Class: Color::RGB

Inherits:
Object
  • Object
show all
Defined in:
lib/color/rgb.rb,
lib/color.rb,
lib/color/rgb-colors.rb

Overview

An RGB colour object.

Defined Under Namespace

Modules: Metallic

Constant Summary collapse

PDF_FORMAT_STR =

The format of a DeviceRGB colour for PDF. In color-tools 2.0 this will be removed from this package and added back as a modification by the PDF::Writer package.

"%.3f %.3f %.3f %s"
AliceBlue = 
Color::RGB.new(0xf0, 0xf8, 0xff)
AntiqueWhite = 
Color::RGB.new(0xfa, 0xeb, 0xd7)
Aqua = 
Color::RGB.new(0x00, 0xff, 0xff)
Aquamarine = 
Color::RGB.new(0x7f, 0xff, 0xd4)
Azure = 
Color::RGB.new(0xf0, 0xff, 0xff)
Beige = 
Color::RGB.new(0xf5, 0xf5, 0xdc)
Bisque = 
Color::RGB.new(0xff, 0xe4, 0xc4)
Black = 
Color::RGB.new(0, 0, 0)
BlanchedAlmond = 
Color::RGB.new(0xff, 0xeb, 0xcd)
Blue = 
Color::RGB.new(0x00, 0x00, 0xff)
BlueViolet = 
Color::RGB.new(0x8a, 0x2b, 0xe2)
Brown = 
Color::RGB.new(0xa5, 0x2a, 0x2a)
BurlyWood = 
Color::RGB.new(0xde, 0xb8, 0x87)
Burlywood = 
BurlyWood
CadetBlue = 
Color::RGB.new(0x5f, 0x9e, 0xa0)
Carnation = 
Color::RGB.new(0xff, 0x5e, 0xd0)
Cayenne = 
Color::RGB.new(0x8d, 0x00, 0x00)
Chartreuse = 
Color::RGB.new(0x7f, 0xff, 0x00)
Chocolate = 
Color::RGB.new(0xd2, 0x69, 0x1e)
Coral = 
Color::RGB.new(0xff, 0x7f, 0x50)
CornflowerBlue = 
Color::RGB.new(0x64, 0x95, 0xed)
Cornsilk = 
Color::RGB.new(0xff, 0xf8, 0xdc)
Crimson = 
Color::RGB.new(0xdc, 0x14, 0x3c)
Cyan = 
Color::RGB.new(0x00, 0xff, 0xff)
DarkBlue = 
Color::RGB.new(0x00, 0x00, 0x8b)
DarkCyan = 
Color::RGB.new(0x00, 0x8b, 0x8b)
DarkGoldenRod = 
Color::RGB.new(0xb8, 0x86, 0x0b)
DarkGoldenrod = 
DarkGoldenRod
DarkGray = 
Color::RGB.new(0xa9, 0xa9, 0xa9)
DarkGreen = 
Color::RGB.new(0x00, 0x64, 0x00)
DarkGrey = 
DarkGray
DarkKhaki = 
Color::RGB.new(0xbd, 0xb7, 0x6b)
DarkMagenta = 
Color::RGB.new(0x8b, 0x00, 0x8b)
DarkOliveGreen = 
Color::RGB.new(0x55, 0x6b, 0x2f)
DarkOrange = 
Color::RGB.new(0xff, 0x8c, 0x00)
DarkOrchid = 
Color::RGB.new(0x99, 0x32, 0xcc)
DarkRed = 
Color::RGB.new(0x8b, 0x00, 0x00)
DarkSalmon = 
Color::RGB.new(0xe9, 0x96, 0x7a)
DarkSeaGreen = 
Color::RGB.new(0x8f, 0xbc, 0x8f)
DarkSlateBlue = 
Color::RGB.new(0x48, 0x3d, 0x8b)
DarkSlateGray = 
Color::RGB.new(0x2f, 0x4f, 0x4f)
DarkSlateGrey = 
DarkSlateGray
DarkTurquoise = 
Color::RGB.new(0x00, 0xce, 0xd1)
DarkViolet = 
Color::RGB.new(0x94, 0x00, 0xd3)
DarkoliveGreen = 
DarkOliveGreen
Darkorange = 
Color::RGB.new(0xff, 0x8c, 0x00)
Darksalmon = 
DarkSalmon
DeepPink = 
Color::RGB.new(0xff, 0x14, 0x93)
DeepSkyBlue = 
Color::RGB.new(0x00, 0xbf, 0xbf)
DimGray = 
Color::RGB.new(0x69, 0x69, 0x69)
DimGrey = 
DimGray
DodgerBlue = 
Color::RGB.new(0x1e, 0x90, 0xff)
Feldspar = 
Color::RGB.new(0xd1, 0x92, 0x75)
FireBrick = 
Color::RGB.new(0xb2, 0x22, 0x22)
