How do I parse a hex color string in Ruby? - abachrome — Practical Ruby Gems

Abachrome parses hex color strings with Abachrome.from_hex, accepting #RGB, #RRGGBB, and the bare forms without the # prefix.

require 'abachrome'

red   = Abachrome.from_hex('#ff0000')
green = Abachrome.from_hex('#0f0')       # shorthand
blue  = Abachrome.from_hex('0000ff')     # no leading #

puts red.rgb_hex    # => "ff0000"
puts green.rgb_hex  # => "00ff00"

Reading the Components

Once parsed, the color lives in sRGB space and exposes its channels as floating-point values in the 0.0–1.0 range:

color = Abachrome.from_hex('#3a86ff')

puts color.coordinates[0]  # red   => ~0.227
puts color.coordinates[1]  # green => ~0.525
puts color.coordinates[2]  # blue  => 1.0

Round-Tripping to CSS

Use Abachrome::Outputs::CSS.format to emit a CSS-safe hex string, or format_rgb for an rgb() function value:

color = Abachrome.from_hex('#3a86ff')

Abachrome::Outputs::CSS.format(color)      # => "#3a86ff"
Abachrome::Outputs::CSS.format_rgb(color)  # => "rgb(58, 134, 255)"

Notes

Hex parsing is case-insensitive (#FF0000 and #ff0000 are equivalent).
Alpha channels are not expressed in hex strings; use Abachrome.from_rgb with a fourth argument if you need transparency.