Method: ColorLib::HSL#to_rgb

Defined in:
lib/color_lib/hsl.rb

#to_rgb(ignored = nil) ⇒ Object

Converting to HSL as adapted from Foley and Van-Dam from www.bobpowell.net/RGBHSB.htm.

NOTE:

  • If the colour’s luminosity is near zero, the colour is always black.

  • If the colour’s luminosity is near one, the colour is always white.

  • If the colour’s saturation is near zero, the colour is always a shade of grey and is based only on the luminosity of the colour.



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# File 'lib/color_lib/hsl.rb', line 79

def to_rgb(ignored = nil)
  return ColorLib::RGB.new if ColorLib.near_zero_or_less?(@l)
  return ColorLib::RGB.new(0xff, 0xff, 0xff) if ColorLib.near_one_or_more?(@l)
  return ColorLib::RGB.from_fraction(@l, @l, @l) if ColorLib.near_zero?(@s)

  # Is the value less than 0.5?
  if ColorLib.near_zero_or_less?(@l - 0.5)
    tmp2 = @l * (1.0 + @s.to_f)
  else
    tmp2 = @l + @s - (@l * @s.to_f)
  end
  tmp1 = 2.0 * @l - tmp2

  tmp3 = [@h + (1.0 / 3.0), @h, @h - (1.0 / 3.0)]

  rgb = tmp3.map { |hue|
    hue += 1.0 if ColorLib.near_zero_or_less?(hue)
    hue -= 1.0 if ColorLib.near_one_or_more?(hue)

    if ColorLib.near_zero_or_less?((6.0 * hue) - 1.0)
      tmp1 + ((tmp2 - tmp1) * hue * 6.0)
    elsif ColorLib.near_zero_or_less?((2.0 * hue) - 1.0)
      tmp2
    elsif ColorLib.near_zero_or_less?((3.0 * hue) - 2.0)
      tmp1 + (tmp2 - tmp1) * ((2 / 3.0) - hue) * 6.0
    else
      tmp1
    end
  }

  ColorLib::RGB.from_fraction(*rgb)
end