Class: IQ::Color::RGBA

Inherits:
RGB
  • Object
show all
Defined in:
lib/iq/color/rgba.rb

Overview

A class for representing RGB values with an alpha channel.

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(red, green, blue, alpha = 1.0) ⇒ RGBA

Returns a new IQ::Color::RGBA instance with the supplied rgb and alpha values.

Raises:

  • (ArgumentError) 


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# File 'lib/iq/color/rgba.rb', line 7

def initialize(red, green, blue, alpha = 1.0)
  raise ArgumentError, 'Alpha value must be an integer of float' unless alpha.is_a?(Integer) || alpha.is_a?(Float)
  raise ArgumentError, 'Alpha value must be between 0.0 and 1.0' if alpha < 0 || alpha > 1
  super red, green, blue
  @alpha = alpha.to_f
end

Instance Attribute Details

#alpha ⇒ Object (readonly)

Returns the value of attribute alpha.



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# File 'lib/iq/color/rgba.rb', line 4

def alpha
  @alpha
end

Class Method Details

.from_css(css_string) ⇒ Object

Returns a new instance based on the css string supplied. Accepts hex, ‘rgb’ and ‘rgba’ notation e.g. '#fed', '#ffeedd', 'rgb(255,238,221)' and 'rgb(255,238,221,1.0)' (note that white space is allowed either side of the commas).

If an 'rgba' string is supplied then the ‘a’ segment is the alpha value between 0 and 1 (0 is fully transparent and 1 is fully opaque).

A value of 'transparent' may be supplied as a shortcut for rgba(0,0,0,0).

More on CSS3 colour strings can be found at: www.w3.org/TR/css3-color



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# File 'lib/iq/color/rgba.rb', line 33

def self.from_css(css_string)
  if css_string == 'transparent'
    new 0, 0, 0, 0
  elsif match = css_string.match(/^rgba\(#{COLOR_MATCH},#{COLOR_MATCH},#{COLOR_MATCH},#{FLOAT_MATCH}\)$/)
    # 'rgba(n,n,n,n)' notation
    new _flatten_percentage(match[1]), _flatten_percentage(match[2]), _flatten_percentage(match[3]), match[4].to_f
  else
    super css_string
  end
end

Instance Method Details

#to_css ⇒ Object

Returns the color as a css rgba string e.g. 'rgba(14,20,40,0.4)'.



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# File 'lib/iq/color/rgba.rb', line 15

def to_css
  'rgba(%d,%d,%d,%s)' % [red, green, blue, alpha]
end