elm/libraries/Graphics/Color.elm

module Graphics.Color (rgba,rgb,hsva,hsv,
                       complement,
                       red,lime,blue,
                       yellow,cyan,magenta,
                       maroon,navy,green,
                       teal,purple,
                       violet,forestGreen,
                       black,white,gray,grey,
                       linear,radial) where

data Color = Color Int Int Int Float

-- Create RGB colors with an alpha component for transparency. The alpha component is specified with numbers between 0 and 1.
rgba : Int -> Int -> Int -> Float -> Color
rgba = Color

-- Create RGB colors from numbers between 0 and 255 inclusive.
rgb : Int -> Int -> Int -> Color
rgb r g b = Color r g b 1

red  : Color
red  = Color 255  0   0  1
lime : Color
lime = Color  0  255  0  1
blue : Color
blue = Color  0   0  255 1

yellow  : Color
yellow  = Color 255 255  0  1
cyan    : Color
cyan    = Color  0  255 255 1
magenta : Color
magenta = Color 255  0  255 1

black : Color
black = Color  0   0   0  1
white : Color
white = Color 255 255 255 1

gray : Color
gray = Color 128 128 128 1
grey : Color
grey = Color 128 128 128 1

maroon : Color
maroon = Color 128  0   0  1
navy   : Color
navy   = Color  0   0  128 1
green  : Color
green  = Color  0  128  0  1

teal   : Color
teal   = Color  0  128 128 1
purple : Color
purple = Color 128  0  128 1

violet : Color
violet = Color 238 130 238 1
forestGreen : Color
forestGreen = Color 34 139 34 1

-- Produce a “complementary color”.
-- The two colors will accent each other.
complement : Color -> Color

-- Create HSV colors with an alpha component for transparency.
-- The alpha component is specified with numbers between 0 and 1.
hsva : Int -> Float -> Float -> Float -> Color

-- Create HSV colors. HSV stands for hue-saturation-value.
--
-- Hue is a degree from 0 to 360 representing a color wheel: red at 0°,
-- green at 120°, blue at 240°, and red again at 360°.
-- This makes it easy to cycle through colors and compute color complements,
-- triads, tetrads, etc.
--
-- Saturation is a number between 1 and 0 where lowering this number makes
-- your color more grey. This can help you tone a color down.
--
-- Value is also a number between 1 and 0. Lowering this number makes your
-- color more black.
--
-- Look up the “HSV cylinder” for more information.
hsv : Int -> Float -> Float -> Color

data Gradient
  = Linear (Float,Float) (Float,Float) [(Float,Color)]
  | Radial (Float,Float) Float (Float,Float) Float [(Float,Color)]

linear : (Number,Number) -> (Number,Number) -> [(Float,Color)] -> Gradient
linear = Linear
radial : (Number,Number) -> Number ->
         (Number,Number) -> Number -> [(Float,Color)] -> Gradient
radial = Radial