KeyEventPostProcessor


1   /*
2    * @(#)KeyEventPostProcessor.java   1.5 03/12/19
3    *
4    * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
5    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
6    */
7   package java.awt;
8   
9   import java.awt.event.KeyEvent  ;
10  
11  
12  /**
13   * A KeyEventPostProcessor cooperates with the current KeyboardFocusManager
14   * in the final resolution of all unconsumed KeyEvents. KeyEventPostProcessors
15   * registered with the current KeyboardFocusManager will receive KeyEvents
16   * after the KeyEvents have been dispatched to and handled by their targets.
17   * KeyEvents that would have been otherwise discarded because no Component in
18   * the application currently owns the focus will also be forwarded to
19   * registered KeyEventPostProcessors. This will allow applications to implement
20   * features that require global KeyEvent post-handling, such as menu shortcuts.
21   * <p>
22   * Note that the KeyboardFocusManager itself implements KeyEventPostProcessor.
23   * By default, the current KeyboardFocusManager will be the final
24   * KeyEventPostProcessor in the chain. The current KeyboardFocusManager cannot
25   * be completely deregistered as a KeyEventPostProcessor. However, if a
26   * KeyEventPostProcessor reports that no further post-processing of the
27   * KeyEvent should take place, the AWT will consider the event fully handled
28   * and will take no additional action with regard to the event. (While it is
29   * possible for client code to register the current KeyboardFocusManager as
30   * a KeyEventPostProcessor one or more times, this is usually unnecessary and
31   * not recommended.)
32   *
33   * @author David Mendenhall
34   * @version 1.5, 12/19/03
35   *
36   * @see KeyboardFocusManager#addKeyEventPostProcessor
37   * @see KeyboardFocusManager#removeKeyEventPostProcessor
38   * @since 1.4
39   */
40  public interface KeyEventPostProcessor {
41  
42      /**
43       * This method is called by the current KeyboardFocusManager, requesting
44       * that this KeyEventPostProcessor perform any necessary post-processing
45       * which should be part of the KeyEvent's final resolution. At the time
46       * this method is invoked, typically the KeyEvent has already been
47       * dispatched to and handled by its target. However, if no Component in
48       * the application currently owns the focus, then the KeyEvent has not
49       * been dispatched to any Component. Typically, KeyEvent post-processing
50       * will be used to implement features which require global KeyEvent
51       * post-handling, such as menu shortcuts. Note that if a
52       * KeyEventPostProcessor wishes to dispatch the KeyEvent, it must use
53       * <code>redispatchEvent</code> to prevent the AWT from recursively
54       * requesting that this KeyEventPostProcessor perform post-processing
55       * of the event again.
56       * <p>
57       * If an implementation of this method returns <code>false</code>, then the
58       * KeyEvent is passed to the next KeyEventPostProcessor in the chain,
59       * ending with the current KeyboardFocusManager. If an implementation
60       * returns <code>true</code>, the KeyEvent is assumed to have been fully
61       * handled (although this need not be the case), and the AWT will take no
62       * further action with regard to the KeyEvent. If an implementation
63       * consumes the KeyEvent but returns <code>false</code>, the consumed
64       * event will still be passed to the next KeyEventPostProcessor in the
65       * chain. It is important for developers to check whether the KeyEvent has
66       * been consumed before performing any post-processing of the KeyEvent. By
67       * default, the current KeyboardFocusManager will perform no post-
68       * processing in response to a consumed KeyEvent.
69       *
70       * @param e the KeyEvent to post-process
71       * @return <code>true</code> if the AWT should take no further action with
72       *         regard to the KeyEvent; <code>false</code> otherwise
73       * @see KeyboardFocusManager#redispatchEvent
74       */
75      boolean postProcessKeyEvent(KeyEvent   e);
76  }
77
A to Z: JavaDoc & Examples Daily Java News & Articles Open Source Projects Open Source Codes Free Computer Books Remove Frame
Popular Tags