llvm-gcc-4.0/libjava/javax/swing/plaf/basic/BasicScrollBarUI.java

/* BasicScrollBarUI.java --
   Copyright (C) 2004, 2005  Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
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02111-1307 USA.

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making a combined work based on this library.  Thus, the terms and
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As a special exception, the copyright holders of this library give you
permission to link this library with independent modules to produce an
executable, regardless of the license terms of these independent
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terms of your choice, provided that you also meet, for each linked
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package javax.swing.plaf.basic;

import java.awt.Color;
import java.awt.Component;
import java.awt.Container;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Insets;
import java.awt.LayoutManager;
import java.awt.Point;
import java.awt.Polygon;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;

import javax.swing.BoundedRangeModel;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JScrollBar;
import javax.swing.SwingConstants;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
import javax.swing.UIDefaults;
import javax.swing.UIManager;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.plaf.ComponentUI;
import javax.swing.plaf.ScrollBarUI;

/**
 * The Basic Look and Feel UI delegate for JScrollBar.
 */
public class BasicScrollBarUI extends ScrollBarUI implements LayoutManager,
                                                             SwingConstants
{
  /**
   * A helper class that listens to the two JButtons on each end of the
   * JScrollBar.
   */
  protected class ArrowButtonListener extends MouseAdapter
  {
    /**
     * Move the thumb in the direction specified by the  button's arrow. If
     * this button is held down, then it should keep moving the thumb.
     *
     * @param e The MouseEvent fired by the JButton.
     */
    public void mousePressed(MouseEvent e)
    {
      scrollTimer.stop();
      scrollListener.setScrollByBlock(false);
      if (e.getSource() == incrButton)
	scrollListener.setDirection(POSITIVE_SCROLL);
      else
	scrollListener.setDirection(NEGATIVE_SCROLL);
      scrollTimer.start();
    }

    /**
     * Stops the thumb when the JButton is released.
     *
     * @param e The MouseEvent fired by the JButton.
     */
    public void mouseReleased(MouseEvent e)
    {
      scrollTimer.stop();
    }
  }

  /**
   * A helper class that listens to the ScrollBar's model for ChangeEvents.
   */
  protected class ModelListener implements ChangeListener
  {
    /**
     * Called when the model changes.
     *
     * @param e The ChangeEvent fired by the model.
     */
    public void stateChanged(ChangeEvent e)
    {
      //       System.err.println(this + ".stateChanged()");
      calculatePreferredSize();
      layoutContainer(scrollbar);
      getThumbBounds();
      scrollbar.repaint();
    }
  }

  /**
   * A helper class that listens to the ScrollBar's properties.
   */
  public class PropertyChangeHandler implements PropertyChangeListener
  {
    /**
     * Called when one of the ScrollBar's properties change.
     *
     * @param e The PropertyChangeEvent fired by the ScrollBar.
     */
    public void propertyChange(PropertyChangeEvent e)
    {
      if (e.getPropertyName().equals("model"))
        {
	  ((BoundedRangeModel) e.getOldValue()).removeChangeListener(modelListener);
	  scrollbar.getModel().addChangeListener(modelListener);
	  getThumbBounds();
        }
      else if (e.getPropertyName().equals("orientation"))
        {
	  incrButton.removeMouseListener(buttonListener);
	  decrButton.removeMouseListener(buttonListener);
	  incrButton = createIncreaseButton(scrollbar.getOrientation());
	  decrButton = createDecreaseButton(scrollbar.getOrientation());
	  incrButton.addMouseListener(buttonListener);
	  decrButton.addMouseListener(buttonListener);
	  calculatePreferredSize();
	  layoutContainer(scrollbar);
        }
      layoutContainer(scrollbar);
      scrollbar.repaint();
    }
  }

  /**
   * A helper class that listens for events from the timer that is used to
   * move the thumb.
   */
  protected class ScrollListener implements ActionListener
  {
    /** The direction the thumb moves in. */
    private transient int direction;

    /** Whether movement will be in blocks. */
    private transient boolean block;

    /**
     * Creates a new ScrollListener object. The default is scrolling
     * positively with block movement.
     */
    public ScrollListener()
    {
      direction = POSITIVE_SCROLL;
      block = true;
    }

    /**
     * Creates a new ScrollListener object using the given direction and
     * block.
     *
     * @param dir The direction to move in.
     * @param block Whether movement will be in blocks.
     */
    public ScrollListener(int dir, boolean block)
    {
      direction = dir;
      this.block = block;
    }

