summaryrefslogtreecommitdiff
path: root/libjava/classpath/java/awt/dnd/DropTarget.java
blob: e5180d074c08469a3da0d13484bc0c04639ce4c1 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
/* DropTarget.java --
   Copyright (C) 2002, 2003, 2004  Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU Classpath is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU Classpath; see the file COPYING.  If not, write to the
Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
02110-1301 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
conditions of the GNU General Public License cover the whole
combination.

As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
modules, and to copy and distribute the resulting executable under
terms of your choice, provided that you also meet, for each linked
independent module, the terms and conditions of the license of that
module.  An independent module is a module which is not derived from
or based on this library.  If you modify this library, you may extend
this exception to your version of the library, but you are not
obligated to do so.  If you do not wish to do so, delete this
exception statement from your version. */


package java.awt.dnd;

import java.awt.Component;
import java.awt.GraphicsEnvironment;
import java.awt.HeadlessException;
import java.awt.Insets;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.datatransfer.FlavorMap;
import java.awt.datatransfer.SystemFlavorMap;
import java.awt.dnd.peer.DropTargetPeer;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.peer.ComponentPeer;
import java.awt.peer.LightweightPeer;
import java.io.Serializable;
import java.util.EventListener;
import java.util.TooManyListenersException;

import javax.swing.Timer;

/**
 * @author Michael Koch
 * @since 1.2
 */
public class DropTarget
  implements DropTargetListener, EventListener, Serializable
{
  /**
   * Compatible with JDK 1.2+
   */
  private static final long serialVersionUID = -6283860791671019047L;

  protected static class DropTargetAutoScroller
    implements ActionListener
  {
    /**
     * The threshold that keeps the autoscroller running.
     */
    private static final int HYSTERESIS = 10;

    /**
     * The initial timer delay.
     */
    private static final int DELAY = 100;

    private Component component;
    private Point point;

    /**
     * The timer that triggers autoscrolling.
     */
    private Timer timer;

    /**
     * The outer region of the scroller. This is the component's size.
     */
    private Rectangle outer;

    /**
     * The inner region of the scroller. This is the component size without
     * the autoscroll insets.
     */
    private Rectangle inner;

    protected DropTargetAutoScroller (Component c, Point p)
    {
      component = c;
      point = p;
      timer = new Timer(DELAY, this);
      timer.setCoalesce(true);
      timer.start();
    }

    protected void updateLocation (Point newLocn)
    {
      Point previous = point;
      point = newLocn;
      if (Math.abs(point.x - previous.x) > HYSTERESIS
          || Math.abs(point.y - previous.y) > HYSTERESIS)
        {
          if (timer.isRunning())
            timer.stop();
        }
      else
        {
          if (! timer.isRunning())
            timer.start();
        }
    }

    protected void stop ()
    {
      timer.start();
    }

    public void actionPerformed (ActionEvent e)
    {
      Autoscroll autoScroll = (Autoscroll) component;

      // First synchronize the inner and outer rectangles.
      Insets i = autoScroll.getAutoscrollInsets();
      int width = component.getWidth();
      int height = component.getHeight();
      if (width != outer.width || height != outer.height)
        outer.setBounds(0, 0, width, height);
      if (inner.x != i.left || inner.y != i.top)
        inner.setLocation(i.left, i.top);
      int inWidth = width - i.left - i.right;
      int inHeight = height - i.top - i.bottom;
      if (inWidth != inner.width || inHeight != inner.height)
        inner.setSize(inWidth, inHeight);

      // Scroll if the outer rectangle contains the location, but the
      // inner doesn't.
      if (outer.contains(point) && ! inner.contains(point))
        autoScroll.autoscroll(point);
    }
  }

  private Component component;
  private FlavorMap flavorMap;
  private int actions;
  private DropTargetPeer peer;
  private DropTargetContext dropTargetContext;
  private DropTargetListener dropTargetListener;
  private DropTarget.DropTargetAutoScroller autoscroller;
  private boolean active = true;

  /**
   * Creates a <code>DropTarget</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless()
   * returns true.
   */
  public DropTarget ()
  {
    this (null, DnDConstants.ACTION_COPY_OR_MOVE, null, true, null);
  }

  /**
   * Creates a <code>DropTarget</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless()
   * returns true.
   */
  public DropTarget (Component c, DropTargetListener dtl)
  {
    this (c, DnDConstants.ACTION_COPY_OR_MOVE, dtl, true, null);
  }

  /**
   * Creates a <code>DropTarget</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless()
   * returns true.
   */
  public DropTarget (Component c, int i, DropTargetListener dtl)
  {
    this (c, i, dtl, true, null);
  }

  /**
   * Creates a <code>DropTarget</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless()
   * returns true.
   */
  public DropTarget (Component c, int i, DropTargetListener dtl, boolean b)
  {
    this (c, i, dtl, b, null);
  }

