Color.hs

module Graphics.Vty.Attributes.Color where
import Data.Word

-- | Abstract data type representing a color.
--
-- Currently the foreground and background color are specified as points in either a:
--
-- * 16 color palette. Where the first 8 colors are equal to the 8 colors of the ISO 6429 (ANSI) 8
-- color palette and the second 8 colors are bright/vivid versions of the first 8 colors.
--
-- * 240 color palette. This palette is a regular sampling of the full RGB colorspace for the first
-- 224 colors. The remaining 16 colors is a greyscale palette.
--
-- The 8 ISO 6429 (ANSI) colors are as follows:
--
-- 0. black
--
-- 1. red
--
-- 2. green
--
-- 3. yellow
--
-- 4. blue
--
-- 5. magenta
--
-- 6. cyan
--
-- 7. white
--
-- The mapping from points in the 240 color palette to colors actually displayable by the terminal
-- depends on the number of colors the terminal claims to support. Which is usually determined by
-- the terminfo "colors" property. If this property is not being accurately reported then the color
-- reproduction will be incorrect.
--
-- If the terminal reports <= 16 colors then the 240 color palette points are only mapped to the 8
-- color pallete. I'm not sure of the RGB points for the "bright" colors which is why they are not
-- addressable via the 240 color palette.
--
-- If the terminal reports > 16 colors then the 240 color palette points are mapped to the nearest
-- points in a ("color count" - 16) subsampling of the 240 color palette.
--
-- All of this assumes the terminals are behaving similarly to xterm and rxvt when handling colors.
-- And that the individual colors have not been remapped by the user. There may be a way to verify
-- this through terminfo but I don't know it.
--
-- Seriously, terminal color support is INSANE.
data Color = ISOColor !Word8 | Color240 !Word8
deriving ( Eq, Show )