Chart.Core.js

/*!
 * Chart.js
 * http://chartjs.org/
 * Version: {{ version }}
 *
 * Copyright 2015 Nick Downie
 * Released under the MIT license
 * https://github.com/nnnick/Chart.js/blob/master/LICENSE.md
 */


(function(){

	"use strict";

	//Declare root variable - window in the browser, global on the server
	var root = this,
		previous = root.Chart;

	//Occupy the global variable of Chart, and create a simple base class
	var Chart = function(context){
		var chart = this;
		this.canvas = context.canvas;

		this.ctx = context;

		//Variables global to the chart
		var computeDimension = function(element,dimension)
		{
			if (element['offset'+dimension])
			{
				return element['offset'+dimension];
			}
			else
			{
				return document.defaultView.getComputedStyle(element).getPropertyValue(dimension);
			}
		};

		var width = this.width = computeDimension(context.canvas,'Width') || context.canvas.width;
		var height = this.height = computeDimension(context.canvas,'Height') || context.canvas.height;

		// Firefox requires this to work correctly
		context.canvas.width  = width;
		context.canvas.height = height;

		width = this.width = context.canvas.width;
		height = this.height = context.canvas.height;
		this.aspectRatio = this.width / this.height;
		//High pixel density displays - multiply the size of the canvas height/width by the device pixel ratio, then scale.
		helpers.retinaScale(this);

		return this;
	};
	//Globally expose the defaults to allow for user updating/changing
	Chart.defaults = {
		global: {
			// Boolean - Whether to animate the chart
			animation: true,

			// Number - Number of animation steps
			animationSteps: 60,

			// String - Animation easing effect
			animationEasing: "easeOutQuart",

			// Boolean - If we should show the scale at all
			showScale: true,

			// Boolean - If we want to override with a hard coded scale
			scaleOverride: false,

			// ** Required if scaleOverride is true **
			// Number - The number of steps in a hard coded scale
			scaleSteps: null,
			// Number - The value jump in the hard coded scale
			scaleStepWidth: null,
			// Number - The scale starting value
			scaleStartValue: null,

			// String - Colour of the scale line
			scaleLineColor: "rgba(0,0,0,.1)",

			// Number - Pixel width of the scale line
			scaleLineWidth: 1,

			// Boolean - Whether to show labels on the scale
			scaleShowLabels: true,

			// Interpolated JS string - can access value
			scaleLabel: "<%=value%>",

			// Boolean - Whether the scale should stick to integers, and not show any floats even if drawing space is there
			scaleIntegersOnly: true,

			// Boolean - Whether the scale should start at zero, or an order of magnitude down from the lowest value
			scaleBeginAtZero: false,

			// String - Scale label font declaration for the scale label
			scaleFontFamily: "'Helvetica Neue', 'Helvetica', 'Arial', sans-serif",

			// Number - Scale label font size in pixels
			scaleFontSize: 12,

			// String - Scale label font weight style
			scaleFontStyle: "normal",

			// String - Scale label font colour
			scaleFontColor: "#666",

			// Boolean - whether or not the chart should be responsive and resize when the browser does.
			responsive: false,

			// Boolean - whether to maintain the starting aspect ratio or not when responsive, if set to false, will take up entire container
			maintainAspectRatio: true,

			// Boolean - Determines whether to draw tooltips on the canvas or not - attaches events to touchmove & mousemove
			showTooltips: true,

			// Boolean - Determines whether to draw built-in tooltip or call custom tooltip function
			customTooltips: false,

			// Array - Array of string names to attach tooltip events
			tooltipEvents: ["mousemove", "touchstart", "touchmove", "mouseout"],

			// String - Tooltip background colour
			tooltipFillColor: "rgba(0,0,0,0.8)",

			// String - Tooltip label font declaration for the scale label
			tooltipFontFamily: "'Helvetica Neue', 'Helvetica', 'Arial', sans-serif",

			// Number - Tooltip label font size in pixels
			tooltipFontSize: 14,

			// String - Tooltip font weight style
			tooltipFontStyle: "normal",

			// String - Tooltip label font colour
			tooltipFontColor: "#fff",

			// String - Tooltip title font declaration for the scale label
			tooltipTitleFontFamily: "'Helvetica Neue', 'Helvetica', 'Arial', sans-serif",

			// Number - Tooltip title font size in pixels
			tooltipTitleFontSize: 14,

			// String - Tooltip title font weight style
			tooltipTitleFontStyle: "bold",

			// String - Tooltip title font colour
			tooltipTitleFontColor: "#fff",

			// Number - pixel width of padding around tooltip text
			tooltipYPadding: 6,

			// Number - pixel width of padding around tooltip text
			tooltipXPadding: 6,

			// Number - Size of the caret on the tooltip
			tooltipCaretSize: 8,

			// Number - Pixel radius of the tooltip border
			tooltipCornerRadius: 6,

			// Number - Pixel offset from point x to tooltip edge
			tooltipXOffset: 10,

			// String - Template string for single tooltips
			tooltipTemplate: "<%if (label){%><%=label%>: <%}%><%= value %>",

			// String - Template string for single tooltips
			multiTooltipTemplate: "<%= value %>",

			// String - Colour behind the legend colour block
			multiTooltipKeyBackground: '#fff',

			// Function - Will fire on animation progression.
			onAnimationProgress: function(){},

			// Function - Will fire on animation completion.
			onAnimationComplete: function(){}

		}
	};

	//Create a dictionary of chart types, to allow for extension of existing types
	Chart.types = {};

	//Global Chart helpers object for utility methods and classes
	var helpers = Chart.helpers = {};

		//-- Basic js utility methods
	var each = helpers.each = function(loopable,callback,self){
			var additionalArgs = Array.prototype.slice.call(arguments, 3);
			// Check to see if null or undefined firstly.
			if (loopable){
				if (loopable.length === +loopable.length){
					var i;
					for (i=0; i<loopable.length; i++){
						callback.apply(self,[loopable[i], i].concat(additionalArgs));
					}
				}
				else{
					for (var item in loopable){
						callback.apply(self,[loopable[item],item].concat(additionalArgs));
					}
				}
			}
		},
		clone = helpers.clone = function(obj){
			var objClone = {};
			each(obj,function(value,key){
				if (obj.hasOwnProperty(key)){
					objClone[key] = value;
				}
			});
			return objClone;
		},
		extend = helpers.extend = function(base){
			each(Array.prototype.slice.call(arguments,1), function(extensionObject) {
				each(extensionObject,function(value,key){
					if (extensionObject.hasOwnProperty(key)){
						base[key] = value;
					}
				});
			});
			return base;
		},
		merge = helpers.merge = function(base,master){
			//Merge properties in left object over to a shallow clone of object right.
			var args = Array.prototype.slice.call(arguments,0);
			args.unshift({});
			return extend.apply(null, args);
		},
		indexOf = helpers.indexOf = function(arrayToSearch, item){
			if (Array.prototype.indexOf) {
				return arrayToSearch.indexOf(item);
			}
			else{
				for (var i = 0; i < arrayToSearch.length; i++) {
					if (arrayToSearch[i] === item) return i;
				}
				return -1;
			}
		},
		where = helpers.where = function(collection, filterCallback){
			var filtered = [];

			helpers.each(collection, function(item){
				if (filterCallback(item)){
					filtered.push(item);
				}
			});

			return filtered;
		},
		findNextWhere = helpers.findNextWhere = function(arrayToSearch, filterCallback, startIndex){
			// Default to start of the array
			if (!startIndex){
				startIndex = -1;
			}
			for (var i = startIndex + 1; i < arrayToSearch.length; i++) {
				var currentItem = arrayToSearch[i];
				if (filterCallback(currentItem)){
					return currentItem;
				}
			}
		},
		findPreviousWhere = helpers.findPreviousWhere = function(arrayToSearch, filterCallback, startIndex){
			// Default to end of the array
			if (!startIndex){
				startIndex = arrayToSearch.length;
			}
			for (var i = startIndex - 1; i >= 0; i--) {
				var currentItem = arrayToSearch[i];
				if (filterCallback(currentItem)){
					return currentItem;
				}
			}
		},
		inherits = helpers.inherits = function(extensions){
			//Basic javascript inheritance based on the model created in Backbone.js
			var parent = this;
			var ChartElement = (extensions && extensions.hasOwnProperty("constructor")) ? extensions.constructor : function(){ return parent.apply(this, arguments); };

			var Surrogate = function(){ this.constructor = ChartElement;};
			Surrogate.prototype = parent.prototype;
			ChartElement.prototype = new Surrogate();

