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package java.awt;

import java.awt.event.KeyEvent;



A KeyEventPostProcessor cooperates with the current KeyboardFocusManager
in the final resolution of all unconsumed KeyEvents. KeyEventPostProcessors
registered with the current KeyboardFocusManager will receive KeyEvents
after the KeyEvents have been dispatched to and handled by their targets.
KeyEvents that would have been otherwise discarded because no Component in
the application currently owns the focus will also be forwarded to
registered KeyEventPostProcessors. This will allow applications to implement
features that require global KeyEvent post-handling, such as menu shortcuts.


Note that the KeyboardFocusManager itself implements KeyEventPostProcessor.
By default, the current KeyboardFocusManager will be the final
KeyEventPostProcessor in the chain. The current KeyboardFocusManager cannot
be completely deregistered as a KeyEventPostProcessor. However, if a
KeyEventPostProcessor reports that no further post-processing of the
KeyEvent should take place, the AWT will consider the event fully handled
and will take no additional action with regard to the event. (While it is
possible for client code to register the current KeyboardFocusManager as
a KeyEventPostProcessor one or more times, this is usually unnecessary and
not recommended.)

Author:David Mendenhall
See Also:
Since:1.4
/**
 * A KeyEventPostProcessor cooperates with the current KeyboardFocusManager
 * in the final resolution of all unconsumed KeyEvents. KeyEventPostProcessors
 * registered with the current KeyboardFocusManager will receive KeyEvents
 * after the KeyEvents have been dispatched to and handled by their targets.
 * KeyEvents that would have been otherwise discarded because no Component in
 * the application currently owns the focus will also be forwarded to
 * registered KeyEventPostProcessors. This will allow applications to implement
 * features that require global KeyEvent post-handling, such as menu shortcuts.
 * <p>
 * Note that the KeyboardFocusManager itself implements KeyEventPostProcessor.
 * By default, the current KeyboardFocusManager will be the final
 * KeyEventPostProcessor in the chain. The current KeyboardFocusManager cannot
 * be completely deregistered as a KeyEventPostProcessor. However, if a
 * KeyEventPostProcessor reports that no further post-processing of the
 * KeyEvent should take place, the AWT will consider the event fully handled
 * and will take no additional action with regard to the event. (While it is
 * possible for client code to register the current KeyboardFocusManager as
 * a KeyEventPostProcessor one or more times, this is usually unnecessary and
 * not recommended.)
 *
 * @author David Mendenhall
 *
 * @see KeyboardFocusManager#addKeyEventPostProcessor
 * @see KeyboardFocusManager#removeKeyEventPostProcessor
 * @since 1.4
 */
public interface KeyEventPostProcessor {

    
This method is called by the current KeyboardFocusManager, requesting
that this KeyEventPostProcessor perform any necessary post-processing
which should be part of the KeyEvent's final resolution. At the time
this method is invoked, typically the KeyEvent has already been
dispatched to and handled by its target. However, if no Component in
the application currently owns the focus, then the KeyEvent has not
been dispatched to any Component. Typically, KeyEvent post-processing
will be used to implement features which require global KeyEvent
post-handling, such as menu shortcuts. Note that if a
KeyEventPostProcessor wishes to dispatch the KeyEvent, it must use
redispatchEvent to prevent the AWT from recursively
requesting that this KeyEventPostProcessor perform post-processing
of the event again.


If an implementation of this method returns false, then the
KeyEvent is passed to the next KeyEventPostProcessor in the chain,
ending with the current KeyboardFocusManager. If an implementation
returns true, the KeyEvent is assumed to have been fully
handled (although this need not be the case), and the AWT will take no
further action with regard to the KeyEvent. If an implementation
consumes the KeyEvent but returns false, the consumed
event will still be passed to the next KeyEventPostProcessor in the
chain. It is important for developers to check whether the KeyEvent has
been consumed before performing any post-processing of the KeyEvent. By
default, the current KeyboardFocusManager will perform no post-
processing in response to a consumed KeyEvent.

Params:
  • e – the KeyEvent to post-process
See Also:
Returns:true if the AWT should take no further action with
        regard to the KeyEvent; false otherwise
/**
     * This method is called by the current KeyboardFocusManager, requesting
     * that this KeyEventPostProcessor perform any necessary post-processing
     * which should be part of the KeyEvent's final resolution. At the time
     * this method is invoked, typically the KeyEvent has already been
     * dispatched to and handled by its target. However, if no Component in
     * the application currently owns the focus, then the KeyEvent has not
     * been dispatched to any Component. Typically, KeyEvent post-processing
     * will be used to implement features which require global KeyEvent
     * post-handling, such as menu shortcuts. Note that if a
     * KeyEventPostProcessor wishes to dispatch the KeyEvent, it must use
     * <code>redispatchEvent</code> to prevent the AWT from recursively
     * requesting that this KeyEventPostProcessor perform post-processing
     * of the event again.
     * <p>
     * If an implementation of this method returns <code>false</code>, then the
     * KeyEvent is passed to the next KeyEventPostProcessor in the chain,
     * ending with the current KeyboardFocusManager. If an implementation
     * returns <code>true</code>, the KeyEvent is assumed to have been fully
     * handled (although this need not be the case), and the AWT will take no
     * further action with regard to the KeyEvent. If an implementation
     * consumes the KeyEvent but returns <code>false</code>, the consumed
     * event will still be passed to the next KeyEventPostProcessor in the
     * chain. It is important for developers to check whether the KeyEvent has
     * been consumed before performing any post-processing of the KeyEvent. By
     * default, the current KeyboardFocusManager will perform no post-
     * processing in response to a consumed KeyEvent.
     *
     * @param e the KeyEvent to post-process
     * @return <code>true</code> if the AWT should take no further action with
     *         regard to the KeyEvent; <code>false</code> otherwise
     * @see KeyboardFocusManager#redispatchEvent
     */
    boolean postProcessKeyEvent(KeyEvent e);
}