Class: Painter::Color

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

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(r, g, b, a = ALPHA_OPAQUE) ⇒ Color

Returns a new instance of Color.



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# File 'lib/painter/color.rb', line 9

def initialize(r, g, b, a = ALPHA_OPAQUE)
  r = self.class.normalize(r, RGB_MAX, :red)
  g = self.class.normalize(g, RGB_MAX, :green)
  b = self.class.normalize(b, RGB_MAX, :blue)
  a = self.class.normalize(a, ALPHA_MAX, :alpha)

  init_with_rgba(self.class.pack(r, g, b, a))
end

Instance Attribute Details

#rgba ⇒ Object (readonly) Also known as: to_i

Returns the value of attribute rgba.



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# File 'lib/painter/color.rb', line 3

def rgba
  @rgba
end

Class Method Details

.normalize(value, max, component = nil) ⇒ Object

:nodoc:



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# File 'lib/painter/color.rb', line 39

def self.normalize(value, max, component = nil)   #:nodoc:
  case value
  when Integer
    (value < 0) ? 0 : (value > max) ? max : value
  when Float
    normalize((value * max).round, max, component)
  when Color
    value.send(component)
  else
    return normalize(value.to_i, max) if value.respond_to?(:to_i)
    raise TypeError
  end
end

.pack(r, g, b, a) ⇒ Object

:nodoc:



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# File 'lib/painter/color.rb', line 25

def self.pack(r, g, b, a)   #:nodoc:
  (a << 24) + (r << 16) + (g << 8) + b
end

Instance Method Details

#alpha ⇒ Object Also known as: a

Return the alpha component of this color (0..ALPHA_MAX).



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# File 'lib/painter/color.rb', line 95

def alpha
  (rgba & 0x7F000000) >> 24
end

#alpha=(value) ⇒ Object Also known as: a=

Modify the alpha component of this color. If this color is associated with a palette entry, this also modifies the palette.



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# File 'lib/painter/color.rb', line 102

def alpha=(value)
  self.rgba = (rgba & ~0xFF000000) |
    (self.class.normalize(value, ALPHA_MAX, :alpha) << 24)
end

#blue ⇒ Object Also known as: b

Return the blue component of this color (0..RGB_MAX).



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# File 'lib/painter/color.rb', line 81

def blue
  rgba & 0x0000FF
end

#green ⇒ Object Also known as: g

Return the green component of this color (0..RGB_MAX).



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# File 'lib/painter/color.rb', line 67

def green
  (rgba & 0x00FF00) >> 8
end

#init_with_rgba(rgba, index = nil, palette = nil) ⇒ Object

:nodoc:



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# File 'lib/painter/color.rb', line 18

def init_with_rgba(rgba, index = nil, palette = nil)  #:nodoc:
  @rgba = rgba
  @index = index
  @palette = palette
  self
end

#red ⇒ Object Also known as: r

Return the red component of this color (0..RGB_MAX).



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# File 'lib/painter/color.rb', line 53

def red
  (rgba & 0xFF0000) >> 16
end

#to_s ⇒ Object 



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# File 'lib/painter/color.rb', line 29

def to_s
  s  = 'RGB'
  s += "A" if alpha != ALPHA_OPAQUE
  s += "[#{@index}]" if @index
  s += '#' + [red, green, blue].map { |e| '%02X' % e }.join('')
  s += '%02X' % alpha if alpha != ALPHA_OPAQUE
  s
end