Class: TTY::Color::Support

Inherits:
Object
  • Object
show all
Defined in:
lib/tty/color/support.rb

Constant Summary collapse

SOURCES = 
%w[from_term from_tput from_env from_curses].freeze
ENV_VARS = 
%w[COLORTERM ANSICON].freeze
TERM_REGEX = 
/
color|  # explicitly claims color support in the name
direct| # explicitly claims "direct color" (24 bit) support

#{Mode::TERM_256}|
#{Mode::TERM_64}|
#{Mode::TERM_52}|
#{Mode::TERM_16}|
#{Mode::TERM_8}|

^ansi(\.sys.*)?$|
^cygwin|
^linux|
^putty|
^rxvt|
^screen|
^tmux|
^xterm/xi.freeze

Instance Method Summary collapse

Constructor Details

#initialize(env, verbose: false) ⇒ Support

Initialize a color support



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# File 'lib/tty/color/support.rb', line 30

def initialize(env, verbose: false)
  @env = env
  @verbose = verbose
end

Instance Method Details

#disabled? ⇒ Boolean

Detect if color support has been disabled with NO_COLOR ENV var.

Returns:

  • (Boolean) —

    true when terminal color support has been disabled, false otherwise



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# File 'lib/tty/color/support.rb', line 58

def disabled?
  no_color = @env["NO_COLOR"]
  !(no_color.nil? || no_color.empty?)
end

#from_curses(curses_class = nil) ⇒ Boolean

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Attempt to load curses to check color support

Returns:

  • (Boolean) 


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# File 'lib/tty/color/support.rb', line 97

def from_curses(curses_class = nil)
  return NoValue if TTY::Color.windows?

  require "curses"

  if defined?(Curses)
    curses_class ||= Curses
    curses_class.init_screen
    has_color = curses_class.has_colors?
    curses_class.close_screen
    return has_color
  end
  NoValue
rescue LoadError
  warn "no native curses support" if @verbose
  NoValue
end

#from_env ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Check if environment specifies color variables



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# File 'lib/tty/color/support.rb', line 88

def from_env
  ENV_VARS.any? { |key| @env.key?(key) } || NoValue
end

#from_term ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Inspect environment $TERM variable for color support



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# File 'lib/tty/color/support.rb', line 66

def from_term
  case @env["TERM"]
  when "dumb" then false
  when TERM_REGEX then true
  else NoValue
  end
end

#from_tput ⇒ Object

This method is part of a private API. You should avoid using this method if possible, as it may be removed or be changed in the future.

Shell out to tput to check color support



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# File 'lib/tty/color/support.rb', line 77

def from_tput
  return NoValue unless TTY::Color.command?("tput colors")

  `tput colors 2>/dev/null`.to_i > 2
rescue Errno::ENOENT
  NoValue
end

#support? ⇒ Boolean

Detect if terminal supports color

Returns:

  • (Boolean) —

    true when terminal supports color, false otherwise



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# File 'lib/tty/color/support.rb', line 41

def support?
  return false unless TTY::Color.tty?
  return false if disabled?

  value = false
  SOURCES.each do |from_check|
    break if (value = public_send(from_check)) != NoValue
  end
  value == NoValue ? false : value
end