gcc/libjava/java/awt/ContainerOrderFocusTraversalPolicy.java

/* ContainerOrderFocusTraversalPolicy.java -- 
   Copyright (C) 2002 Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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any later version.

GNU Classpath is distributed in the hope that it will be useful, but
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

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Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.

Linking this library statically or dynamically with other modules is
making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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this exception to your version of the library, but you are not
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exception statement from your version. */


package java.awt;

import java.io.Serializable;

/**
 * @author Michael Koch
 * @since 1.4
 */
public class ContainerOrderFocusTraversalPolicy extends FocusTraversalPolicy
  implements Serializable
{
  /**
   * Compatible to JDK 1.4+
   */
  static final long serialVersionUID = 486933713763926351L;

  private boolean implicitDownCycleTraversal = true;

  /**
   * Creates the <code>ContainerOrderFocusTraversalPolicy</code> object.
   */
  public ContainerOrderFocusTraversalPolicy()
  {
    // Nothing to do here
  }

  /**
   * Returns the Component that should receive the focus after current.
   * root must be a focus cycle root of current.
   *
   * @exception IllegalArgumentException If root is not a focus cycle
   * root of current, or if either root or current is null.
   */
  public Component getComponentAfter(Container root, Component current)
  {
    if (root == null
        || current == null)
      throw new IllegalArgumentException ();
    
    return null;
  }

  /**
   * Returns the Component that should receive the focus before current.
   * root must be a focus cycle root of current.
   *
   * @exception IllegalArgumentException If root is not a focus cycle
   * root of current, or if either root or current is null.
   */
  public Component getComponentBefore(Container root, Component current)
  {
    if (root == null
        || current == null)
      throw new IllegalArgumentException ();

    return null;
  }

  /**
   * Returns the first Component of root that should receive the focus.
   *
   * @exception IllegalArgumentException If root is null.
   */
  public Component getFirstComponent(Container root)
  {
    if (root == null)
      throw new IllegalArgumentException ();

    if (!root.isVisible ()
        || !root.isDisplayable ())
      return null;

    if (accept (root))
      return root;

    Component[] componentArray = root.getComponents ();
    
    for (int i = 0; i < componentArray.length; i++)
      {
        Component component = componentArray [i];
	
        if (component instanceof Container)
          {
            Component result = getLastComponent ((Container) component);

            if (result != null)
              return result;
          }
        else
          {
            if (accept (component))
              return component;
          }
      }

    return null;
  }

  /**
   * Returns the last Component of root that should receive the focus.
   *
   * @exception IllegalArgumentException If root is null.
   */
  public Component getLastComponent(Container root)
  {
    if (root == null)
      throw new IllegalArgumentException ();

    if (!root.isVisible ()
        || !root.isDisplayable ())
      return null;

    if (accept (root))
      return root;

    Component[] componentArray = root.getComponents ();
    
    for (int i = componentArray.length - 1; i >= 0; i++)
      {
        Component component = componentArray [i];
	
        if (component instanceof Container)
          {
            Component result = getLastComponent ((Container) component);

            if (result != null)
              return result;
          }
        else
          {
            if (accept (component))
              return component;
          }
      }

    return null;
  }

  /**
   * Returns the default Component of root that should receive the focus.
   *
   * @exception IllegalArgumentException If root is null.
   */
  public Component getDefaultComponent(Container root)
  {
    return getFirstComponent (root);
  }

  public void setImplicitDownCycleTraversal(boolean value)
  {
    implicitDownCycleTraversal = value;
  }

  public boolean getImplicitDownCycleTraversal()
  {
    return implicitDownCycleTraversal;
  }

  protected boolean accept(Component current)
  {
    return (current.visible
            && current.isDisplayable()
            && current.enabled
            && current.focusable);
  }
} // class ContainerOrderFocusTraversalPolicy