InverseGrayScale

/*
 * Copyright (c) 2001-2017, Zoltan Farkas All Rights Reserved.
 *
 * 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 General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 *
 * Additionally licensed with:
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.spf4j.perf.impl.chart;

import java.awt.Color;
import java.awt.Paint;
import java.io.Serializable;
import org.jfree.chart.renderer.PaintScale;
import org.jfree.chart.util.PublicCloneable;
import org.spf4j.base.CloneFailedException;

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

    private static final long serialVersionUID = 1L;

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

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

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

    /**
     * Creates a new <code>GrayPaintScale</code> instance with default values.
     */
    public InverseGrayScale() {
        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</code> is not
     *       less than <code>upperBound</code>.
     */
    public InverseGrayScale(final double lowerBound, final 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</code> is not
     *       less than <code>upperBound</code>, or <code>alpha</code> is not in
     *       the range 0 to 255.
     *
     * @since 1.0.13
     */
    public InverseGrayScale(final double lowerBound, final double upperBound, final 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. and not " + alpha);

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

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

    /**
     * Returns the upper bound.
     *
     * @return The upper bound.
     *
     * @see #getLowerBound()
     */
    @Override
    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.
     */
    @Override
    public Paint getPaint(final double value) {
        double v = Math.max(value, this.lowerBound);
        v = Math.min(v, this.upperBound);
        int g;
        if (value >= 1) {
            g = 240 -  (int) ((v - this.lowerBound) / (this.upperBound
                - this.lowerBound) * 240.0);
        } else {
            g = 255 -  (int) ((v - this.lowerBound) / (this.upperBound
                - this.lowerBound) * 15.0);
        }
        // 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);
    }

    @Override
    public boolean equals(final Object obj) {
        if (obj == null) {
            return false;
        }
        if (getClass() != obj.getClass()) {
            return false;
        }
        final InverseGrayScale other = (InverseGrayScale) obj;
        if (Double.doubleToLongBits(this.lowerBound) != Double.doubleToLongBits(other.lowerBound)) {
            return false;
        }
        if (Double.doubleToLongBits(this.upperBound) != Double.doubleToLongBits(other.upperBound)) {
            return false;
        }
        return this.alpha == other.alpha;
    }

    @Override
    public int hashCode() {
        int hash = 3;
        hash = 97 * hash
                + (int) (Double.doubleToLongBits(this.lowerBound) ^ (Double.doubleToLongBits(this.lowerBound) >>> 32));
        hash = 97 * hash
                + (int) (Double.doubleToLongBits(this.upperBound) ^ (Double.doubleToLongBits(this.upperBound) >>> 32));
        return  97 * hash + this.alpha;
    }


    /**
     * Returns a clone of this <code>GrayPaintScale</code> instance.
     *
     * @return A clone.
     *
     */
    @Override
    public InverseGrayScale clone() {
        try {
            return (InverseGrayScale) super.clone();
        } catch (CloneNotSupportedException ex) {
           throw new CloneFailedException("Failed cloning " + this,  ex);
        }
    }

    @Override
    public String toString() {
        return "InverseGrayScale{" + "lowerBound=" + lowerBound + ", upperBound=" + upperBound
                + ", alpha=" + alpha + '}';
    }

}