Module: RNDK::Color

Defined in:
lib/rndk/core/color.rb

Overview

The colors that we can print text with.

Internally we call Colors attributes - or attribs.

Usage

First of all, you should call Color#init. If your terminal doesn't support colors (come on, at 2010s?) Colors#has_colors? will tell.

All Widgets that have an attrib argument can use a Color. You call them like this:

color = RNDK::Color[:foreground_background]

If you want to use your terminal's current default background/foreground, use:

color = RNDK::Color[:default_background]
color = RNDK::Color[:foreground]

Also, there are special color modifiers. They change how the color appears and can make some interesting effects:

  • RNDK::Color[:normal]
  • RNDK::Color[:bold]
  • RNDK::Color[:reverse]
  • RNDK::Color[:underline]
  • RNDK::Color[:blink]
  • RNDK::Color[:dim]
  • RNDK::Color[:invisible]
  • RNDK::Color[:standout]

To apply them, "add" to the regular colors with the pipe ('|'):

color = RNDK::Color[:red] | RNDK::Color[:bold]

Examples

wb  = Color[:white_black]
gm  = Color[:green_magenta]
red = Color[:red]
bl  = Color[:default_black]
x   = RNDK::Color[:blue_yellow] | RNDK::Color[:reverse] # guess what?
y   = RNDK::Color[:cyan] | RNDK::Color[:invisible] # opps

Developer Notes

Color#init creates 80 color pairs. Neat!

Also, to extract attributes from a chtype (mix between characters and ncurses colors) use

chtype & RNDK::Color[:extract]

Constant Summary collapse

@@colors =

All possible colors on format :foreground_background.

When background is not specified, it's the current terminal's default.

They're defined on Color#init.

{}
@@attributes =

These special attributes exist even if no color were initialized.

They modify the way colors show on the screen.

{
  :normal    => Ncurses::A_NORMAL,
  :bold      => Ncurses::A_BOLD,
  :reverse   => Ncurses::A_REVERSE,
  :underline => Ncurses::A_UNDERLINE,
  :blink     => Ncurses::A_BLINK,
  :dim       => Ncurses::A_DIM,
  :invisible => Ncurses::A_INVIS,
  :standout  => Ncurses::A_STANDOUT,
   # To extract attributes from a chtype (mix between
  # characters and ncurses colors) use
  # `chtype & RNDK::Color[:extract]
  :extract   => Ncurses::A_ATTRIBUTES
}

Class Method Summary collapse

Class Method Details

.[](label) ⇒ Object

Access individual color pairs or attributes.

If colors were not initialized and user request colors, returns white foreground over default background.



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# File 'lib/rndk/core/color.rb', line 172

def self.[] label
  if @@attributes.include? label
    @@attributes[label]

  elsif @@colors.include? label
    Ncurses.COLOR_PAIR @@colors[label]

  else
    Ncurses.COLOR_PAIR 0
  end
end

.has_colors? ⇒ Boolean

Tells if the current terminal supports colors.

Unless you've been living under a rock, this shouldn't be of any concern.

Returns:

  • (Boolean) 


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# File 'lib/rndk/core/color.rb', line 163

def self.has_colors?
  Ncurses.has_colors
end

.init ⇒ Object

Start support for colors, initializing all color pairs.



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# File 'lib/rndk/core/color.rb', line 94

def self.init
  return unless self.has_colors?

  Ncurses.start_color

  # Will be able to use current terminal's
  # background color (value -1)
  Ncurses.use_default_colors

  # We will initialize 80 color pairs with all
  # combinations from the current Array.
  #
  # They'll have symbols with their names.
  # For example:
  #     Color[:white_black]
  #     Color[:green_magenta]
  color = [[Ncurses::COLOR_WHITE,   :white],
           [Ncurses::COLOR_RED,     :red],
           [Ncurses::COLOR_GREEN,   :green],
           [Ncurses::COLOR_YELLOW,  :yellow],
           [Ncurses::COLOR_BLUE,    :blue],
           [Ncurses::COLOR_MAGENTA, :magenta],
           [Ncurses::COLOR_CYAN,    :cyan],
           [Ncurses::COLOR_BLACK,   :black]]

  limit = if Ncurses.COLORS < 8
          then Ncurses.COLORS
          else 8
          end

  pair = 1
  # Create the color pairs
  (0...limit).each do |fg|
    (0...limit).each do |bg|
      Ncurses.init_pair(pair, color[fg][0], color[bg][0])

      label = "#{color[fg][1]}_#{color[bg][1]}".to_sym
      @@colors[label] = pair
      pair += 1
    end
  end

  # The color pairs with default background and foreground.
  #
  # They'll have symbols with their names and 'default'
  # where the default color is.
  # For example:
  #     Color[:default_black]
  #     Color[:magenta]
  color.each do |bg|
    Ncurses.init_pair(pair, -1, bg[0])

    label = "default_#{bg[1]}".to_sym
    @@colors[label] = pair
    pair += 1
  end
  color.each do |fg|
    Ncurses.init_pair(pair, fg[0], -1)

    label = "#{fg[1]}".to_sym
    @@colors[label] = pair
    pair += 1
  end
end