code: static int darker(int color, float factor) {
      return Color.argb(Color.alpha(color), Math.max((int) (Color.red(color) * factor), 0),
          Math.max((int) (Color.green(color) * factor), 0), Math.max((int) (Color.blue(color) * factor), 0));
    }
docs: Darkens a color by a given factor.
  
  @param color the color to darken
  @param factor The factor to darken the color.
  @return darker version of specified color.