1 /*

     2  * CDDL HEADER START

     3  *

     4  * The contents of this file are subject to the terms of the

     5  * Common Development and Distribution License (the "License").

     6  * You may not use this file except in compliance with the License.

     7  *

     8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE

     9  * or http://www.opensolaris.org/os/licensing.

    10  * See the License for the specific language governing permissions

    11  * and limitations under the License.

    12  *

    13  * When distributing Covered Code, include this CDDL HEADER in each

    14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.

    15  * If applicable, add the following below this CDDL HEADER, with the

    16  * fields enclosed by brackets "[]" replaced with your own identifying

    17  * information: Portions Copyright [yyyy] [name of copyright owner]

    18  *

    19  * CDDL HEADER END

    20  */

    21 

    22 /*

    23  * Copyright (c) 2010, 2012, Oracle and/or its affiliates. All rights reserved.

    24  */

    25 

    26 package com.oracle.solaris.vp.util.swing;

    27 

    28 import java.awt.Component;

    29 import java.awt.event.*;

    30 

    31 /**

    32  * When added as a {@code HierarchyListener}, the {@code ShowingListener} class

    33  * listens for changes in the showing property of a single {@code Component}.  A

    34  * single {@code ShowingListener} should NOT be added as a listener to more than

    35  * one {@code Component}.

    36  */

    37 public class ShowingListener implements HierarchyListener {

    38     //

    39     // Instance data

    40     //

    41 

    42     private Boolean showing;

    43 

    44     //

    45     // HierarchyListener methods

    46     //

    47 

    48     @Override

    49     public void hierarchyChanged(HierarchyEvent e) {

    50 	updateShowing(e.getComponent());

    51     }

    52 

    53     //

    54     // ShowingListener methods

    55     //

    56 

    57     /**

    58      * Calls {@link #componentHidden} or {@link #componentShown} if the

    59      * listening {@code Component}'s showing status has changed (or if neither

    60      * method has been called since this listener was registered).

    61      *

    62      * @param	    comp

    63      *		    the listening {@code Component}

    64      */

    65     public void updateShowing(Component comp) {

    66 	boolean showing = comp.isShowing();

    67 	if (this.showing == null || showing != this.showing) {

    68 	    this.showing = showing;

    69 

    70 	    if (showing) {

    71 		componentShown();

    72 	    } else {

    73 		componentHidden();

    74 	    }

    75 	}

    76     }

    77 

    78     /**

    79      * Called when the listening {@code Component}'s showing status changes to

    80      * {@code false}.

    81      * </p>

    82      * This default implementation does nothing.

    83      */

    84     public void componentHidden() {

    85     }

    86 

    87     /**

    88      * Called when the listening {@code Component}'s showing status changes to

    89      * {@code true}.

    90      * </p>

    91      * This default implementation does nothing.

    92      */

    93     public void componentShown() {

    94     }

    95 }