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 import sun.awt.AWTAccessor;
43 import sun.awt.AWTAccessor.DropTargetContextAccessor;
44
45 /**
46 * A <code>DropTargetContext</code> is created
47 * whenever the logical cursor associated
48 * with a Drag and Drop operation coincides with the visible geometry of
49 * a <code>Component</code> associated with a <code>DropTarget</code>.
50 * The <code>DropTargetContext</code> provides
51 * the mechanism for a potential receiver
52 * of a drop operation to both provide the end user with the appropriate
53 * drag under feedback, but also to effect the subsequent data transfer
54 * if appropriate.
55 *
56 * @since 1.2
57 */
58
59 public class DropTargetContext implements Serializable {
60
61 private static final long serialVersionUID = -634158968993743371L;
62
63 static {
64 AWTAccessor.setDropTargetContextAccessor(new DropTargetContextAccessor() {
65 @Override
66 public void reset(DropTargetContext dtc) {
67 dtc.reset();
68 }
69 @Override
70 public void setDropTargetContextPeer(DropTargetContext dtc,
71 DropTargetContextPeer dtcp) {
72 dtc.setDropTargetContextPeer(dtcp);
73 }
74 });
75 }
76 /**
77 * Construct a <code>DropTargetContext</code>
78 * given a specified <code>DropTarget</code>.
79 *
80 * @param dt the DropTarget to associate with
81 */
82
83 DropTargetContext(DropTarget dt) {
84 super();
85
86 dropTarget = dt;
87 }
88
89 /**
90 * This method returns the <code>DropTarget</code> associated with this
91 * <code>DropTargetContext</code>.
92 *
93 * @return the <code>DropTarget</code> associated with this <code>DropTargetContext</code>
94 */
95
96 public DropTarget getDropTarget() { return dropTarget; }
97
98 /**
99 * This method returns the <code>Component</code> associated with
100 * this <code>DropTargetContext</code>.
101 *
102 * @return the Component associated with this Context
103 */
104
105 public Component getComponent() { return dropTarget.getComponent(); }
106
107 /**
108 * Called when disassociated with the <code>DropTargetContextPeer</code>.
109 */
110 void reset() {
111 dropTargetContextPeer = null;
112 transferable = null;
113 }
114
115 /**
116 * This method sets the current actions acceptable to
117 * this <code>DropTarget</code>.
118 *
119 * @param actions an <code>int</code> representing the supported action(s)
120 */
121
122 protected void setTargetActions(int actions) {
123 DropTargetContextPeer peer = getDropTargetContextPeer();
124 if (peer != null) {
125 synchronized (peer) {
126 peer.setTargetActions(actions);
127 getDropTarget().doSetDefaultActions(actions);
128 }
129 } else {
130 getDropTarget().doSetDefaultActions(actions);
131 }
132 }
133
134 /**
135 * This method returns an <code>int</code> representing the
136 * current actions this <code>DropTarget</code> will accept.
137 *
138 * @return the current actions acceptable to this <code>DropTarget</code>
139 */
140
141 protected int getTargetActions() {
142 DropTargetContextPeer peer = getDropTargetContextPeer();
143 return ((peer != null)
144 ? peer.getTargetActions()
145 : dropTarget.getDefaultActions()
146 );
147 }
148
149 /**
150 * This method signals that the drop is completed and
151 * if it was successful or not.
152 *
153 * @param success true for success, false if not
154 *
155 * @throws InvalidDnDOperationException if a drop is not outstanding/extant
156 */
157
158 public void dropComplete(boolean success) throws InvalidDnDOperationException{
159 DropTargetContextPeer peer = getDropTargetContextPeer();
160 if (peer != null) {
161 peer.dropComplete(success);
162 }
163 }
164
165 /**
166 * accept the Drag.
167 *
168 * @param dragOperation the supported action(s)
169 */
170
171 protected void acceptDrag(int dragOperation) {
172 DropTargetContextPeer peer = getDropTargetContextPeer();
173 if (peer != null) {
174 peer.acceptDrag(dragOperation);
175 }
176 }
177
178 /**
179 * reject the Drag.
