001 /*
002 * Copyright 2001-2003 Sun Microsystems, Inc. All Rights Reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation. Sun designates this
008 * particular file as subject to the "Classpath" exception as provided
009 * by Sun in the LICENSE file that accompanied this code.
010 *
011 * This code is distributed in the hope that it will be useful, but WITHOUT
012 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
013 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
014 * version 2 for more details (a copy is included in the LICENSE file that
015 * accompanied this code).
016 *
017 * You should have received a copy of the GNU General Public License version
018 * 2 along with this work; if not, write to the Free Software Foundation,
019 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
020 *
021 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
022 * CA 95054 USA or visit www.sun.com if you need additional information or
023 * have any questions.
024 */
025
026 package java.awt.dnd;
027
028 /**
029 * An abstract adapter class for receiving drop target events. The methods in
030 * this class are empty. This class exists only as a convenience for creating
031 * listener objects.
032 * <p>
033 * Extend this class to create a <code>DropTargetEvent</code> listener
034 * and override the methods for the events of interest. (If you implement the
035 * <code>DropTargetListener</code> interface, you have to define all of
036 * the methods in it. This abstract class defines a null implementation for
037 * every method except <code>drop(DropTargetDropEvent)</code>, so you only have
038 * to define methods for events you care about.) You must provide an
039 * implementation for at least <code>drop(DropTargetDropEvent)</code>. This
040 * method cannot have a null implementation because its specification requires
041 * that you either accept or reject the drop, and, if accepted, indicate
042 * whether the drop was successful.
043 * <p>
044 * Create a listener object using the extended class and then register it with
045 * a <code>DropTarget</code>. When the drag enters, moves over, or exits
046 * the operable part of the drop site for that <code>DropTarget</code>, when
047 * the drop action changes, and when the drop occurs, the relevant method in
048 * the listener object is invoked, and the <code>DropTargetEvent</code> is
049 * passed to it.
050 * <p>
051 * The operable part of the drop site for the <code>DropTarget</code> is
052 * the part of the associated <code>Component</code>'s geometry that is not
053 * obscured by an overlapping top-level window or by another
054 * <code>Component</code> higher in the Z-order that has an associated active
055 * <code>DropTarget</code>.
056 * <p>
057 * During the drag, the data associated with the current drag operation can be
058 * retrieved by calling <code>getTransferable()</code> on
059 * <code>DropTargetDragEvent</code> instances passed to the listener's
060 * methods.
061 * <p>
062 * Note that <code>getTransferable()</code> on the
063 * <code>DropTargetDragEvent</code> instance should only be called within the
064 * respective listener's method and all the necessary data should be retrieved
065 * from the returned <code>Transferable</code> before that method returns.
066 *
067 * @see DropTargetEvent
068 * @see DropTargetListener
069 *
070 * @author David Mendenhall
071 * @version 1.14, 05/05/07
072 * @since 1.4
073 */
074 public abstract class DropTargetAdapter implements DropTargetListener {
075
076 /**
077 * Called while a drag operation is ongoing, when the mouse pointer enters
078 * the operable part of the drop site for the <code>DropTarget</code>
079 * registered with this listener.
080 *
081 * @param dtde the <code>DropTargetDragEvent</code>
082 */
083 public void dragEnter(DropTargetDragEvent dtde) {
084 }
085
086 /**
087 * Called when a drag operation is ongoing, while the mouse pointer is still
088 * over the operable part of the drop site for the <code>DropTarget</code>
089 * registered with this listener.
090 *
091 * @param dtde the <code>DropTargetDragEvent</code>
092 */
093 public void dragOver(DropTargetDragEvent dtde) {
094 }
095
096 /**
097 * Called if the user has modified
098 * the current drop gesture.
099 *
100 * @param dtde the <code>DropTargetDragEvent</code>
101 */
102 public void dropActionChanged(DropTargetDragEvent dtde) {
103 }
104
105 /**
106 * Called while a drag operation is ongoing, when the mouse pointer has
107 * exited the operable part of the drop site for the
108 * <code>DropTarget</code> registered with this listener.
109 *
110 * @param dte the <code>DropTargetEvent</code>
111 */
112 public void dragExit(DropTargetEvent dte) {
113 }
114 }
|