/*
   Wotonomy: OpenStep design patterns for pure Java applications.
   Copyright (C) 2000 Blacksmith, Inc.
   
   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.
   
  This library is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  Lesser General Public License for more details.
  
  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, see http://www.gnu.org
  */
  
  package net.wotonomy.ui.swing.components;
  
  import java.awt.AWTEventMulticaster;
  import java.awt.BorderLayout;
  import java.awt.Component;
  import java.awt.Container;
  import java.awt.Dimension;
  import java.awt.GridBagConstraints;
  import java.awt.GridBagLayout;
  import java.awt.GridLayout;
  import java.awt.Insets;
  import java.awt.event.ActionEvent;
  import java.awt.event.ActionListener;
  import java.beans.BeanInfo;
  import java.beans.Introspector;
  import java.beans.MethodDescriptor;
  import java.lang.reflect.Method;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.Iterator;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Map;
  
  import javax.swing.Box;
  import javax.swing.JLabel;
  import javax.swing.JPanel;
  import javax.swing.JTextField;
  import javax.swing.SwingConstants;
  
  /***
  * InfoPanel uses labels and textfields (or any other component - see below)
  * to display a list of keys and values in a well-aligned and consistent manner,
  * conforming to alignment and pixel spacing in the java look and feel 
  * <a href="http://java.sun.com/products/jlf/dg/higg.htm#55417">design guidelines</a>. 
  * <BR><BR>
  *
  * Each key is displayed in a label to the left of the component that contains
  * the corresponding value.  Each row is displayed starting at the top of the
  * component's available area.  Each row's height is the maximum preferred
  * height of its components and the field itself gets as much of the width as
  * it can, dependent on the length of the longest label. <BR><BR>
  *
  * The values in the fields can be editable, and the
  * current value can be retrieved using the key - for this reason, unique keys
  * are recommended. <BR><BR>
  *
  * As a convenience, push buttons may be placed across the
  * bottom of the panel in a manner similar to ButtonPanel. <BR><BR>
  *
  * The panel forwards any ActionEvents generated by the components and
  * buttons on it to all registered listeners. <BR><BR>
  *
  * Optionally, any component can be used instead of a textfield.
  * However, <code>get/setValueForKey()</code> and <code>get/setEditable()</code>
  * may not work for those components.  Use <code>getComponentForKey()</code> to
  * access them instead.
  *
  * @author michael@mpowers.net
  * @author $Author: cgruber $
  * @version $Revision: 904 $
  * $Date: 2006-02-18 23:19:05 +0000 (Sat, 18 Feb 2006) $
  */
  public class InfoPanel extends JPanel implements ActionListener
  {
  /***
  * Special label for an empty pair - a label and component
  * that take up space but are hidden from view.  This might
  * be useful for achieving certain layouts.
  */
      public static final String HIDDEN = "(hidden)";
  
      /*** Cache for the introspectComponent method */
      private static Map _method_cache =
        Collections.synchronizedMap( new HashMap(30) );
  
      protected Container listContainer = null;
      protected int hgap;    // set in constructor
      protected int vgap;    // set in constructor
     protected int margin;  // set in constructor
     protected int columns; // set in constructor
     protected List fields = null;
     protected List labels = null;
     protected List fieldSpacers = null; 
     protected ButtonPanel buttonPanel = null;
     protected boolean isEditable = true;
     protected String prefix;
     protected String postfix;
 	protected int labelAnchor;
 	protected int labelAlign;
 //    protected Component marginStrut = null;
 
     // for action multicasting
     protected ActionListener actionListener = null;
     
 /***
 * Constructs an empty InfoPanel.
 */
     public InfoPanel()
     {
         hgap = 12;   // per java l&f guidelines
         vgap = 6;    // java l&f says 11
         columns = 1; // default columns
         margin = 0;  // default margin: none
         prefix = ""; // default prefix: none
         postfix = ":"; // per java l&f guidelines
         fields = new ArrayList();
         labels = new ArrayList();
 		labelAnchor = GridBagConstraints.NORTHWEST; 
 			// per java l&f guidelines (CENTER is nicer)
 		labelAlign = SwingConstants.LEFT; 
 			// per java l&f guidelines
             
         doInitialLayout();
     }
 
 /***
 * Constructs an InfoPanel with the specified labels
 * each paired with a blank textfield.
 * @param labelArray An Array containing the labels in the
 * order in which they should appear from top to bottom.
 * A null value produces an empty panel.
 */
     public InfoPanel( String[] labelArray )
     {
         this();
         setLabels( labelArray );
     }
 
 /***
 * Creates a set of labels and empty textfields after first
 * clearing all existing components on the panel.
 * @param labelArray An Array containing the labels in the order
 * in which they should appear from top to bottom.  A null
 * value will clear the panel.
 */
     public void setLabels( String[] labelArray )
     {
         removeAll();
         if ( labelArray == null ) return; // null clears panel
         for ( int i = 0; i < labelArray.length; i++ )
         {
             addPair( labelArray[i], new JTextField() );
         }
     }
 
 /***
 * Retrieves the labls for the components on the panel
 * in the order in which they are displayed from top WIDTH bottom.
 * These are the keys used to reference values or to reference
 * the components directly.
 * @return An Array of Strings containing the labels.
 */
     public String[] getLabels()
     {
         int length = fields.size();
         String[] labelArray = new String[ length ];
         for ( int i = 0; i < length; i++ )
         {
             labelArray[i] = ((Component)fields.get(i)).getName();
         }
         return labelArray;
     }
 	
 /***
 * Retrieves the constant used to anchor the labels in place.
 * The default value is GridBagConstraints.NORTHWEST.
 */
 	public int getLabelAnchor()
 	{
 		return labelAnchor;
 	}
 
 /***
 * Sets the constant used to anchor the labels in place
 * and reflows the layout.
 * @param anAnchorConstant An anchor constant from
 * GridBagConstraints.
 */
 	public void setLabelAnchor( int anAnchorConstant )
 	{
 		labelAnchor = anAnchorConstant;	
 		updateLabels();
 	}
 
 /***
 * Retrieves the constant used to align the labels in place.
 * The default value is GridBagConstraints.CENTER.
 */
 	public int getLabelAlignment()
 	{
 		return labelAlign;
 	}
 
