1 /*

     2  * Copyright 2001 Sun Microsystems, Inc.  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.  Sun designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    22  * CA 95054 USA or visit www.sun.com if you need additional information or

    23  * have any questions.

    24  */

    25 package java.awt;

    26 

    27 import java.awt.event.KeyEvent;

    28 

    29 

    30 /**

    31  * A KeyEventPostProcessor cooperates with the current KeyboardFocusManager

    32  * in the final resolution of all unconsumed KeyEvents. KeyEventPostProcessors

    33  * registered with the current KeyboardFocusManager will receive KeyEvents

    34  * after the KeyEvents have been dispatched to and handled by their targets.

    35  * KeyEvents that would have been otherwise discarded because no Component in

    36  * the application currently owns the focus will also be forwarded to

    37  * registered KeyEventPostProcessors. This will allow applications to implement

    38  * features that require global KeyEvent post-handling, such as menu shortcuts.

    39  * <p>

    40  * Note that the KeyboardFocusManager itself implements KeyEventPostProcessor.

    41  * By default, the current KeyboardFocusManager will be the final

    42  * KeyEventPostProcessor in the chain. The current KeyboardFocusManager cannot

    43  * be completely deregistered as a KeyEventPostProcessor. However, if a

    44  * KeyEventPostProcessor reports that no further post-processing of the

    45  * KeyEvent should take place, the AWT will consider the event fully handled

    46  * and will take no additional action with regard to the event. (While it is

    47  * possible for client code to register the current KeyboardFocusManager as

    48  * a KeyEventPostProcessor one or more times, this is usually unnecessary and

    49  * not recommended.)

    50  *

    51  * @author David Mendenhall

    52  *

    53  * @see KeyboardFocusManager#addKeyEventPostProcessor

    54  * @see KeyboardFocusManager#removeKeyEventPostProcessor

    55  * @since 1.4

    56  */

    57 public interface KeyEventPostProcessor {

    58 

    59     /**

    60      * This method is called by the current KeyboardFocusManager, requesting

    61      * that this KeyEventPostProcessor perform any necessary post-processing

    62      * which should be part of the KeyEvent's final resolution. At the time

    63      * this method is invoked, typically the KeyEvent has already been

    64      * dispatched to and handled by its target. However, if no Component in

    65      * the application currently owns the focus, then the KeyEvent has not

    66      * been dispatched to any Component. Typically, KeyEvent post-processing

    67      * will be used to implement features which require global KeyEvent

    68      * post-handling, such as menu shortcuts. Note that if a

    69      * KeyEventPostProcessor wishes to dispatch the KeyEvent, it must use

    70      * <code>redispatchEvent</code> to prevent the AWT from recursively

    71      * requesting that this KeyEventPostProcessor perform post-processing

    72      * of the event again.

    73      * <p>

    74      * If an implementation of this method returns <code>false</code>, then the

    75      * KeyEvent is passed to the next KeyEventPostProcessor in the chain,

    76      * ending with the current KeyboardFocusManager. If an implementation

    77      * returns <code>true</code>, the KeyEvent is assumed to have been fully

    78      * handled (although this need not be the case), and the AWT will take no

    79      * further action with regard to the KeyEvent. If an implementation

    80      * consumes the KeyEvent but returns <code>false</code>, the consumed

    81      * event will still be passed to the next KeyEventPostProcessor in the

    82      * chain. It is important for developers to check whether the KeyEvent has

    83      * been consumed before performing any post-processing of the KeyEvent. By

    84      * default, the current KeyboardFocusManager will perform no post-

    85      * processing in response to a consumed KeyEvent.

    86      *

    87      * @param e the KeyEvent to post-process

    88      * @return <code>true</code> if the AWT should take no further action with

    89      *         regard to the KeyEvent; <code>false</code> otherwise

    90      * @see KeyboardFocusManager#redispatchEvent

    91      */

    92     boolean postProcessKeyEvent(KeyEvent e);

    93 }