Colorist: Color Manipulation For WebHeads

While writing color customization code for a recent project, I once again ran into the fact that the existing color gems for Ruby seem to be built for vastly different purposes. To that end, I decided to write a new library for dead-simple manipulation of colors with an emphasis on ease-of-use and being useful for web developers.


gem install colorist

The Basics

To instantiate a color in Colorist, you use a number of methods:

require 'colorist' include Colorist  red = red = 0xff0000.to_color red = "red".to_color red = "#f00".to_color red = Color.from_rgb(255,0,0)

Note: I include Colorist in these examples, but there’s no reason you can’t leave it namespaced i.e. Colorist::Color instead.

The idea is to give maximum flexibility without making it complicated. Once you’ve instantiated a color, you can figure out a few tidbits about it and perform some basic operations:

red.brightness # => 0.299 red.r # => 255 red.invert # => #<Color #00ffff> red.text_color # => #<Color #ffffff> red.to_s # => "#ff0000" red.to_s(:rgb) # => "1.000, 0.000, 0.000"


The real value of Colorist comes in comparison and addition. You can use normal operators with the colors to add them together, subtract them, and compare them based on brightness. You can also do this with the string or numeric representations of colors:

red = 0xff0000.to_color green = 0x00ff00.to_color yellow = red + green yellow = "red".to_color + "green" yellow.to_s # => "#ffff00" red - 0.2 # => #<Color #cc0000>

Comparisons work off of the brightness of a given color. You can also calculate the contrast between two colors using the W3C’s formula:

red = "red".to_color red > "black".to_color # => true red > "white".to_color # => false red.contrast_with("green".to_color) # => 0.500653594771242

Get Coloring!

That’s most of the basic functionality, for all of the details you can view the RDoc on RubyForge. The source is available on GitHub and there is a Lighthouse project for any bugs or feature requests. Enjoy!