1 /*
   2  * Copyright (c) 1996, 2014, 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.datatransfer;
  27 
  28 import sun.datatransfer.DataFlavorUtil;
  29 
  30 import java.util.Objects;
  31 import java.util.Set;
  32 import java.util.HashSet;
  33 import java.util.Arrays;
  34 
  35 import java.io.IOException;
  36 
  37 /**
  38  * A class that implements a mechanism to transfer data using
  39  * cut/copy/paste operations.
  40  * <p>
  41  * {@link FlavorListener}s may be registered on an instance of the
  42  * Clipboard class to be notified about changes to the set of
  43  * {@link DataFlavor}s available on this clipboard (see
  44  * {@link #addFlavorListener}).
  45  *
  46  * @see java.awt.Toolkit#getSystemClipboard
  47  * @see java.awt.Toolkit#getSystemSelection
  48  *
  49  * @author      Amy Fowler
  50  * @author      Alexander Gerasimov
  51  */
  52 public class Clipboard {
  53 
  54     String name;
  55 
  56     /**
  57      * The owner of the clipboard.
  58      */
  59     protected ClipboardOwner owner;
  60     /**
  61      * Contents of the clipboard.
  62      */
  63     protected Transferable contents;
  64 
  65     /**
  66      * An aggregate of flavor listeners registered on this local clipboard.
  67      *
  68      * @since 1.5
  69      */
  70     private Set<FlavorListener> flavorListeners;
  71 
  72     /**
  73      * A set of <code>DataFlavor</code>s that is available on
  74      * this local clipboard. It is used for tracking changes
  75      * of <code>DataFlavor</code>s available on this clipboard.
  76      *
  77      * @since 1.5
  78      */
  79     private Set<DataFlavor> currentDataFlavors;
  80 
  81     /**
  82      * Creates a clipboard object.
  83      * @param name for the clipboard
  84      * @see java.awt.Toolkit#getSystemClipboard
  85      */
  86     public Clipboard(String name) {
  87         this.name = name;
  88     }
  89 
  90     /**
  91      * Returns the name of this clipboard object.
  92      * @return the name of this clipboard object
  93      *
  94      * @see java.awt.Toolkit#getSystemClipboard
  95      */
  96     public String getName() {
  97         return name;
  98     }
  99 
 100     /**
 101      * Sets the current contents of the clipboard to the specified
 102      * transferable object and registers the specified clipboard owner
 103      * as the owner of the new contents.
 104      * <p>
 105      * If there is an existing owner different from the argument
 106      * <code>owner</code>, that owner is notified that it no longer
 107      * holds ownership of the clipboard contents via an invocation
 108      * of <code>ClipboardOwner.lostOwnership()</code> on that owner.
 109      * An implementation of <code>setContents()</code> is free not
 110      * to invoke <code>lostOwnership()</code> directly from this method.
 111      * For example, <code>lostOwnership()</code> may be invoked later on
 112      * a different thread. The same applies to <code>FlavorListener</code>s
 113      * registered on this clipboard.
 114      * <p>
 115      * The method throws <code>IllegalStateException</code> if the clipboard
 116      * is currently unavailable. For example, on some platforms, the system
 117      * clipboard is unavailable while it is accessed by another application.
 118      *
 119      * @param contents the transferable object representing the
 120      *                 clipboard content
 121      * @param owner the object which owns the clipboard content
 122      * @throws IllegalStateException if the clipboard is currently unavailable
 123      * @see java.awt.Toolkit#getSystemClipboard
 124      */
 125     public synchronized void setContents(Transferable contents, ClipboardOwner owner) {
 126         final ClipboardOwner oldOwner = this.owner;
 127         final Transferable oldContents = this.contents;
 128 
 129         this.owner = owner;
 130         this.contents = contents;
 131 
 132         if (oldOwner != null && oldOwner != owner) {
 133             DataFlavorUtil.getDesktopService().invokeOnEventThread(() ->
 134                     oldOwner.lostOwnership(Clipboard.this, oldContents));
 135         }
 136         fireFlavorsChanged();
 137     }
 138 
 139     /**
 140      * Returns a transferable object representing the current contents
 141      * of the clipboard.  If the clipboard currently has no contents,
 142      * it returns <code>null</code>. The parameter Object requestor is
 143      * not currently used.  The method throws
 144      * <code>IllegalStateException</code> if the clipboard is currently
 145      * unavailable.  For example, on some platforms, the system clipboard is
 146      * unavailable while it is accessed by another application.
