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jfreechart example source code file (GrayPaintScale.java)

This example jfreechart source code file (GrayPaintScale.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - jfreechart tags/keywords

awt, clonenotsupportedexception, color, graypaintscale, graypaintscale, illegalargumentexception, illegalargumentexception, io, object, paint, paintscale, publiccloneable, publiccloneable, requires, requires, serializable

The jfreechart GrayPaintScale.java source code

/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2009, by Object Refinery Limited and Contributors.
 *
 * Project Info:  http://www.jfree.org/jfreechart/index.html
 *
 * This library 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 2.1 of the License, or
 * (at your option) any later version.
 *
 * This library 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 this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
 * USA.
 *
 * [Java is a trademark or registered trademark of Sun Microsystems, Inc.
 * in the United States and other countries.]
 *
 * -------------------
 * GrayPaintScale.java
 * -------------------
 * (C) Copyright 2006-2009, by Object Refinery Limited.
 *
 * Original Author:  David Gilbert (for Object Refinery Limited);
 * Contributor(s):   -;
 *
 * Changes
 * -------
 * 05-Jul-2006 : Version 1 (DG);
 * 31-Jan-2007 : Renamed min and max to lowerBound and upperBound (DG);
 * 26-Sep-2007 : Fixed bug 1767315, problem in getPaint() method (DG);
 * 29-Jan-2009 : Added alpha transparency field and hashCode() method (DG);
 *
 */

package org.jfree.chart.renderer;

import java.awt.Color;
import java.awt.Paint;
import java.io.Serializable;

import org.jfree.chart.HashUtilities;
import org.jfree.util.PublicCloneable;

/**
 * A paint scale that returns shades of gray.
 *
 * @since 1.0.4
 */
public class GrayPaintScale
        implements PaintScale, PublicCloneable, Serializable {

    /** The lower bound. */
    private double lowerBound;

    /** The upper bound. */
    private double upperBound;

    /**
     * The alpha transparency (0-255).
     *
     * @since 1.0.13
     */
    private int alpha;

    /**
     * Creates a new <code>GrayPaintScale instance with default values.
     */
    public GrayPaintScale() {
        this(0.0, 1.0);
    }

    /**
     * Creates a new paint scale for values in the specified range.
     *
     * @param lowerBound  the lower bound.
     * @param upperBound  the upper bound.
     *
     * @throws IllegalArgumentException if <code>lowerBound is not
     *       less than <code>upperBound.
     */
    public GrayPaintScale(double lowerBound, double upperBound) {
        this(lowerBound, upperBound, 255);
    }

    /**
     * Creates a new paint scale for values in the specified range.
     *
     * @param lowerBound  the lower bound.
     * @param upperBound  the upper bound.
     * @param alpha  the alpha transparency (0-255).
     *
     * @throws IllegalArgumentException if <code>lowerBound is not
     *       less than <code>upperBound, or alpha is not in
     *       the range 0 to 255.
     *
     * @since 1.0.13
     */
    public GrayPaintScale(double lowerBound, double upperBound, int alpha) {
        if (lowerBound >= upperBound) {
            throw new IllegalArgumentException(
                    "Requires lowerBound < upperBound.");
        }
        if (alpha < 0 || alpha > 255) {
            throw new IllegalArgumentException(
                    "Requires alpha in the range 0 to 255.");

        }
        this.lowerBound = lowerBound;
        this.upperBound = upperBound;
        this.alpha = alpha;
    }

    /**
     * Returns the lower bound.
     *
     * @return The lower bound.
     *
     * @see #getUpperBound()
     */
    public double getLowerBound() {
        return this.lowerBound;
    }

    /**
     * Returns the upper bound.
     *
     * @return The upper bound.
     *
     * @see #getLowerBound()
     */
    public double getUpperBound() {
        return this.upperBound;
    }

    /**
     * Returns the alpha transparency that was specified in the constructor.
     * 
     * @return The alpha transparency (in the range 0 to 255).
     * 
     * @since 1.0.13
     */
    public int getAlpha() {
        return this.alpha;
    }

    /**
     * Returns a paint for the specified value.
     *
     * @param value  the value (must be within the range specified by the
     *         lower and upper bounds for the scale).
     *
     * @return A paint for the specified value.
     */
    public Paint getPaint(double value) {
        double v = Math.max(value, this.lowerBound);
        v = Math.min(v, this.upperBound);
        int g = (int) ((v - this.lowerBound) / (this.upperBound
                - this.lowerBound) * 255.0);
        // FIXME:  it probably makes sense to allocate an array of 256 Colors
        // and lazily populate this array...
        return new Color(g, g, g, this.alpha);
    }

    /**
     * Tests this <code>GrayPaintScale instance for equality with an
     * arbitrary object.  This method returns <code>true if and only
     * if:
     * <ul>
     * <li>obj is not null;
     * <li>obj is an instance of GrayPaintScale;
     * </ul>
     *
     * @param obj  the object (<code>null permitted).
     *
     * @return A boolean.
     */
    public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (!(obj instanceof GrayPaintScale)) {
            return false;
        }
        GrayPaintScale that = (GrayPaintScale) obj;
        if (this.lowerBound != that.lowerBound) {
            return false;
        }
        if (this.upperBound != that.upperBound) {
            return false;
        }
        if (this.alpha != that.alpha) {
            return false;
        }
        return true;
    }

    /**
     * Returns a hash code for this instance.
     *
     * @return A hash code.
     */
    public int hashCode() {
        int hash = 7;
        hash = HashUtilities.hashCode(hash, this.lowerBound);
        hash = HashUtilities.hashCode(hash, this.upperBound);
        hash = 43 * hash + this.alpha;
        return hash;
    }

    /**
     * Returns a clone of this <code>GrayPaintScale instance.
     *
     * @return A clone.
     *
     * @throws CloneNotSupportedException if there is a problem cloning this
     *     instance.
     */
    public Object clone() throws CloneNotSupportedException {
        return super.clone();
    }

}

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