ANSI color test written in Ruby

colortest

#!/usr/bin/env ruby

ColorNameSequence = %w[
  Black
  Red
  Green
  Yellow
  Blue
  Magenta
  Cyan
  White
]

ColorDef = Struct.new( :name, :value )

ForegroundColorSequence =
  [
    ColorDef.new( 'Default', nil ),
    ColorDef.new( '~Default', 7 ),
  ] +
  ColorNameSequence.each_with_index.map{ |name, color_num|
    ColorDef.new( name, 30 + color_num )
  }

BackgroundColorSequence =
  [
    ColorDef.new( 'Default', nil ),
    ColorDef.new( '~Default', 7 ),
  ] +
  ColorNameSequence.each_with_index.map{ |name, color_num|
    ColorDef.new( name,  40 + color_num )
  }

AllAttributesOff = 0
BoldValue        = 1
ItalicValue      = 3
ReverseOnValue   = 7

# Build an ANSI graphics mode escape sequence from array of attribute value numbers.
def gm(*values)
  escape_seq =
    "\x1b" <<
    '[' <<
    ( values.compact.uniq * ';' ) <<
    'm'
end

puts
puts '  Foreground:   ' << ForegroundColorSequence.map{ |c| '%-10s' % c.name } * ' '
puts
puts '              ' << ( '+----------' * ForegroundColorSequence.length )
BackgroundColorSequence.each do |bgc|
  content = ForegroundColorSequence.map{ |fgc| gm( bgc.value, fgc.value ) << 'gYw'.center(10, ' ') << gm( AllAttributesOff ) } * ' '
  puts ( '%12s  |' % ""                ) << content
  puts ( '%12s  |' % "On #{bgc.name}:" ) << content
  content = ForegroundColorSequence.map{ |fgc| gm( bgc.value, fgc.value, BoldValue ) << 'gYw'.center(10, ' ') << gm( AllAttributesOff ) } * ' '
  puts ( '%12s  |' % ""                ) << content
  puts ( '%12s  |' % ""                ) << content
end