    /**
     * Sets the direction to scroll in.
     *
     * @param direction The direction to scroll in.
     */
    public void setDirection(int direction)
    {
      this.direction = direction;
    }

    /**
     * Sets whether scrolling will be done in blocks.
     *
     * @param block Whether scrolling will be in blocks.
     */
    public void setScrollByBlock(boolean block)
    {
      this.block = block;
    }

    /**
     * Called every time the timer reaches its interval.
     *
     * @param e The ActionEvent fired by the timer.
     */
    public void actionPerformed(ActionEvent e)
    {
      if (block)
        {
	  // Only need to check it if it's block scrolling
	  // We only block scroll if the click occurs
	  // in the track.
	  if (! trackListener.shouldScroll(direction))
	    {
	      trackHighlight = NO_HIGHLIGHT;
	      scrollbar.repaint();
	      return;
	    }
	  scrollByBlock(direction);
        }
      else
	scrollByUnit(direction);
    }
  }

  /**
   * Helper class that listens for movement on the track.
   */
  protected class TrackListener extends MouseAdapter
    implements MouseMotionListener
  {
    /** The current X coordinate of the mouse. */
    protected int currentMouseX;

    /** The current Y coordinate of the mouse. */
    protected int currentMouseY;

    /**
     * The offset between the current mouse cursor and the  current value of
     * the scrollbar.
     */
    protected int offset;

    /**
     * This method is called when the mouse is being dragged.
     *
     * @param e The MouseEvent given.
     */
    public void mouseDragged(MouseEvent e)
    {
      currentMouseX = e.getX();
      currentMouseY = e.getY();
      if (scrollbar.getValueIsAdjusting())
        {
	  int value;
	  if (scrollbar.getOrientation() == SwingConstants.HORIZONTAL)
	    value = valueForXPosition(currentMouseX) - offset;
	  else
	    value = valueForYPosition(currentMouseY) - offset;

	  scrollbar.setValue(value);
        }
    }

    /**
     * This method is called when the mouse is moved.
     *
     * @param e The MouseEvent given.
     */
    public void mouseMoved(MouseEvent e)
    {
      // Not interested in where the mouse
      // is unless it is being dragged.
    }

    /**
     * This method is called when the mouse is pressed. When it is pressed,
     * the thumb should move in blocks towards the cursor.
     *
     * @param e The MouseEvent given.
     */
    public void mousePressed(MouseEvent e)
    {
      currentMouseX = e.getX();
      currentMouseY = e.getY();

      int value;
      if (scrollbar.getOrientation() == SwingConstants.HORIZONTAL)
	value = valueForXPosition(currentMouseX);
      else
	value = valueForYPosition(currentMouseY);

      if (value == scrollbar.getValue())
	return;

      if (! thumbRect.contains(e.getPoint()))
        {
	  scrollTimer.stop();
	  scrollListener.setScrollByBlock(true);
	  if (value > scrollbar.getValue())
	    {
	      trackHighlight = INCREASE_HIGHLIGHT;
	      scrollListener.setDirection(POSITIVE_SCROLL);
	    }
	  else
	    {
	      trackHighlight = DECREASE_HIGHLIGHT;
	      scrollListener.setDirection(NEGATIVE_SCROLL);
	    }
	  scrollTimer.start();
        }
      else
        {
	  // We'd like to keep track of where the cursor
	  // is inside the thumb.
	  // This works because the scrollbar's value represents 
	  // "lower" edge of the thumb. The value at which
	  // the cursor is at must be greater or equal
	  // to that value.
	  scrollbar.setValueIsAdjusting(true);
	  offset = value - scrollbar.getValue();
        }
      scrollbar.repaint();
    }

    /**
     * This method is called when the mouse is released. It should stop
     * movement on the thumb
     *
     * @param e The MouseEvent given.
     */
    public void mouseReleased(MouseEvent e)
    {
      trackHighlight = NO_HIGHLIGHT;
      scrollTimer.stop();

      if (scrollbar.getValueIsAdjusting())
	scrollbar.setValueIsAdjusting(false);
      scrollbar.repaint();
    }