Firebrick = 
FireBrick
FloralWhite = 
Color::RGB.new(0xff, 0xfa, 0xf0)
ForestGreen = 
Color::RGB.new(0x22, 0x8b, 0x22)
Fuchsia = 
Color::RGB.new(0xff, 0x00, 0xff)
Gainsboro = 
Color::RGB.new(0xdc, 0xdc, 0xdc)
GhostWhite = 
Color::RGB.new(0xf8, 0xf8, 0xff)
Gold = 
Color::RGB.new(0xff, 0xd7, 0x00)
GoldenRod = 
Color::RGB.new(0xda, 0xa5, 0x20)
Goldenrod = 
GoldenRod
Gray = 
Color::RGB.new(0x80, 0x80, 0x80)
Gray10 = 
Color::RGB.from_percentage(10, 10, 10)
Gray20 = 
Color::RGB.from_percentage(20, 20, 20)
Gray30 = 
Color::RGB.from_percentage(30, 30, 30)
Gray40 = 
Color::RGB.from_percentage(40, 40, 40)
Gray50 = 
Color::RGB.from_percentage(50, 50, 50)
Gray60 = 
Color::RGB.from_percentage(60, 60, 60)
Gray70 = 
Color::RGB.from_percentage(70, 70, 70)
Gray80 = 
Color::RGB.from_percentage(80, 80, 80)
Gray90 = 
Color::RGB.from_percentage(90, 90, 90)
Green = 
Color::RGB.new(0x00, 0x80, 0x00)
GreenYellow = 
Color::RGB.new(0xad, 0xff, 0x2f)
Grey = 
Gray
Grey10 = 
Gray10
Grey20 = 
Gray20
Grey30 = 
Gray30
Grey40 = 
Gray40
Grey50 = 
Gray50
Grey60 = 
Gray60
Grey70 = 
Gray70
Grey80 = 
Gray80
Grey90 = 
Gray90
HoneyDew = 
Color::RGB.new(0xf0, 0xff, 0xf0)
Honeydew = 
HoneyDew
HotPink = 
Color::RGB.new(0xff, 0x69, 0xb4)
IndianRed = 
Color::RGB.new(0xcd, 0x5c, 0x5c)
Indigo = 
Color::RGB.new(0x4b, 0x00, 0x82)
Ivory = 
Color::RGB.new(0xff, 0xff, 0xf0)
Khaki = 
Color::RGB.new(0xf0, 0xe6, 0x8c)
Lavender = 
Color::RGB.new(0xe6, 0xe6, 0xfa)
LavenderBlush = 
Color::RGB.new(0xff, 0xf0, 0xf5)
LawnGreen = 
Color::RGB.new(0x7c, 0xfc, 0x00)
LemonChiffon = 
Color::RGB.new(0xff, 0xfa, 0xcd)
LightBlue = 
Color::RGB.new(0xad, 0xd8, 0xe6)
LightCoral = 
Color::RGB.new(0xf0, 0x80, 0x80)
LightCyan = 
Color::RGB.new(0xe0, 0xff, 0xff)
LightGoldenRodYellow = 
Color::RGB.new(0xfa, 0xfa, 0xd2)
LightGoldenrodYellow = 
LightGoldenRodYellow
LightGray = 
Color::RGB.new(0xd3, 0xd3, 0xd3)
LightGreen = 
Color::RGB.new(0x90, 0xee, 0x90)
LightGrey = 
LightGray
LightPink = 
Color::RGB.new(0xff, 0xb6, 0xc1)
LightSalmon = 
Color::RGB.new(0xff, 0xa0, 0x7a)
LightSeaGreen = 
Color::RGB.new(0x20, 0xb2, 0xaa)
LightSkyBlue = 
Color::RGB.new(0x87, 0xce, 0xfa)
LightSlateBlue = 
Color::RGB.new(0x84, 0x70, 0xff)
LightSlateGray = 
Color::RGB.new(0x77, 0x88, 0x99)
LightSlateGrey = 
LightSlateGray
LightSteelBlue = 
Color::RGB.new(0xb0, 0xc4, 0xde)
LightYellow = 
Color::RGB.new(0xff, 0xff, 0xe0)
Lightsalmon = 
LightSalmon
LightsteelBlue = 
LightSteelBlue
Lime = 
Color::RGB.new(0x00, 0xff, 0x00)
LimeGreen = 
Color::RGB.new(0x32, 0xcd, 0x32)
Linen = 
Color::RGB.new(0xfa, 0xf0, 0xe6)
Magenta = 
Color::RGB.new(0xff, 0x00, 0xff)
Maroon = 
Color::RGB.new(0x80, 0x00, 0x00)
MediumAquaMarine = 
Color::RGB.new(0x66, 0xcd, 0xaa)
MediumAquamarine = 
MediumAquaMarine
MediumBlue = 
