1 /*
2 * Copyright (c) 1997, 2014, 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
26 package java.awt.dnd;
27
28 import java.util.TooManyListenersException;
29
30 import java.io.IOException;
31 import java.io.ObjectInputStream;
32 import java.io.ObjectOutputStream;
33 import java.io.Serializable;
34
35 import java.awt.Component;
36 import java.awt.Dimension;
37 import java.awt.GraphicsEnvironment;
38 import java.awt.HeadlessException;
39 import java.awt.Insets;
40 import java.awt.Point;
41 import java.awt.Rectangle;
42 import java.awt.Toolkit;
43 import java.awt.event.ActionEvent;
44 import java.awt.event.ActionListener;
45 import java.awt.datatransfer.FlavorMap;
46 import java.awt.datatransfer.SystemFlavorMap;
47 import javax.swing.Timer;
48 import java.awt.peer.ComponentPeer;
49 import java.awt.peer.LightweightPeer;
50 import java.awt.dnd.peer.DropTargetPeer;
51
52
53 /**
54 * The <code>DropTarget</code> is associated
55 * with a <code>Component</code> when that <code>Component</code>
56 * wishes
57 * to accept drops during Drag and Drop operations.
58 * <P>
59 * Each
60 * <code>DropTarget</code> is associated with a <code>FlavorMap</code>.
61 * The default <code>FlavorMap</code> hereafter designates the
62 * <code>FlavorMap</code> returned by <code>SystemFlavorMap.getDefaultFlavorMap()</code>.
63 *
64 * @since 1.2
65 */
66
67 public class DropTarget implements DropTargetListener, Serializable {
68
69 private static final long serialVersionUID = -6283860791671019047L;
70
71 /**
72 * Creates a new DropTarget given the <code>Component</code>
73 * to associate itself with, an <code>int</code> representing
74 * the default acceptable action(s) to
75 * support, a <code>DropTargetListener</code>
76 * to handle event processing, a <code>boolean</code> indicating
77 * if the <code>DropTarget</code> is currently accepting drops, and
78 * a <code>FlavorMap</code> to use (or null for the default <CODE>FlavorMap</CODE>).
79 * <P>
80 * The Component will receive drops only if it is enabled.
81 * @param c The <code>Component</code> with which this <code>DropTarget</code> is associated
82 * @param ops The default acceptable actions for this <code>DropTarget</code>
83 * @param dtl The <code>DropTargetListener</code> for this <code>DropTarget</code>
84 * @param act Is the <code>DropTarget</code> accepting drops.
85 * @param fm The <code>FlavorMap</code> to use, or null for the default <CODE>FlavorMap</CODE>
86 * @exception HeadlessException if GraphicsEnvironment.isHeadless()
87 * returns true
88 * @see java.awt.GraphicsEnvironment#isHeadless
89 */
90 public DropTarget(Component c, int ops, DropTargetListener dtl,
91 boolean act, FlavorMap fm)
92 throws HeadlessException
93 {
94 if (GraphicsEnvironment.isHeadless()) {
95 throw new HeadlessException();
96 }
97
98 component = c;
99
100 setDefaultActions(ops);
101
102 if (dtl != null) try {
103 addDropTargetListener(dtl);
104 } catch (TooManyListenersException tmle) {
105 // do nothing!
106 }
107
108 if (c != null) {
109 c.setDropTarget(this);
110 setActive(act);
111 }
112
113 if (fm != null) {
114 flavorMap = fm;
115 } else {
116 flavorMap = SystemFlavorMap.getDefaultFlavorMap();
117 }
118 }
119
120 /**
121 * Creates a <code>DropTarget</code> given the <code>Component</code>
122 * to associate itself with, an <code>int</code> representing
123 * the default acceptable action(s)
124 * to support, a <code>DropTargetListener</code>
125 * to handle event processing, and a <code>boolean</code> indicating
126 * if the <code>DropTarget</code> is currently accepting drops.
127 * <P>
128 * The Component will receive drops only if it is enabled.
129 * @param c The <code>Component</code> with which this <code>DropTarget</code> is associated
130 * @param ops The default acceptable actions for this <code>DropTarget</code>
131 * @param dtl The <code>DropTargetListener</code> for this <code>DropTarget</code>
132 * @param act Is the <code>DropTarget</code> accepting drops.
