1 /* JPanel.java -- 2 Copyright (C) 2002, 2004, 2006, Free Software Foundation, Inc. 3 4 This file is part of GNU Classpath. 5 6 GNU Classpath is free software; you can redistribute it and/or modify 7 it under the terms of the GNU General Public License as published by 8 the Free Software Foundation; either version 2, or (at your option) 9 any later version. 10 11 GNU Classpath is distributed in the hope that it will be useful, but 12 WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 General Public License for more details. 15 16 You should have received a copy of the GNU General Public License 17 along with GNU Classpath; see the file COPYING. If not, write to the 18 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 19 02110-1301 USA. 20 21 Linking this library statically or dynamically with other modules is 22 making a combined work based on this library. Thus, the terms and 23 conditions of the GNU General Public License cover the whole 24 combination. 25 26 As a special exception, the copyright holders of this library give you 27 permission to link this library with independent modules to produce an 28 executable, regardless of the license terms of these independent 29 modules, and to copy and distribute the resulting executable under 30 terms of your choice, provided that you also meet, for each linked 31 independent module, the terms and conditions of the license of that 32 module. An independent module is a module which is not derived from 33 or based on this library. If you modify this library, you may extend 34 this exception to your version of the library, but you are not 35 obligated to do so. If you do not wish to do so, delete this 36 exception statement from your version. */ 37 38 39 package javax.swing; 40 41 import java.awt.FlowLayout; 42 import java.awt.LayoutManager; 43 44 import javax.accessibility.Accessible; 45 import javax.accessibility.AccessibleContext; 46 import javax.accessibility.AccessibleRole; 47 import javax.swing.plaf.PanelUI; 48 49 /** 50 * An instance of JPanel can be added to a panel, frame etc 51 * 52 * @author Ronald Veldema (rveldema@cs.vu.nl) 53 */ 54 public class JPanel extends JComponent implements Accessible 55 { 56 /** 57 * Provides accessibility support for <code>JPanel</code>. 58 * 59 * @author Roman Kennke (roman@kennke.org) 60 */ 61 protected class AccessibleJPanel extends AccessibleJComponent 62 { 63 /** 64 * Creates a new instance of <code>AccessibleJPanel</code>. 65 */ AccessibleJPanel()66 protected AccessibleJPanel() 67 { 68 // Nothing to do here. 69 } 70 71 /** 72 * Returns the accessible role for <code>JPanel</code>, which is 73 * {@link AccessibleRole#PANEL}. 74 * 75 * @return the accessible role for <code>JPanel</code> 76 */ getAccessibleRole()77 public AccessibleRole getAccessibleRole() 78 { 79 return AccessibleRole.PANEL; 80 } 81 } 82 83 /** 84 * Creates a new panel with a new instance of {@link FlowLayout} as the 85 * layout manager and double-buffering enabled. 86 */ JPanel()87 public JPanel() 88 { 89 this(new FlowLayout(), true); 90 } 91 92 /** 93 * Creates a new panel with double-buffering enabled or disabled as 94 * specified. The default layout manager is an instance of 95 * {@link FlowLayout}. 96 * 97 * @param isDoubleBuffered a flag that controls whether or not 98 * double-buffering is enabled. 99 */ JPanel(boolean isDoubleBuffered)100 public JPanel(boolean isDoubleBuffered) 101 { 102 this(new FlowLayout(), isDoubleBuffered); 103 } 104 105 /** 106 * Creates a new panel with the specified layout manager. Double-buffering 107 * is enabled by default. 108 * 109 * @param layout the layout manager (<code>null</code> permitted). 110 */ JPanel(LayoutManager layout)111 public JPanel(LayoutManager layout) 112 { 113 this(layout, true); 114 } 115 116 /** 117 * Creates a new panel with the specified layout manager and 118 * double-buffering. 119 * 120 * @param layout the layout manager (<code>null</code> permitted). 121 * @param isDoubleBuffered a flag that controls whether or not 122 * double-buffering is enabled. 123 */ JPanel(LayoutManager layout, boolean isDoubleBuffered)124 public JPanel(LayoutManager layout, boolean isDoubleBuffered) 125 { 126 setLayout(layout); 127 setOpaque(true); 128 setDoubleBuffered(isDoubleBuffered); 129 updateUI(); 130 } 131 132 /** 133 * Returns the suffix (<code>"PanelUI"</code> in this case) used to 134 * determine the class name for a UI delegate that can provide the look and 135 * feel for a <code>JPanel</code>. 136 * 137 * @return <code>"PanelUI"</code>. 138 */ getUIClassID()139 public String getUIClassID() 140 { 141 return "PanelUI"; 142 } 143 144 /** 145 * Sets the UI delegate for the <code>JPanel</code> component. 146 * 147 * @param ui the UI delegate. 148 * 149 * @since 1.4 150 * @see #getUI() 151 */ setUI(PanelUI ui)152 public void setUI(PanelUI ui) 153 { 154 super.setUI(ui); 155 } 156 157 /** 158 * Returns the UI delegate for the <code>JPanel</code> component. 159 * 160 * @return The UI delegate. 161 * 162 * @since 1.4 163 * @see #setUI(PanelUI) 164 */ getUI()165 public PanelUI getUI() 166 { 167 return (PanelUI) ui; 168 } 169 170 /** 171 * Sets this panel's UI delegate to the default (obtained from the 172 * {@link UIManager}) for the current look and feel. 173 */ updateUI()174 public void updateUI() 175 { 176 setUI((PanelUI) UIManager.getUI(this)); 177 } 178 179 /** 180 * Returns the object that provides accessibility features for this 181 * <code>JPanel</code> component. 182 * 183 * @return The accessible context (an instance of {@link AccessibleJPanel}). 184 */ getAccessibleContext()185 public AccessibleContext getAccessibleContext() 186 { 187 if (accessibleContext == null) 188 accessibleContext = new AccessibleJPanel(); 189 return accessibleContext; 190 } 191 192 /** 193 * Returns an implementation-dependent string describing the attributes of 194 * this <code>JPanel</code>. 195 * 196 * @return A string describing the attributes of this <code>JPanel</code> 197 * (never <code>null</code>). 198 */ paramString()199 protected String paramString() 200 { 201 return super.paramString(); 202 } 203 } 204