Color::RGB.new(0x00, 0x00, 0xcd)
MediumOrchid = 
Color::RGB.new(0xba, 0x55, 0xd3)
MediumPurple = 
Color::RGB.new(0x93, 0x70, 0xdb)
MediumSeaGreen = 
Color::RGB.new(0x3c, 0xb3, 0x71)
MediumSlateBlue = 
Color::RGB.new(0x7b, 0x68, 0xee)
MediumSpringGreen = 
Color::RGB.new(0x00, 0xfa, 0x9a)
MediumTurquoise = 
Color::RGB.new(0x48, 0xd1, 0xcc)
MediumVioletRed = 
Color::RGB.new(0xc7, 0x15, 0x85)
MidnightBlue = 
Color::RGB.new(0x19, 0x19, 0x70)
MintCream = 
Color::RGB.new(0xf5, 0xff, 0xfa)
MistyRose = 
Color::RGB.new(0xff, 0xe4, 0xe1)
Moccasin = 
Color::RGB.new(0xff, 0xe4, 0xb5)
Color::RGB.new(0xff, 0xde, 0xad)
Color::RGB.new(0x00, 0x00, 0x80)
OldLace = 
Color::RGB.new(0xfd, 0xf5, 0xe6)
Olive = 
Color::RGB.new(0x80, 0x80, 0x00)
OliveDrab = 
Color::RGB.new(0x6b, 0x8e, 0x23)
Olivedrab = 
OliveDrab
Orange = 
Color::RGB.new(0xff, 0xa5, 0x00)
OrangeRed = 
Color::RGB.new(0xff, 0x45, 0x00)
Orchid = 
Color::RGB.new(0xda, 0x70, 0xd6)
PaleGoldenRod = 
Color::RGB.new(0xee, 0xe8, 0xaa)
PaleGoldenrod = 
PaleGoldenRod
PaleGreen = 
Color::RGB.new(0x98, 0xfb, 0x98)
PaleTurquoise = 
Color::RGB.new(0xaf, 0xee, 0xee)
PaleVioletRed = 
Color::RGB.new(0xdb, 0x70, 0x93)
PapayaWhip = 
Color::RGB.new(0xff, 0xef, 0xd5)
PeachPuff = 
Color::RGB.new(0xff, 0xda, 0xb9)
Peachpuff = 
PeachPuff
Peru = 
Color::RGB.new(0xcd, 0x85, 0x3f)
Pink = 
Color::RGB.new(0xff, 0xc0, 0xcb)
Plum = 
Color::RGB.new(0xdd, 0xa0, 0xdd)
PowderBlue = 
Color::RGB.new(0xb0, 0xe0, 0xe6)
Purple = 
Color::RGB.new(0x80, 0x00, 0x80)
Red = 
Color::RGB.new(0xff, 0x00, 0x00)
RosyBrown = 
Color::RGB.new(0xbc, 0x8f, 0x8f)
RoyalBlue = 
Color::RGB.new(0x41, 0x69, 0xe1)
SaddleBrown = 
Color::RGB.new(0x8b, 0x45, 0x13)
Salmon = 
Color::RGB.new(0xfa, 0x80, 0x72)
SandyBrown = 
Color::RGB.new(0xf4, 0xa4, 0x60)
SeaGreen = 
Color::RGB.new(0x2e, 0x8b, 0x57)
SeaShell = 
Color::RGB.new(0xff, 0xf5, 0xee)
Seashell = 
SeaShell
Sienna = 
Color::RGB.new(0xa0, 0x52, 0x2d)
Silver = 
Color::RGB.new(0xc0, 0xc0, 0xc0)
SkyBlue = 
Color::RGB.new(0x87, 0xce, 0xeb)
SlateBlue = 
Color::RGB.new(0x6a, 0x5a, 0xcd)
SlateGray = 
Color::RGB.new(0x70, 0x80, 0x90)
SlateGrey = 
SlateGray
Snow = 
Color::RGB.new(0xff, 0xfa, 0xfa)
SpringGreen = 
Color::RGB.new(0x00, 0xff, 0x7f)
SteelBlue = 
Color::RGB.new(0x46, 0x82, 0xb4)
Tan = 
Color::RGB.new(0xd2, 0xb4, 0x8c)
Teal = 
Color::RGB.new(0x00, 0x80, 0x80)
Thistle = 
Color::RGB.new(0xd8, 0xbf, 0xd8)
Tomato = 
Color::RGB.new(0xff, 0x63, 0x47)
Turquoise = 
Color::RGB.new(0x40, 0xe0, 0xd0)
Violet = 
Color::RGB.new(0xee, 0x82, 0xee)
VioletRed = 
Color::RGB.new(0xd0, 0x20, 0x90)
Wheat = 
Color::RGB.new(0xf5, 0xde, 0xb3)
White = 
Color::RGB.new(0xff, 0xff, 0xff)
WhiteSmoke = 
Color::RGB.new(0xf5, 0xf5, 0xf5)
Yellow = 
Color::RGB.new(0xff, 0xff, 0x00)
YellowGreen = 
Color::RGB.new(0x9a, 0xcd, 0x32)

