Source for javax.swing.JPanel

   1: /* JPanel.java --
   2:    Copyright (C) 2002, 2004 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:      */
  66:     public 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:      */
  77:     public AccessibleRole getAccessibleRole()
  78:     {
  79:       return AccessibleRole.PANEL;
  80:     }
  81:   }
  82: 
  83:   public JPanel()
  84:   {
  85:     this(new FlowLayout(), true);
  86:   }
  87: 
  88:   public JPanel(boolean double_buffered)
  89:   {
  90:     this(new FlowLayout(), double_buffered);
  91:   }
  92: 
  93:   public JPanel(LayoutManager layout)
  94:   {
  95:     this(layout, true);
  96:   }
  97: 
  98:   public JPanel(LayoutManager layout, boolean isDoubleBuffered)
  99:   {
 100:     if (layout == null)
 101:       {
 102:         // TODO: Is this correct? Or should we throw a NPE?
 103:         layout = new FlowLayout();
 104:       }
 105:     setLayout(layout); 
 106:     setOpaque(true); 
 107: 
 108:     updateUI();    
 109:   } 
 110: 
 111:   public String getUIClassID()
 112:   {
 113:     return "PanelUI";
 114:   }
 115: 
 116:   public void setUI(PanelUI ui)
 117:   {
 118:     super.setUI(ui);
 119:   }
 120: 
 121:   public PanelUI getUI()
 122:   {
 123:     return (PanelUI) ui;
 124:   }
 125: 
 126:   public void updateUI()
 127:   {
 128:     setUI((PanelUI) UIManager.getUI(this));
 129:   }
 130: 
 131:   public AccessibleContext getAccessibleContext()
 132:   {
 133:     if (accessibleContext == null)
 134:       accessibleContext = new AccessibleJPanel();
 135:     return accessibleContext;
 136:   }
 137:     
 138:   protected  String paramString()
 139:   {
 140:     return super.paramString();
 141:   }
 142: }