1 /*
2 * Copyright (c) 1997, 2015, 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.awt.Component;
29
30 import java.awt.datatransfer.DataFlavor;
31 import java.awt.datatransfer.Transferable;
32 import java.awt.datatransfer.UnsupportedFlavorException;
33
34 import java.awt.dnd.peer.DropTargetContextPeer;
35
36 import java.io.IOException;
37 import java.io.Serializable;
38
39 import java.util.Arrays;
40 import java.util.List;
41
42
43 /**
44 * A <code>DropTargetContext</code> is created
45 * whenever the logical cursor associated
46 * with a Drag and Drop operation coincides with the visible geometry of
47 * a <code>Component</code> associated with a <code>DropTarget</code>.
48 * The <code>DropTargetContext</code> provides
49 * the mechanism for a potential receiver
50 * of a drop operation to both provide the end user with the appropriate
51 * drag under feedback, but also to effect the subsequent data transfer
52 * if appropriate.
53 *
54 * @since 1.2
55 */
56
57 public class DropTargetContext implements Serializable {
58
59 private static final long serialVersionUID = -634158968993743371L;
60
61 /**
62 * Construct a <code>DropTargetContext</code>
63 * given a specified <code>DropTarget</code>.
64 *
65 * @param dt the DropTarget to associate with
66 */
67
68 DropTargetContext(DropTarget dt) {
69 super();
70
71 dropTarget = dt;
72 }
73
74 /**
75 * This method returns the <code>DropTarget</code> associated with this
76 * <code>DropTargetContext</code>.
77 *
78 * @return the <code>DropTarget</code> associated with this <code>DropTargetContext</code>
79 */
80
81 public DropTarget getDropTarget() { return dropTarget; }
82
83 /**
84 * This method returns the <code>Component</code> associated with
85 * this <code>DropTargetContext</code>.
86 *
87 * @return the Component associated with this Context
88 */
89
90 public Component getComponent() { return dropTarget.getComponent(); }
91
92 /**
93 * Called when associated with the peer object.
94 *
95 * @param dtcp the peer object
96 * @throws IllegalArgumentException if provided peer is not supported
97 */
98 public void addNotify(final Object dtcp) throws IllegalArgumentException {
99 if (dtcp instanceof DropTargetContextPeer) {
100 dropTargetContextPeer = (DropTargetContextPeer) dtcp;
101 } else {
102 throw new IllegalArgumentException("Unsupported peer");
103 }
104 }
105
106 /**
107 * Called when disassociated with the <code>DropTargetContextPeer</code>.
108 */
109 public void removeNotify() {
110 dropTargetContextPeer = null;
111 transferable = null;
112 }
113
114 /**
115 * This method sets the current actions acceptable to
116 * this <code>DropTarget</code>.
117 *
118 * @param actions an <code>int</code> representing the supported action(s)
119 */
120
121 protected void setTargetActions(int actions) {
122 DropTargetContextPeer peer = getDropTargetContextPeer();
123 if (peer != null) {
124 synchronized (peer) {
125 peer.setTargetActions(actions);
126 getDropTarget().doSetDefaultActions(actions);
127 }
128 } else {
129 getDropTarget().doSetDefaultActions(actions);
130 }
131 }
132
133 /**
134 * This method returns an <code>int</code> representing the
135 * current actions this <code>DropTarget</code> will accept.
136 *
137 * @return the current actions acceptable to this <code>DropTarget</code>
138 */
139
140 protected int getTargetActions() {
141 DropTargetContextPeer peer = getDropTargetContextPeer();
142 return ((peer != null)
143 ? peer.getTargetActions()
144 : dropTarget.getDefaultActions()
145 );
146 }
147
148 /**
149 * This method signals that the drop is completed and
150 * if it was successful or not.
151 *
152 * @param success true for success, false if not
153 *
154 * @throws InvalidDnDOperationException if a drop is not outstanding/extant
155 */
156
157 public void dropComplete(boolean success) throws InvalidDnDOperationException{
158 DropTargetContextPeer peer = getDropTargetContextPeer();
159 if (peer != null) {
160 peer.dropComplete(success);
161 }
162 }
163
164 /**
165 * accept the Drag.
