01 /*
02 * Copyright 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 KeyEventPostProcessor cooperates with the current KeyboardFocusManager
31 * in the final resolution of all unconsumed KeyEvents. KeyEventPostProcessors
32 * registered with the current KeyboardFocusManager will receive KeyEvents
33 * after the KeyEvents have been dispatched to and handled by their targets.
34 * KeyEvents that would have been otherwise discarded because no Component in
35 * the application currently owns the focus will also be forwarded to
36 * registered KeyEventPostProcessors. This will allow applications to implement
37 * features that require global KeyEvent post-handling, such as menu shortcuts.
38 * <p>
39 * Note that the KeyboardFocusManager itself implements KeyEventPostProcessor.
40 * By default, the current KeyboardFocusManager will be the final
41 * KeyEventPostProcessor in the chain. The current KeyboardFocusManager cannot
42 * be completely deregistered as a KeyEventPostProcessor. However, if a
43 * KeyEventPostProcessor reports that no further post-processing of the
44 * KeyEvent should take place, the AWT will consider the event fully handled
45 * and will take no additional action with regard to the event. (While it is
46 * possible for client code to register the current KeyboardFocusManager as
47 * a KeyEventPostProcessor one or more times, this is usually unnecessary and
48 * not recommended.)
49 *
50 * @author David Mendenhall
51 * @version 1.12, 05/05/07
52 *
53 * @see KeyboardFocusManager#addKeyEventPostProcessor
54 * @see KeyboardFocusManager#removeKeyEventPostProcessor
55 * @since 1.4
56 */
57 public interface KeyEventPostProcessor {
58
59 /**
60 * This method is called by the current KeyboardFocusManager, requesting
61 * that this KeyEventPostProcessor perform any necessary post-processing
62 * which should be part of the KeyEvent's final resolution. At the time
63 * this method is invoked, typically the KeyEvent has already been
64 * dispatched to and handled by its target. However, if no Component in
65 * the application currently owns the focus, then the KeyEvent has not
66 * been dispatched to any Component. Typically, KeyEvent post-processing
67 * will be used to implement features which require global KeyEvent
68 * post-handling, such as menu shortcuts. Note that if a
69 * KeyEventPostProcessor wishes to dispatch the KeyEvent, it must use
70 * <code>redispatchEvent</code> to prevent the AWT from recursively
71 * requesting that this KeyEventPostProcessor perform post-processing
72 * of the event again.
73 * <p>
74 * If an implementation of this method returns <code>false</code>, then the
75 * KeyEvent is passed to the next KeyEventPostProcessor in the chain,
76 * ending with the current KeyboardFocusManager. If an implementation
77 * returns <code>true</code>, the KeyEvent is assumed to have been fully
78 * handled (although this need not be the case), and the AWT will take no
79 * further action with regard to the KeyEvent. If an implementation
80 * consumes the KeyEvent but returns <code>false</code>, the consumed
81 * event will still be passed to the next KeyEventPostProcessor in the
82 * chain. It is important for developers to check whether the KeyEvent has
83 * been consumed before performing any post-processing of the KeyEvent. By
84 * default, the current KeyboardFocusManager will perform no post-
85 * processing in response to a consumed KeyEvent.
86 *
87 * @param e the KeyEvent to post-process
88 * @return <code>true</code> if the AWT should take no further action with
89 * regard to the KeyEvent; <code>false</code> otherwise
90 * @see KeyboardFocusManager#redispatchEvent
91 */
92 boolean postProcessKeyEvent(KeyEvent e);
93 }
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