Java example source code file (ColorModelHSL.java)

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Java - Java tags/keywords

colormodelhsl, hsltorgb, hue, lightness, non\-nls, override, rgbtohsl, saturation, transparency

The ColorModelHSL.java Java example source code

/*
 * Copyright (c) 2008, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code 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
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package javax.swing.colorchooser;

final class ColorModelHSL extends ColorModel {

    ColorModelHSL() {
        super("hsl", "Hue", "Saturation", "Lightness", "Transparency"); // NON-NLS: components
    }

    @Override
    void setColor(int color, float[] space) {
        super.setColor(color, space);
        RGBtoHSL(space, space);
        space[3] = 1.0f - space[3];
    }

    @Override
    int getColor(float[] space) {
        space[3] = 1.0f - space[3];
        HSLtoRGB(space, space);
        return super.getColor(space);
    }

    @Override
    int getMaximum(int index) {
        return (index == 0) ? 360 : 100;
    }

    @Override
    float getDefault(int index) {
        return (index == 0) ? -1.0f : (index == 2) ? 0.5f : 1.0f;
    }

    /**
     * Converts HSL components of a color to a set of RGB components.
     *
     * @param hsl  a float array with length equal to
     *             the number of HSL components
     * @param rgb  a float array with length of at least 3
     *             that contains RGB components of a color
     * @return a float array that contains RGB components
     */
    private static float[] HSLtoRGB(float[] hsl, float[] rgb) {
        if (rgb == null) {
            rgb = new float[3];
        }
        float hue = hsl[0];
        float saturation = hsl[1];
        float lightness = hsl[2];

        if (saturation > 0.0f) {
            hue = (hue < 1.0f) ? hue * 6.0f : 0.0f;
            float q = lightness + saturation * ((lightness > 0.5f) ? 1.0f - lightness : lightness);
            float p = 2.0f * lightness - q;
            rgb[0]= normalize(q, p, (hue < 4.0f) ? (hue + 2.0f) : (hue - 4.0f));
            rgb[1]= normalize(q, p, hue);
            rgb[2]= normalize(q, p, (hue < 2.0f) ? (hue + 4.0f) : (hue - 2.0f));
        }
        else {
            rgb[0] = lightness;
            rgb[1] = lightness;
            rgb[2] = lightness;
        }
        return rgb;
    }

    /**
     * Converts RGB components of a color to a set of HSL components.
     *
     * @param rgb  a float array with length of at least 3
     *             that contains RGB components of a color
     * @param hsl  a float array with length equal to
     *             the number of HSL components
     * @return a float array that contains HSL components
     */
    private static float[] RGBtoHSL(float[] rgb, float[] hsl) {
        if (hsl == null) {
            hsl = new float[3];
        }
        float max = max(rgb[0], rgb[1], rgb[2]);
        float min = min(rgb[0], rgb[1], rgb[2]);

        float summa = max + min;
        float saturation = max - min;
        if (saturation > 0.0f) {
            saturation /= (summa > 1.0f)
                    ? 2.0f - summa
                    : summa;
        }
        hsl[0] = getHue(rgb[0], rgb[1], rgb[2], max, min);
        hsl[1] = saturation;
        hsl[2] = summa / 2.0f;
        return hsl;
    }

    /**
     * Returns the smaller of three color components.
     *
     * @param red    the red component of the color
     * @param green  the green component of the color
     * @param blue   the blue component of the color
     * @return the smaller of {@code red}, {@code green} and {@code blue}
     */
    static float min(float red, float green, float blue) {
        float min = (red < green) ? red : green;
        return (min < blue) ? min : blue;
    }

    /**
     * Returns the larger of three color components.
     *
     * @param red    the red component of the color
     * @param green  the green component of the color
     * @param blue   the blue component of the color
     * @return the larger of {@code red}, {@code green} and {@code blue}
     */
    static float max(float red, float green, float blue) {
        float max = (red > green) ? red : green;
        return (max > blue) ? max : blue;
    }

    /**
     * Calculates the hue component for HSL and HSV color spaces.
     *
     * @param red    the red component of the color
     * @param green  the green component of the color
     * @param blue   the blue component of the color
     * @param max    the larger of {@code red}, {@code green} and {@code blue}
     * @param min    the smaller of {@code red}, {@code green} and {@code blue}
     * @return the hue component
     */
    static float getHue(float red, float green, float blue, float max, float min) {
        float hue = max - min;
        if (hue > 0.0f) {
            if (max == red) {
                hue = (green - blue) / hue;
                if (hue < 0.0f) {
                    hue += 6.0f;
                }
            }
            else if (max == green) {
                hue = 2.0f + (blue - red) / hue;
            }
            else /*max == blue*/ {
                hue = 4.0f + (red - green) / hue;
            }
            hue /= 6.0f;
        }
        return hue;
    }

    private static float normalize(float q, float p, float color) {
        if (color < 1.0f) {
            return p + (q - p) * color;
        }
        if (color < 3.0f) {
            return q;
        }
        if (color < 4.0f) {
            return p + (q - p) * (4.0f - color);
        }
        return p;
    }
}