			ChartElement.extend = inherits;

			if (extensions) extend(ChartElement.prototype, extensions);

			ChartElement.__super__ = parent.prototype;

			return ChartElement;
		},
		noop = helpers.noop = function(){},
		uid = helpers.uid = (function(){
			var id=0;
			return function(){
				return "chart-" + id++;
			};
		})(),
		warn = helpers.warn = function(str){
			//Method for warning of errors
			if (window.console && typeof window.console.warn === "function") console.warn(str);
		},
		amd = helpers.amd = (typeof define === 'function' && define.amd),
		//-- Math methods
		isNumber = helpers.isNumber = function(n){
			return !isNaN(parseFloat(n)) && isFinite(n);
		},
		max = helpers.max = function(array){
			return Math.max.apply( Math, array );
		},
		min = helpers.min = function(array){
			return Math.min.apply( Math, array );
		},
		cap = helpers.cap = function(valueToCap,maxValue,minValue){
			if(isNumber(maxValue)) {
				if( valueToCap > maxValue ) {
					return maxValue;
				}
			}
			else if(isNumber(minValue)){
				if ( valueToCap < minValue ){
					return minValue;
				}
			}
			return valueToCap;
		},
		getDecimalPlaces = helpers.getDecimalPlaces = function(num){
			if (num%1!==0 && isNumber(num)){
				var s = num.toString();
				if(s.indexOf("e-") < 0){
					// no exponent, e.g. 0.01
					return s.split(".")[1].length;
				}
				else if(s.indexOf(".") < 0) {
					// no decimal point, e.g. 1e-9
					return parseInt(s.split("e-")[1]);
				}
				else {
					// exponent and decimal point, e.g. 1.23e-9
					var parts = s.split(".")[1].split("e-");
					return parts[0].length + parseInt(parts[1]);
				}
			}
			else {
				return 0;
			}
		},
		toRadians = helpers.radians = function(degrees){
			return degrees * (Math.PI/180);
		},
		// Gets the angle from vertical upright to the point about a centre.
		getAngleFromPoint = helpers.getAngleFromPoint = function(centrePoint, anglePoint){
			var distanceFromXCenter = anglePoint.x - centrePoint.x,
				distanceFromYCenter = anglePoint.y - centrePoint.y,
				radialDistanceFromCenter = Math.sqrt( distanceFromXCenter * distanceFromXCenter + distanceFromYCenter * distanceFromYCenter);


			var angle = Math.PI * 2 + Math.atan2(distanceFromYCenter, distanceFromXCenter);

			//If the segment is in the top left quadrant, we need to add another rotation to the angle
			if (distanceFromXCenter < 0 && distanceFromYCenter < 0){
				angle += Math.PI*2;
			}

			return {
				angle: angle,
				distance: radialDistanceFromCenter
			};
		},
		aliasPixel = helpers.aliasPixel = function(pixelWidth){
			return (pixelWidth % 2 === 0) ? 0 : 0.5;
		},
		splineCurve = helpers.splineCurve = function(FirstPoint,MiddlePoint,AfterPoint,t){
			//Props to Rob Spencer at scaled innovation for his post on splining between points
			//http://scaledinnovation.com/analytics/splines/aboutSplines.html
			var d01=Math.sqrt(Math.pow(MiddlePoint.x-FirstPoint.x,2)+Math.pow(MiddlePoint.y-FirstPoint.y,2)),
				d12=Math.sqrt(Math.pow(AfterPoint.x-MiddlePoint.x,2)+Math.pow(AfterPoint.y-MiddlePoint.y,2)),
				fa=t*d01/(d01+d12),// scaling factor for triangle Ta
				fb=t*d12/(d01+d12);
			return {
				inner : {
					x : MiddlePoint.x-fa*(AfterPoint.x-FirstPoint.x),
					y : MiddlePoint.y-fa*(AfterPoint.y-FirstPoint.y)
				},
				outer : {
					x: MiddlePoint.x+fb*(AfterPoint.x-FirstPoint.x),
					y : MiddlePoint.y+fb*(AfterPoint.y-FirstPoint.y)
				}
			};
		},
		calculateOrderOfMagnitude = helpers.calculateOrderOfMagnitude = function(val){
			return Math.floor(Math.log(val) / Math.LN10);
		},
		calculateScaleRange = helpers.calculateScaleRange = function(valuesArray, drawingSize, textSize, startFromZero, integersOnly){

			//Set a minimum step of two - a point at the top of the graph, and a point at the base
			var minSteps = 2,
				maxSteps = Math.floor(drawingSize/(textSize * 1.5)),
				skipFitting = (minSteps >= maxSteps);

			var maxValue = max(valuesArray),
				minValue = min(valuesArray);

			// We need some degree of seperation here to calculate the scales if all the values are the same
			// Adding/minusing 0.5 will give us a range of 1.
			if (maxValue === minValue){
				maxValue += 0.5;
				// So we don't end up with a graph with a negative start value if we've said always start from zero
				if (minValue >= 0.5 && !startFromZero){
					minValue -= 0.5;
				}
				else{
					// Make up a whole number above the values
					maxValue += 0.5;
				}
			}

			var	valueRange = Math.abs(maxValue - minValue),
				rangeOrderOfMagnitude = calculateOrderOfMagnitude(valueRange),
				graphMax = Math.ceil(maxValue / (1 * Math.pow(10, rangeOrderOfMagnitude))) * Math.pow(10, rangeOrderOfMagnitude),
				graphMin = (startFromZero) ? 0 : Math.floor(minValue / (1 * Math.pow(10, rangeOrderOfMagnitude))) * Math.pow(10, rangeOrderOfMagnitude),
				graphRange = graphMax - graphMin,
				stepValue = Math.pow(10, rangeOrderOfMagnitude),
				numberOfSteps = Math.round(graphRange / stepValue);

			//If we have more space on the graph we'll use it to give more definition to the data
			while((numberOfSteps > maxSteps || (numberOfSteps * 2) < maxSteps) && !skipFitting) {
				if(numberOfSteps > maxSteps){
					stepValue *=2;
					numberOfSteps = Math.round(graphRange/stepValue);
					// Don't ever deal with a decimal number of steps - cancel fitting and just use the minimum number of steps.
					if (numberOfSteps % 1 !== 0){
						skipFitting = true;
					}
				}
				//We can fit in double the amount of scale points on the scale
				else{
					//If user has declared ints only, and the step value isn't a decimal
					if (integersOnly && rangeOrderOfMagnitude >= 0){
						//If the user has said integers only, we need to check that making the scale more granular wouldn't make it a float
						if(stepValue/2 % 1 === 0){
							stepValue /=2;
							numberOfSteps = Math.round(graphRange/stepValue);
						}
						//If it would make it a float break out of the loop
						else{
							break;
						}
					}
					//If the scale doesn't have to be an int, make the scale more granular anyway.
					else{
						stepValue /=2;
						numberOfSteps = Math.round(graphRange/stepValue);
					}

				}
			}

			if (skipFitting){
				numberOfSteps = minSteps;
				stepValue = graphRange / numberOfSteps;
			}

			return {
				steps : numberOfSteps,
				stepValue : stepValue,
				min : graphMin,
				max	: graphMin + (numberOfSteps * stepValue)
			};

