1 /*
2 * Copyright (c) 1997, 2017, 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 java.beans.JavaBean;
34 import java.beans.BeanProperty;
35
36 import sun.awt.SunToolkit;
37
38 import javax.accessibility.*;
39
40 /**
41 * <code>JLayeredPane</code> adds depth to a JFC/Swing container,
42 * allowing components to overlap each other when needed.
43 * An <code>Integer</code> object specifies each component's depth in the
44 * container, where higher-numbered components sit "on top" of other
45 * components.
46 * For task-oriented documentation and examples of using layered panes see
47 * <a href="http://docs.oracle.com/javase/tutorial/uiswing/components/layeredpane.html">How to Use a Layered Pane</a>,
48 * a section in <em>The Java Tutorial</em>.
49 *
50 * <table class="borderless" style="float:right">
51 * <caption style="display:none">Example</caption>
52 * <TR>
53 * <TD style="text-align:center">
54 * <P STYLE="TEXT-ALIGN:CENTER"><IMG SRC="doc-files/JLayeredPane-1.gif"
55 * alt="The following text describes this image."
56 * WIDTH="269" HEIGHT="264" STYLE="FLOAT:BOTTOM; BORDER=0">
57 * </TD>
58 * </TR>
59 * </TABLE>
60 * For convenience, <code>JLayeredPane</code> divides the depth-range
61 * into several different layers. Putting a component into one of those
62 * layers makes it easy to ensure that components overlap properly,
63 * without having to worry about specifying numbers for specific depths:
64 * <DL>
65 * <DT>DEFAULT_LAYER</DT>
66 * <DD>The standard layer, where most components go. This the bottommost
67 * layer.
68 * <DT>PALETTE_LAYER</DT>
69 * <DD>The palette layer sits over the default layer. Useful for floating
70 * toolbars and palettes, so they can be positioned above other components.
71 * <DT>MODAL_LAYER</DT>
72 * <DD>The layer used for modal dialogs. They will appear on top of any
73 * toolbars, palettes, or standard components in the container.
74 * <DT>POPUP_LAYER</DT>
75 * <DD>The popup layer displays above dialogs. That way, the popup windows
76 * associated with combo boxes, tooltips, and other help text will appear
77 * above the component, palette, or dialog that generated them.
78 * <DT>DRAG_LAYER</DT>
79 * <DD>When dragging a component, reassigning it to the drag layer ensures
80 * that it is positioned over every other component in the container. When
81 * finished dragging, it can be reassigned to its normal layer.
82 * </DL>
83 * The <code>JLayeredPane</code> methods <code>moveToFront(Component)</code>,
84 * <code>moveToBack(Component)</code> and <code>setPosition</code> can be used
85 * to reposition a component within its layer. The <code>setLayer</code> method
86 * can also be used to change the component's current layer.
87 *
88 * <h2>Details</h2>
89 * <code>JLayeredPane</code> manages its list of children like
90 * <code>Container</code>, but allows for the definition of a several
91 * layers within itself. Children in the same layer are managed exactly
92 * like the normal <code>Container</code> object,
93 * with the added feature that when children components overlap, children
94 * in higher layers display above the children in lower layers.
95 * <p>
96 * Each layer is a distinct integer number. The layer attribute can be set
97 * on a <code>Component</code> by passing an <code>Integer</code>
98 * object during the add call.<br> For example:
99 * <PRE>
100 * layeredPane.add(child, JLayeredPane.DEFAULT_LAYER);
101 * or
102 * layeredPane.add(child, Integer.valueOf.valueOf(10));
103 * </PRE>
104 * The layer attribute can also be set on a Component by calling<PRE>
105 * layeredPaneParent.setLayer(child, 10)</PRE>
106 * on the <code>JLayeredPane</code> that is the parent of component. The layer
107 * should be set <i>before</i> adding the child to the parent.
108 * <p>
109 * Higher number layers display above lower number layers. So, using
110 * numbers for the layers and letters for individual components, a
111 * representative list order would look like this:<PRE>
112 * 5a, 5b, 5c, 2a, 2b, 2c, 1a </PRE>
113 * where the leftmost components are closest to the top of the display.
114 * <p>
115 * A component can be moved to the top or bottom position within its
116 * layer by calling <code>moveToFront</code> or <code>moveToBack</code>.
117 * <p>
118 * The position of a component within a layer can also be specified directly.
