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| 1 | +/* | |
| 2 | + * Copyright (c) 2000, 2001, Oracle and/or its affiliates. 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. Oracle designates this | |
| 8 | + * particular file as subject to the "Classpath" exception as provided | |
| 9 | + * by Oracle 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA | |
| 22 | + * or visit www.oracle.com if you need additional information or have any | |
| 23 | + * 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 | +} | |