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13   * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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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  @FunctionalInterface
58  public interface KeyEventPostProcessor {
59  
60      /**
61       * This method is called by the current KeyboardFocusManager, requesting
62       * that this KeyEventPostProcessor perform any necessary post-processing
63       * which should be part of the KeyEvent's final resolution. At the time
64       * this method is invoked, typically the KeyEvent has already been
65       * dispatched to and handled by its target. However, if no Component in
66       * the application currently owns the focus, then the KeyEvent has not
67       * been dispatched to any Component. Typically, KeyEvent post-processing
68       * will be used to implement features which require global KeyEvent
69       * post-handling, such as menu shortcuts. Note that if a
70       * KeyEventPostProcessor wishes to dispatch the KeyEvent, it must use
71       * <code>redispatchEvent</code> to prevent the AWT from recursively
72       * requesting that this KeyEventPostProcessor perform post-processing
73       * of the event again.
74       * <p>
75       * If an implementation of this method returns <code>false</code>, then the
76       * KeyEvent is passed to the next KeyEventPostProcessor in the chain,
77       * ending with the current KeyboardFocusManager. If an implementation
78       * returns <code>true</code>, the KeyEvent is assumed to have been fully
79       * handled (although this need not be the case), and the AWT will take no
80       * further action with regard to the KeyEvent. If an implementation
81       * consumes the KeyEvent but returns <code>false</code>, the consumed
82       * event will still be passed to the next KeyEventPostProcessor in the
83       * chain. It is important for developers to check whether the KeyEvent has
84       * been consumed before performing any post-processing of the KeyEvent. By
85       * default, the current KeyboardFocusManager will perform no post-
86       * processing in response to a consumed KeyEvent.
87       *
88       * @param e the KeyEvent to post-process
89       * @return <code>true</code> if the AWT should take no further action with
90       *         regard to the KeyEvent; <code>false</code> otherwise
91       * @see KeyboardFocusManager#redispatchEvent
92       */
93      boolean postProcessKeyEvent(KeyEvent e);
94  }