/*
* Copyright (c) 2002-2007 JGoodies Karsten Lentzsch. All Rights Reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* o Redistributions of source code must retain the above copyright notice,
* this list of conditions and the following disclaimer.
*
* o Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* o Neither the name of JGoodies Karsten Lentzsch nor the names of
* its contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE
* OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE,
* EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package com.jgoodies.forms.util;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import javax.swing.LookAndFeel;
import javax.swing.UIManager;
/**
* Consists only of static utility methods.
*
* This class may be merged with the FormLayoutUtils extra - or not. *
*
* @author Karsten Lentzsch
* @version $Revision$
*/
public final class Utilities {
// Instance *************************************************************
private Utilities() {
// Suppresses default constructor, ensuring non-instantiability.
}
/**
* Lazily checks and answers whether the Aqua look&feel is active.
*
* @return true if the current look&feel is Aqua
*/
public static boolean isLafAqua() {
if (cachedIsLafAqua == null) {
cachedIsLafAqua = Boolean.valueOf(computeIsLafAqua());
ensureLookAndFeelChangeHandlerRegistered();
}
return cachedIsLafAqua.booleanValue();
}
// Caching and Lazily Computing the Laf State *****************************
/**
* Holds the cached result of the Aqua l&f check.
* Is invalidated by the <code>LookAndFeelChangeHandler</code>
* if the look&feel changes.
*/
private static Boolean cachedIsLafAqua;
/**
* Describes whether the <code>LookAndFeelChangeHandler</code>
* has been registered with the <code>UIManager</code> or not.
* It is registered lazily when the first cached l&f state is computed.
*/
private static boolean lafChangeHandlerRegistered = false;
private static synchronized void ensureLookAndFeelChangeHandlerRegistered() {
if (!lafChangeHandlerRegistered) {
UIManager.addPropertyChangeListener(new LookAndFeelChangeHandler());
lafChangeHandlerRegistered = true;
}
}
/**
* Computes and answers whether the Aqua look&feel is active.
*
* @return true if the current look&feel is Aqua
*/
private static boolean computeIsLafAqua() {
LookAndFeel laf = UIManager.getLookAndFeel();
return laf.getName().startsWith("Mac OS X Aqua");
}
/**
* Listens to changes of the Look and Feel and invalidates the cache.
*/
private static final class LookAndFeelChangeHandler implements
PropertyChangeListener {
/**
* Invalidates the cached laf states, if the UIManager has fired
* any property change event. Since we need to handle look&feel
* changes only, we check the event's property name to be
* "lookAndFeel" or <code>null</code>. The check for null is necessary
* to handle the special event where property name, old and new value
* are all <code>null</code> to indicate that multiple properties
* have changed.
*
* @param evt describes the property change
*/
public void propertyChange(PropertyChangeEvent evt) {
String propertyName = evt.getPropertyName();
if ((propertyName == null) || propertyName.equals("lookAndFeel")) {
cachedIsLafAqua = null;
}
}
}
}