Represents a Color and can be converted into multiple formats

gistfile1.js

/**
 *  class Color
 **/
var Color = Class.create((function() {
	
	function _testFormatSupport(format) {
		var el = document.createElement("span");
		var oldColor = el.style.color = "red";
		try {
			el.style.color = format;
		} catch (e) {}
		return el.style.color != oldColor;
	}
	var SUPPORTS_RGB = _testFormatSupport("rgb(0,0,0)"),
	    SUPPORTS_RGBA = (SUPPORTS_RGB && _testFormatSupport("rgba(0,0,0,0)"));

	return {
		/**
		 *  new Color();
		
		Methods store data in "data" object
		Instantions convert into rgba automatically
		If data doesn't exist for method, convert from RGB, store it, return it.
		
		 **/
		initialize: function() {
			this.data = {};
		},
		
		css: function() {
			var o = this.rgbaObject();
			if (SUPPORTS_RGBA) return this.rgbaCss();
			if (o.a == 0) return "transparent";
			if (SUPPORTS_RGB) return this.rgbCss();
			return hex();
		},
		rgb: function() {
			if (!("rgb" in this.data)) {
				var o = this.rgbaObject();
				this.data.rgb = [o.r, o.g, o.b].join(",");
			}
			return this.data.rgb;
		},
		rgbCss: function() {
			if (!("rgbCss" in this.data)) this.data.rgbCss = ("rgb(" + this.rgb() + ")");
			return this.data.rgbCss;
		},
		rgba: function() {
			if (!("rgba" in this.data)) {
				var o = this.rgbaObject();
				this.data.rgba = [o.r, o.g, o.b, o.a].join(",");
			}
			return this.data.rgba;
		},
		rgbaCss: function() {
			if (!("rgbaCss" in this.data)) this.data.rgbaCss = ("rgba(" + this.rgba() + ")");
			return this.data.rgbaCss;
		},
		rgbaObject: function() {
			// Defaults to black transparent.
			if (!("rgbaObject" in this.data)) this.data.rgbaObject = {r: 0, g: 0, b: 0, a: 0};
			return this.data.rgbaObject;
		},
		hex: function() {
			if (!("hex" in this.data)) {
				var o = this.rgbaObject();
				this.data.hex = "#" + o.r.toColorPart() + o.g.toColorPart() + o.b.toColorPart();
			}
			return this.data.hex;
		},
		
		/**
		 *  Color#hsv() -> Object
		 *  Returns on object with `h`, `s` and `v` properties.
		 **/
		hsv: function() {
			if (!("hsv" in this.data)) {
				var o = this.rgbaObject(),
					r = o.r/255,
					g = o.g/255,
					b = o.b/255,
					max = Math.max(r, g, b),
					min = Math.min(r, g, b),
					h, s, v = max,
					d = max - min;

			    s = max == 0 ? 0 : d / max;

				if (max == min) {
					h = 0; // achromatic
				} else {
					switch (max) {
						case r: h = (g - b) / d + (g < b ? 6 : 0); break;
						case g: h = (b - r) / d + 2; break;
						case b: h = (r - g) / d + 4; break;
					}
					h /= 6;
				}
				this.data.hsv = {h:h, s:s, v:v};
			}
			return this.data.hsv;
		},

		inspect: function() {
			return "#<Color: " + this.rgba() + ">";
		},
		
		toString: function() { return "[object Color]"; }
	};
})());

Object.extend(Color, (function() {
	function _hsvToRgba(h, s, v) {
	    var r, g, b;
	    var i = Math.floor(h * 6);
	    var f = h * 6 - i;
	    var p = v * (1 - s);
	    var q = v * (1 - f * s);
	    var t = v * (1 - (1 - f) * s);

	    switch(i % 6){
	        case 0: r = v; g = t; b = p; break;
	        case 1: r = q; g = v; b = p; break;
	        case 2: r = p; g = v; b = t; break;
	        case 3: r = p; g = q; b = v; break;
	        case 4: r = t; g = p; b = v; break;
	        case 5: r = v; g = p; b = q; break;
	    }
	    return {r: Math.round(r * 255), g: Math.round(g * 255), b: Math.round(b * 255), a: 1};
	}

	function _hexToRgba(hex) {
		return {
			r: parseInt(hex.substring(0,2), 16),
			g: parseInt(hex.substring(2,4), 16),
			b: parseInt(hex.substring(4,6), 16),
			a: 1
		};
	}

	return {
		TryParse: function(value) {
			if (Object.isString(value)) {
				var match;
				if (value.match(/^(#)?[a-z0-9]{3}$/i) || value.match(/^(#)?[a-z0-9]{6}$/i)) { // From 3 or 6 hex
					return Color.Hex(value);
				} else if ((value.match(/\d+/g) || []).length >= 3) { // any RGB(A) format
					return Color.RGB(value);
				}
			}
			// return transparent color by default.
			var color = new Color();
			return color;
		},
		
		/**
		 *  Color.RGB(value1[, value2, value3[, alpha = 1]]) -> Color
		 * 
		 *  Creates a color object out of a single string or individual rgba values.
		 **/
		RGB: function(red, green, blue, alpha) {
			var rgba = {}, value = red;
			if (arguments.length == 1) {
				// Parse out of string...
				var match = (value || "").match(/\d+/g);
				if (!match || match.length < 3) throw 'Color.RGB, "Invalid Argument."';
				rgba = {
					r: parseInt(match[0]) || 0,
					g: parseInt(match[1]) || 0,
					b: parseInt(match[2]) || 0,
					a: (typeof match[3] == "string") ? parseFloat(match[3]) : 1
				};
			} else if (arguments.length >= 3) {
				rgba = {r: red, g: green, b: blue, a: (typeof alpha == "undefined") ? 1 : parseFloat(alpha) };
			} else throw 'Color.RGB, "Invalid Argument."';

			var color = new Color();
			color.data.rgbaObject = rgba;
			return color;
		},
		Hex: function(value) {
			if (!Object.isString(value)) throw 'Color.Hex, "Invalid argument."';
			value = value.replace("#","");
			if (value.match(/^[a-z0-9]{3}$/i)) { // From short HEX 3
				value = value[0] + value[0] + value[1] + value[1] + value[2] + value[2];
			}
			if (value.match(/^[a-z0-9]{6}$/i)) { // From long HEX 6
				var color = new Color();
				color.data.hex = "#" + value;
				color.data.rgbaObject = _hexToRgba(value);
				return color;
			}
			throw 'Color#Hex, "Invalid argument, value is not in HEX format."';
		},
		HSV: function(h, s, v) {
			if (arguments.length != 3) throw 'Color.HSV, "Invalid arguments."';
			var color = new Color();
			color.data.hsv = {h:h, s:s, v:v};
			color.data.rgbaObject = _hsvToRgba(h, s, v);
			return color;
		}
	};
})());