting, add/remove, etc). 287 * Normally you should use the instance method setLayer(), in order to 288 * get the desired side-effects (like repainting). 289 * 290 * @param c the JComponent to move 291 * @param layer an int specifying the layer to move it to 292 * @see #setLayer 293 */ 294 public static void putLayer(JComponent c, int layer) { 295 /// MAKE SURE THIS AND setLayer(Component c, int layer, int position) are SYNCED 296 Integer layerObj; 297 298 layerObj = new Integer(layer); 299 c.putClientProperty(LAYER_PROPERTY, layerObj); 300 } 301 302 /** Gets the layer property for a JComponent, it 303 * does not cause any side effects like setLayer(). (painting, add/remove, etc) 304 * Normally you should use the instance method getLayer(). 305 * 306 * @param c the JComponent to check 307 * @return an int specifying the component's layer 308 */ 309 public static int getLayer(JComponent c) { 310 Integer i; 311 if((i = (Integer)c.getClientProperty(LAYER_PROPERTY)) != null) 312 return i.intValue(); 313 return DEFAULT_LAYER.intValue(); 314 } 315 316 /** Convenience method that returns the first JLayeredPane which 317 * contains the specified component. Note that all JFrames have a 318 * JLayeredPane at their root, so any component in a JFrame will 319 * have a JLayeredPane parent. 320 * 321 * @param c the Component to check 322 * @return the JLayeredPane that contains the component, or 323 * null if no JLayeredPane is found in the component 324 * hierarchy 325 * @see JFrame 326 * @see JRootPane 327 */ 328 public static JLayeredPane getLayeredPaneAbove(Component c) { 329 if(c == null) return null; 330 331 Component parent = c.getParent(); 332 while(parent != null && !(parent instanceof JLayeredPane)) 333 parent = parent.getParent(); 334 return (JLayeredPane)parent; 335 } 336 337 /** Sets the layer attribute on the specified component, 338 * making it the bottommost component in that layer. 339 * Should be called before adding to parent. 340 * 341 * @param c the Component to set the layer for 342 * @param layer an int specifying the layer to set, where 343 * lower numbers are closer to the bottom 344 */ 345 public void setLayer(Component c, int layer) { 346 setLayer(c, layer, -1); 347 } 348 349 /** Sets the layer attribute for the specified component and 350 * also sets its position within that layer. 351 * 352 * @param c the Component to set the layer for 353 * @param layer an int specifying the layer to set, where 354 * lower numbers are closer to the bottom 355 * @param position an int specifying the position within the 356 * layer, where 0 is the topmost position and -1 357 * is the bottommost position 358 */ 359 public void setLayer(Component c, int layer, int position) { 360 Integer layerObj; 361 layerObj = getObjectForLayer(layer); 362 363 if(layer == getLayer(c) && position == getPosition(c)) { 364 repaint(c.getBounds()); 365 return; 366 } 367 368 /// MAKE SURE THIS AND putLayer(JComponent c, int layer) are SYNCED 369 if(c instanceof JComponent) 370 ((JComponent)c).putClientProperty(LAYER_PROPERTY, layerObj); 371 else 372 getComponentToLayer().put(c, layerObj); 373 374 if(c.getParent() == null || c.getParent() != this) { 375 repaint(c.getBounds()); 376 return; 377 } 378 379 int index = insertIndexForLayer(c, layer, position); 380 381 setComponentZOrder(c, index); 382 repaint(c.getBounds()); 383 } 384 385 /** 386 * Returns the layer attribute for the specified Component. 387 * 388 * @param c the Component to check 389 * @return an int specifying the component's current layer 390 */ 391 public int getLayer(Component c) { 392 Integer i; 393 if(c instanceof JComponent) 394 i = (Integer)((JComponent)c).getClientProperty(LAYER_PROPERTY); 395 else 396 i = getComponentToLayer().get(c); 397 398 if(i == null) 399 return DEFAULT_LAYER.intValue(); 400 return i.intValue(); 401 } 402 403 /** 404 * Returns the index of the specified Component. 