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Ruby gem for colorizing printed text on ANSI terminals

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README.markdown

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'

p 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"

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
  • italic (not well supported by terminal emulators).

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

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

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

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

String mixin

If you don't like wrapping every string you want to colorize with Rainbow() you can include all the rainbow presenter methods directly in a String class by requiring rainbow/ext/string:

require 'rainbow/ext/string'

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

This way of using Rainbow is not recommended though as it pollutes String's public interface with methods that are presentation specific.

NOTE: the mixing doesn't include shortcut methods for changing text color, you should use "string".color(:blue) instead of "string".blue

NOTE: the mixin is included in String by default in rainbow 1.x versions. In rainbow 2.x the behavior was changed - if you're upgrading from 1.x to 2.x and you used direct String methods then you can either require the string extension as shown above or update your code to use the new presenter API.

Color specification

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

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

  • color name as a symbol (:black, :red, :green, :yellow, :blue, :magenta, :cyan, :white): Rainbow("hello").color(:yellow). This can be simplified to Rainbow("hello").yellow

  • 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.

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.

Windows support

For Windows support, you should install the following gems:

gem install windows-pr win32console

If the above gems aren't installed then all strings are returned unmodified.

Installation

Add it to your Gemfile:

gem 'rainbow'

Or just install it via rubygems:

gem install rainbow

Authors

Marcin Kulik and great open-source contributors.

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