/*
* Copyright (c) 1997, 1998, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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*/
package javax.swing.plaf;
/**
* This interface is used to mark objects created by ComponentUI delegates.
* The <code>ComponentUI.installUI()</code> and
* <code>ComponentUI.uninstallUI()</code> methods can use this interface
* to decide if a properties value has been overridden. For example, the
* JList cellRenderer property is initialized by BasicListUI.installUI(),
* only if it's initial value is null:
* <pre>
* if (list.getCellRenderer() == null) {
* list.setCellRenderer((ListCellRenderer)(UIManager.get("List.cellRenderer")));
* }
* </pre>
* At uninstallUI() time we reset the property to null if its value
* is an instance of UIResource:
* <pre>
* if (list.getCellRenderer() instanceof UIResource) {
* list.setCellRenderer(null);
* }
*</pre>
* This pattern applies to all properties except the java.awt.Component
* properties font, foreground, and background. If one of these
* properties isn't initialized, or is explicitly set to null,
* its container provides the value. For this reason the
* <code>"== null"</code> is unreliable when installUI() is called
* to dynamically change a components look and feel. So at installUI()
* time we check to see if the current value is a UIResource:
*<pre>
* if (!(list.getFont() instanceof UIResource)) {
* list.setFont(UIManager.getFont("List.font"));
* }
* </pre>
*
* @see ComponentUI
* @author Hans Muller
*
*/
public interface UIResource {
}