    /**
     * A helper method that decides whether we should keep scrolling in the
     * given direction.
     *
     * @param direction The direction to check for.
     *
     * @return Whether the thumb should keep scrolling.
     */
    public boolean shouldScroll(int direction)
    {
      int value;
      if (scrollbar.getOrientation() == HORIZONTAL)
	value = valueForXPosition(currentMouseX);
      else
	value = valueForYPosition(currentMouseY);

      if (direction == POSITIVE_SCROLL)
	return (value > scrollbar.getValue());
      else
	return (value < scrollbar.getValue());
    }
  }

  /** The listener that listens to the JButtons. */
  protected ArrowButtonListener buttonListener;

  /** The listener that listens to the model. */
  protected ModelListener modelListener;

  /** The listener that listens to the scrollbar for property changes. */
  protected PropertyChangeListener propertyChangeListener;

  /** The listener that listens to the timer. */
  protected ScrollListener scrollListener;

  /** The listener that listens for MouseEvents on the track. */
  protected TrackListener trackListener;

  /** The JButton that decrements the scrollbar's value. */
  protected JButton decrButton;

  /** The JButton that increments the scrollbar's value. */
  protected JButton incrButton;

  /** The dimensions of the maximum thumb size. */
  protected Dimension maximumThumbSize;

  /** The dimensions of the minimum thumb size. */
  protected Dimension minimumThumbSize;

  /** The color of the thumb. */
  protected Color thumbColor;

  /** The outer shadow of the thumb. */
  protected Color thumbDarkShadowColor;

  /** The top and left edge color for the thumb. */
  protected Color thumbHighlightColor;

  /** The outer light shadow for the thumb. */
  protected Color thumbLightShadowColor;

  /** The color that is used when the mouse press occurs in the track. */
  protected Color trackHighlightColor;

  /** The color of the track. */
  protected Color trackColor;

  /** The size and position of the track. */
  protected Rectangle trackRect;

  /** The size and position of the thumb. */
  protected Rectangle thumbRect;

  /** Indicates that the decrease highlight should be painted. */
  protected static final int DECREASE_HIGHLIGHT = 1;

  /** Indicates that the increase highlight should be painted. */
  protected static final int INCREASE_HIGHLIGHT = 2;

  /** Indicates that no highlight should be painted. */
  protected static final int NO_HIGHLIGHT = 0;

  /** Indicates that the scrolling direction is positive. */
  private static final int POSITIVE_SCROLL = 1;

  /** Indicates that the scrolling direction is negative. */
  private static final int NEGATIVE_SCROLL = -1;

  /** The cached preferred size for the scrollbar. */
  private transient Dimension preferredSize;

  /** The current highlight status. */
  protected int trackHighlight;

  /** FIXME: Use this for something (presumably mouseDragged) */
  protected boolean isDragging;

  /** The timer used to move the thumb when the mouse is held. */
  protected Timer scrollTimer;

  /** The scrollbar this UI is acting for. */
  protected JScrollBar scrollbar;

  /**
   * This method adds a component to the layout.
   *
   * @param name The name to associate with the component that is added.
   * @param child The Component to add.
   */
  public void addLayoutComponent(String name, Component child)
  {
    // You should not be adding stuff to this component.
    // The contents are fixed.
  }

  /**
   * This method configures the scrollbar's colors. This can be  done by
   * looking up the standard colors from the Look and Feel defaults.
   */
  protected void configureScrollBarColors()
  {
    UIDefaults defaults = UIManager.getLookAndFeelDefaults();

    trackColor = defaults.getColor("ScrollBar.track");
    trackHighlightColor = defaults.getColor("ScrollBar.trackHighlight");
    thumbColor = defaults.getColor("ScrollBar.thumb");
    thumbHighlightColor = defaults.getColor("ScrollBar.thumbHighlight");
    thumbDarkShadowColor = defaults.getColor("ScrollBar.thumbDarkShadow");
    thumbLightShadowColor = defaults.getColor("ScrollBar.thumbLightShadow");
  }

  /**
   * This method creates an ArrowButtonListener.
   *
   * @return A new ArrowButtonListener.
   */
  protected ArrowButtonListener createArrowButtonListener()
  {
    return new ArrowButtonListener();
  }

  /**
   * This method creates a new JButton with the appropriate icon for the
   * orientation.
   *
   * @param orientation The orientation this JButton uses.
   *
   * @return The increase JButton.
   */
  protected JButton createIncreaseButton(int orientation)
  {
    if (incrButton == null)
      incrButton = new BasicArrowButton((orientation == SwingConstants.HORIZONTAL)
                                        ? SwingConstants.EAST
                                        : SwingConstants.SOUTH);
    else
      {
	if (orientation == SwingConstants.HORIZONTAL)
	  ((BasicArrowButton) incrButton).setDirection(SwingConstants.EAST);
	else
	  ((BasicArrowButton) incrButton).setDirection(SwingConstants.SOUTH);
      }
    return incrButton;
  }