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(r = 0, g = 0, b = 0) ⇒ RGB

Creates an RGB colour object from the standard range 0..255.

Color::RGB.new(32, 64, 128)
Color::RGB.new(0x20, 0x40, 0x80)



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# File 'lib/color/rgb.rb', line 68

def initialize(r = 0, g = 0, b = 0)
  @r = r / 255.0
  @g = g / 255.0
  @b = b / 255.0
end

Class Method Details

.from_fraction(r = 0.0, g = 0.0, b = 0.0) ⇒ Object

Creates an RGB colour object from fractional values 0..1.

Color::RGB.from_fraction(.3, .2, .1)



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# File 'lib/color/rgb.rb', line 19

def from_fraction(r = 0.0, g = 0.0, b = 0.0)
  colour = Color::RGB.new
  colour.r = r
  colour.g = g
  colour.b = b
  colour
end

.from_html(html_colour) ⇒ Object

Creates an RGB colour object from an HTML colour descriptor (e.g., "fed" or "#cabbed;".

Color::RGB.from_html("fed")
Color::RGB.from_html("#fed")
Color::RGB.from_html("#cabbed")
Color::RGB.from_html("cabbed")



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# File 'lib/color/rgb.rb', line 34

def from_html(html_colour)
  html_colour = html_colour.gsub(%r{[#;]}, '')
  case html_colour.size
  when 3
    colours = html_colour.scan(%r{[0-9A-Fa-f]}).map { |el| (el * 2).to_i(16) }
  when 6
    colours = html_colour.scan(%r<[0-9A-Fa-f]{2}>).map { |el| el.to_i(16) }
  else
    raise ArgumentError
  end

  Color::RGB.new(*colours)
end

.from_percentage(r = 0, g = 0, b = 0) ⇒ Object

Creates an RGB colour object from percentages 0..100.