		},
		/* jshint ignore:start */
		// Blows up jshint errors based on the new Function constructor
		//Templating methods
		//Javascript micro templating by John Resig - source at http://ejohn.org/blog/javascript-micro-templating/
		template = helpers.template = function(templateString, valuesObject){

			// If templateString is function rather than string-template - call the function for valuesObject

			if(templateString instanceof Function){
			 	return templateString(valuesObject);
		 	}

			var cache = {};
			function tmpl(str, data){
				// Figure out if we're getting a template, or if we need to
				// load the template - and be sure to cache the result.
				var fn = !/\W/.test(str) ?
				cache[str] = cache[str] :

				// Generate a reusable function that will serve as a template
				// generator (and which will be cached).
				new Function("obj",
					"var p=[],print=function(){p.push.apply(p,arguments);};" +

					// Introduce the data as local variables using with(){}
					"with(obj){p.push('" +

					// Convert the template into pure JavaScript
					str
						.replace(/[\r\t\n]/g, " ")
						.split("<%").join("\t")
						.replace(/((^|%>)[^\t]*)'/g, "$1\r")
						.replace(/\t=(.*?)%>/g, "',$1,'")
						.split("\t").join("');")
						.split("%>").join("p.push('")
						.split("\r").join("\\'") +
					"');}return p.join('');"
				);

				// Provide some basic currying to the user
				return data ? fn( data ) : fn;
			}
			return tmpl(templateString,valuesObject);
		},
		/* jshint ignore:end */
		generateLabels = helpers.generateLabels = function(templateString,numberOfSteps,graphMin,stepValue){
			var labelsArray = new Array(numberOfSteps);
			if (templateString){
				each(labelsArray,function(val,index){
					labelsArray[index] = template(templateString,{value: (graphMin + (stepValue*(index+1)))});
				});
			}
			return labelsArray;
		},
		//--Animation methods
		//Easing functions adapted from Robert Penner's easing equations
		//http://www.robertpenner.com/easing/
		easingEffects = helpers.easingEffects = {
			linear: function (t) {
				return t;
			},
			easeInQuad: function (t) {
				return t * t;
			},
			easeOutQuad: function (t) {
				return -1 * t * (t - 2);
			},
			easeInOutQuad: function (t) {
				if ((t /= 1 / 2) < 1){
					return 1 / 2 * t * t;
				}
				return -1 / 2 * ((--t) * (t - 2) - 1);
			},
			easeInCubic: function (t) {
				return t * t * t;
			},
			easeOutCubic: function (t) {
				return 1 * ((t = t / 1 - 1) * t * t + 1);
			},
			easeInOutCubic: function (t) {
				if ((t /= 1 / 2) < 1){
					return 1 / 2 * t * t * t;
				}
				return 1 / 2 * ((t -= 2) * t * t + 2);
			},
			easeInQuart: function (t) {
				return t * t * t * t;
			},
			easeOutQuart: function (t) {
				return -1 * ((t = t / 1 - 1) * t * t * t - 1);
			},
			easeInOutQuart: function (t) {
				if ((t /= 1 / 2) < 1){
					return 1 / 2 * t * t * t * t;
				}
				return -1 / 2 * ((t -= 2) * t * t * t - 2);
			},
			easeInQuint: function (t) {
				return 1 * (t /= 1) * t * t * t * t;
			},
			easeOutQuint: function (t) {
				return 1 * ((t = t / 1 - 1) * t * t * t * t + 1);
			},
			easeInOutQuint: function (t) {
				if ((t /= 1 / 2) < 1){
					return 1 / 2 * t * t * t * t * t;
				}
				return 1 / 2 * ((t -= 2) * t * t * t * t + 2);
			},
			easeInSine: function (t) {
				return -1 * Math.cos(t / 1 * (Math.PI / 2)) + 1;
			},
			easeOutSine: function (t) {
				return 1 * Math.sin(t / 1 * (Math.PI / 2));
			},
			easeInOutSine: function (t) {
				return -1 / 2 * (Math.cos(Math.PI * t / 1) - 1);
			},
			easeInExpo: function (t) {
				return (t === 0) ? 1 : 1 * Math.pow(2, 10 * (t / 1 - 1));
			},
			easeOutExpo: function (t) {
				return (t === 1) ? 1 : 1 * (-Math.pow(2, -10 * t / 1) + 1);
			},
			easeInOutExpo: function (t) {
				if (t === 0){
					return 0;
				}
				if (t === 1){
					return 1;
				}
				if ((t /= 1 / 2) < 1){
					return 1 / 2 * Math.pow(2, 10 * (t - 1));
				}
				return 1 / 2 * (-Math.pow(2, -10 * --t) + 2);
			},
			easeInCirc: function (t) {
				if (t >= 1){
					return t;
				}
				return -1 * (Math.sqrt(1 - (t /= 1) * t) - 1);
			},
			easeOutCirc: function (t) {
				return 1 * Math.sqrt(1 - (t = t / 1 - 1) * t);
			},
			easeInOutCirc: function (t) {
				if ((t /= 1 / 2) < 1){
					return -1 / 2 * (Math.sqrt(1 - t * t) - 1);
				}
				return 1 / 2 * (Math.sqrt(1 - (t -= 2) * t) + 1);
			},
			easeInElastic: function (t) {
				var s = 1.70158;
				var p = 0;
				var a = 1;
				if (t === 0){
					return 0;
				}
				if ((t /= 1) == 1){
					return 1;
				}
				if (!p){
					p = 1 * 0.3;
				}
				if (a < Math.abs(1)) {
					a = 1;
					s = p / 4;
				} else{
					s = p / (2 * Math.PI) * Math.asin(1 / a);
				}
				return -(a * Math.pow(2, 10 * (t -= 1)) * Math.sin((t * 1 - s) * (2 * Math.PI) / p));
			},
			easeOutElastic: function (t) {
				var s = 1.70158;
				var p = 0;
				var a = 1;
				if (t === 0){
					return 0;
				}
				if ((t /= 1) == 1){
					return 1;
				}
				if (!p){
					p = 1 * 0.3;
				}
				if (a < Math.abs(1)) {
					a = 1;
					s = p / 4;
				} else{
					s = p / (2 * Math.PI) * Math.asin(1 / a);
				}
				return a * Math.pow(2, -10 * t) * Math.sin((t * 1 - s) * (2 * Math.PI) / p) + 1;
			},
			easeInOutElastic: function (t) {
				var s = 1.70158;
				var p = 0;
				var a = 1;
				if (t === 0){
					return 0;
				}
				if ((t /= 1 / 2) == 2){
					return 1;
				}
				if (!p){
					p = 1 * (0.3 * 1.5);
				}
				if (a < Math.abs(1)) {
					a = 1;
					s = p / 4;
				} else {
					s = p / (2 * Math.PI) * Math.asin(1 / a);
				}
				if (t < 1){
					return -0.5 * (a * Math.pow(2, 10 * (t -= 1)) * Math.sin((t * 1 - s) * (2 * Math.PI) / p));}
				return a * Math.pow(2, -10 * (t -= 1)) * Math.sin((t * 1 - s) * (2 * Math.PI) / p) * 0.5 + 1;
			},
			easeInBack: function (t) {
				var s = 1.70158;
				return 1 * (t /= 1) * t * ((s + 1) * t - s);
			},
			easeOutBack: function (t) {
				var s = 1.70158;
				return 1 * ((t = t / 1 - 1) * t * ((s + 1) * t + s) + 1);
			},
			easeInOutBack: function (t) {
				var s = 1.70158;
				if ((t /= 1 / 2) < 1){
					return 1 / 2 * (t * t * (((s *= (1.525)) + 1) * t - s));
				}
				return 1 / 2 * ((t -= 2) * t * (((s *= (1.525)) + 1) * t + s) + 2);
			},
			easeInBounce: function (t) {
				return 1 - easingEffects.easeOutBounce(1 - t);
			},
			easeOutBounce: function (t) {
				if ((t /= 1) < (1 / 2.75)) {
					return 1 * (7.5625 * t * t);
				} else if (t < (2 / 2.75)) {
					return 1 * (7.5625 * (t -= (1.5 / 2.75)) * t + 0.75);
				} else if (t < (2.5 / 2.75)) {
					return 1 * (7.5625 * (t -= (2.25 / 2.75)) * t + 0.9375);
				} else {
					return 1 * (7.5625 * (t -= (2.625 / 2.75)) * t + 0.984375);
				}
			},
			easeInOutBounce: function (t) {
				if (t < 1 / 2){
					return easingEffects.easeInBounce(t * 2) * 0.5;
				}
				return easingEffects.easeOutBounce(t * 2 - 1) * 0.5 + 1 * 0.5;
			}
		},
		//Request animation polyfill - http://www.paulirish.com/2011/requestanimationframe-for-smart-animating/
		requestAnimFrame = helpers.requestAnimFrame = (function(){
			return window.requestAnimationFrame ||
				window.webkitRequestAnimationFrame ||
				window.mozRequestAnimationFrame ||
				window.oRequestAnimationFrame ||
				window.msRequestAnimationFrame ||
				function(callback) {
					return window.setTimeout(callback, 1000 / 60);
				};
		})(),
		cancelAnimFrame = helpers.cancelAnimFrame = (function(){
			return window.cancelAnimationFrame ||
				window.webkitCancelAnimationFrame ||
				window.mozCancelAnimationFrame ||
				window.oCancelAnimationFrame ||
				window.msCancelAnimationFrame ||
				function(callback) {
					return window.clearTimeout(callback, 1000 / 60);
				};
		})(),
		animationLoop = helpers.animationLoop = function(callback,totalSteps,easingString,onProgress,onComplete,chartInstance){

