chromatism/src/conversions/hsl.js

A simple set of utility functions for colours.

import negativeModulo from '../helpers/negative-modulo'

export default {
  rgb: value => {
    if (value.s === 0) {
      var grey = (value.l / 100) * 255
      return {
        r: grey,
        g: grey,
        b: grey
      }
    } else {
      var tempOne, tempTwo, tempHue
      if (value.l >= 50) {
        tempOne = ((value.l / 100) + (value.s / 100)) - ((value.l / 100) * (value.s / 100))
      } else {
        tempOne = (value.l / 100) * (1 + (value.s / 100))
      }
      tempTwo = (2 * (value.l / 100)) - tempOne
      tempHue = value.h / 360
      var tempR = (tempHue + 0.333) % 1
      var tempG = tempHue
      var tempB = negativeModulo((tempHue - 0.333), 1)
      var r, g, b
      if ((6 * tempR) < 1) {
        r = tempTwo + ((tempOne - tempTwo) * 6 * tempR)
      } else if ((2 * tempR) < 1) {
        r = tempOne
      } else if ((3 * tempR) < 2) {
        r = tempTwo + ((tempOne - tempTwo) * ((0.666 - tempR) * 6))
      } else {
        r = tempTwo
      }
      if ((6 * tempG) < 1) {
        g = tempTwo + ((tempOne - tempTwo) * 6 * tempG)
      } else if ((2 * tempG) < 1) {
        g = tempOne
      } else if ((3 * tempG) < 2) {
        g = tempTwo + ((tempOne - tempTwo) * ((0.666 - tempG) * 6))
      } else {
        g = tempTwo
      }
      if ((6 * tempB) < 1) {
        b = tempTwo + ((tempOne - tempTwo) * 6 * tempB)
      } else if ((2 * tempB) < 1) {
        b = tempOne
      } else if ((3 * tempB) < 2) {
        b = tempTwo + ((tempOne - tempTwo) * ((0.666 - tempB) * 6))
      } else {
        b = tempTwo
      }
      if (r < 0) {
        r = 0
      }
      if (g < 0) {
        g = 0
      }
      if (b < 0) {
        b = 0
      }
      return {
        r: r * 255,
        g: g * 255,
        b: b * 255
      }
    }
  },

  csshsl: value => 'hsl(' + Math.round(value.h) + ',' + Math.round(value.s) + '%,' + Math.round(value.l) + '%)',

  hsv: value => {
    const normalized = Object.assign({}, value, {
      s: value.s / 100,
      l: value.l / 100
    })
    var luminence = normalized.s * (normalized.l < 0.5 ? normalized.l : 1 - normalized.l)

    var h = normalized.h
    var s = (2 * luminence) / (normalized.l + luminence)
    var v = normalized.l + luminence

    return { h: h, s: s * 100, v: v * 100 }
  }
}