Colour manipulation class

This is an old class I originally wrote for PHP years ago and then ported to Javascript. I have also written from scratch a similar class in Python, which I intend to use as a base and port back to Javascript as version colour.js version 2. Until then, main documentation is in the source code.

Get the module with npm:

npm install --save colour.js

Import it (Coffeescript syntax):

Colour = require 'colour.js'

You can install the script via bower or download it manually.

bower install --save colour.js

Include the script on your page. In the browser it is attached to the window object.

• A new colour is black by default:

  black = new Colour()

• Array of red, green and blue intensities (float 0~1):

  pink = new Colour [1, 0.7, 0.7]

• Another colour object to make a copy:

  black = new Colour()
  anotherBlack = new Colour black

• Greyscale lightness (float 0~1 where 0 is black, 1 is white):

  lightGrey = new Colour 0.8

• Hex colour string; all of the following are valid:

  red = new Colour '#f00'
  green = new Colour '0f0'
  blue = new Colour '0000ff'
  cyan = new Colour '#00ffff'

• CSS3 colour name (case insensitive):

  greenyellow = new Colour 'greenyellow'
  goldenrod = new Colour 'GOLDENrod'

That's all the constructor supports but you can also make a new colour and then call one of the replacement routines:

reddish = new Colour().hsv 0, 0.8, 0.5

There are various functions which either get or set (replace) the colour. These return the component, array of components or string if called with no arguments or replace the colour if arguments are given. In the case of those with multiple components for example rgb, the values can be given as separate arguments or as an array of the components. When setting a colour, the object being operated on is returned.

• rgb: get or set red, green and blue components as floats 0~1
• rgb255: as rgb but with components as ints 0~255
• rgb100: as rgb but with components as ints 0~100
• r, red, g, green, b, blue: get or set the component as a float 0~1
• hsv: get or set hue (float 0360), saturation (float 01) and value (float 0~1) components
• hsv100: as hsv but with saturation and value components on an int 0~100 scale
• hex: get or set the colour's hex string. When setting can be w ith or without a leading hash and can be in 3 or 6 digit form. When getting, false can be passed to suppress the leading hash.

These only set and don't have a version which gets.

• gr, grey, gray: set red, green and blue components all to the given intensity (float 0~1), defaulting to 0.5

These return a new colour by default, or modify and return the current colour if the last argument is set to false. With no arguments they return a component or other metric.

• h, hue: get or alter the hue (float 0~360)
• s, saturation: get or alter the saturation (float 0~1)
• v, value: get or alter the value (float 0~1)
• shade, sh: get or set the shade. Shade is calculated by summing the red, green and blue components and dividing by 3.

These return a new colour by default, or modify and return the current colour if the last argument is set to false.

• desaturate: shortcut to saturation with 0 as the first argument
• shiftshade, shsh: brighten or darken the colour by moving in a straight line towards black (negative values) or white (positive values), by the given proportion, where -1 will result in black, 0 will result in no change to the colour, 1 will result in white
• shifthue, shh: rotate the hue by the given angle (float 0~360)
• shiftsaturation, shs: saturate or desaturate the colour by the given proportion, where -1 will completely desaturate the colour 0 will cause no change and 1 will completely saturate it
• shiftvalue, shv: lighten or darken the colour by shifting its HSV value by the given proportion, where -1 will result in black, 0 will cause no change and 1 will result in a bright colour
• halfsat, hs: takes either hue (float 0360) and value (float 01) or just value (float 0~1) (using the current colour's hue). Produces a washed out shade of the given lightness.
• mix: mix the current colour with the given colour (Colour object or any single argument the constructor can take) by the given amount (default 0.5)
• xarashade, xs: convenience method to shift saturation and value with arguments which match those in the Xara colour picker's shade editor. The first argument affects saturation (-100 gives full saturation, 0 gives no change, 100 desaturates) and the second affects value (-100 gives black, 0 gives no change, 100 gives a bright colour).

• swatch: return an HTML fragment depicting a colour swatch. Arguments are [bool showhex = true, [string cssclass = ""]].
• rgburl: return a query string in the form r=0&g=0.3&b=1, with red, green and blue components as floats 0~1

• hsvtorgb: takes hue (float 0360), saturation (float 01), value (float 01) or an array of the save components, returns array of red, green and blue components as floats 01
• rgbtohsv: takes red, green and blue components (float 01) or an array of the same, returns array of hue (float 0360), saturation (float 01) and value (float 01)
• hextorgb: takes a colour string in 3 or 6 digit hex notation with or without a leading hash and returns an array of red, green and blue components as floats 0~1
• rgbtohex: takes red, green and blue components (float 0~1) or an array of the same, plus optionally a boolean for whether to include a leading hash (default true) returns the colour as a hex string