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 }