Class: Abachrome::Parsers::CSS

Inherits:
Object
  • Object
show all
Defined in:
lib/abachrome/parsers/css.rb

Class Method Summary collapse

Class Method Details

.hsl_to_rgb(h, s, l) ⇒ Object

Color space conversion functions



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# File 'lib/abachrome/parsers/css.rb', line 353

def self.hsl_to_rgb(h, s, l)
  h /= 360.0 # Normalize hue to 0-1

  c = (1 - ((2 * l) - 1).abs) * s
  x = c * (1 - (((h * 6) % 2) - 1).abs)
  m = l - (c / 2)

  if h < 1.0 / 6
    r = c
    g = x
    b = 0
  elsif h < 2.0 / 6
    r = x
    g = c
    b = 0
  elsif h < 3.0 / 6
    r = 0
    g = c
    b = x
  elsif h < 4.0 / 6
    r = 0
    g = x
    b = c
  elsif h < 5.0 / 6
    r = x
    g = 0
    b = c
  else
    r = c
    g = 0
    b = x
  end

  [r + m, g + m, b + m]
end

.hwb_to_rgb(h, w, b) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 389

def self.hwb_to_rgb(h, w, b)
  # Normalize values
  h /= 360.0

  # Calculate RGB from HSL equivalent
  if w + b >= 1
    gray = w / (w + b)
    [gray, gray, gray]
  else
    rgb = hsl_to_rgb(h * 360, 1, 0.5)
    r, g, b_rgb = rgb

    # Apply whiteness and blackness
    r = (r * (1 - w - b)) + w
    g = (g * (1 - w - b)) + w
    b_rgb = (b_rgb * (1 - w - b)) + w

    [r, g, b_rgb]
  end
end

.lab_to_xyz(l, a, b) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 410

def self.lab_to_xyz(l, a, b)
  # CIELAB to XYZ conversion (D65 white point)
  y = (l + 16) / 116
  x = (a / 500) + y
  z = y - (b / 200)

  x = x**3 > 0.008856 ? x**3 : (x - (16 / 116)) / 7.787
  y = y**3 > 0.008856 ? y**3 : (y - (16 / 116)) / 7.787
  z = z**3 > 0.008856 ? z**3 : (z - (16 / 116)) / 7.787

  # D65 white point
  x *= 0.95047
  y *= 1.0
  z *= 1.08883

  [x, y, z]
end

.lch_to_lab(l, c, h) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 428

def self.lch_to_lab(l, c, h)
  h_rad = h * Math::PI / 180.0
  a = c * Math.cos(h_rad)
  b = c * Math.sin(h_rad)
  [l, a, b]
end

.parse(input) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 24

def self.parse(input)
  return nil unless input.is_a?(String)

  input = input.strip.downcase

  # Try named colors first
  named_color = parse_named_color(input)
  return named_color if named_color

  # Try hex colors
  hex_color = Hex.parse(input)
  return hex_color if hex_color

  # Try functional notation
  parse_functional_color(input)
end

.parse_angle_value(str) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 333

def self.parse_angle_value(str)
  return nil unless str

  if str.end_with?("deg")
    str.chomp("deg").to_f
  elsif str.end_with?("rad")
    str.chomp("rad").to_f * 180.0 / Math::PI
  elsif str.end_with?("grad")
    str.chomp("grad").to_f * 0.9
  elsif str.end_with?("turn")
    str.chomp("turn").to_f * 360.0
  else
    str.to_f # Assume degrees
  end
rescue StandardError
  nil
end

.parse_color_function(params) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 160

def self.parse_color_function(params)
  # Parse color(space values...)
  parts = params.split(/\s+/, 2)
  return nil unless parts.length == 2

  space = parts[0]
  values_str = parts[1]

  case space
  when "srgb"
    values = parse_color_values(values_str, 3)
    return nil unless values

    r, g, b = values
    Color.from_rgb(r, g, b)
  when "srgb-linear"
    values = parse_color_values(values_str, 3)
    return nil unless values

    r, g, b = values
    Color.from_lrgb(r, g, b)
  when "display-p3"
    # For now, approximate as sRGB
    values = parse_color_values(values_str, 3)
    return nil unless values

    r, g, b = values
    Color.from_rgb(r, g, b)
  when "a98-rgb"
    # For now, approximate as sRGB
    values = parse_color_values(values_str, 3)
    return nil unless values

    r, g, b = values
    Color.from_rgb(r, g, b)
  when "prophoto-rgb"
    # For now, approximate as sRGB
    values = parse_color_values(values_str, 3)
    return nil unless values

    r, g, b = values
    Color.from_rgb(r, g, b)
  when "rec2020"
    # For now, approximate as sRGB
    values = parse_color_values(values_str, 3)
    return nil unless values

    r, g, b = values
    Color.from_rgb(r, g, b)
  end
end

.parse_color_values(str, expected_count) ⇒ Object

Helper methods for parsing values



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# File 'lib/abachrome/parsers/css.rb', line 214

def self.parse_color_values(str, expected_count)
  values = str.split(/\s*,\s*/).map(&:strip)
  return nil unless values.length == expected_count

  values.map do |v|
    parse_numeric_value(v)
  end.compact
end

.parse_functional_color(input) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 53

def self.parse_functional_color(input)
  case input
  when /^rgb\((.+)\)$/
    parse_rgb(::Regexp.last_match(1))
  when /^rgba\((.+)\)$/
    parse_rgba(::Regexp.last_match(1))
  when /^hsl\((.+)\)$/
    parse_hsl(::Regexp.last_match(1))
  when /^hsla\((.+)\)$/
    parse_hsla(::Regexp.last_match(1))
  when /^hwb\((.+)\)$/
    parse_hwb(::Regexp.last_match(1))
  when /^lab\((.+)\)$/
    parse_lab(::Regexp.last_match(1))
  when /^lch\((.+)\)$/
    parse_lch(::Regexp.last_match(1))
  when /^oklab\((.+)\)$/
    parse_oklab(::Regexp.last_match(1))
  when /^oklch\((.+)\)$/
    parse_oklch(::Regexp.last_match(1))
  when /^color\((.+)\)$/
    parse_color_function(::Regexp.last_match(1))
  end
end

.parse_hsl(params) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 94

def self.parse_hsl(params)
  values = parse_hsl_values(params, 3)
  return nil unless values

  h, s, l = values
  rgb = hsl_to_rgb(h, s, l)
  Color.from_rgb(*rgb)
end

.parse_hsl_values(str, expected_count) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 223

def self.parse_hsl_values(str, expected_count)
  values = str.split(/\s*,\s*/).map(&:strip)
  return nil unless values.length == expected_count

  parsed = []
  values.each_with_index do |v, i|
    val = if i.zero? # Hue
            parse_angle_value(v)

          else # Saturation, Lightness, Alpha
            parse_percentage_or_number(v)

          end
    return nil unless val

    parsed << val
  end
  parsed
end

.parse_hsla(params) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 103

def self.parse_hsla(params)
  values = parse_hsl_values(params, 4)
  return nil unless values

  h, s, l, a = values
  rgb = hsl_to_rgb(h, s, l)
  Color.from_rgb(*rgb, a)
end

.parse_hwb(params) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 112

def self.parse_hwb(params)
  values = parse_hwb_values(params)
  return nil unless values

  h, w, b, a = values
  rgb = hwb_to_rgb(h, w, b)
  Color.from_rgb(*rgb, a)
end

.parse_hwb_values(str) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 243

def self.parse_hwb_values(str)
  values = str.split(/\s*,\s*/).map(&:strip)
  return nil unless values.length >= 3

  h = parse_angle_value(values[0])
  w = parse_percentage_or_number(values[1])
  b = parse_percentage_or_number(values[2])
  a = values[3] ? parse_numeric_value(values[3]) : 1.0

  return nil unless h && w && b && a

  [h, w, b, a]
end

.parse_lab(params) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 121

def self.parse_lab(params)
  values = parse_lab_values(params, 3)
  return nil unless values

  l, a, b = values
  # Convert CIELAB to XYZ, then to sRGB
  xyz = lab_to_xyz(l, a, b)
  rgb = xyz_to_rgb(*xyz)
  Color.from_rgb(*rgb)
end

.parse_lab_values(str, expected_count) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 257

def self.parse_lab_values(str, expected_count)
  values = str.split(/\s+/, expected_count).map(&:strip)
  return nil unless values.length == expected_count

  l = parse_percentage_or_number(values[0])
  a = parse_numeric_value(values[1])
  b = parse_numeric_value(values[2])

  return nil unless l && a && b

  [l, a, b]
end

.parse_lch(params) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 132

def self.parse_lch(params)
  values = parse_lch_values(params, 3)
  return nil unless values

  l, c, h = values
  # Convert CIELCH to CIELAB, then to XYZ, then to sRGB
  lab = lch_to_lab(l, c, h)
  xyz = lab_to_xyz(*lab)
  rgb = xyz_to_rgb(*xyz)
  Color.from_rgb(*rgb)
end

.parse_lch_values(str, expected_count) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 270

def self.parse_lch_values(str, expected_count)
  values = str.split(/\s+/, expected_count).map(&:strip)
  return nil unless values.length == expected_count

  l = parse_percentage_or_number(values[0])
  c = parse_numeric_value(values[1])
  h = parse_angle_value(values[2])

  return nil unless l && c && h

  [l, c, h]
end

.parse_named_color(input) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 41

def self.parse_named_color(input)
  # Check if input matches a named color
  rgb_values = Named::CSS.method(input.to_sym)&.call
  return nil unless rgb_values

  # Convert 0-255 RGB values to 0-1 range
  r, g, b = rgb_values.map { |v| v / 255.0 }
  Color.from_rgb(r, g, b)
rescue NameError
  nil
end

.parse_numeric_value(str) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 309

def self.parse_numeric_value(str)
  return nil unless str

  if str.end_with?("%")
    (str.chomp("%").to_f / 100.0)
  else
    str.to_f
  end
rescue StandardError
  nil
end

.parse_oklab(params) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 144

def self.parse_oklab(params)
  values = parse_oklab_values(params, 3)
  return nil unless values

  l, a, b = values
  Color.from_oklab(l, a, b)
end

.parse_oklab_values(str, expected_count) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 283

def self.parse_oklab_values(str, expected_count)
  values = str.split(/\s+/, expected_count).map(&:strip)
  return nil unless values.length == expected_count

  l = parse_percentage_or_number(values[0])
  a = parse_numeric_value(values[1])
  b = parse_numeric_value(values[2])

  return nil unless l && a && b

  [l, a, b]
end

.parse_oklch(params) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 152

def self.parse_oklch(params)
  values = parse_oklch_values(params, 3)
  return nil unless values

  l, c, h = values
  Color.from_oklch(l, c, h)
end

.parse_oklch_values(str, expected_count) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 296

def self.parse_oklch_values(str, expected_count)
  values = str.split(/\s+/, expected_count).map(&:strip)
  return nil unless values.length == expected_count

  l = parse_percentage_or_number(values[0])
  c = parse_numeric_value(values[1])
  h = parse_angle_value(values[2])

  return nil unless l && c && h

  [l, c, h]
end

.parse_percentage_or_number(str) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 321

def self.parse_percentage_or_number(str)
  return nil unless str

  if str.end_with?("%")
    str.chomp("%").to_f / 100.0
  else
    str.to_f
  end
rescue StandardError
  nil
end

.parse_rgb(params) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 78

def self.parse_rgb(params)
  values = parse_color_values(params, 3)
  return nil unless values

  r, g, b = values
  Color.from_rgb(r, g, b)
end

.parse_rgba(params) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 86

def self.parse_rgba(params)
  values = parse_color_values(params, 4)
  return nil unless values

  r, g, b, a = values
  Color.from_rgb(r, g, b, a)
end

.xyz_to_rgb(x, y, z) ⇒ Object 



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# File 'lib/abachrome/parsers/css.rb', line 435

def self.xyz_to_rgb(x, y, z)
  # XYZ to linear RGB
  r = (x * 3.2406) + (y * -1.5372) + (z * -0.4986)
  g = (x * -0.9689) + (y * 1.8758) + (z *  0.0415)
  b = (x * 0.0557) + (y * -0.2040) + (z *  1.0570)

  # Linear RGB to sRGB
  [r, g, b].map do |v|
    if v > 0.0031308
      (1.055 * (v**(1 / 2.4))) - 0.055
    else
      12.92 * v
    end
  end
end