Rainbow

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Rainbow is a ruby gem for colorizing printed text on ANSI terminals.

It provides a string presenter object, which adds several methods to your strings for wrapping them in ANSI escape codes. These codes when printed in a terminal change text attributes like text color, background color, intensity etc.

Usage

To make your string colored wrap it with Rainbow() presenter and call .color(<color name>) on it.

Example

require 'rainbow'

puts Rainbow("this is red").red + " and " + Rainbow("this on yellow bg").bg(:yellow) + " and " + Rainbow("even bright underlined!").underline.bright

# => "\e[31mthis is red\e[0m and \e[43mthis on yellow bg\e[0m and \e[4m\e[1meven bright underlined!\e[0m"

Screenshot of the previous code in a terminal

Or, watch this video example

Rainbow presenter API

Rainbow presenter adds the following methods to presented string:

  • color(c) (with foreground, and fg aliases)
  • background(c) (with bg alias)
  • bright
  • underline
  • blink
  • inverse
  • hide
  • faint (not well supported by terminal emulators)
  • italic (not well supported by terminal emulators)
  • cross_out, strike

Text color can also be changed by calling a method named by a color:

  • black
  • red
  • green
  • yellow
  • blue
  • magenta
  • cyan
  • white
  • aqua
  • silver
  • aliceblue
  • indianred

All of the methods return self (the presenter object) so you can chain method calls:

Rainbow("hola!").blue.bright.underline

Refinement

If you want to use the Refinements version, you can:

require 'rainbow/refinement'
using Rainbow
puts "Hi!".green

Here's an IRB session example:

>> 'Hello, World!'.blue.bright.underline
NoMethodError: undefined method `blue' for "Hello, World!":String
    (ripl):1:in `<main>'
>> using Rainbow
=> main
>> 'Hello, World!'.blue.bright.underline
=> "\e[34m\e[1m\e[4mHello, World!\e[0m"

Color specification

Both color and background accept color specified in any of the following ways:

  • ANSI color number (where 0 is black, 1 is red, 2 is green and so on): Rainbow("hello").color(1)

  • ANSI color name or X11 color name as a symbol: Rainbow("hello").color(:yellow). This can be simplified to Rainbow("hello").yellow

See Color list for all available color names.
Note that ANSI colors can be changed in accordance with terminal setting.
But X11 color is just a syntax sugar for RGB triplet. So you always see what you specified.

  • RGB triplet as separate values in the range 0-255: Rainbow("hello").color(115, 23, 98)

  • RGB triplet as a hex string: Rainbow("hello").color("FFC482") or Rainbow("hello").color("#FFC482")

When you specify a color with a RGB triplet rainbow finds the nearest match from 256 colors palette. Note that it requires a 256-colors capable terminal to display correctly.

Example: Choose a random color

You can pick a random color with Rainbow, it's a one-liner:

colors = Range.new(0,7).to_a
"whoop dee doop".chars.map { |char| Rainbow(char).color(colors.sample) }.join
# => "\e[36mw\e[0m\e[37mh\e[0m\e[34mo\e[0m\e[34mo\e[0m\e[37mp\e[0m\e[34m \e[0m\e[36md\e[0m\e[33me\e[0m\e[34me\e[0m\e[37m \e[0m\e[32md\e[0m\e[35mo\e[0m\e[33mo\e[0m\e[36mp\e[0m"

colors = [:aliceblue, :antiquewhite, :aqua, :aquamarine, :azure, :beige, :bisque, :blanchedalmond, :blueviolet]
"whoop dee doop".chars.map { |char| Rainbow(char).color(colors.sample) }.join
# => "\e[38;5;135mw\e[0m\e[38;5;230mh\e[0m\e[38;5;231mo\e[0m\e[38;5;135mo\e[0m\e[38;5;231mp\e[0m\e[38;5;231m \e[0m\e[38;5;122md\e[0m\e[38;5;231me\e[0m\e[38;5;231me\e[0m\e[38;5;230m \e[0m\e[38;5;122md\e[0m\e[38;5;51mo\e[0m\e[38;5;51mo\e[0m\e[38;5;51mp\e[0m"

Configuration

Rainbow can be enabled/disabled globally by setting:

Rainbow.enabled = true/false

When disabled all the methods return an unmodified string (Rainbow("hello").red == "hello").

It's enabled by default, unless STDOUT/STDERR is not a TTY or a terminal is dumb.

Advanced usage

Rainbow() and Rainbow.enabled operate on the global Rainbow wrapper instance. If you would like to selectively enable/disable coloring in separate parts of your application you can get a new Rainbow wrapper instance for each of them and control the state of coloring during the runtime.

rainbow_one = Rainbow.new
rainbow_two = Rainbow.new

rainbow_one.enabled = false

Rainbow("hello").red          # => "\e[31mhello\e[0m" ("hello" if not on TTY)
rainbow_one.wrap("hello").red # => "hello"
rainbow_two.wrap("hello").red # => "\e[31mhello\e[0m" ("hello" if not on TTY)

By default each new instance inherits enabled/disabled state from the global Rainbow.enabled.

This feature comes handy for example when you have multiple output formatters in your application and some of them print to a terminal but others write to a file. Normally rainbow would detect that STDIN/STDERR is a TTY and would colorize all the strings, even the ones that go through file writing formatters. You can easily solve that by disabling coloring for the Rainbow instances that are used by formatters with file output.

Installation

Add it to your Gemfile:

gem 'rainbow'

Or just install it via rubygems:

gem install rainbow

Color list

ANSI colors

black, red, green, yellow, blue, magenta, cyan, white

X11 colors

aliceblue, antiquewhite, aqua, aquamarine, azure, beige, bisque, blanchedalmond, blueviolet, brown, burlywood, cadetblue, chartreuse, chocolate, coral, cornflower, cornsilk, crimson, darkblue, darkcyan, darkgoldenrod, darkgray, darkgreen, darkkhaki, darkmagenta, darkolivegreen, darkorange, darkorchid, darkred, darksalmon, darkseagreen, darkslateblue, darkslategray, darkturquoise, darkviolet, deeppink, deepskyblue, dimgray, dodgerblue, firebrick, floralwhite, forestgreen, fuchsia, gainsboro, ghostwhite, gold, goldenrod, gray, greenyellow, honeydew, hotpink, indianred, indigo, ivory, khaki, lavender, lavenderblush, lawngreen, lemonchiffon, lightblue, lightcoral, lightcyan, lightgoldenrod, lightgray, lightgreen, lightpink, lightsalmon, lightseagreen, lightskyblue, lightslategray, lightsteelblue, lightyellow, lime, limegreen, linen, maroon, mediumaquamarine, mediumblue, mediumorchid, mediumpurple, mediumseagreen, mediumslateblue, mediumspringgreen, mediumturquoise, mediumvioletred, midnightblue, mintcream, mistyrose, moccasin, navajowhite, navyblue, oldlace, olive, olivedrab, orange, orangered, orchid, palegoldenrod, palegreen, paleturquoise, palevioletred, papayawhip, peachpuff, peru, pink, plum, powderblue, purple, rebeccapurple, rosybrown, royalblue, saddlebrown, salmon, sandybrown, seagreen, seashell, sienna, silver, skyblue, slateblue, slategray, snow, springgreen, steelblue, tan, teal, thistle, tomato, turquoise, violet, webgray, webgreen, webmaroon, webpurple, wheat, whitesmoke, yellowgreen

Authors

Marcin Kulik and great open-source contributors.