source: josm/trunk/src/org/openstreetmap/josm/gui/FileDrop.java@ 8126

Last change on this file since 8126 was 8126, checked in by Don-vip, 9 years ago

fix Sonar issue squid:S2444 - Lazy initialization of "static" fields should be "synchronized"
  • Property svn:eol-style set to native
File size: 26.5 KB
Line 
1/* code from: http://iharder.sourceforge.net/current/java/filedrop/
2 (public domain) with only very small additions */
3package org.openstreetmap.josm.gui;
4
5import java.awt.Color;
6import java.awt.Component;
7import java.awt.Container;
8import java.awt.datatransfer.DataFlavor;
9import java.awt.datatransfer.Transferable;
10import java.awt.datatransfer.UnsupportedFlavorException;
11import java.awt.dnd.DnDConstants;
12import java.awt.dnd.DropTarget;
13import java.awt.dnd.DropTargetDragEvent;
14import java.awt.dnd.DropTargetDropEvent;
15import java.awt.dnd.DropTargetEvent;
16import java.awt.dnd.DropTargetListener;
17import java.awt.event.HierarchyEvent;
18import java.awt.event.HierarchyListener;
19import java.io.BufferedReader;
20import java.io.File;
21import java.io.IOException;
22import java.io.Reader;
23import java.net.URI;
24import java.util.ArrayList;
25import java.util.Arrays;
26import java.util.List;
27import java.util.TooManyListenersException;
28
29import javax.swing.BorderFactory;
30import javax.swing.JComponent;
31import javax.swing.border.Border;
32
33import org.openstreetmap.josm.Main;
34import org.openstreetmap.josm.actions.OpenFileAction;
35
36/**
37 * This class makes it easy to drag and drop files from the operating
38 * system to a Java program. Any {@link java.awt.Component} can be
39 * dropped onto, but only {@link javax.swing.JComponent}s will indicate
40 * the drop event with a changed border.
41 * <p>
42 * To use this class, construct a new <tt>FileDrop</tt> by passing
43 * it the target component and a <tt>Listener</tt> to receive notification
44 * when file(s) have been dropped. Here is an example:
45 * <p>
46 * <code>
47 * JPanel myPanel = new JPanel();
48 * new FileDrop( myPanel, new FileDrop.Listener()
49 * { public void filesDropped( java.io.File[] files )
50 * {
51 * // handle file drop
52 * ...
53 * } // end filesDropped
54 * }); // end FileDrop.Listener
55 * </code>
56 * <p>
57 * You can specify the border that will appear when files are being dragged by
58 * calling the constructor with a {@link javax.swing.border.Border}. Only
59 * <tt>JComponent</tt>s will show any indication with a border.
60 * <p>
61 * You can turn on some debugging features by passing a <tt>PrintStream</tt>
62 * object (such as <tt>System.out</tt>) into the full constructor. A <tt>null</tt>
63 * value will result in no extra debugging information being output.
64 * <p>
65 *
66 * <p>I'm releasing this code into the Public Domain. Enjoy.
67 * </p>
68 * <p><em>Original author: Robert Harder, rharder@usa.net</em></p>
69 * <p>2007-09-12 Nathan Blomquist -- Linux (KDE/Gnome) support added.</p>
70 *
71 * @author Robert Harder
72 * @author rharder@users.sf.net
73 * @version 1.0.1
74 * @since 1231
75 */
76public class FileDrop
77{
78 private transient Border normalBorder;
79 private transient DropTargetListener dropListener;
80
81 /** Discover if the running JVM is modern enough to have drag and drop. */
82 private static Boolean supportsDnD;
83
84 // Default border color
85 private static Color defaultBorderColor = new Color( 0f, 0f, 1f, 0.25f );
86
87 /**
88 * Constructor for JOSM file drop
89 * @param c The drop target
90 */
91 public FileDrop(final Component c){
92 this(
93 c, // Drop target
94 BorderFactory.createMatteBorder( 2, 2, 2, 2, defaultBorderColor ), // Drag border
95 true, // Recursive
96 new FileDrop.Listener(){
97 @Override
98 public void filesDropped( File[] files ){
99 // start asynchronous loading of files
100 OpenFileAction.OpenFileTask task = new OpenFileAction.OpenFileTask(Arrays.asList(files), null);
101 task.setRecordHistory(true);
102 Main.worker.submit(task);
103 }
104 }
105 );
106 }
107
108 /**
109 * Full constructor with a specified border and debugging optionally turned on.
