module Color

Constants

COLOR_EPSILON: The maximum “resolution” for colour math; if any value is less than or equal to this value, it is treated as zero.
COLOR_TOLERANCE: The tolerance for comparing the components of two colours. In general, colours are considered equal if all of their components are within this tolerance value of each other.
COLOR_VERSION
GreyScale: A colour object representing shades of grey. Used primarily in PDF document creation.

Public Class Methods

coerce(a, b) click to toggle source

Coerces, if possible, the second given colour object to the first given colour object type. This will probably involve colour conversion and therefore a loss of fidelity.

# File lib/color.rb, line 91
def coerce(a, b)
  a.coerce(b)
end

equivalent?(a, b) click to toggle source

Returns true if the two colours are roughly equivalent. If colour conversions are required, this all conversions will be implemented using the default conversion mechanism.

# File lib/color.rb, line 84
def equivalent?(a, b)
  a.to_a.zip(a.coerce(b).to_a).all? { |(x, y)| near?(x, y) }
end

near?(x, y) click to toggle source

Returns true if the two values provided are near each other.

# File lib/color.rb, line 77
def near?(x, y)
  (x - y).abs <= Color::COLOR_TOLERANCE
end

near_one?(value) click to toggle source

Returns true if the value is within COLOR_EPSILON of one.

# File lib/color.rb, line 66
def near_one?(value)
  near_zero?(value - 1.0)
end

near_one_or_more?(value) click to toggle source

Returns true if the value is within COLOR_EPSILON of one or more than one.

# File lib/color.rb, line 72
def near_one_or_more?(value)
  (value > 1.0 or near_one?(value))
end

near_zero?(value) click to toggle source

Returns true if the value is less than COLOR_EPSILON.

# File lib/color.rb, line 55
def near_zero?(value)
  (value.abs <= Color::COLOR_EPSILON)
end

near_zero_or_less?(value) click to toggle source

Returns true if the value is within COLOR_EPSILON of zero or less than zero.

# File lib/color.rb, line 61
def near_zero_or_less?(value)
  (value < 0.0 or near_zero?(value))
end

new(values, mode = :rgb) click to toggle source

Provides a thin veneer over the Color module to make it seem like this is Color 0.1.0 (a class) and not Color 1.4 (a module). This “constructor” will be removed in the future.

mode = :hsl: values must be an array of [ hue deg, sat %, lum % ]. A Color::HSL object will be created.
mode = :rgb: values will either be an HTML-style colour string or an array of [ red, green, blue ] (range 0 .. 255). A Color::RGB object will be created.
mode = :cmyk: values must be an array of [ cyan %, magenta %, yellow %, black % ]. A Color::CMYK object will be created.

# File lib/color.rb, line 167
def new(values, mode = :rgb)
  warn "Color.new has been deprecated. Use Color::#{mode.to_s.upcase}.new instead."
  color = case mode
          when :hsl
            Color::HSL.new(*values)
          when :rgb
            values = [ values ].flatten
            if values.size == 1
              Color::RGB.from_html(*values)
            else
              Color::RGB.new(*values)
            end
          when :cmyk
            Color::CMYK.new(*values)
          end
  color.to_hsl
end

normalize(value) click to toggle source

Normalizes the value to the range (0.0) .. (1.0).

# File lib/color.rb, line 96
def normalize(value)
  if near_zero_or_less? value
    0.0
  elsif near_one_or_more? value
    1.0
  else
    value
  end
end

Also aliased as: normalize_fractional

normalize_16bit(value)

Alias for: normalize_word

normalize_8bit(value)

Alias for: normalize_byte

normalize_byte(value) click to toggle source

Normalize the value to the range (0) .. (255).

# File lib/color.rb, line 121
def normalize_byte(value)
  normalize_to_range(value, 0..255).to_i
end

Also aliased as: normalize_8bit

normalize_fractional(value)

Alias for: normalize

normalize_to_range(value, range) click to toggle source

Normalizes the value to the specified range.

# File lib/color.rb, line 108
def normalize_to_range(value, range)
  range = (range.end..range.begin) if (range.end < range.begin)

  if value <= range.begin
    range.begin
  elsif value >= range.end
    range.end
  else
    value
  end
end

normalize_word(value) click to toggle source

Normalize the value to the range (0) .. (65535).

# File lib/color.rb, line 127
def normalize_word(value)
  normalize_to_range(value, 0..65535).to_i
end

Also aliased as: normalize_16bit

Public Instance Methods

==(other) click to toggle source

Compares the other colour to this one. The other colour will be coerced to the same type as the current colour. Such converted colour comparisons will always be more approximate than non-converted comparisons.

If the other colour cannot be coerced to the current colour class, a NoMethodError exception will be raised.

All values are compared as floating-point values, so two colours will be reported equivalent if all component values are within COLOR_TOLERANCE of each other.

# File lib/color.rb, line 33
def ==(other)
  Color.equivalent?(self, other)
end

name() click to toggle source

The primary name for the colour.

# File lib/color.rb, line 38
def name
  names.first
end

names() click to toggle source

All names for the colour.

# File lib/color.rb, line 43
def names
  self.names = nil unless defined? @names
  @names
end