133 * @exception HeadlessException if GraphicsEnvironment.isHeadless()
134 * returns true
135 * @see java.awt.GraphicsEnvironment#isHeadless
136 */
137 public DropTarget(Component c, int ops, DropTargetListener dtl,
138 boolean act)
139 throws HeadlessException
140 {
141 this(c, ops, dtl, act, null);
142 }
143
144 /**
145 * Creates a <code>DropTarget</code>.
146 * @exception HeadlessException if GraphicsEnvironment.isHeadless()
147 * returns true
148 * @see java.awt.GraphicsEnvironment#isHeadless
149 */
150 public DropTarget() throws HeadlessException {
151 this(null, DnDConstants.ACTION_COPY_OR_MOVE, null, true, null);
152 }
153
154 /**
155 * Creates a <code>DropTarget</code> given the <code>Component</code>
156 * to associate itself with, and the <code>DropTargetListener</code>
157 * to handle event processing.
158 * <P>
159 * The Component will receive drops only if it is enabled.
160 * @param c The <code>Component</code> with which this <code>DropTarget</code> is associated
161 * @param dtl The <code>DropTargetListener</code> for this <code>DropTarget</code>
162 * @exception HeadlessException if GraphicsEnvironment.isHeadless()
163 * returns true
164 * @see java.awt.GraphicsEnvironment#isHeadless
165 */
166 public DropTarget(Component c, DropTargetListener dtl)
167 throws HeadlessException
168 {
169 this(c, DnDConstants.ACTION_COPY_OR_MOVE, dtl, true, null);
170 }
171
172 /**
173 * Creates a <code>DropTarget</code> given the <code>Component</code>
174 * to associate itself with, an <code>int</code> representing
175 * the default acceptable action(s) to support, and a
176 * <code>DropTargetListener</code> to handle event processing.
177 * <P>
178 * The Component will receive drops only if it is enabled.
179 * @param c The <code>Component</code> with which this <code>DropTarget</code> is associated
180 * @param ops The default acceptable actions for this <code>DropTarget</code>
181 * @param dtl The <code>DropTargetListener</code> for this <code>DropTarget</code>
182 * @exception HeadlessException if GraphicsEnvironment.isHeadless()
183 * returns true
184 * @see java.awt.GraphicsEnvironment#isHeadless
185 */
186 public DropTarget(Component c, int ops, DropTargetListener dtl)
187 throws HeadlessException
188 {
189 this(c, ops, dtl, true);
190 }
191
192 /**
193 * Note: this interface is required to permit the safe association
194 * of a DropTarget with a Component in one of two ways, either:
195 * <code> component.setDropTarget(droptarget); </code>
196 * or <code> droptarget.setComponent(component); </code>
197 * <P>
198 * The Component will receive drops only if it is enabled.
199 * @param c The new <code>Component</code> this <code>DropTarget</code>
200 * is to be associated with.
201 */
202
203 public synchronized void setComponent(Component c) {
204 if (component == c || component != null && component.equals(c))
205 return;
206
207 Component old;
208 ComponentPeer oldPeer = null;
209
210 if ((old = component) != null) {
211 clearAutoscroll();
212
213 component = null;
214
215 if (componentPeer != null) {
216 oldPeer = componentPeer;
217 removeNotify(componentPeer);
218 }
219
220 old.setDropTarget(null);
221
222 }
223
224 if ((component = c) != null) try {
225 c.setDropTarget(this);
226 } catch (Exception e) { // undo the change
227 if (old != null) {
228 old.setDropTarget(this);
229 addNotify(oldPeer);
230 }
231 }
232 }
233
234 /**
235 * Gets the <code>Component</code> associated
236 * with this <code>DropTarget</code>.
237 *
238 * @return the current <code>Component</code>
239 */
240
241 public synchronized Component getComponent() {
242 return component;
243 }
244
245 /**
246 * Sets the default acceptable actions for this <code>DropTarget</code>
247 *
248 * @param ops the default actions
249 * @see java.awt.dnd.DnDConstants
250 */
251
252 public void setDefaultActions(int ops) {
253 getDropTargetContext().setTargetActions(ops & (DnDConstants.ACTION_COPY_OR_MOVE | DnDConstants.ACTION_REFERENCE));
254 }
255
256 /*
257 * Called by DropTargetContext.setTargetActions()
258 * with appropriate synchronization.
259 */
260 void doSetDefaultActions(int ops) {
261 actions = ops;
262 }
263
264 /**
265 * Gets an <code>int</code> representing the
266 * current action(s) supported by this <code>DropTarget</code>.
267 *
268 * @return the current default actions
269 */
270
271 public int getDefaultActions() {
272 return actions;
273 }
274
275 /**
276 * Sets the DropTarget active if <code>true</code>,
277 * inactive if <code>false</code>.