Color::RGB.from_percentage(10, 20 30)



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# File 'lib/color/rgb.rb', line 12

def from_percentage(r = 0, g = 0, b = 0)
  from_fraction(r / 100.0, g / 100.0, b / 100.0)
end

Instance Method Details

#+(other) ⇒ Object

Adds another colour to the current colour. The other colour will be converted to RGB before addition. This conversion depends upon a #to_rgb method on the other colour.

The addition is done using the RGB Accessor methods to ensure a valid colour in the result.



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# File 'lib/color/rgb.rb', line 401

def +(other)
  other = other.to_rgb
  rgb = self.dup

  rgb.r += other.r
  rgb.g += other.g
  rgb.b += other.b

  rgb
end

#-(other) ⇒ Object

Subtracts another colour to the current colour. The other colour will be converted to RGB before subtraction. This conversion depends upon a #to_rgb method on the other colour.

The subtraction is done using the RGB Accessor methods to ensure a valid colour in the result.



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# File 'lib/color/rgb.rb', line 418

def -(other)
  other = other.to_rgb
  rgb = self.dup

  rgb.r -= other.r
  rgb.g -= other.g
  rgb.b -= other.b

  rgb
end

#==(other) ⇒ Object

Compares the other colour to this one. The other colour will be converted to RGB before comparison, so the comparison between a RGB colour and a non-RGB colour will be approximate and based on the other colour’s default #to_rgb conversion. If there is no #to_rgb conversion, this will raise an exception. This will report that two RGB colours are equivalent if all component values are within COLOR_TOLERANCE of each other.



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# File 'lib/color/rgb.rb', line 56

def ==(other)
  other = other.to_rgb
  other.kind_of?(Color::RGB) and
  ((@r - other.r).abs <= Color::COLOR_TOLERANCE) and
  ((@g - other.g).abs <= Color::COLOR_TOLERANCE) and
  ((@b - other.b).abs <= Color::COLOR_TOLERANCE)
end

#adjust_brightness(percent) ⇒ Object

Returns a new colour with the brightness adjusted by the specified percentage. Negative percentages will darken the colour; positive percentages will brighten the colour.

Color::RGB::DarkBlue.adjust_brightness(10)
Color::RGB::DarkBlue.adjust_brightness(-10)



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# File 'lib/color/rgb.rb', line 269

def adjust_brightness(percent)
  percent /= 100.0
  percent += 1.0
  percent  = [ percent, 2.0 ].min
  percent  = [ 0.0, percent ].max

  hsl      = to_hsl
  hsl.l   *= percent
  hsl.to_rgb
end

#adjust_hue(percent) ⇒ Object

Returns a new colour with the hue adjusted by the specified percentage. Negative percentages will reduce the hue; positive percentages will increase the hue.

Color::RGB::DarkBlue.adjust_hue(10)
Color::RGB::DarkBlue.adjust_hue(-10)



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# File 'lib/color/rgb.rb', line 303

def adjust_hue(percent)
  percent  /= 100.0
  percent  += 1.0
  percent  = [ percent, 2.0 ].min
  percent  = [ 0.0, percent ].max

  hsl      = to_hsl
  hsl.h   *= percent
  hsl.to_rgb
end

#adjust_saturation(percent) ⇒ Object

Returns a new colour with the saturation adjusted by the specified percentage. Negative percentages will reduce the saturation; positive percentages will increase the saturation.

Color::RGB::DarkBlue.adjust_saturation(10)
Color::RGB::DarkBlue.adjust_saturation(-10)



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# File 'lib/color/rgb.rb', line 286

def adjust_saturation(percent)
  percent  /= 100.0
  percent  += 1.0
  percent  = [ percent, 2.0 ].min
  percent  = [ 0.0, percent ].max

  hsl      = to_hsl
  hsl.s   *= percent
  hsl.to_rgb
end

#b ⇒ Object

Returns the blue component of the colour as a fraction in the range 0.0 .. 1.0.



