{-# OPTIONS_HADDOCK hide #-} -- | -- -- Copyright: -- This file is part of the package byline. It is subject to the -- license terms in the LICENSE file found in the top-level -- directory of this distribution and at: -- -- https://github.com/pjones/byline -- -- No part of this package, including this file, may be copied, -- modified, propagated, or distributed except according to the -- terms contained in the LICENSE file. -- -- License: BSD-2-Clause module Byline.Internal.Color ( Color (..), black, red, green, yellow, blue, magenta, cyan, white, rgb, colorAsANSI, colorAsIndex256, colorAsRGB, nearestColor, term256Locations, ) where import Byline.Internal.Types import qualified Data.Colour.CIE as C import qualified Data.Colour.SRGB as C import qualified System.Console.ANSI as ANSI -- | Standard ANSI color by name. -- -- @since 1.0.0.0 black, red, green, yellow, blue, magenta, cyan, white :: Color black = ColorCode ANSI.Black red = ColorCode ANSI.Red green = ColorCode ANSI.Green yellow = ColorCode ANSI.Yellow blue = ColorCode ANSI.Blue magenta = ColorCode ANSI.Magenta cyan = ColorCode ANSI.Cyan white = ColorCode ANSI.White -- | Specify a color using a RGB triplet where each component is in -- the range @[0 .. 255]@. The actual rendered color will depend on -- the terminal. -- -- If the terminal advertises that it supports 256 colors, the color -- given to this function will be converted to the nearest color in -- the 216-color pallet supported by the terminal. (216 colors -- because the first 16 are the standard colors and the last 24 are -- grayscale entries.) -- -- However, if the terminal doesn't support extra colors, or doesn't -- have a @TERMINFO@ entry (e.g., Windows) then the nearest standard -- color will be chosen. -- -- Nearest colors are calculated using their CIE distance from one -- another. -- -- See also: -- -- * -- * -- -- @since 1.0.0.0 rgb :: Word8 -> Word8 -> Word8 -> Color rgb r g b = ColorRGB (r, g, b) -- | Convert a Byline color to an ANSI color. -- -- @since 1.0.0.0 colorAsANSI :: Color -> ANSI.Color colorAsANSI (ColorCode c) = c colorAsANSI (ColorRGB c) = nearestColor c ansiColorLocations -- | Convert a Byline color to an index into a terminal 256-color palette. -- -- @since 1.0.0.0 colorAsIndex256 :: Color -> Word8 colorAsIndex256 = \case ColorCode c -> ANSI.xtermSystem ANSI.Dull c ColorRGB c -> nearestColor c term256Locations -- | Convert a Byline color to a 'C.Colour'. If the color is -- specified using an ANSI color name then return that color code -- instead. This allows the terminal to pick the color on its own. -- -- @since 1.0.0.0 colorAsRGB :: Color -> Either ANSI.Color (C.Colour Float) colorAsRGB = \case ColorCode c -> Left c ColorRGB (r, g, b) -> Right (C.sRGB24 r g b) -- | Find the nearest color given a full RGB color. -- -- @since 1.0.0.0 nearestColor :: Bounded a => -- | Original color. (Word8, Word8, Word8) -> -- | List of colors and locations. [(a, (Double, Double, Double))] -> -- | Destination color. a nearestColor (r, g, b) table = case listToMaybe (sortColors $ distances table) of Nothing -> minBound -- Should never happen. Just (c, _) -> c where location :: (Double, Double, Double) location = C.cieXYZView (C.sRGB24 r g b) distance :: (Double, Double, Double) -> (Double, Double, Double) -> Double distance (x1, y1, z1) (x2, y2, z2) = sqrt ((x ** 2) + (y ** 2) + (z ** 2)) where x = x1 - x2 y = y1 - y2 z = z1 - z2 distances :: [(a, (Double, Double, Double))] -> [(a, Double)] distances = map (second (distance location)) sortColors :: [(a, Double)] -> [(a, Double)] sortColors = sortBy (comparing snd) -- | Get the CIE locations for the standard ANSI colors. -- -- Locations are based on the default xterm colors. See also: -- -- * -- * -- -- @since 1.0.0.0 ansiColorLocations :: [(ANSI.Color, (Double, Double, Double))] ansiColorLocations = [ (ANSI.Black, (0.0, 0.0, 0.0)), (ANSI.Red, (0.2518, 0.1298, 0.0118)), (ANSI.Green, (0.2183, 0.4366, 0.0728)), (ANSI.Yellow, (0.4701, 0.5664, 0.0846)), (ANSI.Blue, (0.1543, 0.0617, 0.8126)), (ANSI.Magenta, (0.3619, 0.1739, 0.592)), (ANSI.Cyan, (0.3285, 0.4807, 0.653)), (ANSI.White, (0.7447, 0.7835, 0.8532)) ] -- | All of the allowed colors for 256 color terminals. -- -- @since 1.0.0.0 term256Locations :: [(Word8, (Double, Double, Double))] term256Locations = zipWith (\c i -> (i, C.cieXYZView c)) colors [16 ..] where colors :: [C.Colour Double] colors = do r <- [0.0, 0.2 .. 1.0] g <- [0.0, 0.2 .. 1.0] b <- [0.0, 0.2 .. 1.0] return (C.sRGB r g b)