405 * This is the absolute index, ignoring layers. 406 * Index numbers, like position numbers, have the topmost component 407 * at index zero. Larger numbers are closer to the bottom. 408 * 409 * @param c the Component to check 410 * @return an int specifying the component's index 411 */ 412 public int getIndexOf(Component c) { 413 int i, count; 414 415 count = getComponentCount(); 416 for(i = 0; i < count; i++) { 417 if(c == getComponent(i)) 418 return i; 419 } 420 return -1; 421 } 422 /** 423 * Moves the component to the top of the components in its current layer 424 * (position 0). 425 * 426 * @param c the Component to move 427 * @see #setPosition(Component, int) 428 */ 429 public void moveToFront(Component c) { 430 setPosition(c, 0); 431 } 432 433 /** 434 * Moves the component to the bottom of the components in its current layer 435 * (position -1). 436 * 437 * @param c the Component to move 438 * @see #setPosition(Component, int) 439 */ 440 public void moveToBack(Component c) { 441 setPosition(c, -1); 442 } 443 444 /** 445 * Moves the component to <code>position</code> within its current layer, 446 * where 0 is the topmost position within the layer and -1 is the bottommost 447 * position. 448 * <p> 449 * <b>Note:</b> Position numbering is defined by java.awt.Container, and 450 * is the opposite of layer numbering. Lower position numbers are closer 451 * to the top (0 is topmost), and higher position numbers are closer to 452 * the bottom. 453 * 454 * @param c the Component to move 455 * @param position an int in the range -1..N-1, where N is the number of 456 * components in the component's current layer 457 */ 458 public void setPosition(Component c, int position) { 459 setLayer(c, getLayer(c), position); 460 } 461 462 /** 463 * Get the relative position of the component within its layer. 464 * 465 * @param c the Component to check 466 * @return an int giving the component's position, where 0 is the 467 * topmost position and the highest index value = the count 468 * count of components at that layer, minus 1 469 * 470 * @see #getComponentCountInLayer 471 */ 472 public int getPosition(Component c) { 473 int i, startLayer, curLayer, startLocation, pos = 0; 474 475 getComponentCount(); 476 startLocation = getIndexOf(c); 477 478 if(startLocation == -1) 479 return -1; 480 481 startLayer = getLayer(c); 482 for(i = startLocation - 1; i >= 0; i--) { 483 curLayer = getLayer(getComponent(i)); 484 if(curLayer == startLayer) 485 pos++; 486 else 487 return pos; 488 } 489 return pos; 490 } 491 492 /** Returns the highest layer value from all current children. 493 * Returns 0 if there are no children. 494 * 495 * @return an int indicating the layer of the topmost component in the 496 * pane, or zero if there are no children 497 */ 498 public int highestLayer() { 499 if(getComponentCount() > 0) 500 return getLayer(getComponent(0)); 501 return 0; 502 } 503 504 /** Returns the lowest layer value from all current children. 505 * Returns 0 if there are no children. 506 * 507 * @return an int indicating the layer of the bottommost component in the 508 * pane, or zero if there are no children 509 */ 510 public int lowestLayer() { 511 int count = getComponentCount(); 512 if(count > 0) 513 return getLayer(getComponent(count-1)); 514 return 0; 515 } 516 517 /** 518 * Returns the number of children currently in the specified layer. 519 * 520 * @param layer an int specifying the layer to check 521 * @return an int specifying the number of components in that layer 522 */ 523 public int getComponentCountInLayer(int layer) { 524 int i, count, curLayer; 525 int layerCount = 0; 526 527 count = getComponentCount(); 528 for(i = 0; i < count; i++) { 529 curLayer = getLayer(getComponent(i)); 530 if(curLayer == layer) { 531 layerCount++; 532 /// Short circut the counting when we have them all 533 } else if(layerCount > 0 || curLayer < layer) { 534 break; 535 } 536 } 537 538 return layerCount; 539 } 540 541 /** 542 * Returns an array of the components in the specified layer. 