  /**
   * This method creates a new JButton with the appropriate icon for the
   * orientation.
   *
   * @param orientation The orientation this JButton uses.
   *
   * @return The decrease JButton.
   */
  protected JButton createDecreaseButton(int orientation)
  {
    if (decrButton == null)
      decrButton = new BasicArrowButton((orientation == SwingConstants.HORIZONTAL)
                                        ? SwingConstants.WEST
                                        : SwingConstants.NORTH);
    else
      {
	if (orientation == SwingConstants.HORIZONTAL)
	  ((BasicArrowButton) decrButton).setDirection(SwingConstants.WEST);
	else
	  ((BasicArrowButton) decrButton).setDirection(SwingConstants.NORTH);
      }
    return decrButton;
  }

  /**
   * This method creates a new ModelListener.
   *
   * @return A new ModelListener.
   */
  protected ModelListener createModelListener()
  {
    return new ModelListener();
  }

  /**
   * This method creates a new PropertyChangeListener.
   *
   * @return A new PropertyChangeListener.
   */
  protected PropertyChangeListener createPropertyChangeListener()
  {
    return new PropertyChangeHandler();
  }

  /**
   * This method creates a new ScrollListener.
   *
   * @return A new ScrollListener.
   */
  protected ScrollListener createScrollListener()
  {
    return new ScrollListener();
  }

  /**
   * This method creates a new TrackListener.
   *
   * @return A new TrackListener.
   */
  protected TrackListener createTrackListener()
  {
    return new TrackListener();
  }

  /**
   * This method returns a new BasicScrollBarUI.
   *
   * @param c The JComponent to create a UI for.
   *
   * @return A new BasicScrollBarUI.
   */
  public static ComponentUI createUI(JComponent c)
  {
    return new BasicScrollBarUI();
  }

  /**
   * This method returns the maximum size for this JComponent.
   *
   * @param c The JComponent to measure the maximum size for.
   *
   * @return The maximum size for the component.
   */
  public Dimension getMaximumSize(JComponent c)
  {
    return getPreferredSize(c);
  }

  /**
   * This method returns the maximum thumb size.
   *
   * @return The maximum thumb size.
   */
  protected Dimension getMaximumThumbSize()
  {
    return maximumThumbSize;
  }

  /**
   * This method returns the minimum size for this JComponent.
   *
   * @param c The JComponent to measure the minimum size for.
   *
   * @return The minimum size for the component.
   */
  public Dimension getMinimumSize(JComponent c)
  {
    return getPreferredSize(c);
  }

  /**
   * This method returns the minimum thumb size.
   *
   * @return The minimum thumb size.
   */
  protected Dimension getMinimumThumbSize()
  {
    return minimumThumbSize;
  }

  /**
   * This method calculates the preferred size since calling
   * getPreferredSize() returns a cached value.
   */
  private void calculatePreferredSize()
  {
    // System.err.println(this + ".calculatePreferredSize()");
    int height;
    int width;
    height = width = 0;

    if (scrollbar.getOrientation() == SwingConstants.HORIZONTAL)
      {
	width += incrButton.getPreferredSize().getWidth();
	width += decrButton.getPreferredSize().getWidth();

	width += (scrollbar.getMaximum() - scrollbar.getMinimum());

	height = Math.max(incrButton.getPreferredSize().height,
	                  decrButton.getPreferredSize().height);
	height = Math.max(getMinimumThumbSize().height, height);
	height = Math.max(20, height);
	height = Math.min(getMaximumThumbSize().height, height);
      }
    else
      {
	height += incrButton.getPreferredSize().getHeight();
	height += decrButton.getPreferredSize().getHeight();

	height += (scrollbar.getMaximum() - scrollbar.getMinimum());

	width = Math.max(incrButton.getPreferredSize().width,
	                 decrButton.getPreferredSize().width);
	width = Math.max(getMinimumThumbSize().width, width);
	width = Math.max(20, width);
	width = Math.min(getMaximumThumbSize().width, width);
      }