110 * With Debugging turned on, more status messages will be displayed to
111 * <tt>out</tt>. A common way to use this constructor is with
112 * <tt>System.out</tt> or <tt>System.err</tt>. A <tt>null</tt> value for
113 * the parameter <tt>out</tt> will result in no debugging output.
114 *
115 * @param c Component on which files will be dropped.
116 * @param dragBorder Border to use on <tt>JComponent</tt> when dragging occurs.
117 * @param recursive Recursively set children as drop targets.
118 * @param listener Listens for <tt>filesDropped</tt>.
119 */
120 public FileDrop(
121 final Component c,
122 final Border dragBorder,
123 final boolean recursive,
124 final Listener listener)
125 {
126
127 if( supportsDnD() )
128 { // Make a drop listener
129 dropListener = new DropTargetListener()
130 { @Override
131 public void dragEnter( DropTargetDragEvent evt )
132 { Main.trace("FileDrop: dragEnter event." );
133
134 // Is this an acceptable drag event?
135 if( isDragOk( evt ) )
136 {
137 // If it's a Swing component, set its border
138 if( c instanceof JComponent )
139 { JComponent jc = (JComponent) c;
140 normalBorder = jc.getBorder();
141 Main.trace("FileDrop: normal border saved." );
142 jc.setBorder( dragBorder );
143 Main.trace("FileDrop: drag border set." );
144 } // end if: JComponent
145
146 // Acknowledge that it's okay to enter
147 evt.acceptDrag( DnDConstants.ACTION_COPY );
148 Main.trace("FileDrop: event accepted." );
149 } // end if: drag ok
150 else
151 { // Reject the drag event
152 evt.rejectDrag();
153 Main.trace("FileDrop: event rejected." );
154 } // end else: drag not ok
155 } // end dragEnter
156
157 @Override
158 public void dragOver( DropTargetDragEvent evt )
159 { // This is called continually as long as the mouse is
160 // over the drag target.
161 } // end dragOver
162
163 @Override
164 public void drop( DropTargetDropEvent evt )
165 { Main.trace("FileDrop: drop event." );
166 try
167 { // Get whatever was dropped
168 Transferable tr = evt.getTransferable();
169
170 // Is it a file list?
171 if (tr.isDataFlavorSupported (DataFlavor.javaFileListFlavor))
172 {
173 // Say we'll take it.
174 evt.acceptDrop ( DnDConstants.ACTION_COPY );
175 Main.trace("FileDrop: file list accepted." );
176
177 // Get a useful list
178 List<?> fileList = (List<?>)tr.getTransferData(DataFlavor.javaFileListFlavor);
179
180 // Convert list to array
181 final File[] files = fileList.toArray(new File[fileList.size()]);
182
183 // Alert listener to drop.
184 if( listener != null ) {
185 listener.filesDropped( files );
186 }
187
188 // Mark that drop is completed.
189 evt.getDropTargetContext().dropComplete(true);
190 Main.trace("FileDrop: drop complete." );
191 } // end if: file list
192 else // this section will check for a reader flavor.
193 {
194 // Thanks, Nathan!
195 // BEGIN 2007-09-12 Nathan Blomquist -- Linux (KDE/Gnome) support added.
196 DataFlavor[] flavors = tr.getTransferDataFlavors();
197 boolean handled = false;
198 for (DataFlavor flavor : flavors) {
199 if (flavor.isRepresentationClassReader()) {
200 // Say we'll take it.
201 evt.acceptDrop(DnDConstants.ACTION_COPY);
202 Main.trace("FileDrop: reader accepted.");
203
204 Reader reader = flavor.getReaderForText(tr);
205
206 BufferedReader br = new BufferedReader(reader);
207
208 if (listener != null) {
209 listener.filesDropped(createFileArray(br));
210 }
211
212 // Mark that drop is completed.
