postcss-colorblind/src/color-transformer.js

A PostCSS plugin to help you see your site as a colorblind person would.

var onecolor = require('onecolor');
var colorblind = require('color-blind');
var hsl = require('hsl-regex');
var hsla = require('hsla-regex');
var rgb = require('rgb-regex');
var rgba = require('rgba-regex');
var hex = require('hex-color-regex');
var hexa = require('hexa-color-regex');
var names = require('css-color-names');

var supportedMethods = {
  hex: 'hex',
  hexa: 'cssa',
  named: 'hex',
  rgb: 'css',
  hsl: 'css',
  rgba: 'cssa',
  hsla: 'cssa'
};

function transform(inputToken, method) {
  var token = inputToken.toLowerCase();
  var ans, type;

  if (hsl().test(token)) {
    type = 'hsl';
  }
  else if (hsla().test(token)) {
    type = 'hsla';
  }
  else if (rgb().test(token)) {
    type = 'rgb';
  }
  else if (rgba().test(token)) {
    type = 'rgba';
  }
  else if (hex({strict:true}).test(token)) {
    type = 'hex';
  }
  else if (hexa({strict:true}).test(token)) {
    type = 'hexa';
  }
  else if (names[token]) {
    type = 'named';
  }
  else {
    return inputToken;
  }
  return _applyColorTransform(token, type, method);
}

function _applyColorTransform(color, type, colorblindTransform) {
  var preTransformColor;
  var opacity;
  if (type === 'hexa') {
    var hexaObject = _separateHexa(color);
    preTransformColor = onecolor(hexaObject.hex);
    opacity = hexaObject.opacity;
  }
  else {
    preTransformColor = onecolor(color)
    opacity = preTransformColor.alpha();
  }
  var colorblindHex = colorblind[colorblindTransform](preTransformColor.hex());
  var postTransformColor = onecolor(colorblindHex);
  var opacityAppliedColor = postTransformColor.alpha(opacity);
  return opacityAppliedColor[supportedMethods[type]]();
}

function _separateHexa(hexa) {
  var opacityHex;
  var colorHex;
  if (hexa.length > 5) {
    opacityHex = hexa.substr(-2);
    colorHex = hexa.substr(-8, 6);
  }
  else {
    opacityHex = hexa.substr(-1);
    opacityHex += opacityHex;
    colorHex = hexa.substr(-4, 3);
  }
  return {
    hex: colorHex,
    opacity: Math.round((parseInt(opacityHex, 16) / 255) * 100) / 100,
  };
}

module.exports = transform;