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# File 'lib/color/rgb.rb', line 378

def b
  @b
end

#b=(bb) ⇒ Object

Sets the blue component of the colour as a fraction in the range 0.0 .. 1.0.



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# File 'lib/color/rgb.rb', line 391

def b=(bb)
  @b = Color.normalize(bb)
end

#blue ⇒ Object

Returns the blue component of the colour in the normal 0 .. 255 range.



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# File 'lib/color/rgb.rb', line 369

def blue
  @b * 255.0
end

#blue=(bb) ⇒ Object

Sets the blue component of the colour in the normal 0 .. 255 range.



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# File 'lib/color/rgb.rb', line 382

def blue=(bb)
  @b = Color.normalize(bb / 255.0)
end

#blue_p ⇒ Object

Returns the blue component of the colour as a percentage.



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# File 'lib/color/rgb.rb', line 373

def blue_p
  @b * 100.0
end

#blue_p=(bb) ⇒ Object

Sets the blue component of the colour as a percentage.



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# File 'lib/color/rgb.rb', line 386

def blue_p=(bb)
  @b = Color.normalize(bb / 100.0)
end

#brightness ⇒ Object

Returns the brightness value for a colour, a number between 0..1. Based on the Y value of YIQ encoding, representing luminosity, or perceived brightness.

This may be modified in a future version of color-tools to use the luminosity value of HSL.



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# File 'lib/color/rgb.rb', line 254

def brightness
  to_yiq.y
end

#css_hsl ⇒ Object

Present the colour as an HSL HTML/CSS colour string (e.g., “hsl(180, 25%, 35%)”). Note that this will perform a #to_hsl operation using the default conversion formula.



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# File 'lib/color/rgb.rb', line 117

def css_hsl
  to_hsl.css_hsl
end

#css_hsla ⇒ Object

Present the colour as an HSLA (with alpha) HTML/CSS colour string (e.g., “hsla(180, 25%, 35%, 1)”). Note that this will perform a #to_hsl operation using the default conversion formula.



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# File 'lib/color/rgb.rb', line 124

def css_hsla
  to_hsl.css_hsla
end

#css_rgb ⇒ Object

Present the colour as an RGB HTML/CSS colour string (e.g., “rgb(0%, 50%, 100%)”). Note that this will perform a #to_rgb operation using the default conversion formula.



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# File 'lib/color/rgb.rb', line 103

def css_rgb
  "rgb(%3.2f%%, %3.2f%%, %3.2f%%)" % [ red_p, green_p, blue_p ]
end

#css_rgba ⇒ Object

Present the colour as an RGBA (with alpha) HTML/CSS colour string (e.g., “rgb(0%, 50%, 100%, 1)”). Note that this will perform a #to_rgb operation using the default conversion formula.



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# File 'lib/color/rgb.rb', line 110

def css_rgba
  "rgba(%3.2f%%, %3.2f%%, %3.2f%%, %3.2f)" % [ red_p, green_p, blue_p, 1 ]
end

#darken_by(percent) ⇒ Object

Mix the RGB hue with Black so that the RGB hue is the specified percentage of the resulting colour. Strictly speaking, this isn’t a darken_by operation.



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# File 'lib/color/rgb.rb', line 231

def darken_by(percent)
  mix_with(Black, percent)
end

#g ⇒ Object

Returns the green component of the colour as a fraction in the range 0.0 .. 1.0.



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# File 'lib/color/rgb.rb', line 351

def g
  @g
end

#g=(gg) ⇒ Object

Sets the green component of the colour as a fraction in the range 0.0 .. 1.0.



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# File 'lib/color/rgb.rb', line 364

def g=(gg)
  @g = Color.normalize(gg)
end

#green ⇒ Object

Returns the green component of the colour in the normal 0 .. 255 range.



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# File 'lib/color/rgb.rb', line 342

def green
  @g * 255.0
end

#green=(gg) ⇒ Object

Sets the green component of the colour in the normal 0 .. 255 range.