    Insets insets = scrollbar.getInsets();

    height += insets.top + insets.bottom;
    width += insets.left + insets.right;

    preferredSize = new Dimension(width, height);
  }

  /**
   * This method returns a cached value of the preferredSize. The only
   * restrictions are: If the scrollbar is horizontal, the height should be
   * the maximum of the height of the JButtons and  the minimum width of the
   * thumb. For vertical scrollbars, the  calculation is similar (swap width
   * for height and vice versa).
   *
   * @param c The JComponent to measure.
   *
   * @return The preferredSize.
   */
  public Dimension getPreferredSize(JComponent c)
  {
    calculatePreferredSize();
    return preferredSize;
  }

  /**
   * This method returns the thumb's bounds based on the  current value of the
   * scrollbar. This method updates the cached value and returns that.
   *
   * @return The thumb bounds.
   */
  protected Rectangle getThumbBounds()
  {
    int max = scrollbar.getMaximum();
    int min = scrollbar.getMinimum();
    int value = scrollbar.getValue();
    int extent = scrollbar.getVisibleAmount();

    // System.err.println(this + ".getThumbBounds()");
    if (max == min)
      {
	thumbRect.x = trackRect.x;
	thumbRect.y = trackRect.y;
	if (scrollbar.getOrientation() == HORIZONTAL)
	  {
	    thumbRect.width = getMinimumThumbSize().width;
	    thumbRect.height = trackRect.height;
	  }
	else
	  {
	    thumbRect.width = trackRect.width;
	    thumbRect.height = getMinimumThumbSize().height;
	  }
	return thumbRect;
      }

    if (scrollbar.getOrientation() == HORIZONTAL)
      {
	thumbRect.x = trackRect.x;
	thumbRect.x += (value - min) * trackRect.width / (max - min);
	thumbRect.y = trackRect.y;

	thumbRect.width = extent * trackRect.width / (max - min);
	thumbRect.height = trackRect.height;
      }
    else
      {
	thumbRect.x = trackRect.x;
	thumbRect.y = trackRect.y + value * trackRect.height / (max - min);

	thumbRect.width = trackRect.width;
	thumbRect.height = extent * trackRect.height / (max - min);
      }
    return thumbRect;
  }

  /**
   * This method calculates the bounds of the track. This method updates the
   * cached value and returns it.
   *
   * @return The track's bounds.
   */
  protected Rectangle getTrackBounds()
  {
    SwingUtilities.calculateInnerArea(scrollbar, trackRect);

    if (scrollbar.getOrientation() == SwingConstants.HORIZONTAL)
      {
	trackRect.width -= incrButton.getPreferredSize().getWidth();
	trackRect.width -= decrButton.getPreferredSize().getWidth();

	trackRect.x += decrButton.getPreferredSize().getWidth();
      }
    else
      {
	trackRect.height -= incrButton.getPreferredSize().getHeight();
	trackRect.height -= decrButton.getPreferredSize().getHeight();

	trackRect.y += incrButton.getPreferredSize().getHeight();
      }
    return trackRect;
  }

  /**
   * This method installs any addition Components that  are a part of or
   * related to this scrollbar.
   */
  protected void installComponents()
  {
    incrButton = createIncreaseButton(scrollbar.getOrientation());
    scrollbar.add(incrButton);
    decrButton = createDecreaseButton(scrollbar.getOrientation());
    scrollbar.add(decrButton);
  }

  /**
   * This method installs the defaults for the scrollbar specified by the
   * Basic Look and Feel.
   */
  protected void installDefaults()
  {
    UIDefaults defaults = UIManager.getLookAndFeelDefaults();

    scrollbar.setForeground(defaults.getColor("ScrollBar.foreground"));
    scrollbar.setBackground(defaults.getColor("ScrollBar.background"));
    scrollbar.setBorder(defaults.getBorder("ScrollBar.border"));
    scrollbar.setOpaque(true);

    maximumThumbSize = defaults.getDimension("ScrollBar.maximumThumbSize");
    minimumThumbSize = defaults.getDimension("ScrollBar.minimumThumbSize");
  }

  /**
   * This method installs the keyboard actions for the scrollbar.
   */
  protected void installKeyboardActions()
  {
    // FIXME: implement.
  }

