elm/libraries/Native/Color.js

Elm.Native.Color = {};
Elm.Native.Color.make = function(elm) {
 elm.Native = elm.Native || {};
 if (elm.Native.Color) return elm.Native.Color;

 var Utils = Elm.Native.Utils.make(elm);

 function complement(rgb) {
     var hsv = toHSV(rgb);
     hsv.hue = (hsv.hue + 180) % 360;
     return toRGB(hsv);
 }

 function hsva(h,s,v,a) {
     var degree = A2(Utils.mod, h * 180 / Math.PI, 360);
     var clr = toRGB({hue:degree, saturation:s, value:v});
     clr._3 = a;
     return clr;
 }

 function hsv(h,s,v) {
     var degree = A2(Utils.mod, h * 180 / Math.PI, 360);
     return toRGB({hue:degree, saturation:s, value:v});
 }

 function toHSV(rgb) {
  var hsv = {};
  var r = rgb._0 / 255.0, g = rgb._1 / 255.0, b = rgb._2 / 255.0;
  var M = Math.max(r,g,b);
  var m = Math.min(r,g,b);
  var c = M - m;

  var h = 0;
       if (c === 0) { h = 0; }
  else if (M === r) { h = ((g - b) / c) % 6; }
  else if (M === g) { h = ((b - r) / c) + 2; }
  else if (M === b) { h = ((r - g) / c) + 4; }
  h *= 60;

  return { value : M, hue : h, saturation : (M === 0 ? 0 : c / M) };
 }

 function between(lo,hi,x) { return lo <= x && x < hi; }
 function norm(n) { return Math.round(n*255); }

 function toRGB(hsv) {
  var c = hsv.value * hsv.saturation;
  var hue = hsv.hue / 60;
  var x = c * (1 - Math.abs((hue % 2) - 1));
  var r = 0, g = 0, b = 0;
       if (between(0,1,hue)) { r = c; g = x; b = 0; }
  else if (between(1,2,hue)) { r = x; g = c; b = 0; }
  else if (between(2,3,hue)) { r = 0; g = c; b = x; }
  else if (between(3,4,hue)) { r = 0; g = x; b = c; }
  else if (between(4,5,hue)) { r = x; g = 0; b = c; }
  else if (between(5,6,hue)) { r = c; g = 0; b = x; }

  var m = hsv.value - c;
  return { ctor:"Color", _0:norm(r+m), _1:norm(g+m), _2:norm(b+m), _3:1 };
 }

 return elm.Native.Color = {
    hsva:F4(hsva),
    hsv:F3(hsv),
    complement:complement
 };

};