543 * 544 * @param layer an int specifying the layer to check 545 * @return an array of Components contained in that layer 546 */ 547 public Component[] getComponentsInLayer(int layer) { 548 int i, count, curLayer; 549 int layerCount = 0; 550 Component[] results; 551 552 results = new Component[getComponentCountInLayer(layer)]; 553 count = getComponentCount(); 554 for(i = 0; i < count; i++) { 555 curLayer = getLayer(getComponent(i)); 556 if(curLayer == layer) { 557 results[layerCount++] = getComponent(i); 558 /// Short circut the counting when we have them all 559 } else if(layerCount > 0 || curLayer < layer) { 560 break; 561 } 562 } 563 564 return results; 565 } 566 567 /** 568 * Paints this JLayeredPane within the specified graphics context. 569 * 570 * @param g the Graphics context within which to paint 571 */ 572 public void paint(Graphics g) { 573 if(isOpaque()) { 574 Rectangle r = g.getClipBounds(); 575 Color c = getBackground(); 576 if(c == null) 577 c = Color.lightGray; 578 g.setColor(c); 579 if (r != null) { 580 g.fillRect(r.x, r.y, r.width, r.height); 581 } 582 else { 583 g.fillRect(0, 0, getWidth(), getHeight()); 584 } 585 } 586 super.paint(g); 587 } 588 589 ////////////////////////////////////////////////////////////////////////////// 590 //// Implementation Details 591 ////////////////////////////////////////////////////////////////////////////// 592 593 /** 594 * Returns the hashtable that maps components to layers. 595 * 596 * @return the Hashtable used to map components to their layers 597 */ 598 protected Hashtable<Component,Integer> getComponentToLayer() { 599 if(componentToLayer == null) 600 componentToLayer = new Hashtable<Component,Integer>(4); 601 return componentToLayer; 602 } 603 604 /** 605 * Returns the Integer object associated with a specified layer. 606 * 607 * @param layer an int specifying the layer 608 * @return an Integer object for that layer 609 */ 610 protected Integer getObjectForLayer(int layer) { 611 Integer layerObj; 612 switch(layer) { 613 case 0: 614 layerObj = DEFAULT_LAYER; 615 break; 616 case 100: 617 layerObj = PALETTE_LAYER; 618 break; 619 case 200: 620 layerObj = MODAL_LAYER; 621 break; 622 case 300: 623 layerObj = POPUP_LAYER; 624 break; 625 case 400: 626 layerObj = DRAG_LAYER; 627 break; 628 default: 629 layerObj = new Integer(layer); 630 } 631 return layerObj; 632 } 633 634 /** 635 * Primitive method that determines the proper location to 636 * insert a new child based on layer and position requests. 637 * 638 * @param layer an int specifying the layer 639 * @param position an int specifying the position within the layer 640 * @return an int giving the (absolute) insertion-index 641 * 642 * @see #getIndexOf 643 */ 644 protected int insertIndexForLayer(int layer, int position) { 645 return insertIndexForLayer(null, layer, position); 646 } 647 648 /** 649 * This method is an extended version of insertIndexForLayer() 650 * to support setLayer which uses Container.setZOrder which does 651 * not remove the component from the containment heirarchy though 652 * we need to ignore it when calculating the insertion index. 