  /**
   * This method installs any listeners for the scrollbar. This method also
   * installs listeners for things such as the JButtons and the timer.
   */
  protected void installListeners()
  {
    scrollListener = createScrollListener();
    trackListener = createTrackListener();
    buttonListener = createArrowButtonListener();
    modelListener = createModelListener();
    propertyChangeListener = createPropertyChangeListener();

    scrollbar.addMouseMotionListener(trackListener);
    scrollbar.addMouseListener(trackListener);

    incrButton.addMouseListener(buttonListener);
    decrButton.addMouseListener(buttonListener);

    scrollbar.addPropertyChangeListener(propertyChangeListener);
    scrollbar.getModel().addChangeListener(modelListener);

    scrollTimer.addActionListener(scrollListener);
  }

  /**
   * This method installs the UI for the component. This can include setting
   * up listeners, defaults,  and components. This also includes initializing
   * any data objects.
   *
   * @param c The JComponent to install.
   */
  public void installUI(JComponent c)
  {
    super.installUI(c);
    if (c instanceof JScrollBar)
      {
	scrollbar = (JScrollBar) c;

	trackRect = new Rectangle();
	thumbRect = new Rectangle();

	scrollTimer = new Timer(200, null);
	scrollTimer.setRepeats(true);

	installComponents();
	installListeners();
	installDefaults();
	configureScrollBarColors();

	calculatePreferredSize();
	layoutContainer(scrollbar);
      }
  }

  /**
   * This method lays out the scrollbar.
   *
   * @param scrollbarContainer The Container to layout.
   */
  public void layoutContainer(Container scrollbarContainer)
  {
    if (scrollbarContainer instanceof JScrollBar)
      {
	if (scrollbar.getOrientation() == SwingConstants.HORIZONTAL)
	  layoutHScrollbar((JScrollBar) scrollbarContainer);
	else
	  layoutVScrollbar((JScrollBar) scrollbarContainer);
      }
  }

  /**
   * This method lays out the scrollbar horizontally.
   *
   * @param sb The JScrollBar to layout.
   */
  protected void layoutHScrollbar(JScrollBar sb)
  {
    // All we have to do is layout the 2 buttons?
    Rectangle vr = new Rectangle();
    SwingUtilities.calculateInnerArea(scrollbar, vr);

    // Update the rectangles.
    getTrackBounds();
    getThumbBounds();

    Dimension incrDims = incrButton.getPreferredSize();
    Dimension decrDims = decrButton.getPreferredSize();

    decrButton.setBounds(vr.x, vr.y, decrDims.width, trackRect.height);
    incrButton.setBounds(trackRect.x + trackRect.width, vr.y, incrDims.width,
                         trackRect.height);
  }

  /**
   * This method lays out the scrollbar vertically.
   *
   * @param sb The JScrollBar to layout.
   */
  protected void layoutVScrollbar(JScrollBar sb)
  {
    Rectangle vr = new Rectangle();
    SwingUtilities.calculateInnerArea(scrollbar, vr);

    // Update rectangles
    getTrackBounds();
    getThumbBounds();

    Dimension incrDims = incrButton.getPreferredSize();
    Dimension decrDims = decrButton.getPreferredSize();

    decrButton.setBounds(vr.x, vr.y, trackRect.width, decrDims.height);
    incrButton.setBounds(vr.x, trackRect.y + trackRect.height,
                         trackRect.width, incrDims.height);
  }

  /**
   * This method returns the minimum size required for the layout.
   *
   * @param scrollbarContainer The Container that is laid out.
   *
   * @return The minimum size.
   */
  public Dimension minimumLayoutSize(Container scrollbarContainer)
  {
    return preferredLayoutSize(scrollbarContainer);
  }

  /**
   * This method is called when the component is painted.
   *
   * @param g The Graphics object to paint with.
   * @param c The JComponent to paint.
   */
  public void paint(Graphics g, JComponent c)
  {
    layoutContainer(scrollbar);
    paintTrack(g, c, getTrackBounds());
    paintThumb(g, c, getThumbBounds());

    if (trackHighlight == INCREASE_HIGHLIGHT)
      paintIncreaseHighlight(g);
    else if (trackHighlight == DECREASE_HIGHLIGHT)
      paintDecreaseHighlight(g);
  }

  /**
   * This method is called when repainting and the mouse is  pressed in the
   * track. It paints the track below the thumb with the trackHighlight
   * color.
   *
   * @param g The Graphics object to paint with.
   */
  protected void paintDecreaseHighlight(Graphics g)
  {
    Color saved = g.getColor();

    g.setColor(trackHighlightColor);
    if (scrollbar.getOrientation() == HORIZONTAL)
      g.fillRect(trackRect.x, trackRect.y, thumbRect.x - trackRect.x,
                 trackRect.height);
    else
      g.fillRect(trackRect.x, trackRect.y, trackRect.width,
                 thumbRect.y - trackRect.y);
    g.setColor(saved);
  }