 147      *
 148      * @param requestor the object requesting the clip data  (not used)
 149      * @return the current transferable object on the clipboard
 150      * @throws IllegalStateException if the clipboard is currently unavailable
 151      * @see java.awt.Toolkit#getSystemClipboard
 152      */
 153     public synchronized Transferable getContents(Object requestor) {
 154         return contents;
 155     }
 156 
 157 
 158     /**
 159      * Returns an array of <code>DataFlavor</code>s in which the current
 160      * contents of this clipboard can be provided. If there are no
 161      * <code>DataFlavor</code>s available, this method returns a zero-length
 162      * array.
 163      *
 164      * @return an array of <code>DataFlavor</code>s in which the current
 165      *         contents of this clipboard can be provided
 166      *
 167      * @throws IllegalStateException if this clipboard is currently unavailable
 168      *
 169      * @since 1.5
 170      */
 171     public DataFlavor[] getAvailableDataFlavors() {
 172         Transferable cntnts = getContents(null);
 173         if (cntnts == null) {
 174             return new DataFlavor[0];
 175         }
 176         return cntnts.getTransferDataFlavors();
 177     }
 178 
 179     /**
 180      * Returns whether or not the current contents of this clipboard can be
 181      * provided in the specified <code>DataFlavor</code>.
 182      *
 183      * @param flavor the requested <code>DataFlavor</code> for the contents
 184      *
 185      * @return <code>true</code> if the current contents of this clipboard
 186      *         can be provided in the specified <code>DataFlavor</code>;
 187      *         <code>false</code> otherwise
 188      *
 189      * @throws NullPointerException if <code>flavor</code> is <code>null</code>
 190      * @throws IllegalStateException if this clipboard is currently unavailable
 191      *
 192      * @since 1.5
 193      */
 194     public boolean isDataFlavorAvailable(DataFlavor flavor) {
 195         if (flavor == null) {
 196             throw new NullPointerException("flavor");
 197         }
 198 
 199         Transferable cntnts = getContents(null);
 200         if (cntnts == null) {
 201             return false;
 202         }
 203         return cntnts.isDataFlavorSupported(flavor);
 204     }
 205 
 206     /**
 207      * Returns an object representing the current contents of this clipboard
 208      * in the specified <code>DataFlavor</code>.
 209      * The class of the object returned is defined by the representation
 210      * class of <code>flavor</code>.
 211      *
 212      * @param flavor the requested <code>DataFlavor</code> for the contents
 213      *
 214      * @return an object representing the current contents of this clipboard
 215      *         in the specified <code>DataFlavor</code>
 216      *
 217      * @throws NullPointerException if <code>flavor</code> is <code>null</code>
 218      * @throws IllegalStateException if this clipboard is currently unavailable
 219      * @throws UnsupportedFlavorException if the requested <code>DataFlavor</code>
 220      *         is not available
 221      * @throws IOException if the data in the requested <code>DataFlavor</code>
 222      *         can not be retrieved
 223      *
 224      * @see DataFlavor#getRepresentationClass
 225      *
 226      * @since 1.5
 227      */
 228     public Object getData(DataFlavor flavor)
 229         throws UnsupportedFlavorException, IOException {
 230         if (flavor == null) {
 231             throw new NullPointerException("flavor");
 232         }
 233 
 234         Transferable cntnts = getContents(null);
 235         if (cntnts == null) {
 236             throw new UnsupportedFlavorException(flavor);
 237         }
 238         return cntnts.getTransferData(flavor);
 239     }
 240 
 241 
 242     /**
 243      * Registers the specified <code>FlavorListener</code> to receive
 244      * <code>FlavorEvent</code>s from this clipboard.
