| J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2000-2001 Sun Microsystems, Inc. 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. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * 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 | /** |
| 31 | * A KeyEventDispatcher cooperates with the current KeyboardFocusManager in the |
| 32 | * targeting and dispatching of all KeyEvents. KeyEventDispatchers registered |
| 33 | * with the current KeyboardFocusManager will receive KeyEvents before they are |
| 34 | * dispatched to their targets, allowing each KeyEventDispatcher to retarget |
| 35 | * the event, consume it, dispatch the event itself, or make other changes. |
| 36 | * <p> |
| 37 | * Note that KeyboardFocusManager itself implements KeyEventDispatcher. By |
| 38 | * default, the current KeyboardFocusManager will be the sink for all KeyEvents |
| 39 | * not dispatched by the registered KeyEventDispatchers. The current |
| 40 | * KeyboardFocusManager cannot be completely deregistered as a |
| 41 | * KeyEventDispatcher. However, if a KeyEventDispatcher reports that it |
| 42 | * dispatched the KeyEvent, regardless of whether it actually did so, the |
| 43 | * KeyboardFocusManager will take no further action with regard to the |
| 44 | * KeyEvent. (While it is possible for client code to register the current |
| 45 | * KeyboardFocusManager as a KeyEventDispatcher one or more times, this is |
| 46 | * usually unnecessary and not recommended.) |
| 47 | * |
| 48 | * @author David Mendenhall |
| 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 | } |