color.js

var Color = function() {
  if (arguments.length == 1)
    [this.r, this.g, this.b] = Color.parse(arguments[0]);
  else if (arguments.length == 3)
    [this.r, this.g, this.b] = arguments;
  else
    throw 'invalid number of arguments, takes one or three arguments';
};

Color.parse = function(color) {
  switch (color.constructor) {
  case String:
    if (/^#?([0-9a-f])([0-9a-f])([0-9a-f])$/i.test(color))
      return arguments.callee(RegExp.$1 + RegExp.$1 +
                              RegExp.$2 + RegExp.$2 +
                              RegExp.$3 + RegExp.$3);
    else if (/^#?([0-9a-f]{6})$/i.test(color))
      return arguments.callee(parseInt('0x' + RegExp.$1));
    else if (color in Color.COLORS)
      return arguments.callee(Color.COLORS[color]);
    else
      throw 'invalid string "' + color + '", ' +
            'takes #XXX, #XXXXXX or COLOR NAME(sharp omittable)';
  case Number:
    return [color >> 16 & 0xff, color >> 8 & 0xff, color & 0xff];
  case Object:
    return [color.r, color.g, color.b];
  case Array:
    return color;
  default:
    throw 'invalid type';
  }
};

Color.converter = {
  rgb2ymck: function(red, green, blue) {
    if (arguments.length == 1) [red, green, blue] = Color.parse(arguments[0]);
    var min = Math.min(1 - red / 255, 1 - green / 255, 1 - blue / 255);
    var a = 1 - min; // FIXME rename variable name "a"
    return [
      (a - blue  / 255) / a * 255,
      (a - green / 255) / a * 255,
      (a - red   / 255) / a * 255,
      min * 255
    ];
  },

  rgb2hsv: function(red, green, blue) {
    if (arguments.length == 1) [red, green, blue] = Color.parse(arguments[0]);
    var max = Math.max(red, green, blue);
    var min = Math.min(red, green, blue);
    var value = max / 255;
    var diff = max - min;
    if (!diff) return [0, 0, value];
    var saturation = diff / max;
    var r = max - red   * 60 / diff;
    var g = max - green * 60 / diff;
    var b = max - blue  * 60 / diff;
    var hue = red == max ? b - g : green == max ? 120 + r - b : 240 + g - r;
    return [hue < 0 ? hue + 360 : hue, saturation, value];
  },

  hsv2rgb: function(hue, saturation, value) {
    var rgb = function(red, green, blue) {
      var fix = function(v) { return v > 255 ? 255 : v < 0 ? 0 : v };
      return [fix(red), fix(green), fix(blue)];
    };

    saturation = Math.ceil(saturation * 255);
    value = Math.ceil(value * 255);
    if (!saturation) return rgb(value, value, value);
    var diff = hue * 6 % 360; // FIXME rename variable name "diff"
    var t1 = (255 - saturation)                      * value / 255;
    var t2 = (255 - saturation * diff / 360)         * value / 255;
    var t3 = (255 - saturation * (360 - diff) / 360) * value / 255;
    var p = Math.floor(hue / 60);
    if      (p == 0) return rgb(value, t3, t1);
    else if (p == 1) return rgb(t2, value, t1);
    else if (p == 2) return rgb(t1, value, t3);
    else if (p == 3) return rgb(t1, t2, value);
    else if (p == 4) return rgb(t3, t1, value);
    else             return rgb(value, t1, t2);
  }
};

Color.prototype = {
  number: function() {
    return (this.r << 8 | this.g) << 8 | this.b;
  },

  name: function() {
    return Color.NAMES[this.number()];
  },

  hex: function() {
    var hex = this.number().toString(16);
    for (var i = hex.length; i < 6; i++) hex = '0' + hex;
    return '#' + hex;
  },

  rgb: function() {
    return Color.parse(this);
  },

  ymck: function() {
    return Color.converter.rgb2ymck(this);
  },

  hsv: function() {
    return Color.converter.rgb2hsv(this);
  },

  pccs: function() {
  },

  munsell: function() {
  },

  toString: function() {
    return this.name() || this.hex();
  },

  red: function(red) {
    return new Color(red, this.g, this.b);
  },

  green: function(green) {
    return new Color(this.r, green, this.b);
  },

  blue: function(blue) {
    return new Color(this.r, this.g, blue);
  },

  yellow: function(yellow) {
    return new Color(yellow, yellow, this.b);
  },

  magenta: function(magenta) {
    return new Color(magenta, this.g, magenta);
  },

  cyan: function(cyan) {
    return new Color(this.r, cyan, cyan);
  },

  hue: function(hue) {
    var [h, s, v] = this.hsv();
    return new Color(Color.converter.hsv2rgb(hue, s, v));
  },

  saturation: function(saturation) {
    var [h, s, v] = this.hsv();
    return new Color(Color.converter.hsv2rgb(h, saturation, v));
  },

  value: function(value) {
    var [h, s, v] = this.hsv();
    return new Color(Color.converter.hsv2rgb(h, s, value));
  },

  clone: function() {
    return new Color(this);
  }
};