  /**
   * This method is called when repainting and the mouse is  pressed in the
   * track. It paints the track above the thumb with the trackHighlight
   * color.
   *
   * @param g The Graphics objet to paint with.
   */
  protected void paintIncreaseHighlight(Graphics g)
  {
    Color saved = g.getColor();

    g.setColor(trackHighlightColor);
    if (scrollbar.getOrientation() == HORIZONTAL)
      g.fillRect(thumbRect.x + thumbRect.width, trackRect.y,
                 trackRect.x + trackRect.width - thumbRect.x - thumbRect.width,
                 trackRect.height);
    else
      g.fillRect(trackRect.x, thumbRect.y + thumbRect.height, trackRect.width,
                 trackRect.y + trackRect.height - thumbRect.y
                 - thumbRect.height);
    g.setColor(saved);
  }

  /**
   * This method paints the thumb.
   *
   * @param g The Graphics object to paint with.
   * @param c The Component that is being painted.
   * @param thumbBounds The thumb bounds.
   */
  protected void paintThumb(Graphics g, JComponent c, Rectangle thumbBounds)
  {
    Color saved = g.getColor();
    Point x;
    Point y;
    Point z;
    Polygon lines;

    g.setColor(thumbHighlightColor);
    x = new Point(thumbBounds.x + 1, thumbBounds.y + 1);
    y = new Point(x);
    y.translate(thumbBounds.width - 2, 0);
    z = new Point(x);
    z.translate(0, thumbBounds.height - 2);

    lines = new Polygon(new int[] { x.x, y.x, z.x },
                        new int[] { x.y, y.y, z.y }, 3);

    g.drawPolygon(lines);

    g.setColor(thumbLightShadowColor);
    x = new Point(thumbBounds.x + thumbBounds.width - 1,
                  thumbBounds.y + thumbBounds.height - 1);
    y = new Point(x);
    y.translate(-(thumbBounds.width - 2), 0);
    z = new Point(x);
    z.translate(0, -(thumbBounds.height - 2));

    lines = new Polygon(new int[] { x.x, y.x, z.x },
                        new int[] { x.y, y.y, z.y }, 3);
    g.drawPolygon(lines);

    g.setColor(thumbDarkShadowColor);
    x = new Point(thumbBounds.x + thumbBounds.width,
                  thumbBounds.y + thumbBounds.height);
    y = new Point(x);
    y.translate(-thumbBounds.width, 0);
    z = new Point(x);
    z.translate(0, -thumbBounds.height);

    lines = new Polygon(new int[] { x.x, y.x, z.x },
                        new int[] { x.y, y.y, z.y }, 3);
    g.drawPolygon(lines);

    g.setColor(thumbColor);
    g.fillRect(thumbBounds.x, thumbBounds.y, thumbBounds.width,
               thumbBounds.height);

    g.setColor(saved);
  }

  /**
   * This method paints the track.
   *
   * @param g The Graphics object to paint with.
   * @param c The JComponent being painted.
   * @param trackBounds The track's bounds.
   */
  protected void paintTrack(Graphics g, JComponent c, Rectangle trackBounds)
  {
    Color saved = g.getColor();
    g.setColor(trackColor);
    g.fill3DRect(trackBounds.x, trackBounds.y, trackBounds.width,
                 trackBounds.height, false);
    g.setColor(saved);
  }

  /**
   * This method returns the preferred size for the layout.
   *
   * @param scrollbarContainer The Container to find a size for.
   *
   * @return The preferred size for the layout.
   */
  public Dimension preferredLayoutSize(Container scrollbarContainer)
  {
    if (scrollbarContainer instanceof JComponent)
      return getPreferredSize((JComponent) scrollbarContainer);
    else
      return null;
  }

  /**
   * This method removes a child component from the layout.
   *
   * @param child The child to remove.
   */
  public void removeLayoutComponent(Component child)
  {
    // You should not be removing stuff from this component.
  }

  /**
   * The method scrolls the thumb by a block in the  direction specified.
   *
   * @param direction The direction to scroll.
   */
  protected void scrollByBlock(int direction)
  {
    scrollbar.setValue(scrollbar.getValue()
                       + scrollbar.getBlockIncrement(direction));
  }

