content: // ===============================================================================
  // Authors: AFRL/RQQD
  // Organization: Air Force Research Laboratory, Aerospace Systems Directorate, Power and Control Division
  // 
  // Copyright (c) 2017 Government of the United State of America, as represented by
  // the Secretary of the Air Force.  No copyright is claimed in the United States under
  // Title 17, U.S. Code.  All Other Rights Reserved.
  // ===============================================================================
  
  /*
   * GRAL: GRAphing Library for Java(R)
   *
   * (C) Copyright 2009-2013 Erich Seifert <dev[at]erichseifert.de>,
   * Michael Seifert <mseifert[at]error-reports.org>
   *
   * This file is part of GRAL.
   *
   * GRAL 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 3 of the License, or
   * (at your option) any later version.
   *
   * GRAL 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 GRAL.  If not, see <http://www.gnu.org/licenses/>.
   */
  package de.erichseifert.gral.plots.colors;
  
  import java.awt.Color;
  import java.awt.Paint;
  import java.util.HashMap;
  import java.util.Map;
  
  import de.erichseifert.gral.util.HaltonSequence;
  import de.erichseifert.gral.util.MathUtils;
  
  /**
   * Class that generates seemingly random colors for specified index values.
   */
  public class QuasiRandomColors extends IndexedColorMapper {
  	/** Version id for serialization. */
  	private static final long serialVersionUID = 3320256963368776894L;
  
  	/** Object for mapping a plot value to a hue. */
  	private final HaltonSequence seqHue = new HaltonSequence(3);
  	/** Object for mapping a plot value to a saturation. */
  	private final HaltonSequence seqSat = new HaltonSequence(5);
  	/** Object for mapping a plot value to a brightness. */
  	private final HaltonSequence seqBrightness = new HaltonSequence(2);
  	/** Cache for colors that have already been generated. */
  	private final Map<Integer, Color> colorCache;
  	/** Variance settings for hue, saturation and brightness. */
  	//FIXME duplicate code! See RandomColors
  	private float[] colorVariance;
  
  	/**
  	 * Creates a new QuasiRandomColors object with default color variance.
  	 */
  	public QuasiRandomColors() {
  		colorCache = new HashMap<Integer, Color>();
  		colorVariance = new float[] {
  			0.00f, 1.00f,  // Hue
  			0.75f, 0.25f,  // Saturation
  			0.25f, 0.75f   // Brightness
  		};
  	}
  
  	/**
  	 * Returns the Paint associated to the specified index value.
  	 * @param index Numeric index.
  	 * @return Paint object.
  	 */
  	@Override
  	public Paint get(int index) {
  		Integer key = Integer.valueOf(index);
  		if (colorCache.containsKey(key)) {
  			return colorCache.get(key);
  		}
  		float[] colorVariance = getColorVariance();
  		float hue = colorVariance[0] + colorVariance[1]*seqHue.next().floatValue();
  		float saturation = colorVariance[2] + colorVariance[3]*seqSat.next().floatValue();
  		float brightness = colorVariance[4] + colorVariance[5]*seqBrightness.next().floatValue();
  		Color color = Color.getHSBColor(
  			hue,
  			MathUtils.limit(saturation, 0f, 1f),
  			MathUtils.limit(brightness, 0f, 1f)
  		);
  		colorCache.put(key, color);
  		return color;
  	}
  
  	/**
  	 * Returns the current color variance.
  	 * @return Range of hue, saturation and brightness a color can have.
  	 */
  	public float[] getColorVariance() {
  		return colorVariance;
  	}
  
  	/**
  	 * Sets the current color variance.
  	 * @param colorVariance Range of hue, saturation and brightness a color
  	 *        can have.
  	 */
  	public void setColorVariance(float[] colorVariance) {
  		this.colorVariance = colorVariance;
  	}
  }
  