180 */
181
182 protected void rejectDrag() {
183 DropTargetContextPeer peer = getDropTargetContextPeer();
184 if (peer != null) {
185 peer.rejectDrag();
186 }
187 }
188
189 /**
190 * called to signal that the drop is acceptable
191 * using the specified operation.
192 * must be called during DropTargetListener.drop method invocation.
193 *
194 * @param dropOperation the supported action(s)
195 */
196
197 protected void acceptDrop(int dropOperation) {
198 DropTargetContextPeer peer = getDropTargetContextPeer();
199 if (peer != null) {
200 peer.acceptDrop(dropOperation);
201 }
202 }
203
204 /**
205 * called to signal that the drop is unacceptable.
206 * must be called during DropTargetListener.drop method invocation.
207 */
208
209 protected void rejectDrop() {
210 DropTargetContextPeer peer = getDropTargetContextPeer();
211 if (peer != null) {
212 peer.rejectDrop();
213 }
214 }
215
216 /**
217 * get the available DataFlavors of the
218 * <code>Transferable</code> operand of this operation.
219 *
220 * @return a <code>DataFlavor[]</code> containing the
221 * supported <code>DataFlavor</code>s of the
222 * <code>Transferable</code> operand.
223 */
224
225 protected DataFlavor[] getCurrentDataFlavors() {
226 DropTargetContextPeer peer = getDropTargetContextPeer();
227 return peer != null ? peer.getTransferDataFlavors() : new DataFlavor[0];
228 }
229
230 /**
231 * This method returns a the currently available DataFlavors
232 * of the <code>Transferable</code> operand
233 * as a <code>java.util.List</code>.
234 *
235 * @return the currently available
236 * DataFlavors as a <code>java.util.List</code>
237 */
238
239 protected List<DataFlavor> getCurrentDataFlavorsAsList() {
240 return Arrays.asList(getCurrentDataFlavors());
241 }
242
243 /**
244 * This method returns a <code>boolean</code>
245 * indicating if the given <code>DataFlavor</code> is
246 * supported by this <code>DropTargetContext</code>.
247 *
248 * @param df the <code>DataFlavor</code>
249 *
250 * @return if the <code>DataFlavor</code> specified is supported
251 */
252
253 protected boolean isDataFlavorSupported(DataFlavor df) {
254 return getCurrentDataFlavorsAsList().contains(df);
255 }
256
257 /**
258 * get the Transferable (proxy) operand of this operation
259 *
260 * @throws InvalidDnDOperationException if a drag is not outstanding/extant
261 *
262 * @return the <code>Transferable</code>
263 */
264
265 protected Transferable getTransferable() throws InvalidDnDOperationException {
266 DropTargetContextPeer peer = getDropTargetContextPeer();
267 if (peer == null) {
268 throw new InvalidDnDOperationException();
269 } else {
270 if (transferable == null) {
271 Transferable t = peer.getTransferable();
272 boolean isLocal = peer.isTransferableJVMLocal();
273 synchronized (this) {
274 if (transferable == null) {
275 transferable = createTransferableProxy(t, isLocal);
276 }
277 }
278 }
279
280 return transferable;
281 }
282 }
283
284 /**
285 * Get the <code>DropTargetContextPeer</code>
286 *
287 * @return the platform peer
288 */
289 DropTargetContextPeer getDropTargetContextPeer() {
290 return dropTargetContextPeer;
291 }
292
293 /**
294 * Sets the {@code DropTargetContextPeer}
295 */
296 void setDropTargetContextPeer(final DropTargetContextPeer dtcp) {
297 dropTargetContextPeer = dtcp;
298 }
299
300 /**
301 * Creates a TransferableProxy to proxy for the specified
302 * Transferable.
303 *
304 * @param t the <tt>Transferable</tt> to be proxied
305 * @param local <tt>true</tt> if <tt>t</tt> represents
306 * the result of a local drag-n-drop operation.
