class ColorCMYK

class ColorCMYK extends ColorCMY {
    
    /**
     * The key (black).
     *
     * @var int
     */
    protected int $key;
    
    /**
     * Create a new CMYK color.
     *
     * @param int $cyan
     *   The cyan.
     * @param int $magenta
     *   The magenta.
     * @param int $yellow
     *   The yellow.
     * @param int $key
     *   The key (black).
     * @param float $opacity
     *   The opacity.
     */
    public function __construct(int $cyan, int $magenta, int $yellow, int $key, float $opacity) {
        parent::__construct($cyan, $magenta, $yellow, $opacity);
        $this->key = $key;
    }
    
    /**
     * Get the key (black).
     *
     * @return int
     *   The amount of black.
     */
    public function getKey() : int {
        return $this->key;
    }
    
    /**
     * {@inheritdoc}
     */
    public function toRgb() : ColorRGB {
        return $this->toCmy()
            ->toRgb();
    }
    
    /**
     * {@inheritdoc}
     */
    public function toCmy() : ColorCMY {
        $cyan = $this->cyan * (1 - $this->key) + $this->key;
        $magenta = $this->magenta * (1 - $this->key) + $this->key;
        $yellow = $this->yellow * (1 - $this->key) + $this->key;
        return new ColorCMY($cyan, $magenta, $yellow, $this->getOpacity());
    }
    
    /**
     * {@inheritdoc}
     */
    public function toHsl() : ColorHSL {
        return $this->toRgb()
            ->toHsl();
    }

}