119 * Valid positions range from 0 up to one less than the number of
120 * components in that layer. A value of -1 indicates the bottommost
121 * position. A value of 0 indicates the topmost position. Unlike layer
122 * numbers, higher position values are <i>lower</i> in the display.
123 * <blockquote>
124 * <b>Note:</b> This sequence (defined by java.awt.Container) is the reverse
125 * of the layer numbering sequence. Usually though, you will use <code>moveToFront</code>,
126 * <code>moveToBack</code>, and <code>setLayer</code>.
127 * </blockquote>
128 * Here are some examples using the method add(Component, layer, position):
129 * Calling add(5x, 5, -1) results in:<PRE>
130 * 5a, 5b, 5c, 5x, 2a, 2b, 2c, 1a </PRE>
131 *
132 * Calling add(5z, 5, 2) results in:<PRE>
133 * 5a, 5b, 5z, 5c, 5x, 2a, 2b, 2c, 1a </PRE>
134 *
135 * Calling add(3a, 3, 7) results in:<PRE>
136 * 5a, 5b, 5z, 5c, 5x, 3a, 2a, 2b, 2c, 1a </PRE>
137 *
138 * Using normal paint/event mechanics results in 1a appearing at the bottom
139 * and 5a being above all other components.
140 * <p>
141 * <b>Note:</b> that these layers are simply a logical construct and LayoutManagers
142 * will affect all child components of this container without regard for
143 * layer settings.
144 * <p>
145 * <strong>Warning:</strong> Swing is not thread safe. For more
146 * information see <a
147 * href="package-summary.html#threading">Swing's Threading
148 * Policy</a>.
149 * <p>
150 * <strong>Warning:</strong>
151 * Serialized objects of this class will not be compatible with
152 * future Swing releases. The current serialization support is
153 * appropriate for short term storage or RMI between applications running
154 * the same version of Swing. As of 1.4, support for long term storage
155 * of all JavaBeans™
156 * has been added to the <code>java.beans</code> package.
157 * Please see {@link java.beans.XMLEncoder}.
158 *
159 * @author David Kloba
160 * @since 1.2
161 */
162 @JavaBean(defaultProperty = "accessibleContext")
163 @SuppressWarnings("serial")
164 public class JLayeredPane extends JComponent implements Accessible {
165 /// Watch the values in getObjectForLayer()
166 /** Convenience object defining the Default layer. Equivalent to Integer.valueOf(0).*/
167 public static final Integer DEFAULT_LAYER = 0;
168 /** Convenience object defining the Palette layer. Equivalent to Integer.valueOf(100).*/
169 public static final Integer PALETTE_LAYER = 100;
170 /** Convenience object defining the Modal layer. Equivalent to Integer.valueOf(200).*/
171 public static final Integer MODAL_LAYER = 200;
172 /** Convenience object defining the Popup layer. Equivalent to Integer.valueOf(300).*/
173 public static final Integer POPUP_LAYER = 300;
174 /** Convenience object defining the Drag layer. Equivalent to Integer.valueOf(400).*/
175 public static final Integer DRAG_LAYER = 400;
176 /** Convenience object defining the Frame Content layer.
177 * This layer is normally only use to position the contentPane and menuBar
178 * components of JFrame.
179 * Equivalent to Integer.valueOf(-30000).
180 * @see JFrame
181 */
182 public static final Integer FRAME_CONTENT_LAYER = -30000;
183
184 /** Bound property */
185 public static final String LAYER_PROPERTY = "layeredContainerLayer";
186 // Hashtable to store layer values for non-JComponent components
187 private Hashtable<Component,Integer> componentToLayer;
188 private boolean optimizedDrawingPossible = true;
189
190
191 //////////////////////////////////////////////////////////////////////////////
192 //// Container Override methods
193 //////////////////////////////////////////////////////////////////////////////
194 /** Create a new JLayeredPane */
195 public JLayeredPane() {
196 setLayout(null);
197 }
198
199 private void validateOptimizedDrawing() {
200 boolean layeredComponentFound = false;
201 synchronized(getTreeLock()) {
202 Integer layer;
203
204 for (Component c : getComponents()) {
205 layer = null;
206
207 if(SunToolkit.isInstanceOf(c, "javax.swing.JInternalFrame") ||
208 (c instanceof JComponent &&
209 (layer = (Integer)((JComponent)c).
