Data.Colour.Double

This module provides Colour, which stores linear RGB (red, green, blue) colour values where each channel is a Double. It also provides arithmetic over such colours, and a few predefined colours.

Documentation

data Colour

The main colour type. It stores three channels (red, green and blue) as linear Double values normally ranging from 0 to 1. (0 represents minimum intensity, 1 represents maximum. Black is therefore Colour 0 0 0 and white is Colour 1 1 1.)

The channel values are stored as strict, unboxed fields, so operating on Colours should be quite efficient in time and space.

The Num and Fractional instances provide arithmetic for Colours. Note that (*) acts channel-wise; this is usually what is wanted.

Constructors

Colour

Fields

red :: !Double

green :: !Double

blue :: !Double

Instances

Eq Colour

Fractional Colour

Num Colour

Ord Colour

Show Colour

cmap :: (Double -> Double) -> Colour -> Colour

Apply a function to every channel in a colour. (Mostly used internally, but exposed here in case it may be useful.)

czip :: (Double -> Double -> Double) -> Colour -> Colour -> Colour

This is similar to zipWith. (Mostly used internally, but exposed here in case it may be useful.)

cfold :: (Double -> Double -> Double) -> Colour -> Double

Use a function to collapse a Colour into a Double. No particular order of application is promised.

grey :: Double -> Colour

Turn a Double into a shade of grey.

cscale :: Double -> Colour -> Colour

Scale a Colour by a specified amount. (That is, change the brightness while not affecting the shade.)

clip :: Colour -> Colour

Take a Colour and clip all channels to the range 0--1 inclusive. Any value outside that range will be replaced with the nearest endpoint (i.e., 0 for negative numbers, 1 for positive numbers higher than 1). Values inside the range are unaffected.

unpack :: Colour -> (Double, Double, Double)

Convert a Colour into a tuple.

pack :: (Double, Double, Double) -> Colour

Convert a tuple into a Colour.

cBlack :: Colour

Constant: Black.

cRed :: Colour

Constant: Red.

cYellow :: Colour

Constant: Yellow.

cGreen :: Colour

Constant: Green.

cCyan :: Colour

Constant: Cyan.

cBlue :: Colour

Constant: Blue.

cMagenta :: Colour

Constant: Magenta.

cWhite :: Colour

Constant: White.