org.eclipse.swt.graphics.RGB.java Source code

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/*******************************************************************************
 * Copyright (c) 2000, 2013 IBM Corporation and others.
 *
 * This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * which accompanies this distribution, and is available at
 * https://www.eclipse.org/legal/epl-2.0/
 *
 * SPDX-License-Identifier: EPL-2.0
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.swt.graphics;

import java.io.*;

import org.eclipse.swt.*;

/**
 * Instances of this class are descriptions of colors in
 * terms of the primary additive color model (red, green and
 * blue). A color may be described in terms of the relative
 * intensities of these three primary colors. The brightness
 * of each color is specified by a value in the range 0 to 255,
 * where 0 indicates no color (blackness) and 255 indicates
 * maximum intensity.
 * <p>
 * The hashCode() method in this class uses the values of the public
 * fields to compute the hash value. When storing instances of the
 * class in hashed collections, do not modify these fields after the
 * object has been inserted.
 * </p>
 * <p>
 * Application code does <em>not</em> need to explicitly release the
 * resources managed by each instance when those instances are no longer
 * required, and thus no <code>dispose()</code> method is provided.
 * </p>
 *
 * @see Color
 * @see <a href="http://www.eclipse.org/swt/snippets/#color">Color and RGB snippets</a>
 * @see <a href="http://www.eclipse.org/swt/">Sample code and further information</a>
 */

public final class RGB implements Serializable {

    /**
     * the red component of the RGB
     */
    public int red;

    /**
     * the green component of the RGB
     */
    public int green;

    /**
     * the blue component of the RGB
     */
    public int blue;

    static final long serialVersionUID = 3258415023461249074L;

    /**
     * Constructs an instance of this class with the given
     * red, green and blue values.
     *
     * @param red the red component of the new instance
     * @param green the green component of the new instance
     * @param blue the blue component of the new instance
     *
     * @exception IllegalArgumentException <ul>
     *    <li>ERROR_INVALID_ARGUMENT - if the red, green or blue argument is not between 0 and 255</li>
     * </ul>
     */
    public RGB(int red, int green, int blue) {
        if ((red > 255) || (red < 0) || (green > 255) || (green < 0) || (blue > 255) || (blue < 0))
            SWT.error(SWT.ERROR_INVALID_ARGUMENT);
        this.red = red;
        this.green = green;
        this.blue = blue;
    }

    /**
    * Constructs an instance of this class with the given
    * hue, saturation, and brightness.
    *
    * @param hue the hue value for the HSB color (from 0 to 360)
    * @param saturation the saturation value for the HSB color (from 0 to 1)
    * @param brightness the brightness value for the HSB color (from 0 to 1)
    *
    * @exception IllegalArgumentException <ul>
    *    <li>ERROR_INVALID_ARGUMENT - if the hue is not between 0 and 360 or
    *    the saturation or brightness is not between 0 and 1</li>
    * </ul>
    *
    * @since 3.2
    */
    public RGB(float hue, float saturation, float brightness) {
        if (hue < 0 || hue > 360 || saturation < 0 || saturation > 1 || brightness < 0 || brightness > 1) {
            SWT.error(SWT.ERROR_INVALID_ARGUMENT);
        }
        float r, g, b;
        if (saturation == 0) {
            r = g = b = brightness;
        } else {
            if (hue == 360)
                hue = 0;
            hue /= 60;
            int i = (int) hue;
            float f = hue - i;
            float p = brightness * (1 - saturation);
            float q = brightness * (1 - saturation * f);
            float t = brightness * (1 - saturation * (1 - f));
            switch (i) {
            case 0:
                r = brightness;
                g = t;
                b = p;
                break;
            case 1:
                r = q;
                g = brightness;
                b = p;
                break;
            case 2:
                r = p;
                g = brightness;
                b = t;
                break;
            case 3:
                r = p;
                g = q;
                b = brightness;
                break;
            case 4:
                r = t;
                g = p;
                b = brightness;
                break;
            case 5:
            default:
                r = brightness;
                g = p;
                b = q;
                break;
            }
        }
        red = (int) (r * 255 + 0.5);
        green = (int) (g * 255 + 0.5);
        blue = (int) (b * 255 + 0.5);
    }

    /**
     * Returns the hue, saturation, and brightness of the color.
     *
     * @return color space values in float format:<ul>
     *             <li>hue (from 0 to 360)</li>
     *             <li>saturation (from 0 to 1)</li>
     *             <li>brightness (from 0 to 1)</li>
     *             </ul>
     * @see #RGB(float, float, float)
     *
     * @since 3.2
     */
    public float[] getHSB() {
        float r = red / 255f;
        float g = green / 255f;
        float b = blue / 255f;
        float max = Math.max(Math.max(r, g), b);
        float min = Math.min(Math.min(r, g), b);
        float delta = max - min;
        float hue = 0;
        float brightness = max;
        float saturation = max == 0 ? 0 : (max - min) / max;
        if (delta != 0) {
            if (r == max) {
                hue = (g - b) / delta;
            } else {
                if (g == max) {
                    hue = 2 + (b - r) / delta;
                } else {
                    hue = 4 + (r - g) / delta;
                }
            }
            hue *= 60;
            if (hue < 0)
                hue += 360;
        }
        return new float[] { hue, saturation, brightness };
    }

    /**
     * Compares the argument to the receiver, and returns true
     * if they represent the <em>same</em> object using a class
     * specific comparison.
     *
     * @param object the object to compare with this object
     * @return <code>true</code> if the object is the same as this object and <code>false</code> otherwise
     *
     * @see #hashCode()
     */
    @Override
    public boolean equals(Object object) {
        if (object == this)
            return true;
        if (!(object instanceof RGB))
            return false;
        RGB rgb = (RGB) object;
        return (rgb.red == this.red) && (rgb.green == this.green) && (rgb.blue == this.blue);
    }

    /**
     * Returns an integer hash code for the receiver. Any two
     * objects that return <code>true</code> when passed to
     * <code>equals</code> must return the same value for this
     * method.
     *
     * @return the receiver's hash
     *
     * @see #equals(Object)
     */
    @Override
    public int hashCode() {
        return (blue << 16) | (green << 8) | red;
    }

    /**
     * Returns a string containing a concise, human-readable
     * description of the receiver.
     *
     * @return a string representation of the <code>RGB</code>
     */
    @Override
    public String toString() {
        return "RGB {" + red + ", " + green + ", " + blue + "}"; //$NON-NLS-1$//$NON-NLS-2$ //$NON-NLS-3$ //$NON-NLS-4$
    }

}