			var currentStep = 0,
				easingFunction = easingEffects[easingString] || easingEffects.linear;

			var animationFrame = function(){
				currentStep++;
				var stepDecimal = currentStep/totalSteps;
				var easeDecimal = easingFunction(stepDecimal);

				callback.call(chartInstance,easeDecimal,stepDecimal, currentStep);
				onProgress.call(chartInstance,easeDecimal,stepDecimal);
				if (currentStep < totalSteps){
					chartInstance.animationFrame = requestAnimFrame(animationFrame);
				} else{
					onComplete.apply(chartInstance);
				}
			};
			requestAnimFrame(animationFrame);
		},
		//-- DOM methods
		getRelativePosition = helpers.getRelativePosition = function(evt){
			var mouseX, mouseY;
			var e = evt.originalEvent || evt,
				canvas = evt.currentTarget || evt.srcElement,
				boundingRect = canvas.getBoundingClientRect();

			if (e.touches){
				mouseX = e.touches[0].clientX - boundingRect.left;
				mouseY = e.touches[0].clientY - boundingRect.top;

			}
			else{
				mouseX = e.clientX - boundingRect.left;
				mouseY = e.clientY - boundingRect.top;
			}

			return {
				x : mouseX,
				y : mouseY
			};

		},
		addEvent = helpers.addEvent = function(node,eventType,method){
			if (node.addEventListener){
				node.addEventListener(eventType,method);
			} else if (node.attachEvent){
				node.attachEvent("on"+eventType, method);
			} else {
				node["on"+eventType] = method;
			}
		},
		removeEvent = helpers.removeEvent = function(node, eventType, handler){
			if (node.removeEventListener){
				node.removeEventListener(eventType, handler, false);
			} else if (node.detachEvent){
				node.detachEvent("on"+eventType,handler);
			} else{
				node["on" + eventType] = noop;
			}
		},
		bindEvents = helpers.bindEvents = function(chartInstance, arrayOfEvents, handler){
			// Create the events object if it's not already present
			if (!chartInstance.events) chartInstance.events = {};

			each(arrayOfEvents,function(eventName){
				chartInstance.events[eventName] = function(){
					handler.apply(chartInstance, arguments);
				};
				addEvent(chartInstance.chart.canvas,eventName,chartInstance.events[eventName]);
			});
		},
		unbindEvents = helpers.unbindEvents = function (chartInstance, arrayOfEvents) {
			each(arrayOfEvents, function(handler,eventName){
				removeEvent(chartInstance.chart.canvas, eventName, handler);
			});
		},
		getMaximumWidth = helpers.getMaximumWidth = function(domNode){
			var container = domNode.parentNode;
			// TODO = check cross browser stuff with this.
			return container.clientWidth;
		},
		getMaximumHeight = helpers.getMaximumHeight = function(domNode){
			var container = domNode.parentNode;
			// TODO = check cross browser stuff with this.
			return container.clientHeight;
		},
		getMaximumSize = helpers.getMaximumSize = helpers.getMaximumWidth, // legacy support
		retinaScale = helpers.retinaScale = function(chart){
			var ctx = chart.ctx,
				width = chart.canvas.width,
				height = chart.canvas.height;

			if (window.devicePixelRatio) {
				ctx.canvas.style.width = width + "px";
				ctx.canvas.style.height = height + "px";
				ctx.canvas.height = height * window.devicePixelRatio;
				ctx.canvas.width = width * window.devicePixelRatio;
				ctx.scale(window.devicePixelRatio, window.devicePixelRatio);
			}
		},
		//-- Canvas methods
		clear = helpers.clear = function(chart){
			chart.ctx.clearRect(0,0,chart.width,chart.height);
		},
		fontString = helpers.fontString = function(pixelSize,fontStyle,fontFamily){
			return fontStyle + " " + pixelSize+"px " + fontFamily;
		},
		longestText = helpers.longestText = function(ctx,font,arrayOfStrings){
			ctx.font = font;
			var longest = 0;
			each(arrayOfStrings,function(string){
				var textWidth = ctx.measureText(string).width;
				longest = (textWidth > longest) ? textWidth : longest;
			});
			return longest;
		},
		drawRoundedRectangle = helpers.drawRoundedRectangle = function(ctx,x,y,width,height,radius){
			ctx.beginPath();
			ctx.moveTo(x + radius, y);
			ctx.lineTo(x + width - radius, y);
			ctx.quadraticCurveTo(x + width, y, x + width, y + radius);
			ctx.lineTo(x + width, y + height - radius);
			ctx.quadraticCurveTo(x + width, y + height, x + width - radius, y + height);
			ctx.lineTo(x + radius, y + height);
			ctx.quadraticCurveTo(x, y + height, x, y + height - radius);
			ctx.lineTo(x, y + radius);
			ctx.quadraticCurveTo(x, y, x + radius, y);
			ctx.closePath();
		};


	//Store a reference to each instance - allowing us to globally resize chart instances on window resize.
	//Destroy method on the chart will remove the instance of the chart from this reference.
	Chart.instances = {};

	Chart.Type = function(data,options,chart){
		this.options = options;
		this.chart = chart;
		this.id = uid();
		//Add the chart instance to the global namespace
		Chart.instances[this.id] = this;

		// Initialize is always called when a chart type is created
		// By default it is a no op, but it should be extended
		if (options.responsive){
			this.resize();
		}
		this.initialize.call(this,data);
	};

