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.
To make your string colored wrap it with
Rainbow() presenter and call
.color(<color name>) on it.
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 adds the following methods to presented string:
italic(not well supported by terminal emulators).
Text color can also be changed by calling a method named by a color:
All of the methods return
self (the presenter object) so you can chain method
If you don't like wrapping every string you want to colorize with
you can include all the rainbow presenter methods directly in a String class by
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.
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):
color name as a symbol (:black, :red, :green, :yellow, :blue, :magenta, :cyan, :white):
Rainbow("hello").color(:yellow). This can be simplified to
RGB triplet as separate values in the range 0-255:
Rainbow("hello").color(115, 23, 98)
RGB triplet as a hex string:
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.
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.
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
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.
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.
Add it to your Gemfile:
Or just install it via rubygems:
gem install rainbow