1 /* 2 * Copyright (c) 2000, 2013, 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 @FunctionalInterface 55 public interface KeyEventDispatcher { 56 57 /** 58 * This method is called by the current KeyboardFocusManager requesting 59 * that this KeyEventDispatcher dispatch the specified event on its behalf. 60 * This KeyEventDispatcher is free to retarget the event, consume it, 61 * dispatch it itself, or make other changes. This capability is typically 62 * used to deliver KeyEvents to Components other than the focus owner. This 63 * can be useful when navigating children of non-focusable Windows in an 64 * accessible environment, for example. Note that if a KeyEventDispatcher 65 * dispatches the KeyEvent itself, it must use <code>redispatchEvent</code> 66 * to prevent the current KeyboardFocusManager from recursively requesting 67 * that this KeyEventDispatcher dispatch the event again. 68 * <p> 69 * If an implementation of this method returns <code>false</code>, then 70 * the KeyEvent is passed to the next KeyEventDispatcher in the chain, 71 * ending with the current KeyboardFocusManager. If an implementation 72 * returns <code>true</code>, the KeyEvent is assumed to have been 73 * dispatched (although this need not be the case), and the current 74 * KeyboardFocusManager will take no further action with regard to the 75 * KeyEvent. In such a case, 76 * <code>KeyboardFocusManager.dispatchEvent</code> should return 77 * <code>true</code> as well. If an implementation consumes the KeyEvent, 78 * but returns <code>false</code>, the consumed event will still be passed 79 * to the next KeyEventDispatcher in the chain. It is important for 80 * developers to check whether the KeyEvent has been consumed before 81 * dispatching it to a target. By default, the current KeyboardFocusManager 82 * will not dispatch a consumed KeyEvent. 83 * 84 * @param e the KeyEvent to dispatch 85 * @return <code>true</code> if the KeyboardFocusManager should take no 86 * further action with regard to the KeyEvent; <code>false</code> 87 * otherwise 88 * @see KeyboardFocusManager#redispatchEvent 89 */ 90 boolean dispatchKeyEvent(KeyEvent e); 91 } --- EOF ---