213 evt.getDropTargetContext().dropComplete(true);
214 Main.trace("FileDrop: drop complete.");
215 handled = true;
216 break;
217 }
218 }
219 if(!handled){
220 Main.trace("FileDrop: not a file list or reader - abort." );
221 evt.rejectDrop();
222 }
223 // END 2007-09-12 Nathan Blomquist -- Linux (KDE/Gnome) support added.
224 } // end else: not a file list
225 } // end try
226 catch ( IOException io)
227 { Main.warn("FileDrop: IOException - abort:" );
228 Main.error(io);
229 evt.rejectDrop();
230 } // end catch IOException
231 catch (UnsupportedFlavorException ufe)
232 { Main.warn("FileDrop: UnsupportedFlavorException - abort:" );
233 Main.error(ufe);
234 evt.rejectDrop();
235 } // end catch: UnsupportedFlavorException
236 finally
237 {
238 // If it's a Swing component, reset its border
239 if( c instanceof JComponent )
240 { JComponent jc = (JComponent) c;
241 jc.setBorder( normalBorder );
242 Main.debug("FileDrop: normal border restored." );
243 } // end if: JComponent
244 } // end finally
245 } // end drop
246
247 @Override
248 public void dragExit( DropTargetEvent evt )
249 { Main.debug("FileDrop: dragExit event." );
250 // If it's a Swing component, reset its border
251 if( c instanceof JComponent )
252 { JComponent jc = (JComponent) c;
253 jc.setBorder( normalBorder );
254 Main.debug("FileDrop: normal border restored." );
255 } // end if: JComponent
256 } // end dragExit
257
258 @Override
259 public void dropActionChanged( DropTargetDragEvent evt )
260 { Main.debug("FileDrop: dropActionChanged event." );
261 // Is this an acceptable drag event?
262 if( isDragOk( evt ) )
263 {
264 evt.acceptDrag( DnDConstants.ACTION_COPY );
265 Main.debug("FileDrop: event accepted." );
266 } // end if: drag ok
267 else
268 { evt.rejectDrag();
269 Main.debug("FileDrop: event rejected." );
270 } // end else: drag not ok
271 } // end dropActionChanged
272 }; // end DropTargetListener
273
274 // Make the component (and possibly children) drop targets
275 makeDropTarget( c, recursive );
276 } // end if: supports dnd
277 else
278 { Main.info("FileDrop: Drag and drop is not supported with this JVM" );
279 } // end else: does not support DnD
280 } // end constructor
281
282 private static synchronized boolean supportsDnD()
283 { // Static Boolean
284 if( supportsDnD == null )
285 {
286 boolean support = false;
287 try {
288 Class.forName( "java.awt.dnd.DnDConstants" );
289 support = true;
290 } catch( Exception e ) {
291 support = false;
292 }
293 supportsDnD = support;
294 } // end if: first time through
295 return supportsDnD.booleanValue();
296 } // end supportsDnD
297
298 // BEGIN 2007-09-12 Nathan Blomquist -- Linux (KDE/Gnome) support added.
299 private static final String ZERO_CHAR_STRING = "" + (char)0;
300 private static File[] createFileArray(BufferedReader bReader)
301 {
302 try {
303 List<File> list = new ArrayList<>();
304 String line = null;
305 while ((line = bReader.readLine()) != null) {
306 try {
307 // kde seems to append a 0 char to the end of the reader
308 if (ZERO_CHAR_STRING.equals(line)) {
309 continue;
310 }
311
312 File file = new File(new URI(line));
313 list.add(file);
314 } catch (Exception ex) {
315 Main.warn("Error with " + line + ": " + ex.getMessage());
316 }
317 }
318
319 return list.toArray(new File[list.size()]);
320 } catch (IOException ex) {
321 Main.warn("FileDrop: IOException");
322 }
323 return new File[0];
324 }
325 // END 2007-09-12 Nathan Blomquist -- Linux (KDE/Gnome) support added.
326
327 private void makeDropTarget( final Component c, boolean recursive )
328 {
329 // Make drop target
330 final DropTarget dt = new DropTarget();
331 try
332 { dt.addDropTargetListener( dropListener );
333 } // end try
334 catch( TooManyListenersException e )
335 { Main.error(e);
336 Main.warn("FileDrop: Drop will not work due to previous error. Do you have another listener attached?" );
337 } // end catch
338
339 // Listen for hierarchy changes and remove the drop target when the parent gets cleared out.
