discourse/lib/color_math.rb

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# frozen_string_literal: true
module ColorMath
# Equivalent to dc-color-brightness() in variables.scss
def self.brightness(color)
rgb = Converters.hex_to_rgb(color)
(rgb[0].to_i * 299 + rgb[1].to_i * 587 + rgb[2].to_i * 114) / 1000.0
end
# Equivalent to dark-light-diff() in variables.scss
def self.dark_light_diff(adjusted_color, comparison_color, lightness, darkness)
if brightness(adjusted_color) < brightness(comparison_color)
scale_color_lightness(adjusted_color, lightness)
else
scale_color_lightness(adjusted_color, darkness)
end
end
# Equivalent to scale_color(color, lightness: ) in sass
def self.scale_color_lightness(color, adjustment)
rgb = Converters.hex_to_rgb(color)
h, s, l = Converters.rgb_to_hsl(*rgb)
l =
if adjustment > 0
l + (100 - l) * adjustment
else
l + l * adjustment
end
rgb = Converters.hsl_to_rgb(h, s, l)
Converters.rgb_to_hex(rgb)
end
module Converters
# Adapted from https://github.com/anilyanduri/color_math
#
# The MIT License (MIT)
#
# Copyright (c) 2016 Anil Yanduri
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in all
# copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
# SOFTWARE.
def self.hex_to_rgb(color)
color = color.gsub(/(.)/, '\1\1') if color.length == 3
raise new RuntimeError("Hex color must be 6 characters") if color.length != 6
color.scan(/../).map { |c| c.to_i(16) }
end
def self.rgb_to_hex(rgb)
rgb.map { |c| c.to_s(16).rjust(2, "0") }.join("")
end
def self.rgb_to_hsl(r, g, b)
r /= 255.0
g /= 255.0
b /= 255.0
max = [r, g, b].max
min = [r, g, b].min
h = (max + min) / 2.0
s = (max + min) / 2.0
l = (max + min) / 2.0
if (max == min)
h = 0
s = 0 # achromatic
else
d = max - min
s = l >= 0.5 ? d / (2.0 - max - min) : d / (max + min)
case max
when r
h = (g - b) / d + (g < b ? 6.0 : 0)
when g
h = (b - r) / d + 2.0
when b
h = (r - g) / d + 4.0
end
h /= 6.0
end
[(h * 360).round, (s * 100).round, (l * 100).round]
end
def self.hsl_to_rgb(h, s, l)
h = h / 360.0
s = s / 100.0
l = l / 100.0
r = 0.0
g = 0.0
b = 0.0
if (s == 0.0)
r = l.to_f
g = l.to_f
b = l.to_f #achromatic
else
q = l < 0.5 ? l * (1 + s) : l + s - l * s
p = 2 * l - q
r = hue_to_rgb(p, q, h + 1 / 3.0)
g = hue_to_rgb(p, q, h)
b = hue_to_rgb(p, q, h - 1 / 3.0)
end
[(r * 255).round, (g * 255).round, (b * 255).round]
end
def self.hue_to_rgb(p, q, t)
t += 1 if (t < 0)
t -= 1 if (t > 1)
return(p + (q - p) * 6 * t) if (t < 1 / 6.0)
return q if (t < 1 / 2.0)
return(p + (q - p) * (2 / 3.0 - t) * 6) if (t < 2 / 3.0)
p
end
end
end