166 *
167 * @param dragOperation the supported action(s)
168 */
169
170 protected void acceptDrag(int dragOperation) {
171 DropTargetContextPeer peer = getDropTargetContextPeer();
172 if (peer != null) {
173 peer.acceptDrag(dragOperation);
174 }
175 }
176
177 /**
178 * reject the Drag.
179 */
180
181 protected void rejectDrag() {
182 DropTargetContextPeer peer = getDropTargetContextPeer();
183 if (peer != null) {
184 peer.rejectDrag();
185 }
186 }
187
188 /**
189 * called to signal that the drop is acceptable
190 * using the specified operation.
191 * must be called during DropTargetListener.drop method invocation.
192 *
193 * @param dropOperation the supported action(s)
194 */
195
196 protected void acceptDrop(int dropOperation) {
197 DropTargetContextPeer peer = getDropTargetContextPeer();
198 if (peer != null) {
199 peer.acceptDrop(dropOperation);
200 }
201 }
202
203 /**
204 * called to signal that the drop is unacceptable.
205 * must be called during DropTargetListener.drop method invocation.
206 */
207
208 protected void rejectDrop() {
209 DropTargetContextPeer peer = getDropTargetContextPeer();
210 if (peer != null) {
211 peer.rejectDrop();
212 }
213 }
214
215 /**
216 * get the available DataFlavors of the
217 * <code>Transferable</code> operand of this operation.
218 *
219 * @return a <code>DataFlavor[]</code> containing the
220 * supported <code>DataFlavor</code>s of the
221 * <code>Transferable</code> operand.
222 */
223
224 protected DataFlavor[] getCurrentDataFlavors() {
225 DropTargetContextPeer peer = getDropTargetContextPeer();
226 return peer != null ? peer.getTransferDataFlavors() : new DataFlavor[0];
227 }
228
229 /**
230 * This method returns a the currently available DataFlavors
231 * of the <code>Transferable</code> operand
232 * as a <code>java.util.List</code>.
233 *
234 * @return the currently available
235 * DataFlavors as a <code>java.util.List</code>
236 */
237
238 protected List<DataFlavor> getCurrentDataFlavorsAsList() {
239 return Arrays.asList(getCurrentDataFlavors());
240 }
241
242 /**
243 * This method returns a <code>boolean</code>
244 * indicating if the given <code>DataFlavor</code> is
245 * supported by this <code>DropTargetContext</code>.
246 *
247 * @param df the <code>DataFlavor</code>
248 *
249 * @return if the <code>DataFlavor</code> specified is supported
250 */
251
252 protected boolean isDataFlavorSupported(DataFlavor df) {
253 return getCurrentDataFlavorsAsList().contains(df);
254 }
255
256 /**
257 * get the Transferable (proxy) operand of this operation
258 *
259 * @throws InvalidDnDOperationException if a drag is not outstanding/extant
260 *
261 * @return the <code>Transferable</code>
262 */
263
264 protected Transferable getTransferable() throws InvalidDnDOperationException {
265 DropTargetContextPeer peer = getDropTargetContextPeer();
266 if (peer == null) {
267 throw new InvalidDnDOperationException();
268 } else {
269 if (transferable == null) {
270 Transferable t = peer.getTransferable();
271 boolean isLocal = peer.isTransferableJVMLocal();
272 synchronized (this) {
273 if (transferable == null) {
274 transferable = createTransferableProxy(t, isLocal);
275 }
276 }
277 }
278
279 return transferable;
280 }
281 }
282
283 /**
284 * Get the <code>DropTargetContextPeer</code>
285 *
286 * @return the platform peer
287 */
288
289 DropTargetContextPeer getDropTargetContextPeer() {
290 return dropTargetContextPeer;
291 }
292
293 /**
294 * Creates a TransferableProxy to proxy for the specified
295 * Transferable.