	//Core methods that'll be a part of every chart type
	extend(Chart.Type.prototype,{
		initialize : function(){return this;},
		clear : function(){
			clear(this.chart);
			return this;
		},
		stop : function(){
			// Stops any current animation loop occuring
			cancelAnimFrame(this.animationFrame);
			return this;
		},
		resize : function(callback){
			this.stop();
			var canvas = this.chart.canvas,
				newWidth = getMaximumWidth(this.chart.canvas),
				newHeight = this.options.maintainAspectRatio ? newWidth / this.chart.aspectRatio : getMaximumHeight(this.chart.canvas);

			canvas.width = this.chart.width = newWidth;
			canvas.height = this.chart.height = newHeight;

			retinaScale(this.chart);

			if (typeof callback === "function"){
				callback.apply(this, Array.prototype.slice.call(arguments, 1));
			}
			return this;
		},
		reflow : noop,
		render : function(reflow){
			if (reflow){
				this.reflow();
			}
			if (this.options.animation && !reflow){
				helpers.animationLoop(
					this.draw,
					this.options.animationSteps,
					this.options.animationEasing,
					this.options.onAnimationProgress,
					this.options.onAnimationComplete,
					this
				);
			}
			else{
				this.draw();
				this.options.onAnimationComplete.call(this);
			}
			return this;
		},
		generateLegend : function(){
			return template(this.options.legendTemplate,this);
		},
		destroy : function(){
			this.clear();
			unbindEvents(this, this.events);
			var canvas = this.chart.canvas;

			// Reset canvas height/width attributes starts a fresh with the canvas context
			canvas.width = this.chart.width;
			canvas.height = this.chart.height;

			// < IE9 doesn't support removeProperty
			if (canvas.style.removeProperty) {
				canvas.style.removeProperty('width');
				canvas.style.removeProperty('height');
			} else {
				canvas.style.removeAttribute('width');
				canvas.style.removeAttribute('height');
			}

			delete Chart.instances[this.id];
		},
		showTooltip : function(ChartElements, forceRedraw){
			// Only redraw the chart if we've actually changed what we're hovering on.
			if (typeof this.activeElements === 'undefined') this.activeElements = [];

			var isChanged = (function(Elements){
				var changed = false;

				if (Elements.length !== this.activeElements.length){
					changed = true;
					return changed;
				}

				each(Elements, function(element, index){
					if (element !== this.activeElements[index]){
						changed = true;
					}
				}, this);
				return changed;
			}).call(this, ChartElements);

			if (!isChanged && !forceRedraw){
				return;
			}
			else{
				this.activeElements = ChartElements;
			}
			this.draw();
			if(this.options.customTooltips){
				this.options.customTooltips(false);
			}
			if (ChartElements.length > 0){
				// If we have multiple datasets, show a MultiTooltip for all of the data points at that index
				if (this.datasets && this.datasets.length > 1) {
					var dataArray,
						dataIndex;

					for (var i = this.datasets.length - 1; i >= 0; i--) {
						dataArray = this.datasets[i].points || this.datasets[i].bars || this.datasets[i].segments;
						dataIndex = indexOf(dataArray, ChartElements[0]);
						if (dataIndex !== -1){
							break;
						}
					}
					var tooltipLabels = [],
						tooltipColors = [],
						medianPosition = (function(index) {

							// Get all the points at that particular index
							var Elements = [],
								dataCollection,
								xPositions = [],
								yPositions = [],
								xMax,
								yMax,
								xMin,
								yMin;
							helpers.each(this.datasets, function(dataset){
								dataCollection = dataset.points || dataset.bars || dataset.segments;
								if (dataCollection[dataIndex] && dataCollection[dataIndex].hasValue()){
									Elements.push(dataCollection[dataIndex]);
								}
							});

							helpers.each(Elements, function(element) {
								xPositions.push(element.x);
								yPositions.push(element.y);


								//Include any colour information about the element
								tooltipLabels.push(helpers.template(this.options.multiTooltipTemplate, element));
								tooltipColors.push({
									fill: element._saved.fillColor || element.fillColor,
									stroke: element._saved.strokeColor || element.strokeColor
								});

							}, this);

							yMin = min(yPositions);
							yMax = max(yPositions);

							xMin = min(xPositions);
							xMax = max(xPositions);

							return {
								x: (xMin > this.chart.width/2) ? xMin : xMax,
								y: (yMin + yMax)/2
							};
						}).call(this, dataIndex);

					new Chart.MultiTooltip({
						x: medianPosition.x,
						y: medianPosition.y,
						xPadding: this.options.tooltipXPadding,
						yPadding: this.options.tooltipYPadding,
						xOffset: this.options.tooltipXOffset,
						fillColor: this.options.tooltipFillColor,
						textColor: this.options.tooltipFontColor,
						fontFamily: this.options.tooltipFontFamily,
						fontStyle: this.options.tooltipFontStyle,
						fontSize: this.options.tooltipFontSize,
						titleTextColor: this.options.tooltipTitleFontColor,
						titleFontFamily: this.options.tooltipTitleFontFamily,
						titleFontStyle: this.options.tooltipTitleFontStyle,
						titleFontSize: this.options.tooltipTitleFontSize,
						cornerRadius: this.options.tooltipCornerRadius,
						labels: tooltipLabels,
						legendColors: tooltipColors,
						legendColorBackground : this.options.multiTooltipKeyBackground,
						title: ChartElements[0].label,
						chart: this.chart,
						ctx: this.chart.ctx,
						custom: this.options.customTooltips
					}).draw();

				} else {
					each(ChartElements, function(Element) {
						var tooltipPosition = Element.tooltipPosition();
						new Chart.Tooltip({
							x: Math.round(tooltipPosition.x),
							y: Math.round(tooltipPosition.y),
							xPadding: this.options.tooltipXPadding,
							yPadding: this.options.tooltipYPadding,
							fillColor: this.options.tooltipFillColor,
							textColor: this.options.tooltipFontColor,
							fontFamily: this.options.tooltipFontFamily,
							fontStyle: this.options.tooltipFontStyle,
							fontSize: this.options.tooltipFontSize,
							caretHeight: this.options.tooltipCaretSize,
							cornerRadius: this.options.tooltipCornerRadius,
							text: template(this.options.tooltipTemplate, Element),
							chart: this.chart,
							custom: this.options.customTooltips
						}).draw();
					}, this);
				}
			}
			return this;
		},
		toBase64Image : function(){
			return this.chart.canvas.toDataURL.apply(this.chart.canvas, arguments);
		}
	});

	Chart.Type.extend = function(extensions){

		var parent = this;

		var ChartType = function(){
			return parent.apply(this,arguments);
		};

		//Copy the prototype object of the this class
		ChartType.prototype = clone(parent.prototype);
		//Now overwrite some of the properties in the base class with the new extensions
		extend(ChartType.prototype, extensions);

		ChartType.extend = Chart.Type.extend;

		if (extensions.name || parent.prototype.name){

			var chartName = extensions.name || parent.prototype.name;
			//Assign any potential default values of the new chart type

			//If none are defined, we'll use a clone of the chart type this is being extended from.
			//I.e. if we extend a line chart, we'll use the defaults from the line chart if our new chart
			//doesn't define some defaults of their own.

			var baseDefaults = (Chart.defaults[parent.prototype.name]) ? clone(Chart.defaults[parent.prototype.name]) : {};

			Chart.defaults[chartName] = extend(baseDefaults,extensions.defaults);

			Chart.types[chartName] = ChartType;

			//Register this new chart type in the Chart prototype
			Chart.prototype[chartName] = function(data,options){
				var config = merge(Chart.defaults.global, Chart.defaults[chartName], options || {});
				return new ChartType(data,config,this);
			};
		} else{
			warn("Name not provided for this chart, so it hasn't been registered");
		}
		return parent;
	};

	Chart.Element = function(configuration){
		extend(this,configuration);
		this.initialize.apply(this,arguments);
		this.save();
	};
	extend(Chart.Element.prototype,{
		initialize : function(){},
		restore : function(props){
			if (!props){
				extend(this,this._saved);
			} else {
				each(props,function(key){
					this[key] = this._saved[key];
				},this);
			}
			return this;
		},
		save : function(){
			this._saved = clone(this);
			delete this._saved._saved;
			return this;
		},
		update : function(newProps){
			each(newProps,function(value,key){
				this._saved[key] = this[key];
				this[key] = value;
			},this);
			return this;
		},
		transition : function(props,ease){
			each(props,function(value,key){
				this[key] = ((value - this._saved[key]) * ease) + this._saved[key];
			},this);
			return this;
		},
		tooltipPosition : function(){
			return {
				x : this.x,
				y : this.y
			};
		},
		hasValue: function(){
			return isNumber(this.value);
		}
	});

