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92 lines
4.5 KiB
Java
92 lines
4.5 KiB
Java
/*
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* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.awt;
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import java.awt.event.KeyEvent;
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/**
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* A KeyEventDispatcher cooperates with the current KeyboardFocusManager in the
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* targeting and dispatching of all KeyEvents. KeyEventDispatchers registered
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* with the current KeyboardFocusManager will receive KeyEvents before they are
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* dispatched to their targets, allowing each KeyEventDispatcher to retarget
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* the event, consume it, dispatch the event itself, or make other changes.
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* <p>
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* Note that KeyboardFocusManager itself implements KeyEventDispatcher. By
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* default, the current KeyboardFocusManager will be the sink for all KeyEvents
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* not dispatched by the registered KeyEventDispatchers. The current
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* KeyboardFocusManager cannot be completely deregistered as a
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* KeyEventDispatcher. However, if a KeyEventDispatcher reports that it
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* dispatched the KeyEvent, regardless of whether it actually did so, the
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* KeyboardFocusManager will take no further action with regard to the
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* KeyEvent. (While it is possible for client code to register the current
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* KeyboardFocusManager as a KeyEventDispatcher one or more times, this is
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* usually unnecessary and not recommended.)
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*
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* @author David Mendenhall
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*
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* @see KeyboardFocusManager#addKeyEventDispatcher
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* @see KeyboardFocusManager#removeKeyEventDispatcher
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* @since 1.4
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*/
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@FunctionalInterface
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public interface KeyEventDispatcher {
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/**
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* This method is called by the current KeyboardFocusManager requesting
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* that this KeyEventDispatcher dispatch the specified event on its behalf.
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* This KeyEventDispatcher is free to retarget the event, consume it,
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* dispatch it itself, or make other changes. This capability is typically
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* used to deliver KeyEvents to Components other than the focus owner. This
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* can be useful when navigating children of non-focusable Windows in an
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* accessible environment, for example. Note that if a KeyEventDispatcher
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* dispatches the KeyEvent itself, it must use {@code redispatchEvent}
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* to prevent the current KeyboardFocusManager from recursively requesting
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* that this KeyEventDispatcher dispatch the event again.
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* <p>
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* If an implementation of this method returns {@code false}, then
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* the KeyEvent is passed to the next KeyEventDispatcher in the chain,
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* ending with the current KeyboardFocusManager. If an implementation
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* returns {@code true}, the KeyEvent is assumed to have been
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* dispatched (although this need not be the case), and the current
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* KeyboardFocusManager will take no further action with regard to the
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* KeyEvent. In such a case,
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* {@code KeyboardFocusManager.dispatchEvent} should return
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* {@code true} as well. If an implementation consumes the KeyEvent,
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* but returns {@code false}, the consumed event will still be passed
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* to the next KeyEventDispatcher in the chain. It is important for
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* developers to check whether the KeyEvent has been consumed before
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* dispatching it to a target. By default, the current KeyboardFocusManager
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* will not dispatch a consumed KeyEvent.
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*
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* @param e the KeyEvent to dispatch
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* @return {@code true} if the KeyboardFocusManager should take no
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* further action with regard to the KeyEvent; {@code false}
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* otherwise
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* @see KeyboardFocusManager#redispatchEvent
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*/
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boolean dispatchKeyEvent(KeyEvent e);
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}
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