source: trunk/src/gcc/libjava/java/awt/CardLayout.java@ 2228

// CardLayout.java - Card-based layout engine

/* Copyright (C) 1999, 2000, 2002, 2003  Free Software Foundation

This file is part of GNU Classpath.

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it under the terms of the GNU General Public License as published by
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Linking this library statically or dynamically with other modules is
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permission to link this library with independent modules to produce an
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package java.awt;

import java.util.Enumeration;
import java.util.Hashtable;
import java.io.Serializable;

/** This class implements a card-based layout scheme.  Each included
 * component is treated as a card.  Only one card can be shown at a
 * time.  This class includes methods for changing which card is
 * shown.
 *
 * @author Tom Tromey <[email protected]>
 * @author Aaron M. Renn ([email protected])
 */
public class CardLayout implements LayoutManager2, Serializable
{
  static final long serialVersionUID = -4328196481005934313L;

  /**
   * Initializes a new instance of <code>CardLayout</code> with horizontal
   * and vertical gaps of 0.
   */
  public CardLayout ()
  {
    this (0, 0);
  }

  /**
   * Create a new <code>CardLayout</code> object with the specified
   * horizontal and vertical gaps.
   * @param hgap The horizontal gap
   * @param vgap The vertical gap
   */
  public CardLayout (int hgap, int vgap)
  {
    this.hgap = hgap;
    this.vgap = vgap;
    this.tab = new Hashtable ();
  }

  /** Add a new component to the layout.  The constraint must be a
   * string which is used to name the component.  This string can
   * later be used to refer to the particular component.
   * @param comp The component to add
   * @param constraints The name by which the component can later be called
   * @exception IllegalArgumentException If `constraints' is not a
   * <code>String</code>
   */
  public void addLayoutComponent (Component comp, Object constraints)
  {
    if (! (constraints instanceof String))
      throw new IllegalArgumentException ("Object " + constraints
                                          + " is not a string");
    tab.put (constraints, comp);
  }

  /** Add a new component to the layout.  The name can be used later
   * to refer to the component.
   * @param name The name by which the component can later be called
   * @param comp The component to add
   * @deprecated This method is deprecated in favor of
   * <code>addLayoutComponent(Component, Object)</code>.
   */
  public void addLayoutComponent (String name, Component comp)
  {
    addLayoutComponent (comp, name);
  }

  /** Cause the first component in the container to be displayed.
   * @param parent The parent container
   */
  public void first (Container parent)
  {
    gotoComponent (parent, FIRST);
  }

  /** Return this layout manager's horizontal gap.  */
  public int getHgap ()
  {
    return hgap;
  }

  /** Return this layout manager's x alignment.  This method always
   * returns Component.CENTER_ALIGNMENT.
   * @param parent Container using this layout manager instance
   */
  public float getLayoutAlignmentX (Container parent)
  {
    return Component.CENTER_ALIGNMENT;
  }

  /** Returns this layout manager's y alignment.  This method always
   * returns Component.CENTER_ALIGNMENT.
   * @param parent Container using this layout manager instance
   */
  public float getLayoutAlignmentY (Container parent)
  {
    return Component.CENTER_ALIGNMENT;
  }

  /** Return this layout manager's vertical gap.  */
  public int getVgap ()
  {
    return vgap;
  }

  /** Invalidate this layout manager's state.  */
  public void invalidateLayout (Container target)
  {
    // Do nothing.
  }

  /** Cause the last component in the container to be displayed.
   * @param parent The parent container
   */
  public void last (Container parent)
  {
    gotoComponent (parent, LAST);
  }

  /**
   * Lays out the container.  This is done by resizing the child components
   * to be the same size as the parent, less insets and gaps.
   *
   * @param parent The parent container.
   */ 
  public void layoutContainer (Container parent)
  {
    synchronized (parent.getTreeLock ())
      {
        int width = parent.width;
        int height = parent.height;

        Insets ins = parent.getInsets ();