1 /* Panel.java -- Simple container object 2 Copyright (C) 1999, 2002, 2004, 2005 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 java.awt; 40 41 import javax.accessibility.Accessible; 42 import javax.accessibility.AccessibleContext; 43 import javax.accessibility.AccessibleRole; 44 45 /** 46 * A panel is a simple container class. It's default layout is the 47 * <code>FlowLayout</code> manager. 48 * 49 * @author Aaron M. Renn (arenn@urbanophile.com) 50 * @author Eric Blake (ebb9@email.byu.edu) 51 * @see FlowLayout 52 * @since 1.0 53 * @status updated to 1.4 54 */ 55 public class Panel extends Container implements Accessible 56 { 57 /** 58 * Compatible with JDK 1.0+. 59 */ 60 private static final long serialVersionUID = -2728009084054400034L; 61 62 /** The cached accessible context. */ 63 private transient AccessibleContext context; 64 65 /** Flag set when the first system-requested paint event is 66 dispatched. */ 67 private transient boolean initialSystemUpdateDone; 68 69 /** Flag set when the first application-requested paint event is 70 consumed. */ 71 private transient boolean initialUpdateConsumed; 72 73 /* 74 * The number used to generate the name returned by getName. 75 */ 76 private static transient long next_panel_number; 77 78 /** 79 * Initializes a new instance of <code>Panel</code> that has a default 80 * layout manager of <code>FlowLayout</code>. 81 */ Panel()82 public Panel() 83 { 84 this(new FlowLayout()); 85 } 86 87 /** 88 * Initializes a new instance of <code>Panel</code> with the specified 89 * layout manager. 90 * 91 * @param layoutManager the layout manager for this object 92 * @since 1.1 93 */ Panel(LayoutManager layoutManager)94 public Panel(LayoutManager layoutManager) 95 { 96 setLayout(layoutManager); 97 } 98 99 /** 100 * Notifies this object to create its native peer. 101 * 102 * @see #isDisplayable() 103 * @see #removeNotify() 104 */ addNotify()105 public void addNotify() 106 { 107 if (peer == null) 108 peer = getToolkit().createPanel(this); 109 super.addNotify(); 110 } 111 112 /** 113 * Gets the AccessibleContext associated with this panel, creating one if 114 * necessary. This always returns an instance of {@link AccessibleAWTPanel}. 115 * 116 * @return the accessibility context of this panel 117 * @since 1.3 118 */ getAccessibleContext()119 public AccessibleContext getAccessibleContext() 120 { 121 if (context == null) 122 context = new AccessibleAWTPanel(); 123 return context; 124 } 125 126 /** 127 * This class provides accessibility support for Panels, and is the 128 * runtime type returned by {@link #getAccessibleContext()}. 129 * 130 * @author Eric Blake (ebb9@email.byu.edu) 131 * @since 1.3 132 */ 133 protected class AccessibleAWTPanel extends AccessibleAWTContainer 134 { 135 /** 136 * Compatible with JDK 1.4+. 137 */ 138 private static final long serialVersionUID = -6409552226660031050L; 139 140 /** 141 * The default constructor. 142 */ AccessibleAWTPanel()143 protected AccessibleAWTPanel() 144 { 145 } 146 147 /** 148 * Get the role of this accessible object, a panel. 149 * 150 * @return the role of the object 151 * @see AccessibleRole#PANEL 152 */ getAccessibleRole()153 public AccessibleRole getAccessibleRole() 154 { 155 return AccessibleRole.PANEL; 156 } 157 } 158 159 /** 160 * Generate a unique name for this panel. 161 * 162 * @return A unique name for this panel. 163 */ generateName()164 String generateName () 165 { 166 return "panel" + getUniqueLong (); 167 } 168 getUniqueLong()169 private static synchronized long getUniqueLong () 170 { 171 return next_panel_number++; 172 } 173 } 174