210 getClientProperty(LAYER_PROPERTY)) != null))
211 {
212 if(layer != null && layer.equals(FRAME_CONTENT_LAYER))
213 continue;
214 layeredComponentFound = true;
215 break;
216 }
217 }
218 }
219
220 if(layeredComponentFound)
221 optimizedDrawingPossible = false;
222 else
223 optimizedDrawingPossible = true;
224 }
225
226 protected void addImpl(Component comp, Object constraints, int index) {
227 int layer;
228 int pos;
229
230 if(constraints instanceof Integer) {
231 layer = ((Integer)constraints).intValue();
232 setLayer(comp, layer);
233 } else
234 layer = getLayer(comp);
235
236 pos = insertIndexForLayer(layer, index);
237 super.addImpl(comp, constraints, pos);
238 comp.validate();
239 comp.repaint();
240 validateOptimizedDrawing();
241 }
242
243 /**
244 * Remove the indexed component from this pane.
245 * This is the absolute index, ignoring layers.
246 *
247 * @param index an int specifying the component to remove
248 * @see #getIndexOf
249 */
250 public void remove(int index) {
251 Component c = getComponent(index);
252 super.remove(index);
253 if (c != null && !(c instanceof JComponent)) {
254 getComponentToLayer().remove(c);
255 }
256 validateOptimizedDrawing();
257 }
258
259 /**
260 * Removes all the components from this container.
261 *
262 * @since 1.5
263 */
264 public void removeAll() {
265 Component[] children = getComponents();
266 Hashtable<Component, Integer> cToL = getComponentToLayer();
267 for (int counter = children.length - 1; counter >= 0; counter--) {
268 Component c = children[counter];
269 if (c != null && !(c instanceof JComponent)) {
270 cToL.remove(c);
271 }
272 }
273 super.removeAll();
274 }
275
276 /**
277 * Returns false if components in the pane can overlap, which makes
278 * optimized drawing impossible. Otherwise, returns true.
279 *
280 * @return false if components can overlap, else true
281 * @see JComponent#isOptimizedDrawingEnabled
282 */
283 @BeanProperty(bound = false)
284 public boolean isOptimizedDrawingEnabled() {
285 return optimizedDrawingPossible;
286 }
287
288
289 //////////////////////////////////////////////////////////////////////////////
290 //// New methods for managing layers
291 //////////////////////////////////////////////////////////////////////////////
292 /** Sets the layer property on a JComponent. This method does not cause
293 * any side effects like setLayer() (painting, add/remove, etc).
294 * Normally you should use the instance method setLayer(), in order to
295 * get the desired side-effects (like repainting).
296 *
297 * @param c the JComponent to move
298 * @param layer an int specifying the layer to move it to
299 * @see #setLayer
300 */
301 public static void putLayer(JComponent c, int layer) {
302 /// MAKE SURE THIS AND setLayer(Component c, int layer, int position) are SYNCED
303 c.putClientProperty(LAYER_PROPERTY, layer);
304 }
305
306 /** Gets the layer property for a JComponent, it
307 * does not cause any side effects like setLayer(). (painting, add/remove, etc)
308 * Normally you should use the instance method getLayer().
309 *
310 * @param c the JComponent to check
311 * @return an int specifying the component's layer
312 */
313 public static int getLayer(JComponent c) {
314 Integer i;
315 if((i = (Integer)c.getClientProperty(LAYER_PROPERTY)) != null)
316 return i.intValue();
317 return DEFAULT_LAYER.intValue();
318 }
319
320 /** Convenience method that returns the first JLayeredPane which
321 * contains the specified component. Note that all JFrames have a
322 * JLayeredPane at their root, so any component in a JFrame will
323 * have a JLayeredPane parent.
324 *
325 * @param c the Component to check
326 * @return the JLayeredPane that contains the component, or
327 * null if no JLayeredPane is found in the component
328 * hierarchy
329 * @see JFrame
330 * @see JRootPane
331 */
332 public static JLayeredPane getLayeredPaneAbove(Component c) {
333 if(c == null) return null;
334
335 Component parent = c.getParent();
336 while(parent != null && !(parent instanceof JLayeredPane))
337 parent = parent.getParent();
338 return (JLayeredPane)parent;
339 }
340
341 /** Sets the layer attribute on the specified component,
342 * making it the bottommost component in that layer.
343 * Should be called before adding to parent.
