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 runs a linear gradient between two colors.
042 * <br><br>
043 * NOTE: This class is serializable, but the serialization format is subject 
044 * to change in future releases and should not be relied upon for persisting 
045 * instances of this class. 
046 * 
047 * @since 1.1
048 */
049@SuppressWarnings("serial")
050public class GradientColorScale extends AbstractColorScale 
051        implements ColorScale {
052
053    /** The color at the low end of the value range. */
054    private final Color lowColor;
055    
056    /** The color at the high end of the value range. */
057    private final Color highColor;
058    
059    /** Storage for the color samples. */
060    private final Color[] colors;
061
062    /**
063     * Creates a new instance with the specified value range and colors.
064     * 
065     * @param range  the data value range ({@code null} not permitted).
066     * @param lowColor  the color for the low end of the data range 
067     *     ({@code null} not permitted).
068     * @param highColor  the color for the high end of the data range 
069     *     ({@code null} not permitted).
070     */
071    public GradientColorScale(Range range, Color lowColor, Color highColor) {
072        super(range);
073        Args.nullNotPermitted(lowColor, "lowColor");
074        Args.nullNotPermitted(highColor, "highColor");
075        this.lowColor = lowColor;
076        this.highColor = highColor;
077        this.colors = new Color[255];
078    }
079
080    /**
081     * Returns the color for the low end of the data value range.
082     * 
083     * @return The color (never {@code null}). 
084     */
085    public Color getLowColor() {
086        return this.lowColor;
087    }
088    
089    /**
090     * Returns the color for the high end of the data value range.
091     * 
092     * @return The color (never {@code null}). 
093     */
094    public Color getHighColor() {
095        return this.highColor;
096    }
097    
098    /**
099     * Returns the number of samples used by this color scale.
100     * 
101     * @return The number of samples. 
102     */
103    public int getSampleCount() {
104        return this.colors.length;
105    }
106
107    /**
108     * Returns the color corresponding to the specified data value.  If this
109     * 
110     * @param value  the data value.
111     * 
112     * @return The color (never {@code null}). 
113     */
114    @Override
115    public Color valueToColor(double value) {
116        Range r = getRange();
117        if (value < r.getMin()) {
118            return valueToColor(r.getMin());
119        }
120        if (value > r.getMax()) {
121            return valueToColor(r.getMax());
122        }
123        double fraction = getRange().percent(value);
124        int i = Math.min((int) (fraction * this.colors.length), 
125                this.colors.length - 1);
126        if (this.colors[i] == null) {
127            float[] lrgba = this.lowColor.getRGBComponents(null);
128            float[] hrgba = this.highColor.getRGBComponents(null);
129            float p = (float) fraction;
130            this.colors[i] = new Color(lrgba[0] * (1 - p) + hrgba[0] * p,
131                    lrgba[1] * (1 - p) + hrgba[1] * p,
132                    lrgba[2] * (1 - p) + hrgba[2] * p,
133                    lrgba[3] * (1 - p) + hrgba[3] * p);
134        }
135        return this.colors[i];
136    }
137    
138    /**
139     * Tests this instance for equality with an arbitrary object.
140     * 
141     * @param obj  the object ({@code null} permitted).
142     * 
143     * @return A boolean. 
144     */
145    @Override
146    public boolean equals(Object obj) {
147        if (obj == this) {
148            return true;
149        }
150        if (!(obj instanceof GradientColorScale)) {
151            return false;
152        }
153        GradientColorScale that = (GradientColorScale) obj;
154        if (!this.lowColor.equals(that.lowColor)) {
155            return false;
156        }
157        if (!this.highColor.equals(that.highColor)) {
158            return false;
159        }
160        return super.equals(obj);
161    }
162
163}