Sass Color Extensions For HSV

gistfile1.rb

class Sass::Script::Color < Sass::Script::Literal
  
  class << self
    
    def new_hsv_float(hue, saturation, value)
      zero_to_threesixty = lambda { |x| x < 0 ? 0 : (x > 360 ? 360 : x) }
      zero_to_onehundred = lambda { |x| x < 0 ? 0 : (x > 100 ? 100 : x) }
      hue        = zero_to_threesixty.call((hue * 360.0).round)
      saturation = zero_to_onehundred.call((saturation * 100.0).round)
      value      = zero_to_onehundred.call((value * 100.0).round)
      new_hsv(hue, saturation, value)
    end
    
    def new_hsv(hue, saturation, value)
      new(hsv_to_rgb(hue, saturation, value))
    end
    
    def rgb_to_hsv(red, green, blue)
      r = red / 255.0
      g = green / 255.0
      b = blue / 255.0
      max = [r, g, b].max
      min = [r, g, b].min
      delta = max - min
      v = max * 100
      if (max != 0.0)
        s = delta / max *100
      else
        s = 0.0
      end
      if (s == 0.0) 
        h = 0.0
      else
        if (r == max)
          h = (g - b) / delta
        elsif (g == max)
          h = 2 + (b - r) / delta
        elsif (b == max)
          h = 4 + (r - g) / delta
        end
        h *= 60.0
        if (h < 0)
          h += 360.0
        end
      end
      [h.round, s.round, v.round]
    end

    def hsv_to_rgb(hue, saturation, value)
      max = lambda { |m,v| m > v ? m : v }
      min = lambda { |m,v| m < v ? m : v }
      h = max.call(0, min.call(360, hue)).to_f
      s = max.call(0, min.call(100, saturation)).to_f
      v = max.call(0, min.call(100, value)).to_f
      s = s / 100.0
      v = v / 100.0
      if s == 0.0
        r = g = b = v
        return [(r * 255).round, (g * 255).round, (b * 255).round]
      end
      h = h / 60.0
      i = h.floor.to_f
      f = h - i
      p = v * (1 - s)
      q = v * (1 - s * f)
      t = v * (1 - s * (1 - f))
      case i
      when 0.0
        r, g, b = v, t, p
      when 1.0
        r, g, b = q, v, p
      when 2.0
        r, g, b = p, v, t
      when 3.0
        r, g, b = p, q, v
      when 4.0
        r, g, b = t, p, v
      else
        r, g, b = v, p, q
      end
      [(r * 255).round, (g * 255).round, (b * 255).round];
    end
    
    def multiply_hsv(color, hd, sd, vd)
      h = color.hsv_h
      s = color.hsv_s
      v = color.hsv_v
      h = h * hd
      s = s * sd
      v = v * vd
      new_hsv(h, s, v)
    end
    
  end
  
  def hsv_h
    rgb_to_hsv!
    @attrs[:hsv_h]
  end
  
  def hsv_s
    rgb_to_hsv!
    @attrs[:hsv_s]
  end
  
  def hsv_v
    rgb_to_hsv!
    @attrs[:hsv_v]
  end
  
  private
  
  def rgb_to_hsv!
    return if @attrs[:hsv_h] && @attrs[:hsv_s] && @attrs[:hsv_v]
    @attrs[:hsv_h], @attrs[:hsv_s], @attrs[:hsv_v] = self.class.rgb_to_hsv(red, green, blue)
  end
  
end