    001/* ===========================================================
    002 * JFreeChart : a free chart library for the Java(tm) platform
    003 * ===========================================================
    004 *
    005 * (C) Copyright 2000-2011, by Object Refinery Limited and Contributors.
    006 *
    007 * Project Info:  http://www.jfree.org/jfreechart/index.html
    008 *
    009 * This library is free software; you can redistribute it and/or modify it
    010 * under the terms of the GNU Lesser General Public License as published by
    011 * the Free Software Foundation; either version 2.1 of the License, or
    012 * (at your option) any later version.
    013 *
    014 * This library is distributed in the hope that it will be useful, but
    015 * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
    016 * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
    017 * License for more details.
    018 *
    019 * You should have received a copy of the GNU Lesser General Public
    020 * License along with this library; if not, write to the Free Software
    021 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
    022 * USA.
    023 *
    024 * [Oracle and Java are registered trademarks of Oracle and/or its affiliates.
    025 * Other names may be trademarks of their respective owners.]
    026 *
    027 * -------------------
    028 * GrayPaintScale.java
    029 * -------------------
    030 * (C) Copyright 2006-2009, by Object Refinery Limited.
    031 *
    032 * Original Author:  David Gilbert (for Object Refinery Limited);
    033 * Contributor(s):   -;
    034 *
    035 * Changes
    036 * -------
    037 * 05-Jul-2006 : Version 1 (DG);
    038 * 31-Jan-2007 : Renamed min and max to lowerBound and upperBound (DG);
    039 * 26-Sep-2007 : Fixed bug 1767315, problem in getPaint() method (DG);
    040 * 29-Jan-2009 : Added alpha transparency field and hashCode() method (DG);
    041 *
    042 */
    043
    044package org.jfree.chart.renderer;
    045
    046import java.awt.Color;
    047import java.awt.Paint;
    048import java.io.Serializable;
    049
    050import org.jfree.chart.HashUtilities;
    051import org.jfree.util.PublicCloneable;
    052
    053/**
    054 * A paint scale that returns shades of gray.
    055 *
    056 * @since 1.0.4
    057 */
    058public class GrayPaintScale
    059        implements PaintScale, PublicCloneable, Serializable {
    060
    061    /** The lower bound. */
    062    private double lowerBound;
    063
    064    /** The upper bound. */
    065    private double upperBound;
    066
    067    /**
    068     * The alpha transparency (0-255).
    069     *
    070     * @since 1.0.13
    071     */
    072    private int alpha;
    073
    074    /**
    075     * Creates a new <code>GrayPaintScale</code> instance with default values.
    076     */
    077    public GrayPaintScale() {
    078        this(0.0, 1.0);
    079    }
    080
    081    /**
    082     * Creates a new paint scale for values in the specified range.
    083     *
    084     * @param lowerBound  the lower bound.
    085     * @param upperBound  the upper bound.
    086     *
    087     * @throws IllegalArgumentException if <code>lowerBound</code> is not
    088     *       less than <code>upperBound</code>.
    089     */
    090    public GrayPaintScale(double lowerBound, double upperBound) {
    091        this(lowerBound, upperBound, 255);
    092    }
    093
    094    /**
    095     * Creates a new paint scale for values in the specified range.
    096     *
    097     * @param lowerBound  the lower bound.
    098     * @param upperBound  the upper bound.
    099     * @param alpha  the alpha transparency (0-255).
    100     *
    101     * @throws IllegalArgumentException if <code>lowerBound</code> is not
    102     *       less than <code>upperBound</code>, or <code>alpha</code> is not in
    103     *       the range 0 to 255.
    104     *
    105     * @since 1.0.13
    106     */
    107    public GrayPaintScale(double lowerBound, double upperBound, int alpha) {
    108        if (lowerBound >= upperBound) {
    109            throw new IllegalArgumentException(
    110                    "Requires lowerBound < upperBound.");
    111        }
    112        if (alpha < 0 || alpha > 255) {
    113            throw new IllegalArgumentException(
    114                    "Requires alpha in the range 0 to 255.");
    115
    116        }
    117        this.lowerBound = lowerBound;
    118        this.upperBound = upperBound;
    119        this.alpha = alpha;
    120    }
    121
    122    /**
    123     * Returns the lower bound.
    124     *
    125     * @return The lower bound.
    126     *
    127     * @see #getUpperBound()
    128     */
    129    public double getLowerBound() {
    130        return this.lowerBound;
    131    }
    132
    133    /**
    134     * Returns the upper bound.
    135     *
    136     * @return The upper bound.
    137     *
    138     * @see #getLowerBound()
    139     */
    140    public double getUpperBound() {
    141        return this.upperBound;
    142    }
    143
    144    /**
    145     * Returns the alpha transparency that was specified in the constructor.
    146     *
    147     * @return The alpha transparency (in the range 0 to 255).
    148     *
    149     * @since 1.0.13
    150     */
    151    public int getAlpha() {
    152        return this.alpha;
    153    }
    154
    155    /**
    156     * Returns a paint for the specified value.
    157     *
    158     * @param value  the value (must be within the range specified by the
    159     *         lower and upper bounds for the scale).
    160     *
    161     * @return A paint for the specified value.
    162     */
    163    public Paint getPaint(double value) {
    164        double v = Math.max(value, this.lowerBound);
    165        v = Math.min(v, this.upperBound);
    166        int g = (int) ((v - this.lowerBound) / (this.upperBound
    167                - this.lowerBound) * 255.0);
    168        // FIXME:  it probably makes sense to allocate an array of 256 Colors
    169        // and lazily populate this array...
    170        return new Color(g, g, g, this.alpha);
    171    }
    172
    173    /**
    174     * Tests this <code>GrayPaintScale</code> instance for equality with an
    175     * arbitrary object.  This method returns <code>true</code> if and only
    176     * if:
    177     * <ul>
    178     * <li><code>obj</code> is not <code>null</code>;</li>
    179     * <li><code>obj</code> is an instance of <code>GrayPaintScale</code>;</li>
    180     * </ul>
    181     *
    182     * @param obj  the object (<code>null</code> permitted).
    183     *
    184     * @return A boolean.
    185     */
    186    public boolean equals(Object obj) {
    187        if (obj == this) {
    188            return true;
    189        }
    190        if (!(obj instanceof GrayPaintScale)) {
    191            return false;
    192        }
    193        GrayPaintScale that = (GrayPaintScale) obj;
    194        if (this.lowerBound != that.lowerBound) {
    195            return false;
    196        }
    197        if (this.upperBound != that.upperBound) {
    198            return false;
    199        }
    200        if (this.alpha != that.alpha) {
    201            return false;
    202        }
    203        return true;
    204    }
    205
    206    /**
    207     * Returns a hash code for this instance.
    208     *
    209     * @return A hash code.
    210     */
    211    public int hashCode() {
    212        int hash = 7;
    213        hash = HashUtilities.hashCode(hash, this.lowerBound);
    214        hash = HashUtilities.hashCode(hash, this.upperBound);
    215        hash = 43 * hash + this.alpha;
    216        return hash;
    217    }
    218
    219    /**
    220     * Returns a clone of this <code>GrayPaintScale</code> instance.
    221     *
    222     * @return A clone.
    223     *
    224     * @throws CloneNotSupportedException if there is a problem cloning this
    225     *     instance.
    226     */
    227    public Object clone() throws CloneNotSupportedException {
    228        return super.clone();
    229    }
    230
    231}