 /***
 * Sets the constant used to align the labels in place
 * and reflows the layout.
 * @param anAlignmentConstant LEFT, CENTER, or RIGHT constants
 * from SwingUtilities.
 */
 	public void setLabelAlignment( int anAlignmentConstant )
 	{
 		labelAlign = anAlignmentConstant;	
 		updateLabels();
 	}
     
 /***
 * Factory method for creating panel spacers.
 * This implementation returns a JPanel with
 * opaque set to false.  Override to customize.
 */    
     public JPanel createPanel()
     {
         JPanel result = new JPanel();
         result.setOpaque( false );
         return result;
     }
 
 /***
 * This method is responsible for the initial layout of the panel.
 * All labels and textfields will later added to listContainer.
 * This method is responsible for initializing listContainer.
 */
     protected void doInitialLayout()
     {
         listContainer = createPanel();
         listContainer.setLayout( new BetterGridBagLayout() );
         this.setLayout( new BorderLayout() ); 
         this.add( listContainer, BorderLayout.NORTH ); 
 
         //listContainer.setBackground( Color.blue ); // useful for testing
         //this.setBackground( Color.red );
     }
 
 /***
 * Changes the horizontal spacing between the label and the components in the panel.
 * Note: Assumes listContainer uses a GridBagLayout.
 * @param newHgap the new spacing, in pixels.  May not be negative.
 */
     public void setHgap( int newHgap )
     {
         if ( newHgap < 0 ) return; // may not be negative
         this.hgap = newHgap;
         updateGaps();
         this.revalidate();
         this.repaint();
 
     }
 
 /***
 * Gets the current horizontal spacing between components.
 * @return the current horizontal spacing, in pixels.
 */
     public int getHgap()
     {
         return this.hgap;
     }
 
 /***
 * Changes the vertical spacing between components in the panel.
 * Note: Assumes listContainer uses a GridBagLayout.
 * @param newVgap the new spacing, in pixels.  May not be negative.
 */
     public void setVgap( int newVgap )
     {
         if ( newVgap < 0 ) return; // may not be negative
         this.vgap = newVgap;
         updateGaps();
         this.revalidate();
         this.repaint();
 
     }
 
 /***
 * Gets the current vertical spacing between components.
 * @return the current vertical spacing, in pixels.
 */
     public int getVgap()
     {
         return this.vgap;
     }
 
 /***
 * Sets the minimum width for the labels column.
 * This left margin will grow if one of the labels
 * is wider than this value.
 * Note: assumes GridBagLayout.
 * @param newMargin the new minimum margin in pixels.  May not be negative.
 */
     public void setMargin( int newMargin )
     {
         if ( newMargin < 0 ) return; // may not be negative
         this.margin = newMargin;
 
         if ( listContainer.getLayout() instanceof GridBagLayout )
         {
             GridBagLayout gridBag = (GridBagLayout) listContainer.getLayout();
             GridBagConstraints constraints = null;
             Component c = null;
             int count = listContainer.getComponentCount();
             for ( int i = 0; i < count; i++ )
             {
                 c = listContainer.getComponent( i );
                 constraints = gridBag.getConstraints( c );
                 if ( constraints.gridy == 0 && constraints.gridx % 2 == 0 )
                 { // if this is a label spacer 
                     // replace it with an appropriately sized box
                     listContainer.remove( c );
                     listContainer.add( Box.createHorizontalStrut( this.margin ), constraints );
                 }
             }
         }
 
         this.revalidate();
         this.repaint();
 
     }
 
 /***
 * Gets the current minimum margin for the labels column.
 * @return the current minimum margin in pixels.
 */
     public int getMargin()
     {
         return this.margin;
     }
 
 /***
 * Sets the number of columns for the panel.
 * Label/Component pairs will start from the top left
 * and fill in to the right before wrapping to the
 * next row.  The default number of columns is one.
 * Note: assumes GridBagLayout.
 * @param newColumns the new number of columns.  May not be less than one.
 */
     public void setColumns( int newColumns )
     {
         if ( newColumns < 1 ) return; // may not be less than one.
         int oldColumns = this.columns;
         this.columns = newColumns;
 
         if ( listContainer.getLayout() instanceof GridBagLayout )
         {
             GridBagLayout gridBag = (GridBagLayout) listContainer.getLayout();
             int count = listContainer.getComponentCount();
             Component[] components = listContainer.getComponents();
             GridBagConstraints[] constraints = new GridBagConstraints[ components.length ];
             for ( int i = 0; i < components.length; i++ )
             {
                 constraints[i] = gridBag.getConstraints( components[i] );
             }
             listContainer.removeAll();
             for ( int i = 0; i < components.length; i++ )
             {
                 if ( constraints[i].gridy != 0 )
                 { // ignore first row which is reserved for spacers.
 
                     // translate component to new position
                     // (columns*2 accounts for two grid columns for one "actual" column)
                     int index = ( constraints[i].gridy - 1 ) * oldColumns*2 + constraints[i].gridx;
                     constraints[i].gridy = ( index / (newColumns*2) ) + 1;
                     constraints[i].gridx = index % (newColumns*2) ;
                     listContainer.add( components[i], constraints[i] );
                 }
             }
             createSpacers(); // replace the spacers
             updateGaps();
         }
 
         this.revalidate();
         this.repaint();
 
     }
 
 /***
 * Sets the vertical weight used for determining how to distribute additional
 * vertical space in the component. 
 * @param aComponent Key that exists in the layout.
 * @return weighty The weight of the component, or -1.0 if not found.
 */
     public double getVerticalWeightForKey( String key )
     {
         Container c = getCompositeComponentForKey( key );
         if ( c == null ) return -1.0;
         if ( ! ( listContainer.getLayout() instanceof GridBagLayout ) ) return -1.0;
         GridBagLayout layout = (GridBagLayout) listContainer.getLayout();
         GridBagConstraints gbc = layout.getConstraints( c );
         return gbc.weighty;
     }
     