296 *
297 * @param t the <tt>Transferable</tt> to be proxied
298 * @param local <tt>true</tt> if <tt>t</tt> represents
299 * the result of a local drag-n-drop operation.
300 * @return the new <tt>TransferableProxy</tt> instance.
301 */
302 protected Transferable createTransferableProxy(Transferable t, boolean local) {
303 return new TransferableProxy(t, local);
304 }
305
306 /****************************************************************************/
307
308
309 /**
310 * <code>TransferableProxy</code> is a helper inner class that implements
311 * <code>Transferable</code> interface and serves as a proxy for another
312 * <code>Transferable</code> object which represents data transfer for
313 * a particular drag-n-drop operation.
314 * <p>
315 * The proxy forwards all requests to the encapsulated transferable
316 * and automatically performs additional conversion on the data
317 * returned by the encapsulated transferable in case of local transfer.
318 */
319
320 protected class TransferableProxy implements Transferable {
321
322 /**
323 * Constructs a <code>TransferableProxy</code> given
324 * a specified <code>Transferable</code> object representing
325 * data transfer for a particular drag-n-drop operation and
326 * a <code>boolean</code> which indicates whether the
327 * drag-n-drop operation is local (within the same JVM).
328 *
329 * @param t the <code>Transferable</code> object
330 * @param local <code>true</code>, if <code>t</code> represents
331 * the result of local drag-n-drop operation
332 */
333 TransferableProxy(Transferable t, boolean local) {
334 proxy = new sun.awt.datatransfer.TransferableProxy(t, local);
335 transferable = t;
336 isLocal = local;
337 }
338
339 /**
340 * Returns an array of DataFlavor objects indicating the flavors
341 * the data can be provided in by the encapsulated transferable.
342 *
343 * @return an array of data flavors in which the data can be
344 * provided by the encapsulated transferable
345 */
346 public DataFlavor[] getTransferDataFlavors() {
347 return proxy.getTransferDataFlavors();
348 }
349
350 /**
351 * Returns whether or not the specified data flavor is supported by
352 * the encapsulated transferable.
353 * @param flavor the requested flavor for the data
354 * @return <code>true</code> if the data flavor is supported,
355 * <code>false</code> otherwise
356 */
357 public boolean isDataFlavorSupported(DataFlavor flavor) {
358 return proxy.isDataFlavorSupported(flavor);
359 }
360
361 /**
362 * Returns an object which represents the data provided by
363 * the encapsulated transferable for the requested data flavor.
364 * <p>
365 * In case of local transfer a serialized copy of the object
366 * returned by the encapsulated transferable is provided when
367 * the data is requested in application/x-java-serialized-object
368 * data flavor.
369 *
370 * @param df the requested flavor for the data
371 * @throws IOException if the data is no longer available
372 * in the requested flavor.
373 * @throws UnsupportedFlavorException if the requested data flavor is
374 * not supported.
375 */
376 public Object getTransferData(DataFlavor df)
377 throws UnsupportedFlavorException, IOException
378 {
379 return proxy.getTransferData(df);
380 }
381
382 /*
383 * fields
384 */
385
386 // We don't need to worry about client code changing the values of
387 // these variables. Since TransferableProxy is a protected class, only
388 // subclasses of DropTargetContext can access it. And DropTargetContext
389 // cannot be subclassed by client code because it does not have a
390 // public constructor.
391
392 /**
393 * The encapsulated <code>Transferable</code> object.
394 */
395 protected Transferable transferable;
396
397 /**
398 * A <code>boolean</code> indicating if the encapsulated
399 * <code>Transferable</code> object represents the result
400 * of local drag-n-drop operation (within the same JVM).
401 */
402 protected boolean isLocal;
403
404 private sun.awt.datatransfer.TransferableProxy proxy;
405 }
406
407 /****************************************************************************/
408
409 /*
410 * fields
411 */
412
413 /**
414 * The DropTarget associated with this DropTargetContext.
415 *
416 * @serial
417 */
418 private final DropTarget dropTarget;
419
420 private transient DropTargetContextPeer dropTargetContextPeer;
421
422 private transient Transferable transferable;
423 }