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# File 'lib/color/rgb.rb', line 355

def green=(gg)
  @g = Color.normalize(gg / 255.0)
end

#green_p ⇒ Object

Returns the green component of the colour as a percentage.



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# File 'lib/color/rgb.rb', line 346

def green_p
  @g * 100.0
end

#green_p=(gg) ⇒ Object

Sets the green component of the colour as a percentage.



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# File 'lib/color/rgb.rb', line 359

def green_p=(gg)
  @g = Color.normalize(gg / 100.0)
end

#html ⇒ Object

Present the colour as an HTML/CSS colour string.



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# File 'lib/color/rgb.rb', line 87

def html
  r = (@r * 255).round
  r = 255 if r > 255

  g = (@g * 255).round
  g = 255 if g > 255

  b = (@b * 255).round
  b = 255 if b > 255

  "#%02x%02x%02x" % [ r, g, b ]
end

#inspect ⇒ Object 



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# File 'lib/color/rgb.rb', line 436

def inspect
  "RGB [#{html}]"
end

#lighten_by(percent) ⇒ Object

Mix the RGB hue with White so that the RGB hue is the specified percentage of the resulting colour. Strictly speaking, this isn’t a darken_by operation.



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# File 'lib/color/rgb.rb', line 224

def lighten_by(percent)
  mix_with(White, percent)
end

#max_rgb_as_grayscale ⇒ Object Also known as: max_rgb_as_greyscale

Retrieve the maxmum RGB value from the current colour as a GrayScale colour



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# File 'lib/color/rgb.rb', line 431

def max_rgb_as_grayscale
    Color::GrayScale.from_fraction([@r, @g, @b].max)
end

#mix_with(mask, opacity) ⇒ Object

Mix the mask colour (which must be an RGB object) with the current colour at the stated opacity percentage (0..100).



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# File 'lib/color/rgb.rb', line 237

def mix_with(mask, opacity)
  opacity /= 100.0
  rgb = self.dup

  rgb.r = (@r * opacity) + (mask.r * (1 - opacity))
  rgb.g = (@g * opacity) + (mask.g * (1 - opacity))
  rgb.b = (@b * opacity) + (mask.b * (1 - opacity))

  rgb
end

#pdf_fill ⇒ Object

Present the colour as a DeviceRGB fill colour string for PDF. This will be removed from the default package in color-tools 2.0.



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# File 'lib/color/rgb.rb', line 76

def pdf_fill
  PDF_FORMAT_STR % [ @r, @g, @b, "rg" ]
end

#pdf_stroke ⇒ Object

Present the colour as a DeviceRGB stroke colour string for PDF. This will be removed from the default package in color-tools 2.0.



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# File 'lib/color/rgb.rb', line 82

def pdf_stroke
  PDF_FORMAT_STR % [ @r, @g, @b, "RG" ]
end

#r ⇒ Object

Returns the red component of the colour as a fraction in the range 0.0 .. 1.0.



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# File 'lib/color/rgb.rb', line 324

def r
  @r
end

#r=(rr) ⇒ Object

Sets the red component of the colour as a fraction in the range 0.0 .. 1.0.



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# File 'lib/color/rgb.rb', line 337

def r=(rr)
  @r = Color.normalize(rr)
end

#red ⇒ Object

Returns the red component of the colour in the normal 0 .. 255 range.



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# File 'lib/color/rgb.rb', line 315

def red
  @r * 255.0
end

#red=(rr) ⇒ Object

Sets the red component of the colour in the normal 0 .. 255 range.



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# File 'lib/color/rgb.rb', line 328

def red=(rr)
  @r = Color.normalize(rr / 255.0)
end

#red_p ⇒ Object

Returns the red component of the colour as a percentage.



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# File 'lib/color/rgb.rb', line 319

def red_p
  @r * 100.0
end

#red_p=(rr) ⇒ Object

Sets the red component of the colour as a percentage.