653 * 654 * @param comp component to ignore when determining index 655 * @param layer an int specifying the layer 656 * @param position an int specifying the position within the layer 657 * @return an int giving the (absolute) insertion-index 658 * 659 * @see #getIndexOf 660 */ 661 private int insertIndexForLayer(Component comp, int layer, int position) { 662 int i, count, curLayer; 663 int layerStart = -1; 664 int layerEnd = -1; 665 int componentCount = getComponentCount(); 666 667 ArrayList<Component> compList = 668 new ArrayList<Component>(componentCount); 669 for (int index = 0; index < componentCount; index++) { 670 if (getComponent(index) != comp) { 671 compList.add(getComponent(index)); 672 } 673 } 674 675 count = compList.size(); 676 for (i = 0; i < count; i++) { 677 curLayer = getLayer(compList.get(i)); 678 if (layerStart == -1 && curLayer == layer) { 679 layerStart = i; 680 } 681 if (curLayer < layer) { 682 if (i == 0) { 683 // layer is greater than any current layer 684 // [ ASSERT(layer > highestLayer()) ] 685 layerStart = 0; 686 layerEnd = 0; 687 } else { 688 layerEnd = i; 689 } 690 break; 691 } 692 } 693 694 // layer requested is lower than any current layer 695 // [ ASSERT(layer < lowestLayer()) ] 696 // put it on the bottom of the stack 697 if (layerStart == -1 && layerEnd == -1) 698 return count; 699 700 // In the case of a single layer entry handle the degenerative cases 701 if (layerStart != -1 && layerEnd == -1) 702 layerEnd = count; 703 704 if (layerEnd != -1 && layerStart == -1) 705 layerStart = layerEnd; 706 707 // If we are adding to the bottom, return the last element 708 if (position == -1) 709 return layerEnd; 710 711 // Otherwise make sure the requested position falls in the 712 // proper range 713 if (position > -1 && layerStart + position <= layerEnd) 714 return layerStart + position; 715 716 // Otherwise return the end of the layer 717 return layerEnd; 718 } 719 720 /** 721 * Returns a string representation of this JLayeredPane. This method 722 * is intended to be used only for debugging purposes, and the 723 * content and format of the returned string may vary between 724 * implementations. The returned string may be empty but may not 725 * be <code>null</code>. 726 * 727 * @return a string representation of this JLayeredPane. 728 */ 729 protected String paramString() { 730 String optimizedDrawingPossibleString = (optimizedDrawingPossible ? 731 "true" : "false"); 732 733 return super.paramString() + 734 ",optimizedDrawingPossible=" + optimizedDrawingPossibleString; 735 } 736 737 ///////////////// 738 // Accessibility support 739 //////////////// 740 741 /** 742 * Gets the AccessibleContext associated with this JLayeredPane. 743 * For layered panes, the AccessibleContext takes the form of an 744 * AccessibleJLayeredPane. 745 * A new AccessibleJLayeredPane instance is created if necessary. 746 * 747 * @return an AccessibleJLayeredPane that serves as the 748 * AccessibleContext of this JLayeredPane 749 */ 750 public AccessibleContext getAccessibleContext() { 751 if (accessibleContext == null) { 752 accessibleContext = new AccessibleJLayeredPane(); 753 } 754 return accessibleContext; 755 } 756 757 /** 758 * This class implements accessibility support for the 759 * <code>JLayeredPane</code> class. It provides an implementation of the 760 * Java Accessibility API appropriate to layered pane user-interface 761 * elements. 762 * <p> 763 * <strong>Warning:</strong> 764 * Serialized objects of this class will not be compatible with 765 * future Swing releases. The current serialization support is 766 * appropriate for short term storage or RMI between applications running 767 * the same version of Swing. As of 1.4, support for long term storage 768 * of all JavaBeans<sup><font size="-2">TM</font></sup> 769 * has been added to the <code>java.beans</code> package. 770 * Please see {@link java.beans.XMLEncoder}. 771 */ 772 @SuppressWarnings("serial") 773 protected class AccessibleJLayeredPane extends AccessibleJComponent { 774 775 /** 776 * Get the role of this object. 777 * 778 * @return an instance of AccessibleRole describing the role of the 779 * object 780 * @see AccessibleRole 781 */ 782 public AccessibleRole getAccessibleRole() { 783 return AccessibleRole.LAYERED_PANE; 784 } 785 } 786 }