(function(names) {
  Color.NAMES = names;
  var colors = {};
  for (var color in names) colors[names[color]] = parseInt(color);
  Color.COLORS = colors;
})({
  0x000000: 'black',
  0x000080: 'navy',
  0x00008b: 'darkblue',
  0x0000cd: 'mediumblue',
  0x0000ff: 'blue',
  0x006400: 'darkgreen',
  0x008000: 'green',
  0x008080: 'teal',
  0x008b8b: 'darkcyan',
  0x00bfff: 'deepskyblue',
  0x00ced1: 'darkturquoise',
  0x00fa9a: 'mediumspringgreen',
  0x00ff00: 'lime',
  0x00ff7f: 'springgreen',
  0x00ffff: 'aqua',
  0x00ffff: 'cyan',
  0x191970: 'midnightblue',
  0x1e90ff: 'dodgerblue',
  0x20b2aa: 'lightseagreen',
  0x228b22: 'forestgreen',
  0x2e8b57: 'seagreen',
  0x2f4f4f: 'darkslategray',
  0x32cd32: 'limegreen',
  0x3cb371: 'mediumseagreen',
  0x40e0d0: 'turquoise',
  0x4169e1: 'royalblue',
  0x4682b4: 'steelblue',
  0x483d8b: 'darkslateblue',
  0x48d1cc: 'mediumturquoise',
  0x4b0082: 'indigo',
  0x556b2f: 'darkolivegreen',
  0x5f9ea0: 'cadetblue',
  0x6495ed: 'cornflowerblue',
  0x66cdaa: 'mediumaquamarine',
  0x696969: 'dimgray',
  0x6a5acd: 'slateblue',
  0x6b8e23: 'olivedrab',
  0x708090: 'slategray',
  0x778899: 'lightslategray',
  0x7b68ee: 'mediumslateblue',
  0x7cfc00: 'lawngreen',
  0x7fff00: 'chartreuse',
  0x7fffd4: 'aquamarine',
  0x800000: 'maroon',
  0x800080: 'purple',
  0x808000: 'olive',
  0x808080: 'gray',
  0x87ceeb: 'skyblue',
  0x87cefa: 'lightskyblue',
  0x8a2be2: 'blueviolet',
  0x8b0000: 'darkred',
  0x8b008b: 'darkmagenta',
  0x8b4513: 'saddlebrown',
  0x8fbc8f: 'darkseagreen',
  0x90ee90: 'lightgreen',
  0x9370db: 'mediumpurple',
  0x9400d3: 'darkviolet',
  0x98fb98: 'palegreen',
  0x9932cc: 'darkorchid',
  0x9acd32: 'yellowgreen',
  0xa0522d: 'sienna',
  0xa52a2a: 'brown',
  0xa9a9a9: 'darkgray',
  0xadd8e6: 'lightblue',
  0xadff2f: 'greenyellow',
  0xafeeee: 'paleturquoise',
  0xb0c4de: 'lightsteelblue',
  0xb0e0e6: 'powderblue',
  0xb22222: 'firebrick',
  0xb8860b: 'darkgoldenrod',
  0xba55d3: 'mediumorchid',
  0xbc8f8f: 'rosybrown',
  0xbdb76b: 'darkkhaki',
  0xc0c0c0: 'silver',
  0xc71585: 'mediumvioletred',
  0xcd5c5c: 'indianred',
  0xcd853f: 'peru',
  0xd2691e: 'chocolate',
  0xd2b48c: 'tan',
  0xd3d3d3: 'lightgrey',
  0xd8bfd8: 'thistle',
  0xda70d6: 'orchid',
  0xdaa520: 'goldenrod',
  0xdb7093: 'palevioletred',
  0xdc143c: 'crimson',
  0xdcdcdc: 'gainsboro',
  0xdda0dd: 'plum',
  0xdeb887: 'burlywood',
  0xe0ffff: 'lightcyan',
  0xe6e6fa: 'lavender',
  0xe9967a: 'darksalmon',
  0xee82ee: 'violet',
  0xeee8aa: 'palegoldenrod',
  0xf08080: 'lightcoral',
  0xf0e68c: 'khaki',
  0xf0f8ff: 'aliceblue',
  0xf0fff0: 'honeydew',
  0xf0ffff: 'azure',
  0xf4a460: 'sandybrown',
  0xf5deb3: 'wheat',
  0xf5f5dc: 'beige',
  0xf5f5f5: 'whitesmoke',
  0xf5fffa: 'mintcream',
  0xf8f8ff: 'ghostwhite',
  0xfa8072: 'salmon',
  0xfaebd7: 'antiquewhite',
  0xfaf0e6: 'linen',
  0xfafad2: 'lightgoldenrodyellow',
  0xfdf5e6: 'oldlace',
  0xff0000: 'red',
  0xff00ff: 'fuchsia',
  0xff00ff: 'magenta',
  0xff1493: 'deeppink',
  0xff4500: 'orangered',
  0xff6347: 'tomato',
  0xff69b4: 'hotpink',
  0xff7f50: 'coral',
  0xff8c00: 'darkorange',
  0xffa07a: 'lightsalmon',
  0xffa500: 'orange',
  0xffb6c1: 'lightpink',
  0xffc0cb: 'pink',
  0xffd700: 'gold',
  0xffdab9: 'peachpuff',
  0xffdead: 'navajowhite',
  0xffe4b5: 'moccasin',
  0xffe4c4: 'bisque',
  0xffe4e1: 'mistyrose',
  0xffebcd: 'blanchedalmond',
  0xffefd5: 'papayawhip',
  0xfff0f5: 'lavenderblush',
  0xfff5ee: 'seashell',
  0xfff8dc: 'cornsilk',
  0xfffacd: 'lemonchiffon',
  0xfffaf0: 'floralwhite',
  0xfffafa: 'snow',
  0xffff00: 'yellow',
  0xffffe0: 'lightyellow',
  0xfffff0: 'ivory',
  0xffffff: 'white'
});