307 * @return the new <tt>TransferableProxy</tt> instance.
308 */
309 protected Transferable createTransferableProxy(Transferable t, boolean local) {
310 return new TransferableProxy(t, local);
311 }
312
313 /****************************************************************************/
314
315
316 /**
317 * <code>TransferableProxy</code> is a helper inner class that implements
318 * <code>Transferable</code> interface and serves as a proxy for another
319 * <code>Transferable</code> object which represents data transfer for
320 * a particular drag-n-drop operation.
321 * <p>
322 * The proxy forwards all requests to the encapsulated transferable
323 * and automatically performs additional conversion on the data
324 * returned by the encapsulated transferable in case of local transfer.
325 */
326
327 protected class TransferableProxy implements Transferable {
328
329 /**
330 * Constructs a <code>TransferableProxy</code> given
331 * a specified <code>Transferable</code> object representing
332 * data transfer for a particular drag-n-drop operation and
333 * a <code>boolean</code> which indicates whether the
334 * drag-n-drop operation is local (within the same JVM).
335 *
336 * @param t the <code>Transferable</code> object
337 * @param local <code>true</code>, if <code>t</code> represents
338 * the result of local drag-n-drop operation
339 */
340 TransferableProxy(Transferable t, boolean local) {
341 proxy = new sun.awt.datatransfer.TransferableProxy(t, local);
342 transferable = t;
343 isLocal = local;
344 }
345
346 /**
347 * Returns an array of DataFlavor objects indicating the flavors
348 * the data can be provided in by the encapsulated transferable.
349 *
350 * @return an array of data flavors in which the data can be
351 * provided by the encapsulated transferable
352 */
353 public DataFlavor[] getTransferDataFlavors() {
354 return proxy.getTransferDataFlavors();
355 }
356
357 /**
358 * Returns whether or not the specified data flavor is supported by
359 * the encapsulated transferable.
360 * @param flavor the requested flavor for the data
361 * @return <code>true</code> if the data flavor is supported,
362 * <code>false</code> otherwise
363 */
364 public boolean isDataFlavorSupported(DataFlavor flavor) {
365 return proxy.isDataFlavorSupported(flavor);
366 }
367
368 /**
369 * Returns an object which represents the data provided by
370 * the encapsulated transferable for the requested data flavor.
371 * <p>
372 * In case of local transfer a serialized copy of the object
373 * returned by the encapsulated transferable is provided when
374 * the data is requested in application/x-java-serialized-object
375 * data flavor.
376 *
377 * @param df the requested flavor for the data
378 * @throws IOException if the data is no longer available
379 * in the requested flavor.
380 * @throws UnsupportedFlavorException if the requested data flavor is
381 * not supported.
382 */
383 public Object getTransferData(DataFlavor df)
384 throws UnsupportedFlavorException, IOException
385 {
386 return proxy.getTransferData(df);
387 }
388
389 /*
390 * fields
391 */
392
393 // We don't need to worry about client code changing the values of
394 // these variables. Since TransferableProxy is a protected class, only
395 // subclasses of DropTargetContext can access it. And DropTargetContext
396 // cannot be subclassed by client code because it does not have a
397 // public constructor.
398
399 /**
400 * The encapsulated <code>Transferable</code> object.
401 */
402 protected Transferable transferable;
403
404 /**
405 * A <code>boolean</code> indicating if the encapsulated
406 * <code>Transferable</code> object represents the result
407 * of local drag-n-drop operation (within the same JVM).
408 */
409 protected boolean isLocal;
410
411 private sun.awt.datatransfer.TransferableProxy proxy;
412 }
413
414 /****************************************************************************/
415
416 /*
417 * fields
418 */
419
420 /**
421 * The DropTarget associated with this DropTargetContext.
422 *
423 * @serial
424 */
425 private final DropTarget dropTarget;
426
427 private transient DropTargetContextPeer dropTargetContextPeer;
428
429 private transient Transferable transferable;
430 }