001/* BasicPanelUI.java 002 Copyright (C) 2002, 2004, 2006, Free Software Foundation, Inc. 003 004This file is part of GNU Classpath. 005 006GNU Classpath is free software; you can redistribute it and/or modify 007it under the terms of the GNU General Public License as published by 008the Free Software Foundation; either version 2, or (at your option) 009any later version. 010 011GNU Classpath is distributed in the hope that it will be useful, but 012WITHOUT ANY WARRANTY; without even the implied warranty of 013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 014General Public License for more details. 015 016You should have received a copy of the GNU General Public License 017along with GNU Classpath; see the file COPYING. If not, write to the 018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 01902110-1301 USA. 020 021Linking this library statically or dynamically with other modules is 022making a combined work based on this library. Thus, the terms and 023conditions of the GNU General Public License cover the whole 024combination. 025 026As a special exception, the copyright holders of this library give you 027permission to link this library with independent modules to produce an 028executable, regardless of the license terms of these independent 029modules, and to copy and distribute the resulting executable under 030terms of your choice, provided that you also meet, for each linked 031independent module, the terms and conditions of the license of that 032module. An independent module is a module which is not derived from 033or based on this library. If you modify this library, you may extend 034this exception to your version of the library, but you are not 035obligated to do so. If you do not wish to do so, delete this 036exception statement from your version. */ 037 038 039package javax.swing.plaf.basic; 040 041import javax.swing.JComponent; 042import javax.swing.JPanel; 043import javax.swing.LookAndFeel; 044import javax.swing.plaf.ComponentUI; 045import javax.swing.plaf.PanelUI; 046 047/** 048 * A UI delegate for the {@link JPanel} component. 049 */ 050public 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}