Class: Color::HSL

Inherits:
Object
  • Object
show all
Defined in:
lib/color/hsl.rb

Overview

An HSL colour object. Internally, the hue (#h), saturation (#s), and luminosity/lightness (#l) values are dealt with as fractional values in the range 0..1.

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(h = 0, s = 0, l = 0) ⇒ HSL

Creates an HSL colour object from the standard values of degrees and percentages (e.g., 145 deg, 30%, 50%).



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# File 'lib/color/hsl.rb', line 47

def initialize(h = 0, s = 0, l = 0)
  @h = h / 360.0
  @s = s / 100.0
  @l = l / 100.0
end

Class Method Details

.from_fraction(h = 0.0, s = 0.0, l = 0.0) ⇒ Object

Creates an HSL colour object from fractional values 0..1.



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# File 'lib/color/hsl.rb', line 21

def from_fraction(h = 0.0, s = 0.0, l = 0.0)
  colour = Color::HSL.new
  colour.h = h
  colour.s = s
  colour.l = l
  colour
end

Instance Method Details

#==(other) ⇒ Object

Compares the other colour to this one. The other colour will be converted to HSL before comparison, so the comparison between a HSL colour and a non-HSL colour will be approximate and based on the other colour’s #to_hsl conversion. If there is no #to_hsl conversion, this will raise an exception. This will report that two HSL values are equivalent if all component values are within Color::COLOR_TOLERANCE of each other.



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# File 'lib/color/hsl.rb', line 37

def ==(other)
  other = other.to_hsl
  other.kind_of?(Color::HSL) and
  ((@h - other.h).abs <= Color::COLOR_TOLERANCE) and
  ((@s - other.s).abs <= Color::COLOR_TOLERANCE) and
  ((@l - other.l).abs <= Color::COLOR_TOLERANCE)
end

#brightness ⇒ Object

Returns the luminosity (#l) of the colour.



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# File 'lib/color/hsl.rb', line 137

def brightness
  @l
end

#css_hsl ⇒ Object

Present the colour as an HSL HTML/CSS colour string (e.g., “hsl(180, 25%, 35%)”).



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# File 'lib/color/hsl.rb', line 74

def css_hsl
  "hsl(%3.2f, %3.2f%%, %3.2f%%)" % [ hue, saturation, luminosity ]
end

#css_hsla ⇒ Object

Present the colour as an HSLA (with alpha) HTML/CSS colour string (e.g., “hsla(180, 25%, 35%, 1)”).



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# File 'lib/color/hsl.rb', line 80

def css_hsla
  "hsla(%3.2f, %3.2f%%, %3.2f%%, %3.2f)" % [ hue, saturation, luminosity, 1 ]
end

#css_rgb ⇒ Object

Present the colour as an RGB HTML/CSS colour string (e.g., “rgb(0%, 50%, 100%)”). Note that this will perform a #to_rgb operation using the default conversion formula.



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# File 'lib/color/hsl.rb', line 61

def css_rgb
  to_rgb.css_rgb
end

#css_rgba ⇒ Object

Present the colour as an RGBA (with alpha) HTML/CSS colour string (e.g., “rgb(0%, 50%, 100%, 1)”). Note that this will perform a #to_rgb operation using the default conversion formula.



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# File 'lib/color/hsl.rb', line 68

def css_rgba
  to_rgb.css_rgba
end

#h ⇒ Object

Returns the hue of the colour in the range 0.0 .. 1.0.



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# File 'lib/color/hsl.rb', line 150

def h
  @h
end

#h=(hh) ⇒ Object

Sets the hue of the colour in the range 0.0 .. 1.0.



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# File 'lib/color/hsl.rb', line 164

def h=(hh)
  @h = Color.normalize(hh)
end

#html ⇒ Object

Present the colour as an HTML/CSS colour string.



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# File 'lib/color/hsl.rb', line 54

def html
  to_rgb.html
end

#hue ⇒ Object

Returns the hue of the colour in degrees.