344 *
345 * @param c the Component to set the layer for
346 * @param layer an int specifying the layer to set, where
347 * lower numbers are closer to the bottom
348 */
349 public void setLayer(Component c, int layer) {
350 setLayer(c, layer, -1);
351 }
352
353 /** Sets the layer attribute for the specified component and
354 * also sets its position within that layer.
355 *
356 * @param c the Component to set the layer for
357 * @param layer an int specifying the layer to set, where
358 * lower numbers are closer to the bottom
359 * @param position an int specifying the position within the
360 * layer, where 0 is the topmost position and -1
361 * is the bottommost position
362 */
363 public void setLayer(Component c, int layer, int position) {
364 Integer layerObj;
365 layerObj = getObjectForLayer(layer);
366
367 if(layer == getLayer(c) && position == getPosition(c)) {
368 repaint(c.getBounds());
369 return;
370 }
371
372 /// MAKE SURE THIS AND putLayer(JComponent c, int layer) are SYNCED
373 if(c instanceof JComponent)
374 ((JComponent)c).putClientProperty(LAYER_PROPERTY, layerObj);
375 else
376 getComponentToLayer().put(c, layerObj);
377
378 if(c.getParent() == null || c.getParent() != this) {
379 repaint(c.getBounds());
380 return;
381 }
382
383 int index = insertIndexForLayer(c, layer, position);
384
385 setComponentZOrder(c, index);
386 repaint(c.getBounds());
387 }
388
389 /**
390 * Returns the layer attribute for the specified Component.
391 *
392 * @param c the Component to check
393 * @return an int specifying the component's current layer
394 */
395 public int getLayer(Component c) {
396 Integer i;
397 if(c instanceof JComponent)
398 i = (Integer)((JComponent)c).getClientProperty(LAYER_PROPERTY);
399 else
400 i = getComponentToLayer().get(c);
401
402 if(i == null)
403 return DEFAULT_LAYER.intValue();
404 return i.intValue();
405 }
406
407 /**
408 * Returns the index of the specified Component.
409 * This is the absolute index, ignoring layers.
410 * Index numbers, like position numbers, have the topmost component
411 * at index zero. Larger numbers are closer to the bottom.
412 *
413 * @param c the Component to check
414 * @return an int specifying the component's index
415 */
416 public int getIndexOf(Component c) {
417 int i, count;
418
419 count = getComponentCount();
420 for(i = 0; i < count; i++) {
421 if(c == getComponent(i))
422 return i;
423 }
424 return -1;
425 }
426 /**
427 * Moves the component to the top of the components in its current layer
428 * (position 0).
429 *
430 * @param c the Component to move
431 * @see #setPosition(Component, int)
432 */
433 public void moveToFront(Component c) {
434 setPosition(c, 0);
435 }
436
437 /**
438 * Moves the component to the bottom of the components in its current layer
439 * (position -1).
440 *
441 * @param c the Component to move
442 * @see #setPosition(Component, int)
443 */
444 public void moveToBack(Component c) {
445 setPosition(c, -1);
446 }
447
448 /**
449 * Moves the component to <code>position</code> within its current layer,
450 * where 0 is the topmost position within the layer and -1 is the bottommost
451 * position.
452 * <p>
453 * <b>Note:</b> Position numbering is defined by java.awt.Container, and
454 * is the opposite of layer numbering. Lower position numbers are closer
455 * to the top (0 is topmost), and higher position numbers are closer to
456 * the bottom.
457 *
458 * @param c the Component to move
459 * @param position an int in the range -1..N-1, where N is the number of
460 * components in the component's current layer
461 */
462 public void setPosition(Component c, int position) {
463 setLayer(c, getLayer(c), position);
464 }
465
466 /**
467 * Get the relative position of the component within its layer.
468 *
469 * @param c the Component to check
470 * @return an int giving the component's position, where 0 is the
471 * topmost position and the highest index value = the count
472 * count of components at that layer, minus 1
473 *
474 * @see #getComponentCountInLayer
475 */
476 public int getPosition(Component c) {
477 int i, startLayer, curLayer, startLocation, pos = 0;
478
479 getComponentCount();
480 startLocation = getIndexOf(c);
481
482 if(startLocation == -1)
483 return -1;
484
485 startLayer = getLayer(c);
486 for(i = startLocation - 1; i >= 0; i--) {
487 curLayer = getLayer(getComponent(i));
488 if(curLayer == startLayer)
489 pos++;
490 else
491 return pos;
492 }
493 return pos;
494 }
495
496 /** Returns the highest layer value from all current children.
