    001/* ===========================================================
    002 * Orson Charts : a 3D chart library for the Java(tm) platform
    003 * ===========================================================
    004 *
    005 * (C)opyright 2013-2016, by Object Refinery Limited.  All rights reserved.
    006 *
    007 * http://www.object-refinery.com/orsoncharts/index.html
    008 *
    009 * This program is free software: you can redistribute it and/or modify
    010 * it under the terms of the GNU General Public License as published by
    011 * the Free Software Foundation, either version 3 of the License, or
    012 * (at your option) any later version.
    013 *
    014 * This program is distributed in the hope that it will be useful,
    015 * but WITHOUT ANY WARRANTY; without even the implied warranty of
    016 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    017 * GNU General Public License for more details.
    018 *
    019 * You should have received a copy of the GNU General Public License
    020 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
    021 *
    022 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates.
    023 * Other names may be trademarks of their respective owners.]
    024 *
    025 * If you do not wish to be bound by the terms of the GPL, an alternative
    026 * commercial license can be purchased.  For details, please see visit the
    027 * Orson Charts home page:
    028 *
    029 * http://www.object-refinery.com/orsoncharts/index.html
    030 *
    031 */
    032
    033package com.orsoncharts.renderer;
    034
    035import java.awt.Color;
    036
    037import com.orsoncharts.Range;
    038import com.orsoncharts.util.ArgChecks;
    039
    040/**
    041 * A color scale that returns all the colors of the rainbow.  Instances of
    042 * this class are immutable and serializable.
    043 * <br><br>
    044 * NOTE: This class is serializable, but the serialization format is subject
    045 * to change in future releases and should not be relied upon for persisting
    046 * instances of this class.
    047 *
    048 * @since 1.1
    049 */
    050@SuppressWarnings("serial")
    051public class RainbowScale extends AbstractColorScale implements ColorScale {
    052
    053    /**
    054     * A range to include all hues.  This can be used for the
    055     * {@code hueSubrange} argument in the constructor.
    056     */
    057    public static final Range ALL_HUES = new Range(0.0, 1.0);
    058
    059    /**
    060     * A hue subrange that restricts colors to the blue to red range.  This can
    061     * be used for the {@code hueSubrange} argument in the constructor.
    062     */
    063    public static final Range BLUE_TO_RED_RANGE = new Range(0.0, 0.6666);
    064
    065    /** Storage for the color samples. */
    066    private Color[] colors;
    067
    068    /**
    069     * The subrange of hues (useful to restrict the scale to the range from
    070     * blue to red, which is common in charts).
    071     */
    072    private Range hueSubrange;
    073
    074    /**
    075     * Creates a new rainbow scale for the specified value range, with 256
    076     * color samples in the blue to red range.
    077     *
    078     * @param range  the range ({@code null} not permitted).
    079     */
    080    public RainbowScale(Range range) {
    081        this(range, 256, BLUE_TO_RED_RANGE);
    082    }
    083
    084    /**
    085     * Creates a new rainbow scale for the specified value range, with the
    086     * given number of samples and hues restricted to the specified range.
    087     *
    088     * @param range  the range ({@code null} not permitted).
    089     * @param samples  the number of samples.
    090     * @param hueSubrange  the hue sub-range.
    091     */
    092    public RainbowScale(Range range, int samples, Range hueSubrange) {
    093        super(range);
    094        ArgChecks.nullNotPermitted(hueSubrange, "hueSubrange");
    095        this.colors = new Color[samples];
    096        this.hueSubrange = hueSubrange;
    097    }
    098
    099    /**
    100     * Returns the number of samples used by this color scale.
    101     *
    102     * @return The number of samples.
    103     */
    104    public int getSampleCount() {
    105        return this.colors.length;
    106    }
    107
    108    /**
    109     * Returns the sub-range of hues used in this scale.
    110     *
    111     * @return The sub-range of hues.
    112     */
    113    public Range getHueSubrange() {
    114        return this.hueSubrange;
    115    }
    116
    117    /**
    118     * Converts a value to a color on the scale.
    119     *
    120     * @param value  the value.
    121     *
    122     * @return A color (never {@code null}).
    123     */
    124    @Override
    125    public Color valueToColor(double value) {
    126        Range r = getRange();
    127        if (value < r.getMin()) {
    128            return valueToColor(r.getMin());
    129        }
    130        if (value > r.getMax()) {
    131            return valueToColor(r.getMax());
    132        }
    133        double fraction = getRange().percent(value);
    134        int i = (int) (fraction * (this.colors.length - 1));
    135        if (this.colors[i] == null) {
    136            this.colors[i] = createRainbowColor(fraction);
    137        }
    138        return this.colors[i];
    139    }
    140
    141    /**
    142     * Creates the rainbow color corresponding to the specified fraction along
    143     * the scale range.
    144     *
    145     * @param fraction  the fraction (0.0 to 1.0).
    146     *
    147     * @return The color.
    148     */
    149    private Color createRainbowColor(double fraction) {
    150        double inv = 1.0 - fraction;
    151        double hue = this.hueSubrange.value(inv);
    152        return Color.getHSBColor((float) hue, 1.0f, 1.0f);
    153    }
    154
    155    /**
    156     * Tests this color scale for equality with an arbitrary object.
    157     *
    158     * @param obj  the object ({@code null} permitted).
    159     *
    160     * @return A boolean.
    161     */
    162    @Override
    163    public boolean equals(Object obj) {
    164        if (obj == this) {
    165            return true;
    166        }
    167        if (!(obj instanceof RainbowScale)) {
    168            return false;
    169        }
    170        RainbowScale that = (RainbowScale) obj;
    171        if (this.colors.length != that.colors.length) {
    172            return false;
    173        }
    174        if (!this.hueSubrange.equals(that.hueSubrange)) {
    175            return false;
    176        }
    177        return super.equals(obj);
    178    }
    179
    180}