001 /* BasicPanelUI.java
002 Copyright (C) 2002, 2004, 2006, Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038
039 package javax.swing.plaf.basic;
040
041 import javax.swing.JComponent;
042 import javax.swing.JPanel;
043 import javax.swing.LookAndFeel;
044 import javax.swing.plaf.ComponentUI;
045 import javax.swing.plaf.PanelUI;
046
047 /**
048 * A UI delegate for the {@link JPanel} component.
049 */
050 public class BasicPanelUI extends PanelUI
051 {
052 /**
053 * A UI delegate that can be shared by all panels (because the delegate is
054 * stateless).
055 */
056 static BasicPanelUI sharedUI;
057
058 /**
059 * Returns a UI delegate for the specified component.
060 *
061 * @param panel the panel.
062 */
063 public static ComponentUI createUI(JComponent panel)
064 {
065 if (sharedUI == null)
066 sharedUI = new BasicPanelUI();
067 return sharedUI;
068 }
069
070 /**
071 * Installs this UI delegate in the specified component.
072 *
073 * @param c the component (should be a {@link JPanel}, <code>null</code> not
074 * permitted).
075 */
076 public void installUI(JComponent c)
077 {
078 super.installUI(c);
079 if (c instanceof JPanel)
080 {
081 JPanel p = (JPanel) c;
082 installDefaults(p);
083 }
084 }
085
086 /**
087 * Installs the defaults for this UI delegate in the specified panel.
088 *
089 * @param p the panel (<code>null</code> not permitted).
090 */
091 protected void installDefaults(JPanel p)
092 {
093 LookAndFeel.installColorsAndFont(p, "Panel.background", "Panel.foreground",
094 "Panel.font");
095
096 // A test against the reference implementation shows that this method will
097 // install a border if one is defined in the UIDefaults table (even though
098 // the BasicLookAndFeel doesn't actually define a "Panel.border"). This
099 // test was written after discovering that a null argument to
100 // uninstallDefaults throws a NullPointerException in
101 // LookAndFeel.uninstallBorder()...
102 LookAndFeel.installBorder(p, "Panel.border");
103 }
104
105 /**
106 * Uninstalls this UI delegate from the specified component.
107 *
108 * @param c the component (<code>null</code> not permitted).
109 */
110 public void uninstallUI(JComponent c)
111 {
112 uninstallDefaults((JPanel) c);
113 }
114
115 /**
116 * Uninstalls the UI defaults for the specified panel.
117 *
118 * @param p the panel (<code>null</code> not permitted).
119 */
120 protected void uninstallDefaults(JPanel p)
121 {
122 // Tests on the reference implementation showed this method:
123 // (1) doesn't actually remove the installed colors and font installed
124 // by installDefaults(), it isn't necessary;
125 // (2) throws a NullPointerException in LookAndFeel.uninstallBorder() if
126 // p is null. Strangely, no border is installed by the
127 // BasicLookAndFeel - perhaps this is needed by another LAF?
128
129 LookAndFeel.uninstallBorder(p);
130 }
131
132 }