278 *
279 * @param isActive sets the <code>DropTarget</code> (in)active.
280 */
281
282 public synchronized void setActive(boolean isActive) {
283 if (isActive != active) {
284 active = isActive;
285 }
286
287 if (!active) clearAutoscroll();
288 }
289
290 /**
291 * Reports whether or not
292 * this <code>DropTarget</code>
293 * is currently active (ready to accept drops).
294 *
295 * @return <CODE>true</CODE> if active, <CODE>false</CODE> if not
296 */
297
298 public boolean isActive() {
299 return active;
300 }
301
302 /**
303 * Adds a new <code>DropTargetListener</code> (UNICAST SOURCE).
304 *
305 * @param dtl The new <code>DropTargetListener</code>
306 *
307 * @throws TooManyListenersException if a
308 * <code>DropTargetListener</code> is already added to this
309 * <code>DropTarget</code>.
310 */
311
312 public synchronized void addDropTargetListener(DropTargetListener dtl) throws TooManyListenersException {
313 if (dtl == null) return;
314
315 if (equals(dtl)) throw new IllegalArgumentException("DropTarget may not be its own Listener");
316
317 if (dtListener == null)
318 dtListener = dtl;
319 else
320 throw new TooManyListenersException();
321 }
322
323 /**
324 * Removes the current <code>DropTargetListener</code> (UNICAST SOURCE).
325 *
326 * @param dtl the DropTargetListener to deregister.
327 */
328
329 public synchronized void removeDropTargetListener(DropTargetListener dtl) {
330 if (dtl != null && dtListener != null) {
331 if(dtListener.equals(dtl))
332 dtListener = null;
333 else
334 throw new IllegalArgumentException("listener mismatch");
335 }
336 }
337
338 /**
339 * Calls <code>dragEnter</code> on the registered
340 * <code>DropTargetListener</code> and passes it
341 * the specified <code>DropTargetDragEvent</code>.
342 * Has no effect if this <code>DropTarget</code>
343 * is not active.
344 *
345 * @param dtde the <code>DropTargetDragEvent</code>
346 *
347 * @throws NullPointerException if this <code>DropTarget</code>
348 * is active and <code>dtde</code> is <code>null</code>
349 *
350 * @see #isActive
351 */
352 public synchronized void dragEnter(DropTargetDragEvent dtde) {
353 isDraggingInside = true;
354
355 if (!active) return;
356
357 if (dtListener != null) {
358 dtListener.dragEnter(dtde);
359 } else
360 dtde.getDropTargetContext().setTargetActions(DnDConstants.ACTION_NONE);
361
362 initializeAutoscrolling(dtde.getLocation());
363 }
364
365 /**
366 * Calls <code>dragOver</code> on the registered
367 * <code>DropTargetListener</code> and passes it
368 * the specified <code>DropTargetDragEvent</code>.
369 * Has no effect if this <code>DropTarget</code>
370 * is not active.
371 *
372 * @param dtde the <code>DropTargetDragEvent</code>
373 *
374 * @throws NullPointerException if this <code>DropTarget</code>
375 * is active and <code>dtde</code> is <code>null</code>
376 *
377 * @see #isActive
378 */
379 public synchronized void dragOver(DropTargetDragEvent dtde) {
380 if (!active) return;
381
382 if (dtListener != null && active) dtListener.dragOver(dtde);
383
384 updateAutoscroll(dtde.getLocation());
385 }
386
387 /**
388 * Calls <code>dropActionChanged</code> on the registered
389 * <code>DropTargetListener</code> and passes it
390 * the specified <code>DropTargetDragEvent</code>.
391 * Has no effect if this <code>DropTarget</code>
392 * is not active.
393 *
394 * @param dtde the <code>DropTargetDragEvent</code>
395 *
396 * @throws NullPointerException if this <code>DropTarget</code>
397 * is active and <code>dtde</code> is <code>null</code>
398 *
399 * @see #isActive
400 */
401 public synchronized void dropActionChanged(DropTargetDragEvent dtde) {
402 if (!active) return;
403
404 if (dtListener != null) dtListener.dropActionChanged(dtde);
405
406 updateAutoscroll(dtde.getLocation());
407 }
408
409 /**
410 * Calls <code>dragExit</code> on the registered
411 * <code>DropTargetListener</code> and passes it
412 * the specified <code>DropTargetEvent</code>.