340 c.addHierarchyListener( new HierarchyListener()
341 { @Override
342 public void hierarchyChanged( HierarchyEvent evt )
343 { Main.trace("FileDrop: Hierarchy changed." );
344 Component parent = c.getParent();
345 if( parent == null )
346 { c.setDropTarget( null );
347 Main.trace("FileDrop: Drop target cleared from component." );
348 } // end if: null parent
349 else
350 { new DropTarget(c, dropListener);
351 Main.trace("FileDrop: Drop target added to component." );
352 } // end else: parent not null
353 } // end hierarchyChanged
354 }); // end hierarchy listener
355 if( c.getParent() != null ) {
356 new DropTarget(c, dropListener);
357 }
358
359 if( recursive && (c instanceof Container ) )
360 {
361 // Get the container
362 Container cont = (Container) c;
363
364 // Get it's components
365 Component[] comps = cont.getComponents();
366
367 // Set it's components as listeners also
368 for (Component comp : comps) {
369 makeDropTarget( comp, recursive);
370 }
371 } // end if: recursively set components as listener
372 } // end dropListener
373
374 /** Determine if the dragged data is a file list. */
375 private boolean isDragOk( final DropTargetDragEvent evt )
376 { boolean ok = false;
377
378 // Get data flavors being dragged
379 DataFlavor[] flavors = evt.getCurrentDataFlavors();
380
381 // See if any of the flavors are a file list
382 int i = 0;
383 while( !ok && i < flavors.length )
384 {
385 // BEGIN 2007-09-12 Nathan Blomquist -- Linux (KDE/Gnome) support added.
386 // Is the flavor a file list?
387 final DataFlavor curFlavor = flavors[i];
388 if( curFlavor.equals( DataFlavor.javaFileListFlavor ) ||
389 curFlavor.isRepresentationClassReader()){
390 ok = true;
391 }
392 // END 2007-09-12 Nathan Blomquist -- Linux (KDE/Gnome) support added.
393 i++;
394 } // end while: through flavors
395
396 // show data flavors
397 if( flavors.length == 0 ) {
398 Main.trace("FileDrop: no data flavors." );
399 }
400 for( i = 0; i < flavors.length; i++ ) {
401 Main.trace(flavors[i].toString() );
402 }
403
404 return ok;
405 } // end isDragOk
406
407 /**
408 * Removes the drag-and-drop hooks from the component and optionally
409 * from the all children. You should call this if you add and remove
410 * components after you've set up the drag-and-drop.
411 * This will recursively unregister all components contained within
412 * <var>c</var> if <var>c</var> is a {@link java.awt.Container}.
413 *
414 * @param c The component to unregister as a drop target
415 * @return {@code true} if at least one item has been removed, {@code false} otherwise
416 */
417 public static boolean remove( Component c)
418 { return remove( c, true );
419 } // end remove
420
421 /**
422 * Removes the drag-and-drop hooks from the component and optionally
423 * from the all children. You should call this if you add and remove
424 * components after you've set up the drag-and-drop.
425 *
426 * @param c The component to unregister
427 * @param recursive Recursively unregister components within a container
428 * @return {@code true} if at least one item has been removed, {@code false} otherwise
429 */
430 public static boolean remove( Component c, boolean recursive )
431 { // Make sure we support dnd.
432 if (supportsDnD()) {
433 Main.trace("FileDrop: Removing drag-and-drop hooks.");
434 c.setDropTarget(null);
435 if (recursive && (c instanceof Container)) {
436 for (Component comp : ((Container) c).getComponents()) {
437 remove(comp, recursive);
438 }
439 return true;
440 } // end if: recursive
441 else return false;
442 } // end if: supports DnD
443 else return false;
444 } // end remove
445
446 /* ******** I N N E R I N T E R F A C E L I S T E N E R ******** */
447
448 /**
449 * Implement this inner interface to listen for when files are dropped. For example
450 * your class declaration may begin like this:
451 * <code>
452 * public class MyClass implements FileDrop.Listener
453 * ...
454 * public void filesDropped( java.io.File[] files )
455 * {
456 * ...
457 * } // end filesDropped
458 * ...
459 * </code>
460 */
461 public static interface Listener {
462
463 /**
464 * This method is called when files have been successfully dropped.