 /***
 * Sets the vertical weight used for determining how to distribute additional
 * vertical space in the component.  By default, all weights are zero, so each
 * component gets its preferred height.  If any weights are specified, then
 * additional space is allocated to those components proportionately.
 * @param aComponent Key that exists in the layout.
 * @param weighty The new weight.
 */
     public void setVerticalWeightForKey( String key, double weighty )
     {
         Container c = getCompositeComponentForKey( key );
         if ( c == null ) return;
         if ( ! ( listContainer.getLayout() instanceof GridBagLayout ) ) return;
         GridBagLayout layout = (GridBagLayout) listContainer.getLayout();
         GridBagConstraints gbc = layout.getConstraints( c );
         gbc.weighty = weighty;
         layout.setConstraints( c, gbc );
         // handle adding on-the-fly
         updateGaps();
         this.revalidate();
         this.repaint();
     }
     
 /***
 * Gets the current number of columns.
 * @return the current number of columns.
 */
     public int getColumns()
     {
         return this.columns;
     }
 
 /***
 * Appends a label containing a key and the specified component
 * to the bottom of the panel.  Any registered action listeners
 * will receive action events from the component - the key corresponding
 * to the component will be used as the action command.
 * @param key A string that will be displayed in a label, preferrably unique.
 * @param component A component that will be placed next to the label.
 * If null, a blank JPanel will be used.
 */
 	public void addPair( String key, Component component )
 	{
 		addRow( key, new Component[] { component } );
 	}
 	
 /***
 * Appends a label containing a key and the specified component
 * to the bottom of the panel.  Any registered action listeners
 * will receive action events from the component - the key corresponding
 * to the component will be used as the action command.
 * @param key A string that will be displayed in a label, preferrably unique.
 * @param component A component that will be placed next to the label.
 * If null, a blank JPanel will appear.
 */
 	public void addRow( String key, Component component )
 	{
 		addRow( key, new Component[] { component } );
 	}
 	
 /***
 * Appends a label containing a key and the specified components
 * to the bottom of the panel.  Any registered action listeners
 * will receive action events from the component - the key corresponding
 * to the component will be used as the action command.
 * @param key A string that will be displayed in a label, preferrably unique.
 * @param components An array of components that will be placed next to the label.
 * Any nulls in the list will be replaced with blank JPanels.
 */
 	public void addRow( 
 		String key, Component[] components )
 	{
 		addCompositeComponent( key, makeCompositeComponent( key, components ) );
 	}
 
 /***
 * Appends a label containing a key and the specified components
 * to the bottom of the panel.  Any registered action listeners
 * will receive action events from the components - the key corresponding
 * to the component will be used as the action command.
 * @param key A string that will be displayed in a label, preferrably unique.
 * @param west A component that will appear to the left of the other components,
 * as wide as its preferred width and as tall as the tallest of the other components.
 * A null will be replaced with a blank JPanel.
 * @param center A component that will appear between the other components, 
 * taking up available space.
 * A null will be replaced with a blank JPanel.
 * @param east A component that will appear to the right of the other components,
 * as wide as its preferred width and as tall as the tallest of the other components.
 * A null will be replaced with a blank JPanel.
 */
 	public void addRow( 
 		String key, Component west, Component center, Component east )
 	{
 		addCompositeComponent( key, 
             makeCompositeComponent( key, 
                 west, center, east ) );
 	}
 
 /***
 * Appends a label containing a key and the specified components
 * to the bottom of the panel.  Any registered action listeners
 * will receive action events from the components - the key corresponding
 * to the component will be used as the action command.
 * @param key A string that will be displayed in a label, preferrably unique.
 * @param west A component that will appear to the left of the other components,
 * as wide as its preferred width and as tall as the tallest of the other components.
 * A null will be replaced with a blank JPanel.
 * @param north A component that will appear above all the other components,
 * as tall as its preferred height and as wide as the info panel itself.
 * @param center A component that will appear between the other components, 
 * taking up available space.  A null will be replaced with a blank JPanel.
 * @param south A component that will appear below all the other components,
 * as tall as its preferred height and as wide as the info panel itself.
 * @param east A component that will appear to the right of the other components,
 * as wide as its preferred width and as tall as the tallest of the other components.
 * A null will be replaced with a blank JPanel.
 */
 	public void addRow( 
 		String key, Component west, Component north, 
         Component center, Component south, Component east )
 	{
 		addCompositeComponent( key, 
             makeCompositeComponent( key, 
                 west, north, center, south, east ) );
 	}
 
 /***
 * Produces a container that contains the specified components,
 * using GridLayout.  Nulls are ignored.
 * This implementation returns a JPanel.
 */
 	protected Container makeCompositeComponent( 
 		String key, Component[] components )
 	{
 		JPanel panel = createPanel();
 		if ( components.length != 0 ) 
 		{
 			panel.setLayout( new GridLayout( 1, components.length, hgap, vgap ) );			
 
 			Component c;
 			for ( int i = 0; i < components.length; i++ )
 			{		
 				c = components[i];
 				if ( c != null )
 				{
 					introspectComponent( c, key );
 					panel.add( c );
 				}
 			}
 		}
 		return panel;
 	}
 
 /***
 * Produces a container that contains the specified components,
 * using BorderLayout.  Nulls are ignored.
 * This implementation returns a JPanel.
 */
 	protected Container makeCompositeComponent( 
 		String key, Component west, Component center, Component east )
 	{
 		JPanel panel = createPanel();
 		panel.setLayout( new BorderLayout( hgap, vgap ) );
 
 		if ( west != null )
 		{
 			introspectComponent( west, key );
 			panel.add( west, BorderLayout.WEST );
 		}
 		
 		if ( center != null )
 		{
 			introspectComponent( center, key );
 			panel.add( center, BorderLayout.CENTER );
 		}
 		
 		if ( east != null )
 		{
 			introspectComponent( east, key );
 			panel.add( east, BorderLayout.EAST );
 		}
 		
 		return panel;
 	}
 
 /***
 * Produces a container that contains the specified components,
 * using BorderLayout.  Nulls are ignored.
 * This implementation returns a JPanel.
 */
 	protected Container makeCompositeComponent( 
 		String key,  Component west, Component north, 
 		Component center, Component south, Component east )
 	{
 		JPanel panel = createPanel();
 		panel.setLayout( new BorderLayout( hgap, vgap ) );
 