 245      * If <code>listener</code> is <code>null</code>, no exception
 246      * is thrown and no action is performed.
 247      *
 248      * @param listener the listener to be added
 249      *
 250      * @see #removeFlavorListener
 251      * @see #getFlavorListeners
 252      * @see FlavorListener
 253      * @see FlavorEvent
 254      * @since 1.5
 255      */
 256     public synchronized void addFlavorListener(FlavorListener listener) {
 257         if (listener == null) {
 258             return;
 259         }
 260 
 261         if (flavorListeners == null) {
 262             flavorListeners = new HashSet<>();
 263             currentDataFlavors = getAvailableDataFlavorSet();
 264         }
 265 
 266         flavorListeners.add(listener);
 267     }
 268 
 269     /**
 270      * Removes the specified <code>FlavorListener</code> so that it no longer
 271      * receives <code>FlavorEvent</code>s from this <code>Clipboard</code>.
 272      * This method performs no function, nor does it throw an exception, if
 273      * the listener specified by the argument was not previously added to this
 274      * <code>Clipboard</code>.
 275      * If <code>listener</code> is <code>null</code>, no exception
 276      * is thrown and no action is performed.
 277      *
 278      * @param listener the listener to be removed
 279      *
 280      * @see #addFlavorListener
 281      * @see #getFlavorListeners
 282      * @see FlavorListener
 283      * @see FlavorEvent
 284      * @since 1.5
 285      */
 286     public synchronized void removeFlavorListener(FlavorListener listener) {
 287         if (listener == null || flavorListeners == null) {
 288             return;
 289         }
 290         flavorListeners.remove(listener);
 291     }
 292 
 293     /**
 294      * Returns an array of all the <code>FlavorListener</code>s currently
 295      * registered on this <code>Clipboard</code>.
 296      *
 297      * @return all of this clipboard's <code>FlavorListener</code>s or an empty
 298      *         array if no listeners are currently registered
 299      * @see #addFlavorListener
 300      * @see #removeFlavorListener
 301      * @see FlavorListener
 302      * @see FlavorEvent
 303      * @since 1.5
 304      */
 305     public synchronized FlavorListener[] getFlavorListeners() {
 306         return flavorListeners == null ? new FlavorListener[0] :
 307             flavorListeners.toArray(new FlavorListener[flavorListeners.size()]);
 308     }
 309 
 310     /**
 311      * Checks change of the <code>DataFlavor</code>s and, if necessary,
 312      * notifies all listeners that have registered interest for notification
 313      * on <code>FlavorEvent</code>s.
 314      *
 315      * @since 1.5
 316      */
 317     private void fireFlavorsChanged() {
 318         if (flavorListeners == null) {
 319             return;
 320         }
 321 
 322         Set<DataFlavor> prevDataFlavors = currentDataFlavors;
 323         currentDataFlavors = getAvailableDataFlavorSet();
 324         if (Objects.equals(prevDataFlavors, currentDataFlavors)) {
 325             return;
 326         }
 327         flavorListeners.forEach(listener ->
 328                 DataFlavorUtil.getDesktopService().invokeOnEventThread(() ->
 329                         listener.flavorsChanged(new FlavorEvent(Clipboard.this))));
 330     }
 331 
 332     /**
 333      * Returns a set of <code>DataFlavor</code>s currently available
 334      * on this clipboard.
 335      *
 336      * @return a set of <code>DataFlavor</code>s currently available
 337      *         on this clipboard
 338      *
 339      * @since 1.5
 340      */
 341     private Set<DataFlavor> getAvailableDataFlavorSet() {
 342         Set<DataFlavor> set = new HashSet<>();
 343         Transferable contents = getContents(null);
 344         if (contents != null) {
 345             DataFlavor[] flavors = contents.getTransferDataFlavors();
 346             if (flavors != null) {
 347                 set.addAll(Arrays.asList(flavors));
 348             }
 349         }
 350         return set;
 351     }
 352 }
--- EOF ---