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://docs.oracle.com/javase/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 }