 		if ( west != null )
 		{
 			introspectComponent( west, key );
 			panel.add( west, BorderLayout.WEST );
 		}
 		
 		if ( north != null )
 		{
 			introspectComponent( north, key );
 			panel.add( north, BorderLayout.WEST );
 		}
 		
 		if ( center != null )
 		{
 			introspectComponent( center, key );
 			panel.add( center, BorderLayout.CENTER );
 		}
 		
 		if ( south != null )
 		{
 			introspectComponent( south, key );
 			panel.add( south, BorderLayout.CENTER );
 		}
 		
 		if ( east != null )
 		{
 			introspectComponent( east, key );
 			panel.add( east, BorderLayout.EAST );
 		}
 		
 		return panel;
 	}
 
 /***
 * Override to return a specific component to be used
 * as a label.  This implementation calls createLabel().
 */
     protected Component createLabelForKey( String aKey )
 	{
 		return createLabel();	
 	}
 
 /***
 * Provided for backwards compatibility, and called by
 * the default implementation of createLabelForKey.
 * This implementation returns a JLabel.
 */
     protected JLabel createLabel()
 	{
 		return new JLabel();	
 	}
 
 /***
 * Appends a label containing a key and the specified component
 * to the bottom of the panel.  Any registered action listeners
 * will receive action events from the component - the key corresponding
 * to the component will be used as the action command.
 * @param key A string that will be displayed in a label, preferrably unique.
 * @param component A component that will be placed next to the label.
 * If null, a stock JTextField will be used.
 */
     protected void addCompositeComponent( String key, Component component )
     {
         if ( key == null )
         {
             key = "";
         }
         Component label = createLabelForKey( key );
         Component field = component;
         if ( field == null )
         {
             field = new JTextField( 15 ); // default to 15 columns
         }
         field.setName( key ); // for association and reference
         label.setName( key ); // ditto
         if ( label instanceof JLabel )
         {
             ((JLabel)label).setHorizontalAlignment( labelAlign );
             ((JLabel)label).setLabelFor( field ); // for accessibility
         }
         if ( "".equals( key ) )
         {
             setText( label, "" );
         }
         else
         {
             setText( label, prefix + key + postfix );
         }
         field.setEnabled( this.isEditable ); // was: setEditable
 
         GridBagConstraints gbc = new GridBagConstraints();
 
         if ( listContainer.getComponentCount() == 0 )
         { // we've just initialized or called removeAll
             createSpacers();
         }
 
         gbc.gridx = ( fields.size() % this.columns ) * 2;
         gbc.gridy = ( fields.size() / this.columns ) + 1; // spacer is at index zero
         gbc.weightx = 0.0;
         gbc.weighty = 0.0;
         gbc.anchor = this.labelAnchor; 
         gbc.fill = GridBagConstraints.HORIZONTAL;
         listContainer.add( label, gbc );
 
 		gbc.fill = GridBagConstraints.BOTH;
         gbc.gridx = gbc.gridx + 1;
 		//FIXME: components default to the labelAnchor - should be different?
         gbc.weightx = 1.0;
         gbc.weighty = 0.0;
         
         listContainer.add( field, gbc );
         
         if ( key.equals( HIDDEN ) )
         { // these components are not to be shown
             setText( label, "     " );
             field.setVisible( false );
         }
 
         fields.add( field ); // using list not map to allow for duplicate keys
         labels.add( label ); // ditto
 
         // handle adding on-the-fly
         updateGaps();
         this.revalidate();
         this.repaint();
     }
 
 /***
 * Introspects a component to set the action command and to add the
 * InfoPanel to its list of ActionListeners.
 * @param aComponent The Component to be introspected.
 * @param aKey The action command to be set.
 */
     protected void introspectComponent( Component aComponent, String aKey )
     {
         // try to set properties of whatever component this might be
         try {
             Method [] methods =
                 (Method []) _method_cache.get( aComponent.getClass() );
             if (methods == null) {
                 Class componentClass = aComponent.getClass();
                 BeanInfo info =
                     Introspector.getBeanInfo( componentClass );
 
                 MethodDescriptor[] descriptors =
                     info.getMethodDescriptors();
                 Method setMethod = null;
                 Method addMethod = null;
                 for ( int i = 0;
                       ((setMethod == null || addMethod == null) &&
                        i < descriptors.length);
                       i++ )
                 {
                     Method m = descriptors[i].getMethod();
                     String name = m.getName ();
                     if ( setMethod == null &&
                          name.equals( "setActionCommand" ) )
                     {
                         setMethod = m;
                     }
                     else if ( addMethod == null &&
                               name.equals( "addActionListener" ) )
                     {
                         addMethod = m;
                     }
                 }
 
                 methods = new Method [] {setMethod, addMethod};
                 _method_cache.put (componentClass, methods);
             }
             if (methods [0] != null) {
               methods [0].invoke( aComponent, new Object[] { aKey } );
             }
             if (methods [1] != null) {
               methods [1].invoke( aComponent, new Object[] { this } );
               listenedToComponents.add( aComponent );
             }
         }
         catch ( Exception exc )
         { // error occured while introspecting... move along.
               System.out.println( "InfoPanel.introspectComponent: " + exc );
         }
     }
     
 /***
 * Called to populate a label component with the specified text.
 * This implementation attempts to call setText(String) on the component.
 * Override to customize.
 */
     protected void setText( Component c, String text )
     {
         try
         {
             Method m = c.getClass().getMethod( "setText", new Class[] { String.class } );
             if ( m != null )
             {
                 m.invoke( c, new Object[] { text } );
             }
         }
         catch ( Exception exc )
         {
             // no such method: ignore
         }
     }
 
