d3/_site/src/core/hsl.js

A small, free JavaScript library for manipulating documents based on data.

/**
 * @param {number=} s
 * @param {number=} l
 */
d3.hsl = function(h, s, l) {
  return arguments.length == 1
      ? d3_rgb_parse("" + h, d3_rgb_hsl, d3_hsl)
      : d3_hsl(+h, +s, +l);
};

function d3_hsl(h, s, l) {
  return {h: h, s: s, l: l, toString: d3_hsl_format};
}

/** @this d3_hsl */
function d3_hsl_format() {
  return "hsl(" + this.h + "," + this.s * 100 + "%," + this.l * 100 + "%)";
}

function d3_hsl_rgb(h, s, l) {
  var m1,
      m2;

  /* Some simple corrections for h, s and l. */
  h = h % 360; if (h < 0) h += 360;
  s = s < 0 ? 0 : s > 1 ? 1 : s;
  l = l < 0 ? 0 : l > 1 ? 1 : l;

  /* From FvD 13.37, CSS Color Module Level 3 */
  m2 = l <= .5 ? l * (1 + s) : l + s - l * s;
  m1 = 2 * l - m2;

  function v(h) {
    if (h > 360) h -= 360;
    else if (h < 0) h += 360;
    if (h < 60) return m1 + (m2 - m1) * h / 60;
    if (h < 180) return m2;
    if (h < 240) return m1 + (m2 - m1) * (240 - h) / 60;
    return m1;
  }

  function vv(h) {
    return Math.round(v(h) * 255);
  }

  return d3_rgb(vv(h + 120), vv(h), vv(h - 120));
}