001 /* DragSourceContext.java --
002 Copyright (C) 2002 Free Software Foundation
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package java.awt.dnd;
040
041 import java.awt.Component;
042 import java.awt.Cursor;
043 import java.awt.Image;
044 import java.awt.Point;
045 import java.awt.datatransfer.Transferable;
046 import java.awt.dnd.peer.DragSourceContextPeer;
047 import java.io.Serializable;
048 import java.util.TooManyListenersException;
049
050 /**
051 * @since 1.2
052 */
053 public class DragSourceContext
054 implements DragSourceListener, DragSourceMotionListener, Serializable
055 {
056 /**
057 * Compatible with JDK 1.2+
058 */
059 static final long serialVersionUID = -115407898692194719L;
060
061 protected static final int DEFAULT = 0;
062 protected static final int ENTER = 1;
063 protected static final int OVER = 2;
064 protected static final int CHANGED = 3;
065
066 private DragSourceContextPeer peer;
067 private Cursor cursor;
068 private Transferable transferable;
069 private DragGestureEvent trigger;
070 private DragSourceListener dragSourceListener;
071 private boolean useCustomCursor;
072 private int sourceActions;
073 private Image image;
074 private Point offset;
075
076 /**
077 * Initializes a drag source context.
078 *
079 * @exception IllegalArgumentException If Component or DragSource of trigger
080 * are null, the drag action for the trigger event is DnDConstants.ACTION_NONE
081 * or if the source actions for the DragGestureRecognizer associated with the
082 * trigger event are equal to DnDConstants.ACTION_NONE.
083 * @exception NullPointerException If peer, trans or trigger is null or if the
084 * image is not null but the offset is.
085 */
086 public DragSourceContext (DragSourceContextPeer peer,
087 DragGestureEvent trigger, Cursor cursor,
088 Image image, Point offset, Transferable trans,
089 DragSourceListener dsl)
090 {
091 if (peer == null
092 || trigger == null || trans == null
093 || (image != null && offset == null))
094 throw new NullPointerException ();
095
096 if (trigger.getComponent () == null
097 || trigger.getDragSource () == null
098 || trigger.getDragAction () == DnDConstants.ACTION_NONE
099 || trigger.getSourceAsDragGestureRecognizer ()
100 .getSourceActions () == DnDConstants.ACTION_NONE)
101 throw new IllegalArgumentException ();
102
103 this.peer = peer;
104 this.trigger = trigger;
105 this.cursor = cursor;
106 this.image = image;
107 this.offset = offset;
108 this.transferable = trans;
109 this.dragSourceListener = dsl;
110 this.sourceActions = trigger.getSourceAsDragGestureRecognizer().getSourceActions();
111
112 setCursor(cursor);
113 updateCurrentCursor(trigger.getDragAction(), sourceActions, DEFAULT);
114 }
115
116 /**
117 * Returns the DragSource object associated with the
118 * DragGestureEvent.
119 *
120 * @return the DragSource associated with the trigger.
121 */
122 public DragSource getDragSource()
123 {
124 return trigger.getDragSource ();
125 }
126
127 /**
128 * Returns the component associated with this.
129 *
130 * @return the component associated with the trigger.
131 */
132 public Component getComponent()
133 {
134 return trigger.getComponent ();
135 }
136
137 /**
138 * Gets the trigger associated with this.
139 *
140 * @return the trigger.
141 */
142 public DragGestureEvent getTrigger()
143 {
144 return trigger;
145 }
146
147 /**
148 * Returns the source actions for the DragGestureRecognizer.
149 *
150 * @return the source actions for DragGestureRecognizer.
151 */
152 public int getSourceActions()
153 {
154 if (sourceActions == 0)
155 sourceActions = trigger.getSourceAsDragGestureRecognizer().getSourceActions();
156 return sourceActions;
157 }
158
159 /**
160 * Sets the cursor for this drag operation to the specified cursor.
161 *
162 * @param cursor c - the Cursor to use, or null to use the default drag
163 * cursor.
164 */
165 public void setCursor(Cursor cursor)
166 {
167 if (cursor == null)
168 useCustomCursor = false;
169 else
170 useCustomCursor = true;
171 this.cursor = cursor;
172 peer.setCursor(cursor);
173 }
174
175 /**
176 * Returns the current cursor or null if the default
177 * drag cursor is used.
178 *
179 * @return the current cursor or null.
180 */
181 public Cursor getCursor()
182 {
183 return cursor;
184 }
185
186 /**
187 * Adds a <code>DragSourceListener</code>.
188 *
189 * @exception TooManyListenersException If a <code>DragSourceListener</code>
190 * has already been added.
191 */
192 public void addDragSourceListener (DragSourceListener dsl)
193 throws TooManyListenersException
194 {
195 if (dragSourceListener != null)
196 throw new TooManyListenersException ();
197
198 dragSourceListener = dsl;
199 }
200
201 public void removeDragSourceListener (DragSourceListener dsl)
202 {
203 if (dragSourceListener == dsl)
204 dragSourceListener = null;
205 }
206
207 /**
208 * This function tells the peer that the DataFlavors have been modified.
209 */
210 public void transferablesFlavorsChanged()
211 {
212 peer.transferablesFlavorsChanged();
213 }
214
215 /**
216 * Calls dragEnter on the listeners registered with this
217 * and with the DragSource.