465 *
466 * @param files An array of <tt>File</tt>s that were dropped.
467 */
468 public abstract void filesDropped( File[] files );
469
470 } // end inner-interface Listener
471
472 /* ******** I N N E R C L A S S ******** */
473
474 /**
475 * At last an easy way to encapsulate your custom objects for dragging and dropping
476 * in your Java programs!
477 * When you need to create a {@link java.awt.datatransfer.Transferable} object,
478 * use this class to wrap your object.
479 * For example:
480 * <pre><code>
481 * ...
482 * MyCoolClass myObj = new MyCoolClass();
483 * Transferable xfer = new TransferableObject( myObj );
484 * ...
485 * </code></pre>
486 * Or if you need to know when the data was actually dropped, like when you're
487 * moving data out of a list, say, you can use the {@link TransferableObject.Fetcher}
488 * inner class to return your object Just in Time.
489 * For example:
490 * <pre><code>
491 * ...
492 * final MyCoolClass myObj = new MyCoolClass();
493 *
494 * TransferableObject.Fetcher fetcher = new TransferableObject.Fetcher()
495 * { public Object getObject(){ return myObj; }
496 * }; // end fetcher
497 *
498 * Transferable xfer = new TransferableObject( fetcher );
499 * ...
500 * </code></pre>
501 *
502 * The {@link java.awt.datatransfer.DataFlavor} associated with
503 * {@link TransferableObject} has the representation class
504 * <tt>net.iharder.dnd.TransferableObject.class</tt> and MIME type
505 * <tt>application/x-net.iharder.dnd.TransferableObject</tt>.
506 * This data flavor is accessible via the static
507 * {@link #DATA_FLAVOR} property.
508 *
509 *
510 * <p>I'm releasing this code into the Public Domain. Enjoy.</p>
511 *
512 * @author Robert Harder
513 * @author rob@iharder.net
514 * @version 1.2
515 */
516 public static class TransferableObject implements Transferable {
517
518 /**
519 * The MIME type for {@link #DATA_FLAVOR} is
520 * <tt>application/x-net.iharder.dnd.TransferableObject</tt>.
521 */
522 public static final String MIME_TYPE = "application/x-net.iharder.dnd.TransferableObject";
523
524 /**
525 * The default {@link java.awt.datatransfer.DataFlavor} for
526 * {@link TransferableObject} has the representation class
527 * <tt>net.iharder.dnd.TransferableObject.class</tt>
528 * and the MIME type
529 * <tt>application/x-net.iharder.dnd.TransferableObject</tt>.
530 */
531 public static final DataFlavor DATA_FLAVOR =
532 new DataFlavor( FileDrop.TransferableObject.class, MIME_TYPE );
533
534 private Fetcher fetcher;
535 private Object data;
536
537 private DataFlavor customFlavor;
538
539 /**
540 * Creates a new {@link TransferableObject} that wraps <var>data</var>.
541 * Along with the {@link #DATA_FLAVOR} associated with this class,
542 * this creates a custom data flavor with a representation class
543 * determined from <code>data.getClass()</code> and the MIME type
544 * <tt>application/x-net.iharder.dnd.TransferableObject</tt>.
545 *
546 * @param data The data to transfer
547 */
548 public TransferableObject( Object data )
549 { this.data = data;
550 this.customFlavor = new DataFlavor( data.getClass(), MIME_TYPE );
551 } // end constructor
552
553 /**
554 * Creates a new {@link TransferableObject} that will return the
555 * object that is returned by <var>fetcher</var>.
556 * No custom data flavor is set other than the default
557 * {@link #DATA_FLAVOR}.
558 *
559 * @see Fetcher
560 * @param fetcher The {@link Fetcher} that will return the data object
561 */
562 public TransferableObject( Fetcher fetcher )
563 { this.fetcher = fetcher;
564 } // end constructor
565
566 /**
567 * Creates a new {@link TransferableObject} that will return the
568 * object that is returned by <var>fetcher</var>.
569 * Along with the {@link #DATA_FLAVOR} associated with this class,
570 * this creates a custom data flavor with a representation class <var>dataClass</var>
571 * and the MIME type
572 * <tt>application/x-net.iharder.dnd.TransferableObject</tt>.
