elm/libraries/Color.elm

module Color where

{-| Library for working with colors. Includes
[RGB](https://en.wikipedia.org/wiki/RGB_color_model) and
[HSV](http://en.wikipedia.org/wiki/HSL_and_HSV) creation, gradients, and
built-in names.

# Creation
@docs rgb, rgba, hsv, hsva, greyscale, grayscale

# From Other Colors
@docs complement

# Gradients
@docs linear, radial

# Built-in Colors
These colors come from the [Tango
palette](http://tango.freedesktop.org/Tango_Icon_Theme_Guidelines)
which provides aesthetically reasonable defaults for colors. Each color also
comes with a light and dark version.

### Standard
@docs red, orange, yellow, green, blue, purple, brown

### Light
@docs lightRed, lightOrange, lightYellow, lightGreen, lightBlue, lightPurple,
    lightBrown

### Dark
@docs darkRed, darkOrange, darkYellow, darkGreen, darkBlue, darkPurple,
    darkBrown

### Eight Shades of Grey
These colors are a compatible series of shades of grey, fitting nicely
with the Tango palette.
@docs white, lightGrey, grey, darkGrey, lightCharcoal, charcoal, darkCharcoal, black

These are identical to the *grey* versions. It seems the spelling is regional, but
that has never helped me remember which one I should be writing.
@docs lightGray, gray, darkGray

-}

import Native.Color
import Basics ((-))

data Color = Color Int Int Int Float

{-| Create RGB colors with an alpha component for transparency.
The alpha component is specified with numbers between 0 and 1. -}
rgba : Int -> Int -> Int -> Float -> Color
rgba = Color

{-| Create RGB colors from numbers between 0 and 255 inclusive. -}
rgb : Int -> Int -> Int -> Color
rgb r g b = Color r g b 1

lightRed    : Color
lightRed    = Color 239 41 41 1
red    : Color
red    = Color 204  0  0 1
darkRed    : Color
darkRed    = Color 164  0  0 1

lightOrange : Color
lightOrange = Color 252 175 62 1
orange : Color
orange = Color 245 121  0 1
darkOrange : Color
darkOrange = Color 206  92  0 1

lightYellow : Color
lightYellow = Color 255 233 79 1
yellow : Color
yellow = Color 237 212  0 1
darkYellow : Color
darkYellow = Color 196 160  0 1

lightGreen  : Color
lightGreen  = Color 138 226  52 1
green  : Color
green  = Color 115 210  22 1
darkGreen  : Color
darkGreen  = Color  78 154   6 1

lightBlue   : Color
lightBlue   = Color 114 159 207 1
blue   : Color
blue   = Color  52 101 164 1
darkBlue   : Color
darkBlue   = Color  32  74 135 1

lightPurple : Color
lightPurple = Color 173 127 168 1
purple : Color
purple = Color 117  80 123 1
darkPurple : Color
darkPurple = Color  92  53 102 1

lightBrown  : Color
lightBrown  = Color 233 185 110 1
brown  : Color
brown  = Color 193 125  17 1
darkBrown  : Color
darkBrown  = Color 143  89   2 1

black         : Color
black         = Color  0   0   0  1
white         : Color
white         = Color 255 255 255 1

lightGrey     : Color
lightGrey     = Color 238 238 236 1
grey          : Color
grey          = Color 211 215 207 1
darkGrey      : Color
darkGrey      = Color 186 189 182 1

lightGray : Color
lightGray = Color 238 238 236 1
gray      : Color
gray      = Color 211 215 207 1
darkGray  : Color
darkGray  = Color 186 189 182 1

lightCharcoal : Color
lightCharcoal = Color 136 138 133 1
charcoal      : Color
charcoal      = Color  85  87  83 1
darkCharcoal  : Color
darkCharcoal  = Color  46  52  54 1

{-| Produce a gray based on the input. 0 is white, 1 is black. -}
grayscale : Float -> Color
grayscale p = hsv 0 0 (1-p)

greyscale : Float -> Color
greyscale p = hsv 0 0 (1-p)

{-| Produce a “complementary color”.
The two colors will accent each other. -}
complement : Color -> Color
complement = Native.Color.complement

{-| Create [HSV colors](http://en.wikipedia.org/wiki/HSL_and_HSV)
with an alpha component for transparency. -}
hsva : Float -> Float -> Float -> Float -> Color
hsva = Native.Color.hsva

{-| Create [HSV colors](http://en.wikipedia.org/wiki/HSL_and_HSV).  This is very
convenient for creating colors that cycle and shift.  Hue is an angle and should
be given in standard Elm angles (radians). -}
hsv : Float -> Float -> Float -> Color
hsv = Native.Color.hsv

data Gradient
  = Linear (Float,Float) (Float,Float) [(Float,Color)]
  | Radial (Float,Float) Float (Float,Float) Float [(Float,Color)]

{-| Create a linear gradient. Takes a start and end point and then a series of
“color stops” that indicate how to interpolate between the start and
end points. See [this example](/edit/examples/Elements/LinearGradient.elm) for a
more visual explanation. -}
linear : (number, number) -> (number, number) -> [(Float,Color)] -> Gradient
linear = Linear

{-| Create a radial gradient. First takes a start point and inner radius.  Then
takes an end point and outer radius. It then takes a series of “color
stops” that indicate how to interpolate between the inner and outer
circles. See [this example](/edit/examples/Elements/RadialGradient.elm) for a
more visual explanation. -}
radial : (number,number) -> number -> (number,number) -> number -> [(Float,Color)] -> Gradient
radial = Radial