413 * Has no effect if this <code>DropTarget</code>
414 * is not active.
415 * <p>
416 * This method itself does not throw any exception
417 * for null parameter but for exceptions thrown by
418 * the respective method of the listener.
419 *
420 * @param dte the <code>DropTargetEvent</code>
421 *
422 * @see #isActive
423 */
424 public synchronized void dragExit(DropTargetEvent dte) {
425 isDraggingInside = false;
426
427 if (!active) return;
428
429 if (dtListener != null && active) dtListener.dragExit(dte);
430
431 clearAutoscroll();
432 }
433
434 /**
435 * Calls <code>drop</code> on the registered
436 * <code>DropTargetListener</code> and passes it
437 * the specified <code>DropTargetDropEvent</code>
438 * if this <code>DropTarget</code> is active.
439 *
440 * @param dtde the <code>DropTargetDropEvent</code>
441 *
442 * @throws NullPointerException if <code>dtde</code> is null
443 * and at least one of the following is true: this
444 * <code>DropTarget</code> is not active, or there is
445 * no a <code>DropTargetListener</code> registered.
446 *
447 * @see #isActive
448 */
449 public synchronized void drop(DropTargetDropEvent dtde) {
450 isDraggingInside = false;
451
452 clearAutoscroll();
453
454 if (dtListener != null && active)
455 dtListener.drop(dtde);
456 else { // we should'nt get here ...
457 dtde.rejectDrop();
458 }
459 }
460
461 /**
462 * Gets the <code>FlavorMap</code>
463 * associated with this <code>DropTarget</code>.
464 * If no <code>FlavorMap</code> has been set for this
465 * <code>DropTarget</code>, it is associated with the default
466 * <code>FlavorMap</code>.
467 *
468 * @return the FlavorMap for this DropTarget
469 */
470
471 public FlavorMap getFlavorMap() { return flavorMap; }
472
473 /**
474 * Sets the <code>FlavorMap</code> associated
475 * with this <code>DropTarget</code>.
476 *
477 * @param fm the new <code>FlavorMap</code>, or null to
478 * associate the default FlavorMap with this DropTarget.
479 */
480
481 public void setFlavorMap(FlavorMap fm) {
482 flavorMap = fm == null ? SystemFlavorMap.getDefaultFlavorMap() : fm;
483 }
484
485 /**
486 * Notify the DropTarget that it has been associated with a Component
487 *
488 **********************************************************************
489 * This method is usually called from java.awt.Component.addNotify() of
490 * the Component associated with this DropTarget to notify the DropTarget
491 * that a ComponentPeer has been associated with that Component.
492 *
493 * Calling this method, other than to notify this DropTarget of the
494 * association of the ComponentPeer with the Component may result in
495 * a malfunction of the DnD system.
496 **********************************************************************
497 *
498 * @param peer The Peer of the Component we are associated with!
499 *
500 */
501
502 public void addNotify(ComponentPeer peer) {
503 if (peer == componentPeer) return;
504
505 componentPeer = peer;
506
507 for (Component c = component;
508 c != null && peer instanceof LightweightPeer; c = c.getParent()) {
509 peer = c.getPeer();
510 }
511
512 if (peer instanceof DropTargetPeer) {
513 nativePeer = peer;
514 ((DropTargetPeer)peer).addDropTarget(this);
515 } else {
516 nativePeer = null;
517 }
518 }
519
520 /**
521 * Notify the DropTarget that it has been disassociated from a Component
522 *
523 **********************************************************************
524 * This method is usually called from java.awt.Component.removeNotify() of
525 * the Component associated with this DropTarget to notify the DropTarget
526 * that a ComponentPeer has been disassociated with that Component.
527 *
528 * Calling this method, other than to notify this DropTarget of the
529 * disassociation of the ComponentPeer from the Component may result in
530 * a malfunction of the DnD system.
531 **********************************************************************
532 *
533 * @param peer The Peer of the Component we are being disassociated from!
534 */
535
536 public void removeNotify(ComponentPeer peer) {
537 if (nativePeer != null)
538 ((DropTargetPeer)nativePeer).removeDropTarget(this);
539
540 componentPeer = nativePeer = null;
541
542 synchronized (this) {
543 if (isDraggingInside) {
544 dragExit(new DropTargetEvent(getDropTargetContext()));
545 }
546 }
547 }
548
549 /**
550 * Gets the <code>DropTargetContext</code> associated
551 * with this <code>DropTarget</code>.
552 *
553 * @return the <code>DropTargetContext</code> associated with this <code>DropTarget</code>.