 /***
 * Creates spacer components on the reserved first grid row
 * for each column of labels and fields.  
 * This allows us to set the margin for those label columns,
 * and set the preferred width of the field columns.
 * A list containing the field spacers should be assigned to
 * the fieldSpacers instance variable.
 */
     private void createSpacers()
     {
         if ( listContainer.getLayout() instanceof GridBagLayout )
         {
             // insert spacers for labels column
             GridBagLayout gridBag = (GridBagLayout) listContainer.getLayout();
             GridBagConstraints constraints = new GridBagConstraints();
             constraints.gridy = 0;
             constraints.fill = GridBagConstraints.HORIZONTAL;
 
             fieldSpacers = new LinkedList();
             Component fieldSpacer;
             for ( int i = 0; i < this.columns; i++ )
             {
                 constraints.gridx = i * 2;
                 listContainer.add( Box.createHorizontalStrut( this.margin ), constraints );
 
                 constraints.gridx = i * 2 + 1;
                 fieldSpacer = Box.createHorizontalStrut( 0 ); 
                 fieldSpacers.add( fieldSpacer );
                 listContainer.add( fieldSpacer, constraints );
             }
         }
     }
 
 /***
 * Updates the insets for all components.
 */
     protected void updateGaps()
     {
         if ( listContainer.getLayout() instanceof GridBagLayout )
         {
             GridBagLayout layout = (GridBagLayout) listContainer.getLayout();
             Component c = null;
             GridBagConstraints gbc = null;
             double totalWeightY = 0.0;
             int count = listContainer.getComponentCount();
             int i;
             for ( i = 0; i < count; i++ )
             {
                 c = listContainer.getComponent( i );
                 gbc = layout.getConstraints( c );
                 totalWeightY += gbc.weighty;
                 if ( (gbc.gridx + 1) % ( this.columns * 2 ) == 0 )
                 { // if last component in row
                     gbc.insets = new Insets( 0, 0, this.vgap, 0 );
                 }
                 else
                 {
                     if ( gbc.gridx % 2 == 0 )
                     { // is a label column - NOTE: uses eleven pixels before component, per l&f guide
                         gbc.insets = new Insets( 0, 0, this.vgap, 11 );
                     }
                     else
                     { // is a component column
                         if ( gbc.gridy != 0 ) 
                         {
                             if ( c instanceof JPanel ) ((JPanel)c).setPreferredSize( null );
                             gbc.insets = new Insets( 0, 0, this.vgap, this.hgap );
                         }
                     }
                 }
                 layout.setConstraints( c, gbc );
             }
             
             //hack: gridbag clumps components in center if weighty is zero
             // if sum of weighty is zero, top-justify the list container
             this.remove( listContainer );
             if ( totalWeightY == 0.0 )
             {
                 this.add( listContainer, BorderLayout.NORTH );
             } 
             else // put list container in center so it will grow
             {
                 this.add( listContainer, BorderLayout.CENTER );
             }
         }
     }
 
 /***
 * Updates the label alignment.
 */
     protected void updateLabels()
     {
         if ( listContainer.getLayout() instanceof GridBagLayout )
         {
             GridBagLayout layout = (GridBagLayout) listContainer.getLayout();
             Component c = null;
             GridBagConstraints gbc = null;
 			Iterator it = labels.iterator();
 			while ( it.hasNext() )
             {
                 c = (Component) it.next();
                 if ( c instanceof JLabel )
                 {
 				    ((JLabel)c).setHorizontalAlignment( labelAlign );
                 }
                 gbc = layout.getConstraints( c );
                 gbc.anchor = this.labelAnchor;
                 layout.setConstraints( c, gbc );
             }
         }
     }
 
 /***
 * Convenience method that uses a stock JTextField.
 * @param key A string that will be displayed in a label, preferrably unique.
 * @param value A string that will be displayed in a textfield.
 */
     public void addPair( String key, String value )
     {
         addPair( key, value, null );
     }
 
 /***
 * Convenience method that uses the specified JTextField or subclass
 * and sets it to the specified value.
 * @param key A string that will be displayed in a label, preferrably unique.
 * @param value A string that will be displayed in a textfield.
 * @param textField A JTextField or subclass that will be used to display the value.
 * If null, a stock JTextField will be used.
 */
     public void addPair( String key, String value, JTextField textField )
     {
         if ( value == null )
         {
             value = "";
         }
         JTextField field = textField;
         if ( field == null )
         {
             field = new JTextField( 15 ); // default to 15 columns
         }
         else
         {
             field = textField;
         }
         field.setText( value );
 
         addPair( key, (Component) field );
     }
 
 /***
 * Removes all components from the list.  Buttons, if any,
 * will remain unchanged - use setButtons( null ) to remove 
 * them.  NOTE: does not call super.removeAll().
 */
     public void removeAll()
     {
         Object component;
         Method method;
         Class[] paramClasses = new Class[] { ActionListener.class };
         Object[] paramObjects = new Object[] { this };
 
         Iterator iterator = listenedToComponents.iterator();
         while ( iterator.hasNext() )
         {
             component = iterator.next();
             try
             {
                 method = component.getClass().getMethod( "removeActionListener", paramClasses );
                 if ( method != null )
                 {
                     method.invoke( component, paramObjects );
                 }
             }
             catch ( Exception exception )
             {
                 // No removeActionListener() method, move along.
             }
         }
 
         listenedToComponents.clear();
         
         listContainer.removeAll();
         fields.clear();
         labels.clear();
         this.revalidate();
         this.repaint();
         
         //FIXME: It is very confusing that this 
         // implementation does not call super.removeAll().
     }
 
 /***
 * Adds one or buttons to the bottom of the panel with the specified labels
 * from left to right.  Any action listeners will receive action events
 * from clicks on these buttons - the supplied label will be used as the action command.
 * @param buttons A string array containing the strings to be used for the button labels
 * and action commands.  A null value will remove the button panel.
 * @see ButtonPanel
 */
     public void setButtons( String[] buttons )
     {
         if ( buttonPanel == null )
         {
             buttonPanel = new ButtonPanel();
             buttonPanel.setInsets( new Insets( 6, 0, 0, 0 ) ); 
 				// button panel has a 11-pixel top inset
 				// and java l&f guide says 17-pixels before command buttons
             buttonPanel.addActionListener( this );
             this.add( buttonPanel, BorderLayout.SOUTH );
         }
         if ( buttons == null )
         {
             this.remove( buttonPanel );
             buttonPanel = null;
         }
         else
         {
             buttonPanel.setLabels( buttons );
         }
 
         this.revalidate();
         this.repaint();
     }
     protected Collection listenedToComponents = new LinkedList();
 
