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... This Source Code Form is subject to the terms of the Mozilla Public License, v. 2.0.
... If a copy of the MPL was not distributed with this file, You can obtain one at https://mozilla.org/MPL/2.0/.
(.require
[library
[lux (.except)
[abstract
[equivalence (.only Equivalence)]]
[control
[function
[predicate (.only Predicate)]]]
[math
[number
["f" frac]
["[0]" int]]]
[meta
[type
["[0]" nominal]]]]]
[//
["[0]" rgb (.only RGB)]])
(type .public Value
Frac)
(with_template [<value> <name>]
[(def .public <name>
Value
<value>)]
[+0.0 least]
[+1.0 most]
)
(def .public (value? it)
(Predicate Frac)
(not (or (f.< ..least it)
(f.> ..most it))))
(def .public value
(-> Frac
Value)
(|>> (f.max ..least)
(f.min ..most)))
(nominal.def .public HSB
(Record
[#hue Value
#saturation Value
#brightness Value])
(def .public equivalence
(Equivalence HSB)
(implementation
(def (= left right)
(`` (and (,, (with_template [<slot>]
[(f.= (the <slot> (nominal.representation left))
(the <slot> (nominal.representation right)))]
[#hue]
[#saturation]
[#brightness]
)))))))
(with_template [<name> <slot>]
[(def .public <name>
(-> HSB
Value)
(|>> nominal.representation
(the <slot>)))]
[hue #hue]
[saturation #saturation]
[brightness #brightness]
)
(def .public (hsb hue saturation brightness)
(-> Frac Frac Frac
HSB)
(nominal.abstraction
[#hue (..value hue)
#saturation (..value saturation)
#brightness (..value brightness)]))
(def top
(-- rgb.limit))
(def rgb_factor
(|> top .int int.frac))
(def down
(-> Nat
Frac)
(|>> .int int.frac (f./ rgb_factor)))
(def up
(-> Frac
Nat)
(|>> (f.* rgb_factor) f.round f.int .nat))
(def .public (of_rgb it)
(-> RGB
HSB)
(let [red (..down (the rgb.#red it))
green (..down (the rgb.#green it))
blue (..down (the rgb.#blue it))
brightness (all f.max red green blue)
range (all f.min red green blue)
chroma (|> brightness (f.- range))
saturation (if (f.= +0.0 brightness)
+0.0
(|> chroma (f./ brightness)))]
(nominal.abstraction
[#hue (cond (f.= +0.0 chroma)
... Achromatic
+0.0
... Chromatic
(and (f.= brightness red)
(not (f.= red blue)))
(|> green (f.- blue)
(f./ chroma)
(f.+ +0.0)
(f./ +6.0))
(f.= brightness green)
(|> blue (f.- red)
(f./ chroma)
(f.+ +2.0)
(f./ +6.0))
... (f.= brightness blue)
(|> red (f.- green)
(f./ chroma)
(f.+ +4.0)
(f./ +6.0)))
#saturation saturation
#brightness brightness])))
(def .public (rgb it)
(-> HSB
RGB)
(let [[hue saturation brightness] (nominal.representation it)
hue (|> hue (f.* +6.0))
i (f.floor hue)
f (|> hue (f.- i))
p (|> +1.0 (f.- saturation) (f.* brightness))
q (|> +1.0 (f.- (f.* f saturation)) (f.* brightness))
t (|> +1.0 (f.- (|> +1.0 (f.- f) (f.* saturation))) (f.* brightness))
v brightness
mod (|> i (f.% +6.0) f.int .nat)
red (when mod 0 v 1 q 2 p 3 p 4 t 5 v _ (undefined))
green (when mod 0 t 1 v 2 v 3 q 4 p 5 p _ (undefined))
blue (when mod 0 p 1 p 2 t 3 v 4 v 5 q _ (undefined))]
(rgb.rgb (..up red)
(..up green)
(..up blue))))
)
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