  /**
   * The method scrolls the thumb by a unit in the direction specified.
   *
   * @param direction The direction to scroll.
   */
  protected void scrollByUnit(int direction)
  {
    scrollbar.setValue(scrollbar.getValue()
                       + scrollbar.getUnitIncrement(direction));
  }

  /**
   * This method sets the thumb's bounds.
   *
   * @param x The X position of the thumb.
   * @param y The Y position of the thumb.
   * @param width The width of the thumb.
   * @param height The height of the thumb.
   */
  protected void setThumbBounds(int x, int y, int width, int height)
  {
    thumbRect.x = x;
    thumbRect.y = y;
    thumbRect.width = width;
    thumbRect.height = height;
  }

  /**
   * This method uninstalls any components that  are a part of or related to
   * this scrollbar.
   */
  protected void uninstallComponents()
  {
    scrollbar.remove(incrButton);
    scrollbar.remove(decrButton);
    incrButton = null;
    decrButton = null;
  }

  /**
   * This method uninstalls any defaults that this scrollbar acquired from the
   * Basic Look and Feel defaults.
   */
  protected void uninstallDefaults()
  {
    scrollbar.setForeground(null);
    scrollbar.setBackground(null);
    scrollbar.setBorder(null);
  }

  /**
   * This method uninstalls any keyboard actions this scrollbar acquired
   * during install.
   */
  protected void uninstallKeyboardActions()
  {
    // FIXME: implement.
  }

  /**
   * This method uninstalls any listeners that were registered during install.
   */
  protected void uninstallListeners()
  {
    scrollTimer.removeActionListener(scrollListener);

    scrollbar.getModel().removeChangeListener(modelListener);
    scrollbar.removePropertyChangeListener(propertyChangeListener);

    decrButton.removeMouseListener(buttonListener);
    incrButton.removeMouseListener(buttonListener);

    scrollbar.removeMouseListener(trackListener);
    scrollbar.removeMouseMotionListener(trackListener);

    propertyChangeListener = null;
    modelListener = null;
    buttonListener = null;
    trackListener = null;
    scrollListener = null;
  }

  /**
   * This method uninstalls the UI. This includes removing any defaults,
   * listeners, and components that this UI may have initialized. It also
   * nulls any instance data.
   *
   * @param c The Component to uninstall for.
   */
  public void uninstallUI(JComponent c)
  {
    uninstallDefaults();
    uninstallListeners();
    uninstallComponents();

    scrollTimer = null;

    thumbRect = null;
    trackRect = null;

    trackColor = null;
    trackHighlightColor = null;
    thumbColor = null;
    thumbHighlightColor = null;
    thumbDarkShadowColor = null;
    thumbLightShadowColor = null;

    scrollbar = null;
  }

  /**
   * This method returns the value in the scrollbar's range given the y
   * coordinate. If the value is out of range, it will return the closest
   * legal value.
   *
   * @param yPos The y coordinate to calculate a value for.
   *
   * @return The value for the y coordinate.
   */
  private int valueForYPosition(int yPos)
  {
    int min = scrollbar.getMinimum();
    int max = scrollbar.getMaximum();
    int len = trackRect.height;

    int value;

    // If the length is 0, you shouldn't be able to even see where the thumb is.
    // This really shouldn't ever happen, but just in case, we'll return the middle.
    if (len == 0)
      return ((max - min) / 2);

    value = ((yPos - trackRect.y) * (max - min) / len + min);

    // If this isn't a legal value, then we'll have to move to one now.
    if (value > max)
      value = max;
    else if (value < min)
      value = min;
    return value;
  }

  /**
   * This method returns the value in the scrollbar's range given the x
   * coordinate. If the value is out of range, it will return the closest
   * legal value.
   *
   * @param xPos The x coordinate to calculate a value for.
   *
   * @return The value for the x coordinate.
   */
  private int valueForXPosition(int xPos)
  {
    int min = scrollbar.getMinimum();
    int max = scrollbar.getMaximum();
    int len = trackRect.width;

    int value;

    // If the length is 0, you shouldn't be able to even see where the slider is.
    // This really shouldn't ever happen, but just in case, we'll return the middle.
    if (len == 0)
      return ((max - min) / 2);

    value = ((xPos - trackRect.x) * (max - min) / len + min);

    // If this isn't a legal value, then we'll have to move to one now.
    if (value > max)
      value = max;
    else if (value < min)
      value = min;
    return value;
  }
}