497 * Returns 0 if there are no children.
498 *
499 * @return an int indicating the layer of the topmost component in the
500 * pane, or zero if there are no children
501 */
502 public int highestLayer() {
503 if(getComponentCount() > 0)
504 return getLayer(getComponent(0));
505 return 0;
506 }
507
508 /** Returns the lowest layer value from all current children.
509 * Returns 0 if there are no children.
510 *
511 * @return an int indicating the layer of the bottommost component in the
512 * pane, or zero if there are no children
513 */
514 public int lowestLayer() {
515 int count = getComponentCount();
516 if(count > 0)
517 return getLayer(getComponent(count-1));
518 return 0;
519 }
520
521 /**
522 * Returns the number of children currently in the specified layer.
523 *
524 * @param layer an int specifying the layer to check
525 * @return an int specifying the number of components in that layer
526 */
527 public int getComponentCountInLayer(int layer) {
528 int i, count, curLayer;
529 int layerCount = 0;
530
531 count = getComponentCount();
532 for(i = 0; i < count; i++) {
533 curLayer = getLayer(getComponent(i));
534 if(curLayer == layer) {
535 layerCount++;
536 /// Short circut the counting when we have them all
537 } else if(layerCount > 0 || curLayer < layer) {
538 break;
539 }
540 }
541
542 return layerCount;
543 }
544
545 /**
546 * Returns an array of the components in the specified layer.
547 *
548 * @param layer an int specifying the layer to check
549 * @return an array of Components contained in that layer
550 */
551 public Component[] getComponentsInLayer(int layer) {
552 int i, count, curLayer;
553 int layerCount = 0;
554 Component[] results;
555
556 results = new Component[getComponentCountInLayer(layer)];
557 count = getComponentCount();
558 for(i = 0; i < count; i++) {
559 curLayer = getLayer(getComponent(i));
560 if(curLayer == layer) {
561 results[layerCount++] = getComponent(i);
562 /// Short circut the counting when we have them all
563 } else if(layerCount > 0 || curLayer < layer) {
564 break;
565 }
566 }
567
568 return results;
569 }
570
571 /**
572 * Paints this JLayeredPane within the specified graphics context.
573 *
574 * @param g the Graphics context within which to paint
575 */
576 public void paint(Graphics g) {
577 if(isOpaque()) {
578 Rectangle r = g.getClipBounds();
579 Color c = getBackground();
580 if(c == null)
581 c = Color.lightGray;
582 g.setColor(c);
583 if (r != null) {
584 g.fillRect(r.x, r.y, r.width, r.height);
585 }
586 else {
587 g.fillRect(0, 0, getWidth(), getHeight());
588 }
589 }
590 super.paint(g);
591 }
592
593 //////////////////////////////////////////////////////////////////////////////
594 //// Implementation Details
595 //////////////////////////////////////////////////////////////////////////////
596
597 /**
598 * Returns the hashtable that maps components to layers.
599 *
600 * @return the Hashtable used to map components to their layers
601 */
602 protected Hashtable<Component,Integer> getComponentToLayer() {
603 if(componentToLayer == null)
604 componentToLayer = new Hashtable<Component,Integer>(4);
605 return componentToLayer;
606 }
607
608 /**
609 * Returns the Integer object associated with a specified layer.
610 *
611 * @param layer an int specifying the layer
612 * @return an Integer object for that layer
613 */
614 protected Integer getObjectForLayer(int layer) {
615 switch(layer) {
616 case 0:
617 return DEFAULT_LAYER;
618 case 100:
619 return PALETTE_LAYER;
620 case 200:
621 return MODAL_LAYER;
622 case 300:
623 return POPUP_LAYER;
624 case 400:
625 return DRAG_LAYER;
626 default:
627 return layer;
628 }
629 }
630
631 /**
632 * Primitive method that determines the proper location to
633 * insert a new child based on layer and position requests.
634 *
635 * @param layer an int specifying the layer
636 * @param position an int specifying the position within the layer
637 * @return an int giving the (absolute) insertion-index
638 *
639 * @see #getIndexOf
640 */
641 protected int insertIndexForLayer(int layer, int position) {
642 return insertIndexForLayer(null, layer, position);
643 }
644
645 /**
646 * This method is an extended version of insertIndexForLayer()
647 * to support setLayer which uses Container.setZOrder which does
648 * not remove the component from the containment hierarchy though
649 * we need to ignore it when calculating the insertion index.
