Color.class.php

<?php
/**
 * lib/classes/Color.class.php - class to mix colors and convert them between different types
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of
 * the License, or (at your option) any later version.
 *
 * @author      Rasmus Fuhse <fuhse@data-quest.de>
 * @license     http://www.gnu.org/licenses/gpl-2.0.html GPL version 2
 * @category    Stud.IP
 */

/**
 * class to mix colors and convert them between different types
 *
 * @since       2.1
 */
class Color {
    /**
     * HTML-4-Standard color-names plus a few additions
     * May be expanded in a later version to allow
     *  X11 color names as described in
     *  http://en.wikipedia.org/wiki/Web_colors
     *
     * @var array
     */
    static $colorstrings = [
        'aqua'           => [0, 255, 255, 1],
        'azure'          => [240, 255, 255, 1],
        'blue'           => [0, 0, 255, 1],
        'cyan'           => [0, 255, 255, 1],
        'darkblue'       => [0, 0, 139, 1],
        'darkred'        => [139, 0, 0, 1],
        'gold'           => [255, 215, 0, 1],
        'gray'           => [128, 128, 128, 1],
        'indigo'         => [75, 0, 130, 1],
        'lightsteelblue' => [176, 196, 222, 1],
        'lightyellow'    => [255, 255, 224, 1],
        'lime'           => [0, 255, 0, 1],
        'magenta'        => [255, 0, 255, 1],
        'navy'           => [0, 0, 128, 1],
        'olive'          => [128, 128, 0, 1],
        'orange'         => [255, 165, 0, 1],
        'pink'           => [255, 192, 203, 1],
        'red'            => [255, 0, 0, 1],
        'purple'         => [128, 0, 128, 1],
        'violet'         => [238, 130, 238, 1],
        'yellow'         => [255, 255, 0, 1],
        'black'          => [0, 0, 0, 1],
        'white'          => [255, 255, 255, 1]
    ];

    /**
     * converts a css-hex-color into a rgba-quadruple
     *
     * @param  string  $color  the color to be converted
     * @return array   colors as rgba-quadruple
     */
    static function hex2array($color) {
        $color = str_replace('#','',$color);
        $arr[0] = hexdec(mb_substr($color,0,2));
        $arr[1] = hexdec(mb_substr($color,2,2));
        $arr[2] = hexdec(mb_substr($color,4,2));
        $arr[3] = 1.0;
        return $arr;
    }

    /**