/*

@(#) $Id: ColorPreview.java,v 1.14 2001-12-20 13:00:27 billh Exp $

VisAD Utility Library: Widgets for use in building applications with
the VisAD interactive analysis and visualization library
Copyright (C) 2017 Nick Rasmussen
VisAD is Copyright (C) 1996 - 2017 Bill Hibbard, Curtis Rueden, Tom
Rink and Dave Glowacki.

This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 1, or (at your option)
any later version.

This program 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 General Public License in file NOTICE for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

package visad.util;

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;

import javax.swing.JPanel;

/**
 * A small preview bar generated for a color widget
 *
 * @author Nick Rasmussen nick@cae.wisc.edu
 * @version $Revision: 1.14 $, $Date: 2001-12-20 13:00:27 $
 * @since Visad Utility Library, 0.5
 */

public class ColorPreview extends JPanel implements ColorChangeListener {

  /** The ColorWidget that this is attached to */
  private ColorMap map;

  /** The height of the ColorPreview */
  private int height = 15;

  /**
   * Constructs a ColorPreview that Listens to the specified
   * widget and has the default height
   *
   * @deprecated Specify the ColorMap instead.
   */
  ColorPreview(ColorWidget widget) {
    this(widget, 15);
  }

  /**
   * Constructs a ColorPreview that listens to the specified
   * ColorWidget and has the specified height
   *
   * @deprecated Specify the ColorMap instead.
   */
  public ColorPreview(ColorWidget widget, int height) {
    this(widget.getColorMap(), height);
  }

  /**
   * Constructs a ColorPreview that Listens to the specified
   * ColorMap and has the default height
   */
  ColorPreview(ColorMap map) {
    this(map, 15);
  }

  /**
   * Constructs a ColorPreview that listens to the specified
   * ColorMap and has the specified height
   */
  public ColorPreview(ColorMap map, int height) {
    this.map = map;
    this.height = height;
    map.addColorChangeListener(this);
  }

  /** Overridden to maintain the preview at the specified height */
  public Dimension getMaximumSize() {
    return new Dimension(Integer.MAX_VALUE, height);
  }

  /** Redraw the entire panel */
  public void paint(Graphics g) {
    updateLeft = 0;
    updateRight = 1;
    update(g);
  }

  /** The location to begin an update */
  private float updateLeft;
  /** The location to end an update */
  private float updateRight;

  /** Updates the nessecary areas of the panel after ColorChangeEvents and paint()
   * @see ColorChangeEvent
   */
  public void update(Graphics g) {

    int leftIndex;
    int rightIndex;

    synchronized(this) {
      leftIndex = (int) Math.floor(updateLeft * getBounds().width);
      rightIndex = (int) Math.floor(updateRight * getBounds().width);
      updateLeft = 1;
      updateRight = 0;
    }

    if (leftIndex > rightIndex) {
      int tmp = leftIndex;
      leftIndex = rightIndex;
      rightIndex = tmp;
    }

    if (leftIndex < 0) {
      leftIndex = 0;
    }
    if (leftIndex >= getBounds().width) {
      leftIndex = getBounds().width - 1;
    }
    if (rightIndex < 0) {
      rightIndex = 0;
    }
    if (rightIndex >= getBounds().width) {
      rightIndex = getBounds().width - 1;
    }

    final float fWidth = (float )getBounds().width;
    int num = (rightIndex - leftIndex) + 1;

    Color[] c = map.getColors((float )leftIndex / fWidth,
                              (float )rightIndex / fWidth,
                              num);

    if (num > c.length) num = c.length; // WLH 20 Dec 2001

    for (int i = 0; i < num; i++) {
      g.setColor(c[i]);
      g.drawLine(i+leftIndex,0,i+leftIndex,getBounds().height - 1);
    }
  }

  /** Implementation of the ColorChangeListener interface
   * @see ColorChangeListener
   */
  public void colorChanged(ColorChangeEvent e) {
    synchronized(this) {
      if (e.getStart() < updateLeft) {
        updateLeft = e.getStart();
      }
      if (e.getEnd() > updateRight) {
        updateRight = e.getEnd();
      }
    }

    // redraw
    validate();
    repaint();
  }

  /** Finds the preferred width of the ColorMap, and returns it with the specified
   * height
   */
  public Dimension getPreferredSize() {
    Dimension d = map.getPreferredSize();
    return new Dimension(d.width, height);
  }

  public void setMap(ColorMap newMap)
  {
    map.removeColorChangeListener(this);
    newMap.addColorChangeListener(this);
    map = newMap;
  }
}