felixarntz/theme-boilerplate

<?php
/**
 * Super_Awesome_Theme_Color_Util class
 *
 * @package Super_Awesome_Theme
 * @license GPL-2.0-or-later
 * @link    https://super-awesome-author.org/themes/super-awesome-theme/
 */

/**
 * Class containing color modification utility methods.
 *
 * @since 1.0.0
 */
final class Super_Awesome_Theme_Color_Util {

    /**
     * Darkens a hex color string about a given percentage.
     *
     * @since 1.0.0
     *
     * @param string $color      Hex color string.
     * @param int    $percentage Percentage to darken about.
     * @return string Darkened hex color string.
     */
    public function darken_color( $color, $percentage ) {
        if ( empty( $color ) ) {
            return $color;
        }

        $rgb = $this->hex_to_rgb( $color );

        $darkened = array();
        foreach ( $rgb as $channel ) {
            $darkened_channel = (int) round( $channel * ( 1.0 - $percentage / 100.0 ) );
            if ( $darkened_channel < 0 ) {
                $darkened_channel = 0;
            }
            $darkened[] = $darkened_channel;
        }

        return $this->rgb_to_hex( $darkened );
    }

    /**
     * Lightens a hex color string about a given percentage.
     *
     * @since 1.0.0
     *
     * @param string $color      Hex color string.
     * @param int    $percentage Percentage to darken about.
     * @return string Lightened hex color string.
     */
    public function lighten_color( $color, $percentage ) {
        if ( empty( $color ) ) {
            return $color;
        }

        $rgb = $this->hex_to_rgb( $color );

        $lightened = array();
        foreach ( $rgb as $channel ) {
            $lightened_channel = (int) round( $channel * ( 1.0 + $percentage / 100.0 ) );
            if ( $lightened_channel > 255 ) {
                $lightened_channel = 255;
            }
            $lightened[] = $lightened_channel;
        }

        return $this->rgb_to_hex( $lightened );
    }

    /**
     * Converts a hex color string into an RGB array.
     *
     * @since 1.0.0
     *
     * @param string $color Hex color string.
     * @return array RGB color array.
     */
    public function hex_to_rgb( $color ) {
        if ( strlen( $color ) === 4 ) {
            $rgb = str_split( substr( $color, 1 ), 1 );
            $rgb = array_map( array( $this, 'duplicate_char' ), $rgb );
        } else {
            $rgb = str_split( substr( $color, 1 ), 2 );
        }

        return array_map( 'hexdec', $rgb );
    }

    /**
     * Converts an RGB array into a hex color string.
     *
     * @since 1.0.0
     *
     * @param array $color RGB color array.
     * @return string Hex color string.
     */
    public function rgb_to_hex( $color ) {
        $hex = array_map( 'zeroise', array_map( 'dechex', $color ), array( 2, 2, 2 ) );

        return '#' . $hex[0] . $hex[1] . $hex[2];
    }

    /**
     * Duplicates a character.
     *
     * @since 1.0.0
     *
     * @param string $char Character to duplicate.
     * @return string The character duplicated.
     */
    protected function duplicate_char( $char ) {
        return $char . $char;
    }
}