Color convertion

colors.js

/**
 * @param {Array} arr  - [140, 255, 1]
 * @returns {Array} [0.5490196078, 1, 0.003921568627]
 */
export function normalizeArray (arr, value) {
  return arr.map(v => v / value)
}

/**
 * @param {Number} colorNum 0xff00ff
 * @return {String} '#ff00ff'
 */
export function colorNumToStr (colorNum) {
  let c = colorNum.toString(16)
  while (c.length < 6) c = `0${c}`
  return `#${c}`
}

/**
 * @param {String} strColor '#ff00ff'
 * @returns {Number} 0xff00ff
 */
export function colorStrToNum (strColor) {
  return parseInt(`0x${strColor.substring(1, strColor.length)}`, 16)
}

/**
 * Convert array of [255, 255, 255] to [1, 1, 1]
 *
 * @param {Array} arr  - [140, 255, 1]
 * @returns {Array} [0.5490196078, 1, 0.003921568627]
 */
export function normalizeRGB (arr) {
  return normalizeArray(arr, 255)
}

/**
 * Convert rgb values to Hex Number
 * @param  {Number} r - 0 - 255
 * @param  {Number} g - 0 - 255
 * @param  {Number} b - 0 - 255
 * @return {Number}   - 0xffffff | 16777215
 */
export function rgbToHex (r, g, b) {
  return (1 << 24) + (r << 16) + (g << 8) + b
}

/**
 * Convert Hex value to RGB (0 to 255 values)
 *
 * @param  {String|Number} value  - Accepts `#ffffff` and 0xffffff
 * @return {Array}              - [255, 255, 255]
 */
export function hexToRgb (value) {
  const v = typeof value === 'number' ? colorNumToStr(value) : value
  var r = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(v)
  return r ? [parseInt(r[1], 16), parseInt(r[2], 16), parseInt(r[3], 16)] : null
}