/* * Copyright (c) 2000, 2001, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package java.awt; import java.awt.event.KeyEvent; /** * A KeyEventDispatcher cooperates with the current KeyboardFocusManager in the * targeting and dispatching of all KeyEvents. KeyEventDispatchers registered * with the current KeyboardFocusManager will receive KeyEvents before they are * dispatched to their targets, allowing each KeyEventDispatcher to retarget * the event, consume it, dispatch the event itself, or make other changes. *
* Note that KeyboardFocusManager itself implements KeyEventDispatcher. By
* default, the current KeyboardFocusManager will be the sink for all KeyEvents
* not dispatched by the registered KeyEventDispatchers. The current
* KeyboardFocusManager cannot be completely deregistered as a
* KeyEventDispatcher. However, if a KeyEventDispatcher reports that it
* dispatched the KeyEvent, regardless of whether it actually did so, the
* KeyboardFocusManager will take no further action with regard to the
* KeyEvent. (While it is possible for client code to register the current
* KeyboardFocusManager as a KeyEventDispatcher one or more times, this is
* usually unnecessary and not recommended.)
*
* @author David Mendenhall
*
* @see KeyboardFocusManager#addKeyEventDispatcher
* @see KeyboardFocusManager#removeKeyEventDispatcher
* @since 1.4
*/
public interface KeyEventDispatcher {
/**
* This method is called by the current KeyboardFocusManager requesting
* that this KeyEventDispatcher dispatch the specified event on its behalf.
* This KeyEventDispatcher is free to retarget the event, consume it,
* dispatch it itself, or make other changes. This capability is typically
* used to deliver KeyEvents to Components other than the focus owner. This
* can be useful when navigating children of non-focusable Windows in an
* accessible environment, for example. Note that if a KeyEventDispatcher
* dispatches the KeyEvent itself, it must use redispatchEvent
* to prevent the current KeyboardFocusManager from recursively requesting
* that this KeyEventDispatcher dispatch the event again.
*
* If an implementation of this method returns false
, then
* the KeyEvent is passed to the next KeyEventDispatcher in the chain,
* ending with the current KeyboardFocusManager. If an implementation
* returns true
, the KeyEvent is assumed to have been
* dispatched (although this need not be the case), and the current
* KeyboardFocusManager will take no further action with regard to the
* KeyEvent. In such a case,
* KeyboardFocusManager.dispatchEvent
should return
* true
as well. If an implementation consumes the KeyEvent,
* but returns false
, the consumed event will still be passed
* to the next KeyEventDispatcher in the chain. It is important for
* developers to check whether the KeyEvent has been consumed before
* dispatching it to a target. By default, the current KeyboardFocusManager
* will not dispatch a consumed KeyEvent.
*
* @param e the KeyEvent to dispatch
* @return true
if the KeyboardFocusManager should take no
* further action with regard to the KeyEvent; false
* otherwise
* @see KeyboardFocusManager#redispatchEvent
*/
boolean dispatchKeyEvent(KeyEvent e);
}