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# File 'lib/color/hsl.rb', line 146

def hue
  @h * 360.0
end

#hue=(hh) ⇒ Object

Sets the hue of the colour in degrees. Colour is perceived as a wheel, so values should be set properly even with negative degree values.



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# File 'lib/color/hsl.rb', line 155

def hue=(hh)
  hh = hh / 360.0

  hh += 1.0 if hh < 0.0
  hh -= 1.0 if hh > 1.0

  @h = Color.normalize(hh)
end

#inspect ⇒ Object 



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# File 'lib/color/hsl.rb', line 207

def inspect
  "HSL [%.2f deg, %.2f%%, %.2f%%]" % [ hue, saturation, luminosity ]
end

#l ⇒ Object

Returns the luminosity of the colour in the range 0.0 .. 1.0.



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# File 'lib/color/hsl.rb', line 190

def l
  @l
end

#l=(ll) ⇒ Object

Sets the luminosity of the colour in the ragne 0.0 .. 1.0.



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# File 'lib/color/hsl.rb', line 199

def l=(ll)
  @l = Color.normalize(ll)
end

#luminosity ⇒ Object Also known as: lightness

Returns the percentage of luminosity of the colour.



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# File 'lib/color/hsl.rb', line 185

def luminosity
  @l * 100.0
end

#luminosity=(ll) ⇒ Object Also known as: lightness=

Sets the percentage of luminosity of the colour.



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# File 'lib/color/hsl.rb', line 194

def luminosity=(ll)
  @l = Color.normalize(ll / 100.0)
end

#mix_with(color, mix_percent = 0.5) ⇒ Object

Mix the mask colour (which will be converted to an HSL colour) with the current colour at the stated mix percentage as a decimal value.

NOTE

This differs from Color::RGB#mix_with.



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# File 'lib/color/hsl.rb', line 215

def mix_with(color, mix_percent = 0.5)
  color   = color.to_hsl
  _h = ((color.h - self.h) * mix_percent) + self.h
  _s = ((color.s - self.s) * mix_percent) + self.s
  _l = ((color.l - self.l) * mix_percent) + self.l

  self.class.from_fraction(_h, _s, _l)
end

#s ⇒ Object

Returns the saturation of the colour in the range 0.0 .. 1.0.



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# File 'lib/color/hsl.rb', line 172

def s
  @s
end

#s=(ss) ⇒ Object

Sets the saturation of the colour in the ragne 0.0 .. 1.0.



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# File 'lib/color/hsl.rb', line 180

def s=(ss)
  @s = Color.normalize(ss)
end

#saturation ⇒ Object

Returns the percentage of saturation of the colour.



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# File 'lib/color/hsl.rb', line 168

def saturation
  @s * 100.0
end

#saturation=(ss) ⇒ Object

Sets the percentage of saturation of the colour.



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# File 'lib/color/hsl.rb', line 176

def saturation=(ss)
  @s = Color.normalize(ss / 100.0)
end

#to_cmyk ⇒ Object

Converts to RGB then CMYK.



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# File 'lib/color/hsl.rb', line 132

def to_cmyk
  to_rgb.to_cmyk
end

#to_greyscale ⇒ Object Also known as: to_grayscale 



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# File 'lib/color/hsl.rb', line 140

def to_greyscale
  Color::GrayScale.from_fraction(@l)
end

#to_hsl ⇒ Object 



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# File 'lib/color/hsl.rb', line 203

def to_hsl
  self
end

#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/hsl.rb', line 93

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

  # Is the value less than 0.5?
  if Color.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 Color.near_zero_or_less?(hue)
    hue -= 1.0 if Color.near_one_or_more?(hue)

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

   Color::RGB.from_fraction(*rgb)
end

#to_yiq ⇒ Object

Converts to RGB then YIQ.



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# File 'lib/color/hsl.rb', line 127

def to_yiq
  to_rgb.to_yiq
end