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# File 'lib/color/rgb.rb', line 332

def red_p=(rr)
  @r = Color.normalize(rr / 100.0)
end

#to_cmyk ⇒ Object

Converts the RGB colour to CMYK. Most colour experts strongly suggest that this is not a good idea (some even suggesting that it’s a very bad idea). CMYK represents additive percentages of inks on white paper, whereas RGB represents mixed colour intensities on a black screen.

However, the colour conversion can be done. The basic method is multi-step:

  1. Convert the R, G, and B components to C, M, and Y components.

    c = 1.0 - r
m = 1.0 - g
y = 1.0 - b

  2. Compute the minimum amount of black (K) required to smooth the colour in inks.

    k = min(c, m, y)

  3. Perform undercolour removal on the C, M, and Y components of the colours because less of each colour is needed for each bit of black. Also, regenerate the black (K) based on the undercolour removal so that the colour is more accurately represented in ink.

    c = min(1.0, max(0.0, c - UCR(k)))
m = min(1.0, max(0.0, m - UCR(k)))
y = min(1.0, max(0.0, y - UCR(k)))
k = min(1.0, max(0.0, BG(k)))

The undercolour removal function and the black generation functions return a value based on the brightness of the RGB colour.



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# File 'lib/color/rgb.rb', line 154

def to_cmyk
  c = 1.0 - @r.to_f
  m = 1.0 - @g.to_f
  y = 1.0 - @b.to_f

  k = [c, m, y].min
  k = k - (k * brightness)

  c = [1.0, [0.0, c - k].max].min
  m = [1.0, [0.0, m - k].max].min
  y = [1.0, [0.0, y - k].max].min
  k = [1.0, [0.0, k].max].min

  Color::CMYK.from_fraction(c, m, y, k)
end

#to_grayscale ⇒ Object Also known as: to_greyscale

Convert to grayscale.



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# File 'lib/color/rgb.rb', line 258

def to_grayscale
  Color::GrayScale.from_fraction(to_hsl.l)
end

#to_hsl ⇒ Object

Returns the HSL colour encoding of the RGB value. The conversions here are based on forumlas from www.easyrgb.com/math.php and elsewhere.



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# File 'lib/color/rgb.rb', line 185

def to_hsl
  min   = [ @r, @g, @b ].min
  max   = [ @r, @g, @b ].max
  delta = (max - min).to_f

  lum   = (max + min) / 2.0

  if Color.near_zero?(delta) # close to 0.0, so it's a grey
    hue = 0
    sat = 0
  else
    if Color.near_zero_or_less?(lum - 0.5)
      sat = delta / (max + min).to_f
    else
      sat = delta / (2 - max - min).to_f
    end

    # This is based on the conversion algorithm from
    # http://en.wikipedia.org/wiki/HSV_color_space#Conversion_from_RGB_to_HSL_or_HSV
    # Contributed by Adam Johnson
    sixth = 1 / 6.0
    if @r == max # Color.near_zero_or_less?(@r - max)
      hue = (sixth * ((@g - @b) / delta))
      hue += 1.0 if @g < @b
    elsif @g == max # Color.near_zero_or_less(@g - max)
      hue = (sixth * ((@b - @r) / delta)) + (1.0 / 3.0)
    elsif @b == max # Color.near_zero_or_less?(@b - max)
      hue = (sixth * ((@r - @g) / delta)) + (2.0 / 3.0)
    end

    hue += 1 if hue < 0
    hue -= 1 if hue > 1
  end
  Color::HSL.from_fraction(hue, sat, lum)
end

#to_rgb(ignored = nil) ⇒ Object 



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# File 'lib/color/rgb.rb', line 170

def to_rgb(ignored = nil)
  self
end

#to_yiq ⇒ Object

Returns the YIQ (NTSC) colour encoding of the RGB value.



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# File 'lib/color/rgb.rb', line 175

def to_yiq
  y = (@r * 0.299) + (@g *  0.587) + (@b *  0.114)
  i = (@r * 0.596) + (@g * -0.275) + (@b * -0.321)
  q = (@r * 0.212) + (@g * -0.523) + (@b *  0.311)
  Color::YIQ.from_fraction(y, i, q)
end