libjava/java/awt/ContainerOrderFocusTraversalPolicy.java

   1 /* ContainerOrderFocusTraversalPolicy.java --
   2    Copyright (C) 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 java.io.Serializable;
  42
  43 /**
  44  * @author Michael Koch
  45  * @since 1.4
  46  */
  47 public class ContainerOrderFocusTraversalPolicy extends FocusTraversalPolicy
  48   implements Serializable
  49 {
  50   /**
  51    * Compatible to JDK 1.4+
  52    */
  53   static final long serialVersionUID = 486933713763926351L;
  54
  55   private boolean implicitDownCycleTraversal = true;
  56
  57   /**
  58    * Creates the <code>ContainerOrderFocusTraversalPolicy</code> object.
  59    */
  60   public ContainerOrderFocusTraversalPolicy()
  61   {
  62     // Nothing to do here
  63   }
  64
  65   /**
  66    * Returns the Component that should receive the focus after current.
  67    * root must be a focus cycle root of current.
  68    *
  69    * @exception IllegalArgumentException If root is not a focus cycle
  70    * root of current, or if either root or current is null.
  71    */
  72   public Component getComponentAfter(Container root, Component current)
  73   {
  74     if (root == null
  75         || current == null)
  76       throw new IllegalArgumentException ();
  77
  78     return null;
  79   }
  80
  81   /**
  82    * Returns the Component that should receive the focus before current.
  83    * root must be a focus cycle root of current.
  84    *
  85    * @exception IllegalArgumentException If root is not a focus cycle
  86    * root of current, or if either root or current is null.
  87    */
  88   public Component getComponentBefore(Container root, Component current)
  89   {
  90     if (root == null
  91         || current == null)
  92       throw new IllegalArgumentException ();
  93
  94     return null;
  95   }
  96
  97   /**
  98    * Returns the first Component of root that should receive the focus.
  99    *
 100    * @exception IllegalArgumentException If root is null.
 101    */
 102   public Component getFirstComponent(Container root)
 103   {
 104     if (root == null)
 105       throw new IllegalArgumentException ();
 106
 107     if (!root.isVisible ()
 108         || !root.isDisplayable ())
 109       return null;
 110
 111     if (accept (root))
 112       return root;
 113
 114     Component[] componentArray = root.getComponents ();
 115
 116     for (int i = 0; i < componentArray.length; i++)
 117       {
 118         Component component = componentArray [i];
 119
 120         if (component instanceof Container)
 121           {
 122             Component result = getLastComponent ((Container) component);
 123
 124             if (result != null)
 125               return result;
 126           }
 127         else
 128           {
 129             if (accept (component))
 130               return component;
 131           }
 132       }
 133
 134     return null;
 135   }
 136
 137   /**
 138    * Returns the last Component of root that should receive the focus.
 139    *
 140    * @exception IllegalArgumentException If root is null.
 141    */
 142   public Component getLastComponent(Container root)
 143   {
 144     if (root == null)
 145       throw new IllegalArgumentException ();
 146
 147     if (!root.isVisible ()
 148         || !root.isDisplayable ())
 149       return null;
 150
 151     if (accept (root))
 152       return root;
 153
 154     Component[] componentArray = root.getComponents ();
 155
 156     for (int i = componentArray.length - 1; i >= 0; i++)
 157       {
 158         Component component = componentArray [i];
 159
 160         if (component instanceof Container)
 161           {
 162             Component result = getLastComponent ((Container) component);
 163
 164             if (result != null)
 165               return result;
 166           }
 167         else
 168           {
 169             if (accept (component))
 170               return component;
 171           }
 172       }
 173
 174     return null;
 175   }
 176
 177   /**
 178    * Returns the default Component of root that should receive the focus.
 179    *
 180    * @exception IllegalArgumentException If root is null.
 181    */
 182   public Component getDefaultComponent(Container root)
 183   {
 184     return getFirstComponent (root);
 185   }
 186
 187   public void setImplicitDownCycleTraversal(boolean value)
 188   {
 189     implicitDownCycleTraversal = value;
 190   }
 191
 192   public boolean getImplicitDownCycleTraversal()
 193   {
 194     return implicitDownCycleTraversal;
 195   }
 196
 197   protected boolean accept(Component current)
 198   {
 199     return (current.visible
 200             && current.isDisplayable()
 201             && current.enabled
 202             && current.focusable);
 203   }
 204 } // class ContainerOrderFocusTraversalPolicy