650 *
651 * @param comp component to ignore when determining index
652 * @param layer an int specifying the layer
653 * @param position an int specifying the position within the layer
654 * @return an int giving the (absolute) insertion-index
655 *
656 * @see #getIndexOf
657 */
658 private int insertIndexForLayer(Component comp, int layer, int position) {
659 int i, count, curLayer;
660 int layerStart = -1;
661 int layerEnd = -1;
662 int componentCount = getComponentCount();
663
664 ArrayList<Component> compList =
665 new ArrayList<Component>(componentCount);
666 for (int index = 0; index < componentCount; index++) {
667 if (getComponent(index) != comp) {
668 compList.add(getComponent(index));
669 }
670 }
671
672 count = compList.size();
673 for (i = 0; i < count; i++) {
674 curLayer = getLayer(compList.get(i));
675 if (layerStart == -1 && curLayer == layer) {
676 layerStart = i;
677 }
678 if (curLayer < layer) {
679 if (i == 0) {
680 // layer is greater than any current layer
681 // [ ASSERT(layer > highestLayer()) ]
682 layerStart = 0;
683 layerEnd = 0;
684 } else {
685 layerEnd = i;
686 }
687 break;
688 }
689 }
690
691 // layer requested is lower than any current layer
692 // [ ASSERT(layer < lowestLayer()) ]
693 // put it on the bottom of the stack
694 if (layerStart == -1 && layerEnd == -1)
695 return count;
696
697 // In the case of a single layer entry handle the degenerative cases
698 if (layerStart != -1 && layerEnd == -1)
699 layerEnd = count;
700
701 if (layerEnd != -1 && layerStart == -1)
702 layerStart = layerEnd;
703
704 // If we are adding to the bottom, return the last element
705 if (position == -1)
706 return layerEnd;
707
708 // Otherwise make sure the requested position falls in the
709 // proper range
710 if (position > -1 && layerStart + position <= layerEnd)
711 return layerStart + position;
712
713 // Otherwise return the end of the layer
714 return layerEnd;
715 }
716
717 /**
718 * Returns a string representation of this JLayeredPane. This method
719 * is intended to be used only for debugging purposes, and the
720 * content and format of the returned string may vary between
721 * implementations. The returned string may be empty but may not
722 * be <code>null</code>.
723 *
724 * @return a string representation of this JLayeredPane.
725 */
726 protected String paramString() {
727 String optimizedDrawingPossibleString = (optimizedDrawingPossible ?
728 "true" : "false");
729
730 return super.paramString() +
731 ",optimizedDrawingPossible=" + optimizedDrawingPossibleString;
732 }
733
734 /////////////////
735 // Accessibility support
736 ////////////////
737
738 /**
739 * Gets the AccessibleContext associated with this JLayeredPane.
740 * For layered panes, the AccessibleContext takes the form of an
741 * AccessibleJLayeredPane.
742 * A new AccessibleJLayeredPane instance is created if necessary.
743 *
744 * @return an AccessibleJLayeredPane that serves as the
745 * AccessibleContext of this JLayeredPane
746 */
747 @BeanProperty(bound = false)
748 public AccessibleContext getAccessibleContext() {
749 if (accessibleContext == null) {
750 accessibleContext = new AccessibleJLayeredPane();
751 }
752 return accessibleContext;
753 }
754
755 /**
756 * This class implements accessibility support for the
757 * <code>JLayeredPane</code> class. It provides an implementation of the
758 * Java Accessibility API appropriate to layered pane user-interface
759 * elements.
760 * <p>
761 * <strong>Warning:</strong>
762 * Serialized objects of this class will not be compatible with
763 * future Swing releases. The current serialization support is
764 * appropriate for short term storage or RMI between applications running
765 * the same version of Swing. As of 1.4, support for long term storage
766 * of all JavaBeans™
767 * has been added to the <code>java.beans</code> package.
768 * Please see {@link java.beans.XMLEncoder}.
769 */
770 @SuppressWarnings("serial")
771 protected class AccessibleJLayeredPane extends AccessibleJComponent {
772
773 /**
774 * Get the role of this object.
775 *
776 * @return an instance of AccessibleRole describing the role of the
777 * object
778 * @see AccessibleRole
779 */
780 public AccessibleRole getAccessibleRole() {
781 return AccessibleRole.LAYERED_PANE;
782 }
783 }
784 }