 /***
 * Retrieves the names of the buttons that are displayed, if any.
 * @return A string array containing the strings used for the button labels
 * and action commands, or null if no buttons have been created.
 * @see ButtonPanel
 */
     public String[] getButtons()
     {
         if ( buttonPanel == null )
         {
             return null; // none created
         }
 
         return buttonPanel.getLabels();
     }
 
 /***
 * Retrieves the actual button panel, if any.
 * @return A button panel, or null if none has been created.
 * @see ButtonPanel
 */
     public ButtonPanel getButtonPanel()
     {
         return buttonPanel;
     }
 
 
 /***
 * Sets whether the values displayed in the panel should be editable.  Defaults to true.
 * @param isEditable Whether the values should be editable.
 */
     public void setEditable( boolean isEditable )
     {
         this.isEditable = isEditable;
         Iterator enumeration = fields.iterator();
         while ( enumeration.hasNext() )
         {
             ( (Component) enumeration.next() ).setEnabled( isEditable );
         }
     }
 
 /***
 * Gets whether the values displayed in the panel are editable.
 * @return Whether the values should be editable.
 */
     public boolean isEditable()
     {
         return this.isEditable;
     }
 
 /***
 * Sets the field associated with the key to the specified value.
 * Note: If the component does not respond to setText() or setString()
 * or setValue() the value will not be set.  JTextFields and the like will work.
 * @param key A string representing the key associated with the field.  Nulls are converted to an empty string.
 * @param value A object to be displayed in the specified field.  Nulls are converted to an empty string.
 */
     public void setValueForKey( String key, Object value )
     {
 		setValueForKey( key, value, 0 );	
 	}
 	
 /***
 * Sets the field associated with the key to the specified value.
 * Note: If the component does not respond to setText() or setString()
 * or setValue() the value will not be set.  JTextFields and the like will work.
 * @param key A string representing the key associated with the field.  Nulls are converted to an empty string.
 * @param value A object to be displayed in the specified field.  Nulls are converted to an empty string.
 */
     public void setValueForKey( String key, Object value, int index )
     {
         if ( key == null )
         {
             key = "";
         }
 
         Container field = null;
 		for ( int i = 0; i < fields.size(); i++ )
 		{
             field = (Container) fields.get(i);
             if ( key.equals( field.getName() ) )
             {
 				setValueForIndex( index, i, value );
 				return;
             }
 		}
         // else not found - ignore
     }
 	
 /***
 * Sets the first field at the specified row index to the specified value.
 * Note: If the component does not respond to setText() or setString()
 * or setValue() the value will not be set.  JTextFields and the like will work.
 * @param row The row index of the component.
 * @param value A object to be displayed in the specified field.  
 * Nulls are converted to an empty string.
 */
     public void setValueForIndex( int row, Object value )
     {
 		setValueForIndex( row, 0, value );	
 	}
 	
 /***
 * Sets the field at the specified row index and column index to the specified value.
 * Note: If the component does not respond to setText() or setString()
 * or setValue() the value will not be set.  JTextFields and the like will work.
 * @param row The row index of the component.
 * @param index The column index of the component.
 * @param value A object to be displayed in the specified field.  
 * Nulls are converted to an empty string.
 */
     public void setValueForIndex( int row, int col, Object value )
     {
 		Container field = (Container) fields.get( row );
 		Component c = field.getComponent( col );
 		setValueForComponent( c, value );
 	}
 	
 
 
 /***
 * Sets the value in the field at the specified index.
 * Note: If the component does not respond to setText() or setString()
 * or setValue() this method will return null.  JTextFields and the like will work.
 * @param A valid index.
 * @param value A object to be displayed in the specified field.
 */
     protected void setValueForComponent( Component aComponent, Object value )
     {
         // try to set a text or string property
         try {
             BeanInfo info = Introspector.getBeanInfo( aComponent.getClass() );
             MethodDescriptor[] methods = info.getMethodDescriptors();
             for ( int i = 0; i < methods.length; i++ )
             {
                 Method m = methods[i].getMethod();
                 Class[] paramTypes = m.getParameterTypes();
                 if ( paramTypes.length == 1 )
                 {
                     if ( m.getName().equals( "setText" ) )
                     {
                         if ( paramTypes[0].getName().equals( String.class.getName() ) )
                         {
                             m.invoke( aComponent, new Object[] { value } );
                         }
                     }
                     if ( m.getName().equals( "setString" ) )
                     {
                         if ( paramTypes[0].getName().equals( String.class.getName() ) )
                         {
                             m.invoke( aComponent, new Object[] { value } );
                         }
                     }
                     if ( m.getName().equals( "setValue" ) )
                     {
                         if ( paramTypes[0].getName().equals( Object.class.getName() ) )
                         {
                             m.invoke( aComponent, new Object[] { value } );
                         }
                     }
                 }
             }
         }
         catch ( Exception exc )
         { // error occured while introspecting... move along.
           // FIXME: should log error in ErrorManager
           System.out.println( "InfoPanel.setValueForComponent: " + exc );
         }
     }
 
 /***
 * Gets the value in the field at the specified index.
 * Note: If the component does not respond to getText() or getString()
 * or getSelectedItem() this method will return null.  JTextFields and the like will work.
 * @param A valid index.
 * @return An object representing the value in the field at the specified index,
 * or null if the component does not have a text property or if the index is out of bounds.
 */
     public Object getValueForIndex( int anIndex )
     {
         return getValueForIndex( anIndex, 0 );
     }
 
 /***
 * Gets the value in the field at the specified row and column.
 * Note: If the component does not respond to getText() or getString()
 * or getSelectedItem() this method will return null.  JTextFields and the like will work.
 * @param A valid index.
 * @return An object representing the value in the field at the specified index,
 * or null if the component does not have a text property or if the index is out of bounds.
 */
     public Object getValueForIndex( int row, int col )
     {
         if ( ( row >= fields.size() ) || ( row < 0 ) )
         { // out of bounds
             return null;
         }
 		
 		Container field = (Container) fields.get( row );
 		Component c = field.getComponent( col );
         return getValueForComponent( c );
     }
 
