;
  }

  /**
   * @return {boolean} TRUE if you need to use a bright color (e.g. 'white'), when
   *                   this color is set as the background.
   */
  get useBrightText() {
    return this.relativeLuminance <= CONTRAST_BRIGHTTEXT_THRESHOLD;
  }

  /**
   * Get the contrast ratio between the current color and a second other color.
   * A common use case is to express the difference between a foreground and a
   * background color in numbers.
   * Formula from W3C's WCAG 2.0 spec's contrast ratio, section 1.4.1,
   * http://www.w3.org/TR/WCAG20/.
   *
   * @param  {Color}  otherColor Color instance to calculate the contrast with
   * @return {number} Contrast ratios can range from 1 to 21, commonly written
   *                  as 1:1 to 21:1.
   */
  contrastRatio(otherColor) {
    if (!(otherColor instanceof Color)) {
      throw new TypeError("The first argument should be an instance of Color");
    }

    let luminance = this.relativeLuminance;
    let otherLuminance = otherColor.relativeLuminance;
    return (
      (Math.max(luminance, otherLuminance) + 0.05) /
      (Math.min(luminance, otherLuminance) + 0.05)
    );
  }

  /**
   * Method to check if the contrast ratio between two colors is high enough to
   * be discernable.
   *
   * @param  {Color}  otherColor Color instance to calculate the contrast with
   * @param  {string} [level]    WCAG conformance level that maps to the minimum
   *                             required contrast ratio. Defaults to 'AA'
   * @return {boolean}
   */
  isContrastRatioAcceptable(otherColor, level = "AA") {
    return this.contrastRatio(otherColor) > CONTRAST_RATIO_LEVELS[level];
  }
}
PK