	Chart.Element.extend = inherits;


	Chart.Point = Chart.Element.extend({
		display: true,
		inRange: function(chartX,chartY){
			var hitDetectionRange = this.hitDetectionRadius + this.radius;
			return ((Math.pow(chartX-this.x, 2)+Math.pow(chartY-this.y, 2)) < Math.pow(hitDetectionRange,2));
		},
		draw : function(){
			if (this.display){
				var ctx = this.ctx;
				ctx.beginPath();

				ctx.arc(this.x, this.y, this.radius, 0, Math.PI*2);
				ctx.closePath();

				ctx.strokeStyle = this.strokeColor;
				ctx.lineWidth = this.strokeWidth;

				ctx.fillStyle = this.fillColor;

				ctx.fill();
				ctx.stroke();
			}


			//Quick debug for bezier curve splining
			//Highlights control points and the line between them.
			//Handy for dev - stripped in the min version.

			// ctx.save();
			// ctx.fillStyle = "black";
			// ctx.strokeStyle = "black"
			// ctx.beginPath();
			// ctx.arc(this.controlPoints.inner.x,this.controlPoints.inner.y, 2, 0, Math.PI*2);
			// ctx.fill();

			// ctx.beginPath();
			// ctx.arc(this.controlPoints.outer.x,this.controlPoints.outer.y, 2, 0, Math.PI*2);
			// ctx.fill();

			// ctx.moveTo(this.controlPoints.inner.x,this.controlPoints.inner.y);
			// ctx.lineTo(this.x, this.y);
			// ctx.lineTo(this.controlPoints.outer.x,this.controlPoints.outer.y);
			// ctx.stroke();

			// ctx.restore();



		}
	});

	Chart.Arc = Chart.Element.extend({
		inRange : function(chartX,chartY){

			var pointRelativePosition = helpers.getAngleFromPoint(this, {
				x: chartX,
				y: chartY
			});

			//Check if within the range of the open/close angle
			var betweenAngles = (pointRelativePosition.angle >= this.startAngle && pointRelativePosition.angle <= this.endAngle),
				withinRadius = (pointRelativePosition.distance >= this.innerRadius && pointRelativePosition.distance <= this.outerRadius);

			return (betweenAngles && withinRadius);
			//Ensure within the outside of the arc centre, but inside arc outer
		},
		tooltipPosition : function(){
			var centreAngle = this.startAngle + ((this.endAngle - this.startAngle) / 2),
				rangeFromCentre = (this.outerRadius - this.innerRadius) / 2 + this.innerRadius;
			return {
				x : this.x + (Math.cos(centreAngle) * rangeFromCentre),
				y : this.y + (Math.sin(centreAngle) * rangeFromCentre)
			};
		},
		draw : function(animationPercent){

			var easingDecimal = animationPercent || 1;

			var ctx = this.ctx;

			ctx.beginPath();

			ctx.arc(this.x, this.y, this.outerRadius, this.startAngle, this.endAngle);

			ctx.arc(this.x, this.y, this.innerRadius, this.endAngle, this.startAngle, true);

			ctx.closePath();
			ctx.strokeStyle = this.strokeColor;
			ctx.lineWidth = this.strokeWidth;

			ctx.fillStyle = this.fillColor;

			ctx.fill();
			ctx.lineJoin = 'bevel';

			if (this.showStroke){
				ctx.stroke();
			}
		}
	});

	Chart.Rectangle = Chart.Element.extend({
		draw : function(){
			var ctx = this.ctx,
				halfWidth = this.width/2,
				leftX = this.x - halfWidth,
				rightX = this.x + halfWidth,
				top = this.base - (this.base - this.y),
				halfStroke = this.strokeWidth / 2;

			// Canvas doesn't allow us to stroke inside the width so we can
			// adjust the sizes to fit if we're setting a stroke on the line
			if (this.showStroke){
				leftX += halfStroke;
				rightX -= halfStroke;
				top += halfStroke;
			}

			ctx.beginPath();

			ctx.fillStyle = this.fillColor;
			ctx.strokeStyle = this.strokeColor;
			ctx.lineWidth = this.strokeWidth;

			// It'd be nice to keep this class totally generic to any rectangle
			// and simply specify which border to miss out.
			ctx.moveTo(leftX, this.base);
			ctx.lineTo(leftX, top);
			ctx.lineTo(rightX, top);
			ctx.lineTo(rightX, this.base);
			ctx.fill();
			if (this.showStroke){
				ctx.stroke();
			}
		},
		height : function(){
			return this.base - this.y;
		},
		inRange : function(chartX,chartY){
			return (chartX >= this.x - this.width/2 && chartX <= this.x + this.width/2) && (chartY >= this.y && chartY <= this.base);
		}
	});

	Chart.Tooltip = Chart.Element.extend({
		draw : function(){

			var ctx = this.chart.ctx;

			ctx.font = fontString(this.fontSize,this.fontStyle,this.fontFamily);

			this.xAlign = "center";
			this.yAlign = "above";

			//Distance between the actual element.y position and the start of the tooltip caret
			var caretPadding = this.caretPadding = 2;

			var tooltipWidth = ctx.measureText(this.text).width + 2*this.xPadding,
				tooltipRectHeight = this.fontSize + 2*this.yPadding,
				tooltipHeight = tooltipRectHeight + this.caretHeight + caretPadding;

			if (this.x + tooltipWidth/2 >this.chart.width){
				this.xAlign = "left";
			} else if (this.x - tooltipWidth/2 < 0){
				this.xAlign = "right";
			}

			if (this.y - tooltipHeight < 0){
				this.yAlign = "below";
			}


			var tooltipX = this.x - tooltipWidth/2,
				tooltipY = this.y - tooltipHeight;

			ctx.fillStyle = this.fillColor;

			// Custom Tooltips
			if(this.custom){
				this.custom(this);
			}
			else{
				switch(this.yAlign)
				{
				case "above":
					//Draw a caret above the x/y
					ctx.beginPath();
					ctx.moveTo(this.x,this.y - caretPadding);
					ctx.lineTo(this.x + this.caretHeight, this.y - (caretPadding + this.caretHeight));
					ctx.lineTo(this.x - this.caretHeight, this.y - (caretPadding + this.caretHeight));
					ctx.closePath();
					ctx.fill();
					break;
				case "below":
					tooltipY = this.y + caretPadding + this.caretHeight;
					//Draw a caret below the x/y
					ctx.beginPath();
					ctx.moveTo(this.x, this.y + caretPadding);
					ctx.lineTo(this.x + this.caretHeight, this.y + caretPadding + this.caretHeight);
					ctx.lineTo(this.x - this.caretHeight, this.y + caretPadding + this.caretHeight);
					ctx.closePath();
					ctx.fill();
					break;
				}

				switch(this.xAlign)
				{
				case "left":
					tooltipX = this.x - tooltipWidth + (this.cornerRadius + this.caretHeight);
					break;
				case "right":
					tooltipX = this.x - (this.cornerRadius + this.caretHeight);
					break;
				}

				drawRoundedRectangle(ctx,tooltipX,tooltipY,tooltipWidth,tooltipRectHeight,this.cornerRadius);

				ctx.fill();

				ctx.fillStyle = this.textColor;
				ctx.textAlign = "center";
				ctx.textBaseline = "middle";
				ctx.fillText(this.text, tooltipX + tooltipWidth/2, tooltipY + tooltipRectHeight/2);
			}
		}
	});

