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| var stringHash = require('string-hash')
/**
* Convert RGB Array to HEX
*
* @param {Array} RGBArray - [R, G, B]
* @returns {String} 6 digits hex starting with #
*/
var RGB2HEX = function (RGBArray) {
var hex = '#'
RGBArray.forEach(function (value) {
if (value < 16) {
hex += 0
}
hex += value.toString(16)
})
return hex
}
/**
* Convert HSL to RGB
*
* @see {@link http://zh.wikipedia.org/wiki/HSL和HSV色彩空间} for further information.
* @param {Number} H Hue ∈ [0, 360)
* @param {Number} S Saturation ∈ [0, 1]
* @param {Number} L Lightness ∈ [0, 1]
* @returns {Array} R, G, B ∈ [0, 255]
*/
var HSL2RGB = function (H, S, L) {
H /= 360
var q = L < 0.5 ? L * (1 + S) : L + S - L * S
var p = 2 * L - q
return [H + 1 / 3, H, H - 1 / 3].map(function (color) {
if (color < 0) {
color++
}
if (color > 1) {
color--
}
if (color < 1 / 6) {
color = p + (q - p) * 6 * color
} else if (color < 0.5) {
color = q
} else if (color < 2 / 3) {
color = p + (q - p) * 6 * (2 / 3 - color)
} else {
color = p
}
return Math.round(color * 255)
})
}
function isArray (o) {
return Object.prototype.toString.call(o) === '[object Array]'
}
/**
* Color Hash Class
*
* @class
*/
var ColorHash = function (options) {
options = options || {}
var LS = [options.lightness, options.saturation].map(function (param) {
param = param || [0.35, 0.5, 0.65] // note that 3 is a prime
return isArray(param) ? param.concat() : [param]
})
this.L = LS[0]
this.S = LS[1]
if (typeof options.hue === 'number') {
options.hue = {min: options.hue, max: options.hue}
}
if (typeof options.hue === 'object' && !isArray(options.hue)) {
options.hue = [options.hue]
}
if (typeof options.hue === 'undefined') {
options.hue = []
}
this.hueRanges = options.hue.map(function (range) {
return {
min: typeof range.min === 'undefined' ? 0 : range.min,
max: typeof range.max === 'undefined' ? 360 : range.max
}
})
this.hash = options.hash || stringHash
}
/**
* Returns the hash in [h, s, l].
* Note that H ∈ [0, 360); S ∈ [0, 1]; L ∈ [0, 1];
*
* @param {String} str string to hash
* @returns {Array} [h, s, l]
*/
ColorHash.prototype.hsl = function (str) {
var H, S, L
var hash = this.hash(str)
if (this.hueRanges.length) {
var range = this.hueRanges[hash % this.hueRanges.length]
var hueResolution = 727 // note that 727 is a prime
H = ((hash / this.hueRanges.length) % hueResolution) * (range.max - range.min) / hueResolution + range.min
} else {
H = hash % 359 // note that 359 is a prime
}
hash = parseInt(hash / 360)
S = this.S[hash % this.S.length]
hash = parseInt(hash / this.S.length)
L = this.L[hash % this.L.length]
return [H, S, L]
}
/**
* Returns the hash in [r, g, b].
* Note that R, G, B ∈ [0, 255]
*
* @param {String} str string to hash
* @returns {Array} [r, g, b]
*/
ColorHash.prototype.rgb = function (str) {
var hsl = this.hsl(str)
return HSL2RGB.apply(this, hsl)
}
/**
* Returns the hash in hex
*
* @param {String} str string to hash
* @returns {String} hex with #
*/
ColorHash.prototype.hex = function (str) {
var rgb = this.rgb(str)
return RGB2HEX(rgb)
}
module.exports = ColorHash
|