218 *
219 * @param e - the DragSourceDragEvent
220 */
221 public void dragEnter(DragSourceDragEvent e)
222 {
223 if (dragSourceListener != null)
224 dragSourceListener.dragEnter(e);
225
226 DragSource ds = getDragSource();
227 DragSourceListener[] dsl = ds.getDragSourceListeners();
228 for (int i = 0; i < dsl.length; i++)
229 dsl[i].dragEnter(e);
230
231 updateCurrentCursor(e.getDropAction(), e.getTargetActions(), ENTER);
232 }
233
234 /**
235 * Calls dragOver on the listeners registered with this
236 * and with the DragSource.
237 *
238 * @param e - the DragSourceDragEvent
239 */
240 public void dragOver(DragSourceDragEvent e)
241 {
242 if (dragSourceListener != null)
243 dragSourceListener.dragOver(e);
244
245 DragSource ds = getDragSource();
246 DragSourceListener[] dsl = ds.getDragSourceListeners();
247 for (int i = 0; i < dsl.length; i++)
248 dsl[i].dragOver(e);
249
250 updateCurrentCursor(e.getDropAction(), e.getTargetActions(), OVER);
251 }
252
253 /**
254 * Calls dragExit on the listeners registered with this
255 * and with the DragSource.
256 *
257 * @param e - the DragSourceEvent
258 */
259 public void dragExit(DragSourceEvent e)
260 {
261 if (dragSourceListener != null)
262 dragSourceListener.dragExit(e);
263
264 DragSource ds = getDragSource();
265 DragSourceListener[] dsl = ds.getDragSourceListeners();
266 for (int i = 0; i < dsl.length; i++)
267 dsl[i].dragExit(e);
268
269 updateCurrentCursor(DnDConstants.ACTION_NONE, DnDConstants.ACTION_NONE,
270 DEFAULT);
271 }
272
273 /**
274 * Calls dropActionChanged on the listeners registered with this
275 * and with the DragSource.
276 *
277 * @param e - the DragSourceDragEvent
278 */
279 public void dropActionChanged(DragSourceDragEvent e)
280 {
281 if (dragSourceListener != null)
282 dragSourceListener.dropActionChanged(e);
283
284 DragSource ds = getDragSource();
285 DragSourceListener[] dsl = ds.getDragSourceListeners();
286 for (int i = 0; i < dsl.length; i++)
287 dsl[i].dropActionChanged(e);
288
289 updateCurrentCursor(e.getDropAction(), e.getTargetActions(), CHANGED);
290 }
291
292 /**
293 * Calls dragDropEnd on the listeners registered with this
294 * and with the DragSource.
295 *
296 * @param e - the DragSourceDropEvent
297 */
298 public void dragDropEnd(DragSourceDropEvent e)
299 {
300 if (dragSourceListener != null)
301 dragSourceListener.dragDropEnd(e);
302
303 DragSource ds = getDragSource();
304 DragSourceListener[] dsl = ds.getDragSourceListeners();
305 for (int i = 0; i < dsl.length; i++)
306 dsl[i].dragDropEnd(e);
307 }
308
309 /**
310 * Calls dragMouseMoved on the listeners registered with the DragSource.
311 *
312 * @param e - the DragSourceDragEvent
313 */
314 public void dragMouseMoved(DragSourceDragEvent e)
315 {
316 DragSource ds = getDragSource();
317 DragSourceMotionListener[] dsml = ds.getDragSourceMotionListeners();
318 for (int i = 0; i < dsml.length; i++)
319 dsml[i].dragMouseMoved(e);
320 }
321
322 /**
323 * Returns the Transferable set with this object.
324 *
325 * @return the transferable.
326 */
327 public Transferable getTransferable()
328 {
329 return transferable;
330 }
331
332 /**
333 * This function sets the drag cursor for the specified operation, actions and
334 * status if the default drag cursor is active. Otherwise, the cursor is not
335 * updated in any way.
336 *
337 * @param dropOp - the current operation.
338 * @param targetAct - the supported actions.
339 * @param status - the status of the cursor (constant).
340 */
341 protected void updateCurrentCursor(int dropOp, int targetAct, int status)
342 {
343 if (! useCustomCursor)
344 {
345 Cursor newCursor = null;
346 switch (status)
347 {
348 default:
349 targetAct = DnDConstants.ACTION_NONE;
350 case ENTER:
351 case CHANGED:
352 case OVER:
353 int action = dropOp & targetAct;
354 if (action == DnDConstants.ACTION_NONE)
355 {
356 if ((dropOp & DnDConstants.ACTION_LINK) != 0)
357 newCursor = DragSource.DefaultLinkNoDrop;
358 else if ((dropOp & DnDConstants.ACTION_MOVE) != 0)
359 newCursor = DragSource.DefaultMoveNoDrop;
360 else
361 newCursor = DragSource.DefaultCopyNoDrop;
362 }
363 else
364 {
365 if ((dropOp & DnDConstants.ACTION_LINK) != 0)
366 newCursor = DragSource.DefaultLinkDrop;
367 else if ((dropOp & DnDConstants.ACTION_MOVE) != 0)
368 newCursor = DragSource.DefaultMoveDrop;
369 else
370 newCursor = DragSource.DefaultCopyDrop;
371 }
372 }
373
374 if (cursor == null || ! cursor.equals(newCursor))
375 {
376 cursor = newCursor;
377 DragSourceContextPeer p = peer;
378 if (p != null)
379 p.setCursor(cursor);
380 }
381 }
382 }
383 } // class DragSourceContext