573 *
574 * @see Fetcher
575 * @param dataClass The {@link java.lang.Class} to use in the custom data flavor
576 * @param fetcher The {@link Fetcher} that will return the data object
577 */
578 public TransferableObject(Class<?> dataClass, Fetcher fetcher )
579 { this.fetcher = fetcher;
580 this.customFlavor = new DataFlavor( dataClass, MIME_TYPE );
581 } // end constructor
582
583 /**
584 * Returns the custom {@link java.awt.datatransfer.DataFlavor} associated
585 * with the encapsulated object or <tt>null</tt> if the {@link Fetcher}
586 * constructor was used without passing a {@link java.lang.Class}.
587 *
588 * @return The custom data flavor for the encapsulated object
589 */
590 public DataFlavor getCustomDataFlavor()
591 { return customFlavor;
592 } // end getCustomDataFlavor
593
594 /* ******** T R A N S F E R A B L E M E T H O D S ******** */
595
596 /**
597 * Returns a two- or three-element array containing first
598 * the custom data flavor, if one was created in the constructors,
599 * second the default {@link #DATA_FLAVOR} associated with
600 * {@link TransferableObject}, and third the
601 * {@link java.awt.datatransfer.DataFlavor#stringFlavor}.
602 *
603 * @return An array of supported data flavors
604 */
605 @Override
606 public DataFlavor[] getTransferDataFlavors()
607 {
608 if( customFlavor != null )
609 return new DataFlavor[]
610 { customFlavor,
611 DATA_FLAVOR,
612 DataFlavor.stringFlavor
613 }; // end flavors array
614 else
615 return new DataFlavor[]
616 { DATA_FLAVOR,
617 DataFlavor.stringFlavor
618 }; // end flavors array
619 } // end getTransferDataFlavors
620
621 /**
622 * Returns the data encapsulated in this {@link TransferableObject}.
623 * If the {@link Fetcher} constructor was used, then this is when
624 * the {@link Fetcher#getObject getObject()} method will be called.
625 * If the requested data flavor is not supported, then the
626 * {@link Fetcher#getObject getObject()} method will not be called.
627 *
628 * @param flavor The data flavor for the data to return
629 * @return The dropped data
630 */
631 @Override
632 public Object getTransferData( DataFlavor flavor )
633 throws UnsupportedFlavorException, IOException
634 {
635 // Native object
636 if( flavor.equals( DATA_FLAVOR ) )
637 return fetcher == null ? data : fetcher.getObject();
638
639 // String
640 if( flavor.equals( DataFlavor.stringFlavor ) )
641 return fetcher == null ? data.toString() : fetcher.getObject().toString();
642
643 // We can't do anything else
644 throw new UnsupportedFlavorException(flavor);
645 } // end getTransferData
646
647 /**
648 * Returns <tt>true</tt> if <var>flavor</var> is one of the supported
649 * flavors. Flavors are supported using the <code>equals(...)</code> method.
650 *
651 * @param flavor The data flavor to check
652 * @return Whether or not the flavor is supported
653 */
654 @Override
655 public boolean isDataFlavorSupported( DataFlavor flavor )
656 {
657 // Native object
658 if( flavor.equals( DATA_FLAVOR ) )
659 return true;
660
661 // String
662 if( flavor.equals( DataFlavor.stringFlavor ) )
663 return true;
664
665 // We can't do anything else
666 return false;
667 } // end isDataFlavorSupported
668
669 /* ******** I N N E R I N T E R F A C E F E T C H E R ******** */
670
671 /**
672 * Instead of passing your data directly to the {@link TransferableObject}
673 * constructor, you may want to know exactly when your data was received
674 * in case you need to remove it from its source (or do anyting else to it).
675 * When the {@link #getTransferData getTransferData(...)} method is called
676 * on the {@link TransferableObject}, the {@link Fetcher}'s
677 * {@link #getObject getObject()} method will be called.
678 *
679 * @author Robert Harder
680 */
681 public static interface Fetcher
682 {
683 /**
684 * Return the object being encapsulated in the
685 * {@link TransferableObject}.
686 *
687 * @return The dropped object
688 */
689 public abstract Object getObject();
690 } // end inner interface Fetcher
691
692 } // end class TransferableObject
693
694} // end class FileDrop
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