484 lines
12 KiB
Java
484 lines
12 KiB
Java
/* CardLayout.java -- Card-based layout engine
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Copyright (C) 1999, 2000, 2002, 2003, 2004 Free Software Foundation
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING. If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library. Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module. An independent module is a module which is not derived from
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or based on this library. If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so. If you do not wish to do so, delete this
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exception statement from your version. */
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package java.awt;
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import java.io.Serializable;
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import java.util.Enumeration;
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import java.util.Hashtable;
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/**
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* This class implements a card-based layout scheme. Each included
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* component is treated as a card. Only one card can be shown at a
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* time. This class includes methods for changing which card is
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* shown.
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*
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* @author Tom Tromey (tromey@redhat.com)
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* @author Aaron M. Renn (arenn@urbanophile.com)
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*/
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public class CardLayout implements LayoutManager2, Serializable
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{
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private static final long serialVersionUID = -4328196481005934313L;
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/**
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* Initializes a new instance of <code>CardLayout</code> with horizontal
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* and vertical gaps of 0.
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*/
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public CardLayout ()
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{
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this (0, 0);
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}
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/**
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* Create a new <code>CardLayout</code> object with the specified
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* horizontal and vertical gaps.
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*
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* @param hgap The horizontal gap
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* @param vgap The vertical gap
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*/
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public CardLayout (int hgap, int vgap)
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{
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this.hgap = hgap;
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this.vgap = vgap;
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this.tab = new Hashtable ();
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}
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/**
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* Add a new component to the layout. The constraint must be a
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* string which is used to name the component. This string can
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* later be used to refer to the particular component.
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*
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* @param comp The component to add
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* @param constraints The name by which the component can later be called
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*
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* @exception IllegalArgumentException If `constraints' is not a
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* <code>String</code>
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*/
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public void addLayoutComponent (Component comp, Object constraints)
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{
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if (! (constraints instanceof String))
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throw new IllegalArgumentException ("Object " + constraints
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+ " is not a string");
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addLayoutComponent ((String) constraints, comp);
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}
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/**
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* Add a new component to the layout. The name can be used later
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* to refer to the component.
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*
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* @param name The name by which the component can later be called
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* @param comp The component to add
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*
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* @deprecated This method is deprecated in favor of
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* <code>addLayoutComponent(Component, Object)</code>.
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*/
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public void addLayoutComponent (String name, Component comp)
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{
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tab.put (name, comp);
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// First component added is the default component.
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comp.setVisible(tab.size() == 1);
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}
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/**
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* Cause the first component in the container to be displayed.
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*
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* @param parent The parent container
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*/
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public void first (Container parent)
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{
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gotoComponent (parent, FIRST);
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}
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/**
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* Return this layout manager's horizontal gap.
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*
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* @return the horizontal gap
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*/
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public int getHgap ()
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{
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return hgap;
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}
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/**
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* Return this layout manager's x alignment. This method always
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* returns Component.CENTER_ALIGNMENT.
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*
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* @param parent Container using this layout manager instance
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*
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* @return the x-axis alignment
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*/
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public float getLayoutAlignmentX (Container parent)
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{
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return Component.CENTER_ALIGNMENT;
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}
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/**
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* Returns this layout manager's y alignment. This method always
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* returns Component.CENTER_ALIGNMENT.
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*
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* @param parent Container using this layout manager instance
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*
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* @return the y-axis alignment
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*/
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public float getLayoutAlignmentY (Container parent)
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{
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return Component.CENTER_ALIGNMENT;
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}
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/**
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* Return this layout manager's vertical gap.
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*
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* @return the vertical gap
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*/
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public int getVgap ()
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{
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return vgap;
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}
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/**
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* Invalidate this layout manager's state.
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*/
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public void invalidateLayout (Container target)
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{
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// Do nothing.
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}
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/**
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* Cause the last component in the container to be displayed.
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*
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* @param parent The parent container
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*/
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public void last (Container parent)
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{
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gotoComponent (parent, LAST);
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}
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/**
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* Lays out the container. This is done by resizing the child components
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* to be the same size as the parent, less insets and gaps.
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*
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* @param parent The parent container.
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*/
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public void layoutContainer (Container parent)
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{
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synchronized (parent.getTreeLock ())
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{
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int width = parent.width;
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int height = parent.height;
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Insets ins = parent.getInsets ();
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int num = parent.ncomponents;
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Component[] comps = parent.component;
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int x = ins.left + hgap;
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int y = ins.top + vgap;
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width = width - 2 * hgap - ins.left - ins.right;
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height = height - 2 * vgap - ins.top - ins.bottom;
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for (int i = 0; i < num; ++i)
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comps[i].setBounds (x, y, width, height);
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}
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}
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/**
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* Get the maximum layout size of the container.
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*
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* @param target The parent container
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*
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* @return the maximum layout size
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*/
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public Dimension maximumLayoutSize (Container target)
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{
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// The JCL says that this returns Integer.MAX_VALUE for both
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// dimensions. But that just seems wrong to me.
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return getSize (target, MAX);
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}
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/**
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* Get the minimum layout size of the container.