554 */
555
556 public DropTargetContext getDropTargetContext() {
557 return dropTargetContext;
558 }
559
560 /**
561 * Creates the DropTargetContext associated with this DropTarget.
562 * Subclasses may override this method to instantiate their own
563 * DropTargetContext subclass.
564 *
565 * This call is typically *only* called by the platform's
566 * DropTargetContextPeer as a drag operation encounters this
567 * DropTarget. Accessing the Context while no Drag is current
568 * has undefined results.
569 * @return the DropTargetContext associated with this DropTarget
570 */
571
572 protected DropTargetContext createDropTargetContext() {
573 return new DropTargetContext(this);
574 }
575
576 /**
577 * Serializes this <code>DropTarget</code>. Performs default serialization,
578 * and then writes out this object's <code>DropTargetListener</code> if and
579 * only if it can be serialized. If not, <code>null</code> is written
580 * instead.
581 *
582 * @serialData The default serializable fields, in alphabetical order,
583 * followed by either a <code>DropTargetListener</code>
584 * instance, or <code>null</code>.
585 * @since 1.4
586 */
587 private void writeObject(ObjectOutputStream s) throws IOException {
588 s.defaultWriteObject();
589
590 s.writeObject(SerializationTester.test(dtListener)
591 ? dtListener : null);
592 }
593
594 /**
595 * Deserializes this <code>DropTarget</code>. This method first performs
596 * default deserialization for all non-<code>transient</code> fields. An
597 * attempt is then made to deserialize this object's
598 * <code>DropTargetListener</code> as well. This is first attempted by
599 * deserializing the field <code>dtListener</code>, because, in releases
600 * prior to 1.4, a non-<code>transient</code> field of this name stored the
601 * <code>DropTargetListener</code>. If this fails, the next object in the
602 * stream is used instead.
603 *
604 * @since 1.4
605 */
606 private void readObject(ObjectInputStream s)
607 throws ClassNotFoundException, IOException
608 {
609 ObjectInputStream.GetField f = s.readFields();
610
611 try {
612 dropTargetContext =
613 (DropTargetContext)f.get("dropTargetContext", null);
614 } catch (IllegalArgumentException e) {
615 // Pre-1.4 support. 'dropTargetContext' was previously transient
616 }
617 if (dropTargetContext == null) {
618 dropTargetContext = createDropTargetContext();
619 }
620
621 component = (Component)f.get("component", null);
622 actions = f.get("actions", DnDConstants.ACTION_COPY_OR_MOVE);
623 active = f.get("active", true);
624
625 // Pre-1.4 support. 'dtListener' was previously non-transient
626 try {
627 dtListener = (DropTargetListener)f.get("dtListener", null);
628 } catch (IllegalArgumentException e) {
629 // 1.4-compatible byte stream. 'dtListener' was written explicitly
630 dtListener = (DropTargetListener)s.readObject();
631 }
632 }
633
634 /*********************************************************************/
635
636 /**
637 * this protected nested class implements autoscrolling
638 */
639
640 protected static class DropTargetAutoScroller implements ActionListener {
641
642 /**
643 * construct a DropTargetAutoScroller
644 *
645 * @param c the <code>Component</code>
646 * @param p the <code>Point</code>
647 */
648
649 protected DropTargetAutoScroller(Component c, Point p) {
650 super();
651
652 component = c;
653 autoScroll = (Autoscroll)component;
654
655 Toolkit t = Toolkit.getDefaultToolkit();
656
657 Integer initial = Integer.valueOf(100);
658 Integer interval = Integer.valueOf(100);
659
660 try {
661 initial = (Integer)t.getDesktopProperty("DnD.Autoscroll.initialDelay");
662 } catch (Exception e) {
663 // ignore
664 }
665
666 try {
667 interval = (Integer)t.getDesktopProperty("DnD.Autoscroll.interval");
668 } catch (Exception e) {
669 // ignore
670 }
671
672 timer = new Timer(interval.intValue(), this);
673
674 timer.setCoalesce(true);
675 timer.setInitialDelay(initial.intValue());
676
677 locn = p;
678 prev = p;
679
680 try {
681 hysteresis = ((Integer)t.getDesktopProperty("DnD.Autoscroll.cursorHysteresis")).intValue();
682 } catch (Exception e) {
683 // ignore
684 }
685
686 timer.start();
687 }
688
689 /**
