index.mjs

/**
 * @module color-parse
 */
import names from 'color-name'

export default parse

/**
 * Base hues
 * http://dev.w3.org/csswg/css-color/#typedef-named-hue
 */
//FIXME: use external hue detector
var baseHues = {
	red: 0,
	orange: 60,
	yellow: 120,
	green: 180,
	blue: 240,
	purple: 300
}

/**
 * Parse color from the string passed
 *
 * @return {Object} A space indicator `space`, an array `values` and `alpha`
 */
function parse (cstr) {
	var m, parts = [], alpha = 1, space

	if (typeof cstr === 'string') {
		//keyword
		if (names[cstr]) {
			parts = names[cstr].slice()
			space = 'rgb'
		}

		//reserved words
		else if (cstr === 'transparent') {
			alpha = 0
			space = 'rgb'
			parts = [0,0,0]
		}

		//hex
		else if (/^#[A-Fa-f0-9]+$/.test(cstr)) {
			var base = cstr.slice(1)
			var size = base.length
			var isShort = size <= 4
			alpha = 1

			if (isShort) {
				parts = [
					parseInt(base[0] + base[0], 16),
					parseInt(base[1] + base[1], 16),
					parseInt(base[2] + base[2], 16)
				]
				if (size === 4) {
					alpha = parseInt(base[3] + base[3], 16) / 255
				}
			}
			else {
				parts = [
					parseInt(base[0] + base[1], 16),
					parseInt(base[2] + base[3], 16),
					parseInt(base[4] + base[5], 16)
				]
				if (size === 8) {
					alpha = parseInt(base[6] + base[7], 16) / 255
				}
			}

			if (!parts[0]) parts[0] = 0
			if (!parts[1]) parts[1] = 0
			if (!parts[2]) parts[2] = 0

			space = 'rgb'
		}

		//color space
		else if (m = /^((?:rgb|hs[lvb]|hwb|cmyk?|xy[zy]|gray|lab|lchu?v?|[ly]uv|lms)a?)\s*\(([^\)]*)\)/.exec(cstr)) {
			var name = m[1]
			var isRGB = name === 'rgb'
			var base = name.replace(/a$/, '')
			space = base
			var size = base === 'cmyk' ? 4 : base === 'gray' ? 1 : 3
			parts = m[2].trim()
				.split(/\s*[,\/]\s*|\s+/)
				.map(function (x, i) {
					//<percentage>
					if (/%$/.test(x)) {
						//alpha
						if (i === size)	return parseFloat(x) / 100
						//rgb
						if (base === 'rgb') return parseFloat(x) * 255 / 100
						return parseFloat(x)
					}
					//hue
					else if (base[i] === 'h') {
						//<deg>
						if (/deg$/.test(x)) {
							return parseFloat(x)
						}
						//<base-hue>
						else if (baseHues[x] !== undefined) {
							return baseHues[x]
						}
					}
					return parseFloat(x)
				})

			if (name === base) parts.push(1)
			alpha = (isRGB) ? 1 : (parts[size] === undefined) ? 1 : parts[size]
			parts = parts.slice(0, size)
		}

		//named channels case
		else if (cstr.length > 10 && /[0-9](?:\s|\/)/.test(cstr)) {
			parts = cstr.match(/([0-9]+)/g).map(function (value) {
				return parseFloat(value)
			})

			space = cstr.match(/([a-z])/ig).join('').toLowerCase()
		}
	}

	//numeric case
	else if (!isNaN(cstr)) {
		space = 'rgb'
		parts = [cstr >>> 16, (cstr & 0x00ff00) >>> 8, cstr & 0x0000ff]
	}

	//array-like
	else if (Array.isArray(cstr) || cstr.length) {
		parts = [cstr[0], cstr[1], cstr[2]]
		space = 'rgb'
		alpha = cstr.length === 4 ? cstr[3] : 1
	}

	//object case - detects css cases of rgb and hsl
	else if (cstr instanceof Object) {
		if (cstr.r != null || cstr.red != null || cstr.R != null) {
			space = 'rgb'
			parts = [
				cstr.r || cstr.red || cstr.R || 0,
				cstr.g || cstr.green || cstr.G || 0,
				cstr.b || cstr.blue || cstr.B || 0
			]
		}
		else {
			space = 'hsl'
			parts = [
				cstr.h || cstr.hue || cstr.H || 0,
				cstr.s || cstr.saturation || cstr.S || 0,
				cstr.l || cstr.lightness || cstr.L || cstr.b || cstr.brightness
			]
		}

		alpha = cstr.a || cstr.alpha || cstr.opacity || 1

		if (cstr.opacity != null) alpha /= 100
	}

	return {
		space: space,
		values: parts,
		alpha: alpha
	}
}