 /***
 * Gets the value in the field associated with the key.
 * Note: If the component does not respond to getText() or getString()
 * or getSelectedItem() this method will return null.  JTextFields and the like will work.
 * @param key An string representing the key associated with the field.  Nulls are converted to an empty string.
 * @return An object representing the value in the field associated with the key,
 * or null if the key does not exist or if the component does not have a text property.
 */
     public Object getValueForKey( String key )
     {
 		return getValueForKey( key, 0 );	
 	}
 
 /***
 * Gets the value in the field associated with the key.
 * Note: If the component does not respond to getText() or getString()
 * or getSelectedItem() this method will return null.  JTextFields and the like will work.
 * @param key An string representing the key associated with the field.  Nulls are converted to an empty string.
 * @return An object representing the value in the field associated with the key,
 * or null if the key does not exist or if the component does not have a text property.
 */
     public Object getValueForKey( String key, int index )
     {
         if ( key == null )
         {
             key = "";
         }
 
         Container field = null;
         Iterator enumeration = fields.iterator();
         while ( enumeration.hasNext() )
         { // finds first value in list with specified key
             field = (Container) enumeration.next();
             if ( key.equals( field.getName() ) )
             {
 				Component c = field.getComponent( index );
 				if ( c != null )
 				{
 					return getValueForComponent( c );
 				}
             }
         }
         // else not found
         return null;
     }
 
 /***
 * Gets the value in the specified component.
 * Note: If the component does not respond to getText() or getString()
 * or getSelectedItem() this method will return null.  JTextFields and the like will work.
 * @param aComponent The specified component.
 * @return An object representing the value in the component.
 * or null if the component does not have a text property.
 */
     protected Object getValueForComponent( Component aComponent )
     {
         // try to get a text or string property
         try
         {
             BeanInfo info = Introspector.getBeanInfo( aComponent.getClass() );
             MethodDescriptor[] methods = info.getMethodDescriptors();
             for ( int i = 0; i < methods.length; i++ )
             {
                 Method m = methods[i].getMethod();
                 Class[] paramTypes = m.getParameterTypes();
                 if ( m.getName().equals( "getText" ) )
                 {
                     if ( paramTypes.length == 0 )
                     {
                         return m.invoke( aComponent, new Object[] {} );
                     }
                 }
                 if ( m.getName().equals( "getString" ) )
                 {
                     if ( paramTypes.length == 0 )
                     {
                         return m.invoke( aComponent, new Object[] {} );
                     }
                 }
                 if ( m.getName().equals( "getSelectedItem" ) )
                 {
                     if ( paramTypes.length == 0 )
                     {
                         return m.invoke( aComponent, new Object[] {} );
                     }
                 }
                 // TODO: should also handle variants of setValue()
             }
         }
         catch ( Exception exc )
         { // error occured while introspecting... move along.
           System.out.println( "InfoPanel.getValueFromComponent: " + exc );
         }
 
         // not found
         return null;
     }
 
 /***
 * Gets the component associated with the key as a JTextField, for backwards compatibility.
 * @param key A string representing the key associated with the component.  Nulls are converted to an empty string.
 * @return A JTextField that contains the value associated with the key,
 * or null if the key does not exist or if the component is not a JTextField.
 */
     public JTextField getFieldForKey( String key )
     {
         Component c = getComponentForKey( key );
         if ( c instanceof JTextField )
         {
             return (JTextField) c;
         }
         return null;
     }
 
 /***
 * Gets the component associated with the key.  If more than one component is associated
 * with the key, returns the first such component.
 * @param key A string representing the key associated with the component.  
 * Nulls are converted to an empty string.
 * @return A component that contains the value associated with the key,
 * or null if the key does not exist.
 */
     public Component getComponentForKey( String key )
     {
 		return getComponentForKey( key, 0 );
 	}
 
 /***
 * Gets the component associated with the key and index.
 * @param key A string representing the key associated with the component.  
 * Nulls are converted to an empty string.
 * @return A component that contains the value associated with the key,
 * or null if the key does not exist.
 */
     public Component getComponentForKey( String key, int index )
     {
 		Container c = getCompositeComponentForKey( key );
 		if ( c == null ) return null;
 		return c.getComponent( index );
     }
 
 /***
 * Gets the component at the specified row.  If more than one component exists
 * on that row, returns the first such component.
 * @return A component or null if the row does not exist.
 */
     public Object getComponentForIndex( int row )
     {
         return getComponentForIndex( row, 0 );
     }
 
 /***
 * Gets the component at the specified row and column.
 * @return A component or null if the index is out of bounds.
 */
     public Object getComponentForIndex( int row, int col )
     {
         if ( ( row > fields.size() ) || ( row < 0 ) )
         { // out of bounds
             return null;
         }
 		
 		Container field = (Container) fields.get( row );
 		return field.getComponent( col );
     }
 
 /***
 * Gets the container associated with the key.
 * @param key A string representing the key associated with the component.  
 * Nulls are converted to an empty string.
 * @return A component that contains the value associated with the key,
 * or null if the key does not exist.
 */
     protected Container getCompositeComponentForKey( String key )
     {
         if ( key == null )
         {
             key = "";
         }
 
         JPanel field = null;
         Iterator enumeration = fields.iterator();
         while ( enumeration.hasNext() )
         { // finds first value in list with specified key
             field = (JPanel) enumeration.next();
             if ( key.equals( field.getName() ) )
             {
                 return field;
             }
         }
 
         // else not found
         return null;
     }
 
 /***
 * Provided for backwards compatibility: calls getLabelComponentForKey.
 * @param key A string representing the key associated with the compoent.
 *            Nulls are converted to an empty string.
 * @return Component label object associated with the key, or null if the key does not exist
 * or if the label component is not an instance of JLabel.
 */
     public JLabel getLabelForKey( String key )
     {
         Component result = getLabelComponentForKey( key );
         if ( result instanceof JLabel ) return (JLabel) result;
         return null;
     }
     
 /***
 * Get the label component associated with the key.
 * @param key A string representing the key associated with the compoent.
 *            Nulls are converted to an empty string.
 * @return Component label object associated with the key, or null if the key does not exist.
 */
     public Component getLabelComponentForKey( String key )
     {
         if ( key == null )
         {
             key = "";
         }
 