	Chart.MultiTooltip = Chart.Element.extend({
		initialize : function(){
			this.font = fontString(this.fontSize,this.fontStyle,this.fontFamily);

			this.titleFont = fontString(this.titleFontSize,this.titleFontStyle,this.titleFontFamily);

			this.height = (this.labels.length * this.fontSize) + ((this.labels.length-1) * (this.fontSize/2)) + (this.yPadding*2) + this.titleFontSize *1.5;

			this.ctx.font = this.titleFont;

			var titleWidth = this.ctx.measureText(this.title).width,
				//Label has a legend square as well so account for this.
				labelWidth = longestText(this.ctx,this.font,this.labels) + this.fontSize + 3,
				longestTextWidth = max([labelWidth,titleWidth]);

			this.width = longestTextWidth + (this.xPadding*2);


			var halfHeight = this.height/2;

			//Check to ensure the height will fit on the canvas
			if (this.y - halfHeight < 0 ){
				this.y = halfHeight;
			} else if (this.y + halfHeight > this.chart.height){
				this.y = this.chart.height - halfHeight;
			}

			//Decide whether to align left or right based on position on canvas
			if (this.x > this.chart.width/2){
				this.x -= this.xOffset + this.width;
			} else {
				this.x += this.xOffset;
			}


		},
		getLineHeight : function(index){
			var baseLineHeight = this.y - (this.height/2) + this.yPadding,
				afterTitleIndex = index-1;

			//If the index is zero, we're getting the title
			if (index === 0){
				return baseLineHeight + this.titleFontSize/2;
			} else{
				return baseLineHeight + ((this.fontSize*1.5*afterTitleIndex) + this.fontSize/2) + this.titleFontSize * 1.5;
			}

		},
		draw : function(){
			// Custom Tooltips
			if(this.custom){
				this.custom(this);
			}
			else{
				drawRoundedRectangle(this.ctx,this.x,this.y - this.height/2,this.width,this.height,this.cornerRadius);
				var ctx = this.ctx;
				ctx.fillStyle = this.fillColor;
				ctx.fill();
				ctx.closePath();

				ctx.textAlign = "left";
				ctx.textBaseline = "middle";
				ctx.fillStyle = this.titleTextColor;
				ctx.font = this.titleFont;

				ctx.fillText(this.title,this.x + this.xPadding, this.getLineHeight(0));

				ctx.font = this.font;
				helpers.each(this.labels,function(label,index){
					ctx.fillStyle = this.textColor;
					ctx.fillText(label,this.x + this.xPadding + this.fontSize + 3, this.getLineHeight(index + 1));

					//A bit gnarly, but clearing this rectangle breaks when using explorercanvas (clears whole canvas)
					//ctx.clearRect(this.x + this.xPadding, this.getLineHeight(index + 1) - this.fontSize/2, this.fontSize, this.fontSize);
					//Instead we'll make a white filled block to put the legendColour palette over.

					ctx.fillStyle = this.legendColorBackground;
					ctx.fillRect(this.x + this.xPadding, this.getLineHeight(index + 1) - this.fontSize/2, this.fontSize, this.fontSize);

					ctx.fillStyle = this.legendColors[index].fill;
					ctx.fillRect(this.x + this.xPadding, this.getLineHeight(index + 1) - this.fontSize/2, this.fontSize, this.fontSize);


				},this);
			}
		}
	});

	Chart.Scale = Chart.Element.extend({
		initialize : function(){
			this.fit();
		},
		buildYLabels : function(){
			this.yLabels = [];

			var stepDecimalPlaces = getDecimalPlaces(this.stepValue);

			for (var i=0; i<=this.steps; i++){
				this.yLabels.push(template(this.templateString,{value:(this.min + (i * this.stepValue)).toFixed(stepDecimalPlaces)}));
			}
			this.yLabelWidth = (this.display && this.showLabels) ? longestText(this.ctx,this.font,this.yLabels) + 10 : 0;
		},
		addXLabel : function(label){
			this.xLabels.push(label);
			this.valuesCount++;
			this.fit();
		},
		removeXLabel : function(){
			this.xLabels.shift();
			this.valuesCount--;
			this.fit();
		},
		// Fitting loop to rotate x Labels and figure out what fits there, and also calculate how many Y steps to use
		fit: function(){
			// First we need the width of the yLabels, assuming the xLabels aren't rotated

			// To do that we need the base line at the top and base of the chart, assuming there is no x label rotation
			this.startPoint = (this.display) ? this.fontSize : 0;
			this.endPoint = (this.display) ? this.height - (this.fontSize * 1.5) - 5 : this.height; // -5 to pad labels

			// Apply padding settings to the start and end point.
			this.startPoint += this.padding;
			this.endPoint -= this.padding;

			// Cache the starting endpoint, excluding the space for x labels
			var cachedEndPoint = this.endPoint;

			// Cache the starting height, so can determine if we need to recalculate the scale yAxis
			var cachedHeight = this.endPoint - this.startPoint,
				cachedYLabelWidth;

			// Build the current yLabels so we have an idea of what size they'll be to start
			/*
			 *	This sets what is returned from calculateScaleRange as static properties of this class:
			 *
				this.steps;
				this.stepValue;
				this.min;
				this.max;
			 *
			 */
			this.calculateYRange(cachedHeight);

			// With these properties set we can now build the array of yLabels
			// and also the width of the largest yLabel
			this.buildYLabels();

			this.calculateXLabelRotation();

			while((cachedHeight > this.endPoint - this.startPoint)){
				cachedHeight = this.endPoint - this.startPoint;
				cachedYLabelWidth = this.yLabelWidth;

				this.calculateYRange(cachedHeight);
				this.buildYLabels();

				// Only go through the xLabel loop again if the yLabel width has changed
				if (cachedYLabelWidth < this.yLabelWidth){
					this.endPoint = cachedEndPoint;
					this.calculateXLabelRotation();
				}
			}

		},
		calculateXLabelRotation : function(){
			//Get the width of each grid by calculating the difference
			//between x offsets between 0 and 1.

			this.ctx.font = this.font;

			var firstWidth = this.ctx.measureText(this.xLabels[0]).width,
				lastWidth = this.ctx.measureText(this.xLabels[this.xLabels.length - 1]).width,
				firstRotated,
				lastRotated;


			this.xScalePaddingRight = lastWidth/2 + 3;
			this.xScalePaddingLeft = (firstWidth/2 > this.yLabelWidth) ? firstWidth/2 : this.yLabelWidth;

			this.xLabelRotation = 0;
			if (this.display){
				var originalLabelWidth = longestText(this.ctx,this.font,this.xLabels),
					cosRotation,
					firstRotatedWidth;
				this.xLabelWidth = originalLabelWidth;
				//Allow 3 pixels x2 padding either side for label readability
				var xGridWidth = Math.floor(this.calculateX(1) - this.calculateX(0)) - 6;

				//Max label rotate should be 90 - also act as a loop counter
				while ((this.xLabelWidth > xGridWidth && this.xLabelRotation === 0) || (this.xLabelWidth > xGridWidth && this.xLabelRotation <= 90 && this.xLabelRotation > 0)){
					cosRotation = Math.cos(toRadians(this.xLabelRotation));

					firstRotated = cosRotation * firstWidth;
					lastRotated = cosRotation * lastWidth;

					// We're right aligning the text now.
					if (firstRotated + this.fontSize / 2 > this.yLabelWidth){
						this.xScalePaddingLeft = firstRotated + this.fontSize / 2;
					}
					this.xScalePaddingRight = this.fontSize/2;


					this.xLabelRotation++;
					this.xLabelWidth = cosRotation * originalLabelWidth;

				}
				if (this.xLabelRotation > 0){
					this.endPoint -= Math.sin(toRadians(this.xLabelRotation))*originalLabelWidth + 3;
				}
			}
			else{
				this.xLabelWidth = 0;
				this.xScalePaddingRight = this.padding;
				this.xScalePaddingLeft = this.padding;
			}

