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KeyEventDispatcher.java
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91 lines (87 loc) · 3.59 KB
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/*
* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
* ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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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.
* <p>
* 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
*/
@FunctionalInterface
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 <code>redispatchEvent</code>
* to prevent the current KeyboardFocusManager from recursively requesting
* that this KeyEventDispatcher dispatch the event again.
* <p>
* If an implementation of this method returns <code>false</code>, then
* the KeyEvent is passed to the next KeyEventDispatcher in the chain,
* ending with the current KeyboardFocusManager. If an implementation
* returns <code>true</code>, 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,
* <code>KeyboardFocusManager.dispatchEvent</code> should return
* <code>true</code> as well. If an implementation consumes the KeyEvent,
* but returns <code>false</code>, 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 <code>true</code> if the KeyboardFocusManager should take no
* further action with regard to the KeyEvent; <code>false</code>
* otherwise
* @see KeyboardFocusManager#redispatchEvent
*/
boolean dispatchKeyEvent(KeyEvent e);
}