01 /*
02 * Copyright 2000-2001 Sun Microsystems, Inc. All Rights Reserved.
03 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
04 *
05 * This code is free software; you can redistribute it and/or modify it
06 * under the terms of the GNU General Public License version 2 only, as
07 * published by the Free Software Foundation. Sun designates this
08 * particular file as subject to the "Classpath" exception as provided
09 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25 package java.awt;
26
27 import java.awt.event.KeyEvent;
28
29 /**
30 * A KeyEventDispatcher cooperates with the current KeyboardFocusManager in the
31 * targeting and dispatching of all KeyEvents. KeyEventDispatchers registered
32 * with the current KeyboardFocusManager will receive KeyEvents before they are
33 * dispatched to their targets, allowing each KeyEventDispatcher to retarget
34 * the event, consume it, dispatch the event itself, or make other changes.
35 * <p>
36 * Note that KeyboardFocusManager itself implements KeyEventDispatcher. By
37 * default, the current KeyboardFocusManager will be the sink for all KeyEvents
38 * not dispatched by the registered KeyEventDispatchers. The current
39 * KeyboardFocusManager cannot be completely deregistered as a
40 * KeyEventDispatcher. However, if a KeyEventDispatcher reports that it
41 * dispatched the KeyEvent, regardless of whether it actually did so, the
42 * KeyboardFocusManager will take no further action with regard to the
43 * KeyEvent. (While it is possible for client code to register the current
44 * KeyboardFocusManager as a KeyEventDispatcher one or more times, this is
45 * usually unnecessary and not recommended.)
46 *
47 * @author David Mendenhall
48 * @version 1.12, 05/05/07
49 *
50 * @see KeyboardFocusManager#addKeyEventDispatcher
51 * @see KeyboardFocusManager#removeKeyEventDispatcher
52 * @since 1.4
53 */
54 public interface KeyEventDispatcher {
55
56 /**
57 * This method is called by the current KeyboardFocusManager requesting
58 * that this KeyEventDispatcher dispatch the specified event on its behalf.
59 * This KeyEventDispatcher is free to retarget the event, consume it,
60 * dispatch it itself, or make other changes. This capability is typically
61 * used to deliver KeyEvents to Components other than the focus owner. This
62 * can be useful when navigating children of non-focusable Windows in an
63 * accessible environment, for example. Note that if a KeyEventDispatcher
64 * dispatches the KeyEvent itself, it must use <code>redispatchEvent</code>
65 * to prevent the current KeyboardFocusManager from recursively requesting
66 * that this KeyEventDispatcher dispatch the event again.
67 * <p>
68 * If an implementation of this method returns <code>false</code>, then
69 * the KeyEvent is passed to the next KeyEventDispatcher in the chain,
70 * ending with the current KeyboardFocusManager. If an implementation
71 * returns <code>true</code>, the KeyEvent is assumed to have been
72 * dispatched (although this need not be the case), and the current
73 * KeyboardFocusManager will take no further action with regard to the
74 * KeyEvent. In such a case,
75 * <code>KeyboardFocusManager.dispatchEvent</code> should return
76 * <code>true</code> as well. If an implementation consumes the KeyEvent,
77 * but returns <code>false</code>, the consumed event will still be passed
78 * to the next KeyEventDispatcher in the chain. It is important for
79 * developers to check whether the KeyEvent has been consumed before
80 * dispatching it to a target. By default, the current KeyboardFocusManager
81 * will not dispatch a consumed KeyEvent.
82 *
83 * @param e the KeyEvent to dispatch
84 * @return <code>true</code> if the KeyboardFocusManager should take no
85 * further action with regard to the KeyEvent; <code>false</code>
86 * otherwise
87 * @see KeyboardFocusManager#redispatchEvent
88 */
89 boolean dispatchKeyEvent(KeyEvent e);
90 }
|