         Component label = null;
         Iterator enumeration = labels.iterator();
         while ( enumeration.hasNext() )
         { // finds first value in list with specified key
             label = (Component) enumeration.next();
             if ( key.equals( label.getName() ) )
             {
                 return label;
             }
         }
 
         // else not found
         return null;
     }
 
 /***
 * Replaces the first component associated with the key.  Any value in the existing
 * component will be copied to the new component.
 * @param key A string representing the key to be associated with the component.  
 * Nulls are converted to an empty string.
 * @param c A component to be placed next to the label corresponding to the key.  
 * Nulls are converted to a JTextField.
 */
     public void setComponentForKey( String key, Component c )
     {
 		setComponentForKey( key, c, 0 );	
 	}
 	
 /***
 * Replaces the component associated with the key.  Any value in the existing
 * component will be copied to the new component.
 * @param key A string representing the key to be associated with the component.  
 * Nulls are converted to an empty string.
 * @param c A component to be placed next to the label corresponding to the key.  
 * Nulls are converted to a JTextField.
 */
     public void setComponentForKey( String key, Component c, int index )
     {
         if ( c == null )
         {
             c = new JTextField( 15 );
         }
         if ( key == null )
         {
             key = "";
         }
 
         Container container = this.getCompositeComponentForKey( key );
 		Component field = container.getComponent( index );
         Object value = this.getValueForKey( key, index );
         if ( field != null )
         {
 			container.remove( index );
 			container.add( c, index );
 			c.setEnabled( this.isEditable );
 			introspectComponent( c, key );
             setValueForComponent( c, value );
         }
     }
 
 /***
 * Replaces the first component in the specified row.  Any value in the existing
 * component will be copied to the new component.
 * @param row A valid index.
 * @param c A component to be placed next to the label corresponding to the key.  
 */
     public void setComponentForIndex( int row, Component c )
     {
 		setComponentForIndex( row, 0, c );	
 	}
 	
 /***
 * Replaces the component associated with the key.  Any value in the existing
 * component will be copied to the new component.
 * @param row A valid index.
 * @param c A component to be placed next to the label corresponding to the key.  
 */
     public void setComponentForIndex( int row, int col, Component c )
     {
 		setComponentForKey( getLabels()[row], c, col );
     }
 
 /***
 * Sets the string that appears before each label's text on the panel.
 * @param aString A String to be used as the label prefix.
 */
     public void setLabelPrefix( String aString )
     {
         prefix = aString;
         setLabels( getLabels() ); // force refresh
     }
 
 /***
 * Gets the string that appears before each label's text on the panel.
 * Defaults to "", an empty string.
 * @return A String that is currently used as the label prefix.
 */
     public String getLabelPrefix()
     {
         return prefix;
     }
 
 /***
 * Sets the string that appears after each label's text on the panel.
 * Defaults to ": ", a colon followed by a space.
 * @param aString A String to be used as the label postfix.
 */
     public void setLabelPostfix( String aString )
     {
         postfix = aString;
         setLabels( getLabels() ); // force refresh
     }
 
 /***
 * Gets the string that appears after each label's text on the panel.
 * @return A String that is currently used as the label postfix.
 */
     public String getLabelPostfix()
     {
         return postfix;
     }
 
 /***
 * Adds an action listener to the list that will be
 * notified by events occurring in the panel.
 * @param l An action listener to be notified.
 */
      public void addActionListener(ActionListener l)
      {
            actionListener = AWTEventMulticaster.add(actionListener, l);
      }
 /***
 * Removes an action listener from the list that will be
 * notified by events occurring in the panel.
 * @param l An action listener to be removed.
 */
      public void removeActionListener(ActionListener l)
      {
            actionListener = AWTEventMulticaster.remove(actionListener, l);
      }
 /***
 * Notifies all registered action listeners of a pending Action Event.
 * @param e An action event to be broadcast.
 */
      protected void broadcastEvent(ActionEvent e)
      {
          if (actionListener != null)
          {
              actionListener.actionPerformed(e);
          }
      }
 
     // interface ActionListener
 
 /***
 * Called by buttons on panel and by other components that
 * might be set to broadcast events to this listener.
 * Simply forwards the action event unchanged.
 * @param e An action event to be received.
 */
      public void actionPerformed(ActionEvent e)
      {
 //        if ( e.getSource() instanceof AbstractButton )
 //        {
             broadcastEvent(e);
 //        }
      }
      
     /***
     * GridBagLayout allocates weightx only after considering
     * the preferred width of the components in a column.
     * We'd prefer that preferred width wasn't considered,
     * so that the layout worked more like a html-table.
     * GridBagLayout is poorly factored for subclassing,
     * so this code is going to get a little bit ugly.
     * Really, what good is a protected method that returns
     * a private class?  Would have liked to just override
     * getLayoutInfo and be done with it.
     */
     private class BetterGridBagLayout extends GridBagLayout
     {
         public Dimension preferredLayoutSize(Container parent) 
         {
             preprocess();
             return super.preferredLayoutSize( parent );
         }
         
         public Dimension minimumLayoutSize(Container parent) 
         {
             preprocess();
             return super.minimumLayoutSize( parent );
         }
 
         
         public void layoutContainer(Container parent) 
         {
             preprocess();
             super.layoutContainer( parent );
         }
 
         protected void preprocess() 
         {
             if ( fieldSpacers == null ) return;
             Iterator i;
             
             // find the field with the widest preferred size
             Component c;
             int maxWidth = 0;
             i = fields.iterator();
             while ( i.hasNext() )
             {
                 c = (Component) i.next();
                 maxWidth = Math.max( maxWidth, 
                     Math.max( c.getPreferredSize().width, c.getMinimumSize().width ) );
             }
             
             // set each column's spacers to that preferred size
             Dimension min = new Dimension( 0, 0 );
             Dimension pref = new Dimension( maxWidth, 0 );
             i = fieldSpacers.iterator();
             while ( i.hasNext() )
             {
                 ((Box.Filler)i.next()).changeShape( min, pref, pref );
             }
         }
     }
 }