690 * update the geometry of the autoscroll region
691 */
692
693 private void updateRegion() {
694 Insets i = autoScroll.getAutoscrollInsets();
695 Dimension size = component.getSize();
696
697 if (size.width != outer.width || size.height != outer.height)
698 outer.reshape(0, 0, size.width, size.height);
699
700 if (inner.x != i.left || inner.y != i.top)
701 inner.setLocation(i.left, i.top);
702
703 int newWidth = size.width - (i.left + i.right);
704 int newHeight = size.height - (i.top + i.bottom);
705
706 if (newWidth != inner.width || newHeight != inner.height)
707 inner.setSize(newWidth, newHeight);
708
709 }
710
711 /**
712 * cause autoscroll to occur
713 *
714 * @param newLocn the <code>Point</code>
715 */
716
717 protected synchronized void updateLocation(Point newLocn) {
718 prev = locn;
719 locn = newLocn;
720
721 if (Math.abs(locn.x - prev.x) > hysteresis ||
722 Math.abs(locn.y - prev.y) > hysteresis) {
723 if (timer.isRunning()) timer.stop();
724 } else {
725 if (!timer.isRunning()) timer.start();
726 }
727 }
728
729 /**
730 * cause autoscrolling to stop
731 */
732
733 protected void stop() { timer.stop(); }
734
735 /**
736 * cause autoscroll to occur
737 *
738 * @param e the <code>ActionEvent</code>
739 */
740
741 public synchronized void actionPerformed(ActionEvent e) {
742 updateRegion();
743
744 if (outer.contains(locn) && !inner.contains(locn))
745 autoScroll.autoscroll(locn);
746 }
747
748 /*
749 * fields
750 */
751
752 private Component component;
753 private Autoscroll autoScroll;
754
755 private Timer timer;
756
757 private Point locn;
758 private Point prev;
759
760 private Rectangle outer = new Rectangle();
761 private Rectangle inner = new Rectangle();
762
763 private int hysteresis = 10;
764 }
765
766 /*********************************************************************/
767
768 /**
769 * create an embedded autoscroller
770 *
771 * @param c the <code>Component</code>
772 * @param p the <code>Point</code>
773 * @return an embedded autoscroller
774 */
775
776 protected DropTargetAutoScroller createDropTargetAutoScroller(Component c, Point p) {
777 return new DropTargetAutoScroller(c, p);
778 }
779
780 /**
781 * initialize autoscrolling
782 *
783 * @param p the <code>Point</code>
784 */
785
786 protected void initializeAutoscrolling(Point p) {
787 if (component == null || !(component instanceof Autoscroll)) return;
788
789 autoScroller = createDropTargetAutoScroller(component, p);
790 }
791
792 /**
793 * update autoscrolling with current cursor location
794 *
795 * @param dragCursorLocn the <code>Point</code>
796 */
797
798 protected void updateAutoscroll(Point dragCursorLocn) {
799 if (autoScroller != null) autoScroller.updateLocation(dragCursorLocn);
800 }
801
802 /**
803 * clear autoscrolling
804 */
805
806 protected void clearAutoscroll() {
807 if (autoScroller != null) {
808 autoScroller.stop();
809 autoScroller = null;
810 }
811 }
812
813 /**
814 * The DropTargetContext associated with this DropTarget.
815 *
816 * @serial
817 */
818 private DropTargetContext dropTargetContext = createDropTargetContext();
819
820 /**
821 * The Component associated with this DropTarget.
822 *
823 * @serial
824 */
825 private Component component;
826
827 /*
828 * That Component's Peer
829 */
830 private transient ComponentPeer componentPeer;
831
832 /*
833 * That Component's "native" Peer
834 */
835 private transient ComponentPeer nativePeer;
836
837
838 /**
839 * Default permissible actions supported by this DropTarget.
840 *
841 * @see #setDefaultActions
842 * @see #getDefaultActions
843 * @serial
844 */
845 int actions = DnDConstants.ACTION_COPY_OR_MOVE;
846
847 /**
848 * <code>true</code> if the DropTarget is accepting Drag & Drop operations.
849 *
850 * @serial
851 */
852 boolean active = true;
853
854 /*
855 * the auto scrolling object
856 */
857
858 private transient DropTargetAutoScroller autoScroller;
859
860 /*
861 * The delegate
862 */
863
864 private transient DropTargetListener dtListener;
865
866 /*
867 * The FlavorMap
868 */
869
870 private transient FlavorMap flavorMap;
871
872 /*
873 * If the dragging is currently inside this drop target
874 */
875 private transient boolean isDraggingInside;
876 }