libjava/java/awt/Panel.java

   1 /* Panel.java -- Simple container object
   2    Copyright (C) 1999, 2002 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., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 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   /**
  66    * Initializes a new instance of <code>Panel</code> that has a default
  67    * layout manager of <code>FlowLayout</code>.
  68    */
  69   public Panel()
  70   {
  71     this(new FlowLayout());
  72   }
  73
  74   /**
  75    * Initializes a new instance of <code>Panel</code> with the specified
  76    * layout manager.
  77    *
  78    * @param layoutManager the layout manager for this object
  79    * @since 1.1
  80    */
  81   public Panel(LayoutManager layoutManager)
  82   {
  83     setLayout(layoutManager);
  84   }
  85
  86   /**
  87    * Notifies this object to create its native peer.
  88    *
  89    * @see #isDisplayable()
  90    * @see #removeNotify()
  91    */
  92   public void addNotify()
  93   {
  94     if (peer == null)
  95       peer = getToolkit().createPanel(this);
  96     super.addNotify();
  97   }
  98
  99   /**
 100    * Gets the AccessibleContext associated with this panel, creating one if
 101    * necessary. This always returns an instance of {@link AccessibleAWTPanel}.
 102    *
 103    * @return the accessibility context of this panel
 104    * @since 1.3
 105    */
 106   public AccessibleContext getAccessibleContext()
 107   {
 108     if (context == null)
 109       context = new AccessibleAWTPanel();
 110     return context;
 111   }
 112
 113   /**
 114    * This class provides accessibility support for Panels, and is the
 115    * runtime type returned by {@link #getAccessibleContext()}.
 116    *
 117    * @author Eric Blake <ebb9@email.byu.edu>
 118    * @since 1.3
 119    */
 120   protected class AccessibleAWTPanel extends AccessibleAWTContainer
 121   {
 122     /**
 123      * Compatible with JDK 1.4+.
 124      */
 125     private static final long serialVersionUID = -6409552226660031050L;
 126
 127     /**
 128      * The default constructor.
 129      */
 130     protected AccessibleAWTPanel()
 131     {
 132     }
 133
 134     /**
 135      * Get the role of this accessible object, a panel.
 136      *
 137      * @return the role of the object
 138      * @see AccessibleRole#PANEL
 139      */
 140     public AccessibleRole getAccessibleRole()
 141     {
 142       return AccessibleRole.PANEL;
 143     }
 144   } // class AccessibleAWTPanel
 145 } // class Panel