The Basics

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

require 'colorist'
include Colorist

red = Color.new(0xff0000)
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"

Operations

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!