001/* ===========================================================
002 * Orson Charts : a 3D chart library for the Java(tm) platform
003 * ===========================================================
004 * 
005 * (C)opyright 2013-2022, by David Gilbert.  All rights reserved.
006 * 
007 * https://github.com/jfree/orson-charts
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 org.jfree.chart3d.renderer;
034
035import java.awt.Color;
036
037import org.jfree.chart3d.data.Range;
038import org.jfree.chart3d.internal.Args;
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        Args.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}