# Difference between revisions of "Library for colours"

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+ | Simple thing for working on colours in the RGB colours space. (The intention being that each component is in the interval 0 <= x <= 1.) You could just use tuples, but this library provides simple colour arithmetic. |
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<haskell> |
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## Revision as of 15:54, 12 April 2007

Simple thing for working on colours in the RGB colours space. (The intention being that each component is in the interval 0 <= x <= 1.) You could just use tuples, but this library provides simple colour arithmetic.

```
module Colour where
data Colour = Colour {red, green, blue :: Double} deriving (Eq, Show)
cmap :: (Double -> Double) -> Colour -> Colour
cmap f (Colour r g b) = Colour (f r) (f g) (f b)
czip :: (Double -> Double -> Double) -> Colour -> Colour -> Colour
czip f (Colour r1 g1 b1) (Colour r2 g2 b2) = Colour (f r1 r2) (f g1 g2) (f b1 b2)
cfold :: (Double -> Double -> Double) -> Colour -> Double
cfold f (Colour r g b) = r `f` g `f` b
cpromote :: Double -> Colour
cpromote x = Colour x x x
instance Num Colour where
(+) = czip (+)
(-) = czip (-)
(*) = czip (*)
negate = cmap negate
abs = cmap abs
signum = cmap signum
fromInteger x = cpromote (fromInteger x)
instance Fractional Colour where
(/) = czip (/)
recip = cmap recip
fromRational x = cpromote (fromRational x)
clip :: (Num n, Ord n) => n -> n
clip n
| n < 0 = 0
| n > 1 = 1
| otherwise = n
cclip :: Colour -> Colour
cclip = cmap clip
quantinize :: Int -> Double -> Int
quantinize max v = floor (v * (fromIntegral max))
```