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| var BKDRHash = require('./bkdr-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 || BKDRHash;
};
/**
* 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;
|