  /**
   * Creates a <code>DropTarget</code> object.
   *
   * @exception HeadlessException If GraphicsEnvironment.isHeadless()
   * returns true.
   */
  public DropTarget (Component c, int i, DropTargetListener dtl, boolean b,
                     FlavorMap fm)
  {
    if (GraphicsEnvironment.isHeadless ())
      throw new HeadlessException ();

    setComponent(c);
    setDefaultActions(i);
    dropTargetListener = dtl;

    if (fm == null)
      flavorMap = SystemFlavorMap.getDefaultFlavorMap();
    else
      flavorMap = fm;

    setActive (b);

    if (c != null)
      c.setDropTarget(this);
  }

  /**
   * Sets the component associated with this drop target object.
   */
  public void setComponent (Component c)
  {
    if (component != null)
      clearAutoscroll();
    component = c;
  }

  /**
   * Returns the component associated with this drop target object.
   */
  public Component getComponent ()
  {
    return component;
  }

  /**
   * Sets the default actions.
   */
  public void setDefaultActions (int ops)
  {
    actions = ops;
  }

  /**
   * Returns the default actions.
   */
  public int getDefaultActions ()
  {
    return actions;
  }

  public void setActive (boolean active)
  {
    this.active = active;
    if (! active)
      clearAutoscroll();
  }

  public boolean isActive()
  {
    return active;
  }

  /**
   * Adds a new <code>DropTargetListener</code>.
   *
   * @exception TooManyListenersException Sun's JDK does not, despite
   * documentation, throw this exception here when you install an additional
   * <code>DropTargetListener</code>.  So to be compatible, we do the same
   * thing.
   */
  public void addDropTargetListener (DropTargetListener dtl)
    throws TooManyListenersException
  {
    if (dtl == null)
      return;

    if (dtl.equals(this))
      throw new IllegalArgumentException();

    if (dropTargetListener != null)
      throw new TooManyListenersException();

    dropTargetListener = dtl;
  }

  public void removeDropTargetListener(DropTargetListener dtl)
  {
    if (dropTargetListener != null)
      dropTargetListener = null;
  }

  public void dragEnter(DropTargetDragEvent dtde)
  {
    if (active)
      {
        if (dropTargetListener != null)
          dropTargetListener.dragEnter(dtde);
        initializeAutoscrolling(dtde.getLocation());
      }
  }

  public void dragOver(DropTargetDragEvent dtde)
  {
    if (active)
      {
        if (dropTargetListener != null)
          dropTargetListener.dragOver(dtde);
        updateAutoscroll(dtde.getLocation());
      }
  }

  public void dropActionChanged(DropTargetDragEvent dtde)
  {
    if (active)
      {
        if (dropTargetListener != null)
          dropTargetListener.dropActionChanged(dtde);
        updateAutoscroll(dtde.getLocation());
      }
  }

  public void dragExit(DropTargetEvent dte)
  {
    if (active)
      {
        if (dropTargetListener != null)
          dropTargetListener.dragExit(dte);
        clearAutoscroll();
      }
  }

  public void drop(DropTargetDropEvent dtde)
  {
    clearAutoscroll();
    if (dropTargetListener != null)
      dropTargetListener.drop(dtde);
  }

  public FlavorMap getFlavorMap()
  {
    return flavorMap;
  }

  public void setFlavorMap(FlavorMap fm)
  {
    flavorMap = fm;
  }

  public void addNotify(ComponentPeer p)
  {
    Component c = component;
    while (c != null && p instanceof LightweightPeer)
      {
        p = c.getPeer();
        c = c.getParent();
      }

    if (p instanceof DropTargetPeer)
      {
        peer = ((DropTargetPeer) p);
        peer.addDropTarget(this);
      }
    else
      peer = null;
  }

  public void removeNotify(ComponentPeer p)
  {
    ((DropTargetPeer) peer).removeDropTarget(this);
    peer = null;
    p = null;
  }

  public DropTargetContext getDropTargetContext()
  {
    if (dropTargetContext == null)
      dropTargetContext = createDropTargetContext ();

    return dropTargetContext;
  }

  protected DropTargetContext createDropTargetContext()
  {
    if (dropTargetContext == null)
      dropTargetContext = new DropTargetContext (this);

    return dropTargetContext;
  }

  protected DropTarget.DropTargetAutoScroller createDropTargetAutoScroller
                                                       (Component c, Point p)
  {
    return new DropTarget.DropTargetAutoScroller (c, p);
  }

  protected void initializeAutoscrolling(Point p)
  {
    if (component instanceof Autoscroll) // Checks for null too.
      autoscroller = createDropTargetAutoScroller (component, p);
  }

  protected void updateAutoscroll(Point dragCursorLocn)
  {
    if (autoscroller != null)
      autoscroller.updateLocation(dragCursorLocn);
  }

  protected void clearAutoscroll()
  {
    if (autoscroller != null)
      {
        autoscroller.stop();
        autoscroller = null;
      }
  }
} // class DropTarget