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*
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* @param target The parent container
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*
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* @return the minimum layout size
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*/
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public Dimension minimumLayoutSize (Container target)
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{
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return getSize (target, MIN);
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}
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/**
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* Cause the next component in the container to be displayed. If
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* this current card is the last one in the deck, the first
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* component is displayed.
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*
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* @param parent The parent container
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*/
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public void next (Container parent)
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{
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gotoComponent (parent, NEXT);
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}
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/**
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* Get the preferred layout size of the container.
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*
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* @param parent The parent container
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*
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* @return the preferred layout size
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*/
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public Dimension preferredLayoutSize (Container parent)
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{
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return getSize (parent, PREF);
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}
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/**
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* Cause the previous component in the container to be displayed.
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* If this current card is the first one in the deck, the last
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* component is displayed.
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*
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* @param parent The parent container
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*/
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public void previous (Container parent)
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{
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gotoComponent (parent, PREV);
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}
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/**
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* Remove the indicated component from this layout manager.
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*
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* @param comp The component to remove
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*/
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public void removeLayoutComponent (Component comp)
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{
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Enumeration e = tab.keys ();
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while (e.hasMoreElements ())
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{
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Object key = e.nextElement ();
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if (tab.get (key) == comp)
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{
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tab.remove (key);
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Container parent = comp.getParent();
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next(parent);
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break;
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}
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}
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}
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/**
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* Set this layout manager's horizontal gap.
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*
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* @param hgap The new gap
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*/
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public void setHgap (int hgap)
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{
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this.hgap = hgap;
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}
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/**
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* Set this layout manager's vertical gap.
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*
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* @param vgap The new gap
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*/
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public void setVgap (int vgap)
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{
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this.vgap = vgap;
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}
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/**
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* Cause the named component to be shown. If the component name is
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* unknown, this method does nothing.
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*
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* @param parent The parent container
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* @param name The name of the component to show
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*/
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public void show (Container parent, String name)
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{
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Object target = tab.get (name);
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if (target != null)
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{
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int num = parent.ncomponents;
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// This is more efficient than calling getComponents().
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Component[] comps = parent.component;
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for (int i = 0; i < num; ++i)
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{
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if (comps[i].isVisible())
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{
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if (target == comps[i])
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return;
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comps[i].setVisible (false);
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}
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}
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((Component) target).setVisible (true);
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}
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}
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/**
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* Returns a string representation of this layout manager.
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*
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* @return A string representation of this object.
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*/
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public String toString ()
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{
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return getClass ().getName () + "[" + hgap + "," + vgap + "]";
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}
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/**
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* This implements first(), last(), next(), and previous().
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*
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* @param parent The parent container
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* @param what The type of goto: FIRST, LAST, NEXT or PREV
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*/
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private void gotoComponent (Container parent, int what)
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{
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synchronized (parent.getTreeLock ())
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{
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int num = parent.ncomponents;
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// This is more efficient than calling getComponents().
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Component[] comps = parent.component;
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if (num == 1)
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{
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comps[0].setVisible(true);
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return;
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}
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int choice = -1;
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if (what == FIRST)
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choice = 0;
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else if (what == LAST)
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choice = num - 1;
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for (int i = 0; i < num; ++i)
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{
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if (comps[i].isVisible ())
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{
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if (what == NEXT)
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{
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choice = i + 1;
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if (choice == num)
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choice = 0;
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}
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else if (what == PREV)
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{
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choice = i - 1;
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if (choice < 0)
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choice = num - 1;
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}
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else if (choice == i)
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{
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// Do nothing if we're already looking at the right
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// component.
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return;
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}
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comps[i].setVisible (false);
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if (choice >= 0)
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break;
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}
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}
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if (choice >= 0 && choice < num)
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comps[choice].setVisible (true);
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}
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}
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// Compute the size according to WHAT.
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private Dimension getSize (Container parent, int what)
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{
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synchronized (parent.getTreeLock ())
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{
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int w = 0, h = 0, num = parent.ncomponents;
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Component[] comps = parent.component;
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for (int i = 0; i < num; ++i)
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{
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Dimension d;
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if (what == MIN)
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d = comps[i].getMinimumSize ();
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else if (what == MAX)
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d = comps[i].getMaximumSize ();
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else
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d = comps[i].getPreferredSize ();
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w = Math.max (d.width, w);
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h = Math.max (d.height, h);
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}
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Insets i = parent.getInsets ();
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w += 2 * hgap + i.right + i.left;
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h += 2 * vgap + i.bottom + i.top;
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// Handle overflow.
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if (w < 0)
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w = Integer.MAX_VALUE;
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if (h < 0)
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h = Integer.MAX_VALUE;
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return new Dimension (w, h);
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}
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}
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/**
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* @serial Horizontal gap value.
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*/
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private int hgap;
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/**
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* @serial Vertical gap value.
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*/
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private int vgap;
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/**
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* @serial Table of named components.
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*/
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private Hashtable tab;
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// These constants are used by the private gotoComponent method.
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private static final int FIRST = 0;
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private static final int LAST = 1;
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private static final int NEXT = 2;
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private static final int PREV = 3;
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// These constants are used by the private getSize method.
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private static final int MIN = 0;
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private static final int MAX = 1;
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private static final int PREF = 2;
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}
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