DropTargetAdapter


1   /*
2    * @(#)DropTargetAdapter.java   1.7 03/12/19
3    *
4    * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7   
8   package java.awt.dnd;
9   
10  /**
11   * An abstract adapter class for receiving drop target events. The methods in
12   * this class are empty. This class exists only as a convenience for creating
13   * listener objects.
14   * <p>
15   * Extend this class to create a <code>DropTargetEvent</code> listener 
16   * and override the methods for the events of interest. (If you implement the 
17   * <code>DropTargetListener</code> interface, you have to define all of
18   * the methods in it. This abstract class defines a null implementation for
19   * every method except <code>drop(DropTargetDropEvent)</code>, so you only have
20   * to define methods for events you care about.) You must provide an
21   * implementation for at least <code>drop(DropTargetDropEvent)</code>. This
22   * method cannot have a null implementation because its specification requires
23   * that you either accept or reject the drop, and, if accepted, indicate
24   * whether the drop was successful.
25   * <p>
26   * Create a listener object using the extended class and then register it with 
27   * a <code>DropTarget</code>. When the drag enters, moves over, or exits
28   * the operable part of the drop site for that <code>DropTarget</code>, when 
29   * the drop action changes, and when the drop occurs, the relevant method in 
30   * the listener object is invoked, and the <code>DropTargetEvent</code> is 
31   * passed to it.
32   * <p>
33   * The operable part of the drop site for the <code>DropTarget</code> is 
34   * the part of the associated <code>Component</code>'s geometry that is not 
35   * obscured by an overlapping top-level window or by another 
36   * <code>Component</code> higher in the Z-order that has an associated active 
37   * <code>DropTarget</code>.
38   * <p>
39   * During the drag, the data associated with the current drag operation can be
40   * retrieved by calling <code>getTransferable()</code> on 
41   * <code>DropTargetDragEvent</code> instances passed to the listener's
42   * methods. 
43   * <p>
44   * Note that <code>getTransferable()</code> on the 
45   * <code>DropTargetDragEvent</code> instance should only be called within the
46   * respective listener's method and all the necessary data should be retrieved
47   * from the returned <code>Transferable</code> before that method returns.
48   *
49   * @see DropTargetEvent
50   * @see DropTargetListener
51   *
52   * @author David Mendenhall
53   * @version 1.7, 12/19/03
54   * @since 1.4
55   */
56  public abstract class DropTargetAdapter implements DropTargetListener   {
57  
58      /**
59       * Called while a drag operation is ongoing, when the mouse pointer enters
60       * the operable part of the drop site for the <code>DropTarget</code>
61       * registered with this listener. 
62       * 
63       * @param dtde the <code>DropTargetDragEvent</code> 
64       */
65      public void dragEnter(DropTargetDragEvent   dtde) {}
66  
67      /**
68       * Called when a drag operation is ongoing, while the mouse pointer is still
69       * over the operable part of the drop site for the <code>DropTarget</code>
70       * registered with this listener.
71       * 
72       * @param dtde the <code>DropTargetDragEvent</code> 
73       */
74      public void dragOver(DropTargetDragEvent   dtde) {}
75  
76      /**
77       * Called if the user has modified 
78       * the current drop gesture.
79       *
80       * @param dtde the <code>DropTargetDragEvent</code>
81       */
82      public void dropActionChanged(DropTargetDragEvent   dtde) {}
83  
84      /**
85       * Called while a drag operation is ongoing, when the mouse pointer has
86       * exited the operable part of the drop site for the
87       * <code>DropTarget</code> registered with this listener.
88       * 
89       * @param dte the <code>DropTargetEvent</code> 
90       */
91      public void dragExit(DropTargetEvent   dte) {}
92  }
93
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags