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# frozen_string_literal: true
##
# \Grayscale is a color object representing shades of gray as a ratio of black to white,
# where 0% (0.0) gray is black and 100% (1.0) gray is white.
#
# \Grayscale colors are immutable Data class instances. Array deconstruction is `[gray]`
# and hash deconstruction is `{g:, gray:}`. See #g, #gray.
class Color::Grayscale
include Color
##
# :attr_reader: brightness
# Returns the grayscale value as a proportion of white (0.0 .. 1.0).
##
# :attr_reader: g
# Returns the grayscale value as a proportion of white (0.0 .. 1.0).
##
# :attr_reader: gray
# Returns the grayscale value as a percentage of white (0.0 .. 100.0).
##
# Creates a grayscale color object from a percentage value (0.0 .. 100.0).
#
# ```ruby
# Color::Grayscale.from_percentage(50) # => Grayscale [0.50%]
# Color::Grayscale.from_values(50) # => Grayscale [0.50%]
# ```
#
# :call-seq:
# from_percentage(g)
# from_percentage(g:)
# from_values(g)
# from_values(g:)
def self.from_percentage(*args, **kwargs)
g =
case [args, kwargs]
in [[g], {}]
g
in [[], {g:}]
g
else
new(*args, **kwargs)
end
new(g: g / 100.0)
end
class << self
alias_method :from_values, :from_percentage
alias_method :from_fraction, :new
alias_method :from_internal, :from_fraction # :nodoc:
end
##
# Creates a grayscale color object from a fractional value (0.0 .. 1.0).
#
# ```ruby
# Color::Grayscale.from_fraction(0.5)
# Color::Grayscale.new(0.5)
# Color::Grayscale[g: 0.5]
# ```
def initialize(g:)
super(g: normalize(g))
end
##
# Coerces the other Color object to grayscale.
def coerce(other) = other.to_grayscale
##
# Convert \Grayscale to Color::CMYK.
def to_cmyk(...) = Color::CMYK.from_fraction(0, 0, 0, 1.0 - g.to_f)
##
# Convert \Grayscale to Color::RGB.
def to_rgb(...) = Color::RGB.from_fraction(g, g, g)
##
def to_grayscale(...) = self
##
# Convert \Grayscale to Color::YIQ.
#
# This approximates the actual value, as I and Q are calculated by treating the
# grayscale value as a RGB value. The Y (intensity or brightness) value is the same as
# the grayscale value.
def to_yiq(...)
y = g
i = (g * 0.596) + (g * -0.275) + (g * -0.321)
q = (g * 0.212) + (g * -0.523) + (g * 0.311)
Color::YIQ.from_fraction(y, i, q)
end
##
# Converts \Grayscale to Color::HSL.
def to_hsl(...) = Color::HSL.from_fraction(0, 0, g)
##
# Converts \Grayscale to Color::CIELAB via Color::RGB.
def to_lab(...) = to_rgb(...).to_lab(...)
##
# Present the color as an HTML/CSS color string (e.g., `#dddddd`).
def html
"##{("%02x" % translate_range(g, to: 0.0..255.0)) * 3}"
end
##
# Present the color as a CSS `rgb` color with optional `alpha`.
#
# ```ruby
# Color::Grayscale[0.5].css # => rgb(50.00% 50.00% 50.00%)
# Color::Grayscale[0.5].css(alpha: 0.75) # => rgb(50.00% 50.00% 50.00% / 0.75)
# ```
def css(alpha: nil)
params = ([css_value(gray, :percent)] * 3).join(" ")
params = "#{params} / #{css_value(alpha)}" if alpha
"rgb(#{params})"
end
##
# Lightens the grayscale color by the stated percent.
def lighten_by(percent) = Color::Grayscale.from_fraction([g + (g * (percent / 100.0)), 1.0].min)
##
# Darken the grayscale color by the stated percent.
def darken_by(percent) = Color::Grayscale.from_fraction([g - (g * (percent / 100.0)), 0.0].max)
##
alias_method :brightness, :g
##
def gray = g * 100.0
##
def inspect = "Grayscale [%.2f%%]" % [gray] # :nodoc:
##
def pretty_print(q) # :nodoc:
q.text "Grayscale"
q.breakable
q.group 2, "[", "]" do
q.text "%.2f%%" % gray
end
end
##
def to_a = [gray] # :nodoc:
##
alias_method :deconstruct, :to_a
##
def deconstruct_keys(_keys) = {g:, gray:}
##
def to_internal = [g] # :nodoc:
##
def components = 1 # :nodoc:
end
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