canvas-sketch-util/lib/rgba-to-hex.js

Utilities for sketching in Canvas, WebGL and generative art

module.exports = rgbaToHex;
function rgbaToHex (rgba) {
  if (!rgba || !Array.isArray(rgba)) {
    throw new TypeError('Must specify an array to convert into a hex code');
  }

  var r = Math.max(0, Math.min(255, Math.round(rgba[0] || 0)));
  var g = Math.max(0, Math.min(255, Math.round(rgba[1] || 0)));
  var b = Math.max(0, Math.min(255, Math.round(rgba[2] || 0)));

  var alpha = rgba[3];
  if (typeof alpha === 'undefined' || !isFinite(alpha)) {
    alpha = 1;
  }
  var a = Math.max(0, Math.min(255, Math.round(alpha * 255)));
  var alphaParam = a === 255 ? '' : (a | 1 << 8).toString(16).slice(1);
  var result = ((b | g << 8 | r << 16) | 1 << 24).toString(16).slice(1) + alphaParam;
  return '#' + result;
}