		},
		// Needs to be overidden in each Chart type
		// Otherwise we need to pass all the data into the scale class
		calculateYRange: noop,
		drawingArea: function(){
			return this.startPoint - this.endPoint;
		},
		calculateY : function(value){
			var scalingFactor = this.drawingArea() / (this.min - this.max);
			return this.endPoint - (scalingFactor * (value - this.min));
		},
		calculateX : function(index){
			var isRotated = (this.xLabelRotation > 0),
				// innerWidth = (this.offsetGridLines) ? this.width - offsetLeft - this.padding : this.width - (offsetLeft + halfLabelWidth * 2) - this.padding,
				innerWidth = this.width - (this.xScalePaddingLeft + this.xScalePaddingRight),
				valueWidth = innerWidth/Math.max((this.valuesCount - ((this.offsetGridLines) ? 0 : 1)), 1),
				valueOffset = (valueWidth * index) + this.xScalePaddingLeft;

			if (this.offsetGridLines){
				valueOffset += (valueWidth/2);
			}

			return Math.round(valueOffset);
		},
		update : function(newProps){
			helpers.extend(this, newProps);
			this.fit();
		},
		draw : function(){
			var ctx = this.ctx,
				yLabelGap = (this.endPoint - this.startPoint) / this.steps,
				xStart = Math.round(this.xScalePaddingLeft);
			if (this.display){
				ctx.fillStyle = this.textColor;
				ctx.font = this.font;
				each(this.yLabels,function(labelString,index){
					var yLabelCenter = this.endPoint - (yLabelGap * index),
						linePositionY = Math.round(yLabelCenter),
						drawHorizontalLine = this.showHorizontalLines;

					ctx.textAlign = "right";
					ctx.textBaseline = "middle";
					if (this.showLabels){
						ctx.fillText(labelString,xStart - 10,yLabelCenter);
					}

					// This is X axis, so draw it
					if (index === 0 && !drawHorizontalLine){
						drawHorizontalLine = true;
					}

					if (drawHorizontalLine){
						ctx.beginPath();
					}

					if (index > 0){
						// This is a grid line in the centre, so drop that
						ctx.lineWidth = this.gridLineWidth;
						ctx.strokeStyle = this.gridLineColor;
					} else {
						// This is the first line on the scale
						ctx.lineWidth = this.lineWidth;
						ctx.strokeStyle = this.lineColor;
					}

					linePositionY += helpers.aliasPixel(ctx.lineWidth);

					if(drawHorizontalLine){
						ctx.moveTo(xStart, linePositionY);
						ctx.lineTo(this.width, linePositionY);
						ctx.stroke();
						ctx.closePath();
					}

					ctx.lineWidth = this.lineWidth;
					ctx.strokeStyle = this.lineColor;
					ctx.beginPath();
					ctx.moveTo(xStart - 5, linePositionY);
					ctx.lineTo(xStart, linePositionY);
					ctx.stroke();
					ctx.closePath();

				},this);

				each(this.xLabels,function(label,index){
					var xPos = this.calculateX(index) + aliasPixel(this.lineWidth),
						// Check to see if line/bar here and decide where to place the line
						linePos = this.calculateX(index - (this.offsetGridLines ? 0.5 : 0)) + aliasPixel(this.lineWidth),
						isRotated = (this.xLabelRotation > 0),
						drawVerticalLine = this.showVerticalLines;

					// This is Y axis, so draw it
					if (index === 0 && !drawVerticalLine){
						drawVerticalLine = true;
					}

					if (drawVerticalLine){
						ctx.beginPath();
					}

					if (index > 0){
						// This is a grid line in the centre, so drop that
						ctx.lineWidth = this.gridLineWidth;
						ctx.strokeStyle = this.gridLineColor;
					} else {
						// This is the first line on the scale
						ctx.lineWidth = this.lineWidth;
						ctx.strokeStyle = this.lineColor;
					}

					if (drawVerticalLine){
						ctx.moveTo(linePos,this.endPoint);
						ctx.lineTo(linePos,this.startPoint - 3);
						ctx.stroke();
						ctx.closePath();
					}


					ctx.lineWidth = this.lineWidth;
					ctx.strokeStyle = this.lineColor;


					// Small lines at the bottom of the base grid line
					ctx.beginPath();
					ctx.moveTo(linePos,this.endPoint);
					ctx.lineTo(linePos,this.endPoint + 5);
					ctx.stroke();
					ctx.closePath();

					ctx.save();
					ctx.translate(xPos,(isRotated) ? this.endPoint + 12 : this.endPoint + 8);
					ctx.rotate(toRadians(this.xLabelRotation)*-1);
					ctx.font = this.font;
					ctx.textAlign = (isRotated) ? "right" : "center";
					ctx.textBaseline = (isRotated) ? "middle" : "top";
					ctx.fillText(label, 0, 0);
					ctx.restore();
				},this);

			}
		}

	});

	Chart.RadialScale = Chart.Element.extend({
		initialize: function(){
			this.size = min([this.height, this.width]);
			this.drawingArea = (this.display) ? (this.size/2) - (this.fontSize/2 + this.backdropPaddingY) : (this.size/2);
		},
		calculateCenterOffset: function(value){
			// Take into account half font size + the yPadding of the top value
			var scalingFactor = this.drawingArea / (this.max - this.min);

			return (value - this.min) * scalingFactor;
		},
		update : function(){
			if (!this.lineArc){
				this.setScaleSize();
			} else {
				this.drawingArea = (this.display) ? (this.size/2) - (this.fontSize/2 + this.backdropPaddingY) : (this.size/2);
			}
			this.buildYLabels();
		},
		buildYLabels: function(){
			this.yLabels = [];

			var stepDecimalPlaces = getDecimalPlaces(this.stepValue);

			for (var i=0; i<=this.steps; i++){
				this.yLabels.push(template(this.templateString,{value:(this.min + (i * this.stepValue)).toFixed(stepDecimalPlaces)}));
			}
		},
		getCircumference : function(){
			return ((Math.PI*2) / this.valuesCount);
		},
		setScaleSize: function(){
			/*
			 * Right, this is really confusing and there is a lot of maths going on here
			 * The gist of the problem is here: https://gist.github.com/nnnick/696cc9c55f4b0beb8fe9
			 *
			 * Reaction: https://dl.dropboxusercontent.com/u/34601363/toomuchscience.gif
			 *
			 * Solution:
			 *
			 * We assume the radius of the polygon is half the size of the canvas at first
			 * at each index we check if the text overlaps.
			 *
			 * Where it does, we store that angle and that index.
			 *
			 * After finding the largest index and angle we calculate how much we need to remove
			 * from the shape radius to move the point inwards by that x.
			 *
			 * We average the left and right distances to get the maximum shape radius that can fit in the box
			 * along with labels.
			 *
			 * Once we have that, we can find the centre point for the chart, by taking the x text protrusion
			 * on each side, removing that from the size, halving it and adding the left x protrusion width.
			 *
			 * This will mean we have a shape fitted to the canvas, as large as it can be with the labels
			 * and position it in the most space efficient manner
			 *
			 * https://dl.dropboxusercontent.com/u/34601363/yeahscience.gif
			 */


			// Get maximum radius of the polygon. Either half the height (minus the text width) or half the width.
			// Use this to calculate the offset + change. - Make sure L/R protrusion is at least 0 to stop issues with centre points
			var largestPossibleRadius = min([(this.height/2 - this.pointLabelFontSize - 5), this.width/2]),
				pointPosition,
				i,
				textWidth,
				halfTextWidth,
				furthestRight = this.width,
				furthestRightIndex,
				furthestRightAngle,
				furthestLeft = 0,
				furthestLeftIndex,
				furthestLeftAngle,
				xProtrusionLeft,
				xProtrusionRight,
				radiusReductionRight,
				radiusReductionLeft,
				maxWidthRadius;
			this.ctx.font = fontString(this.pointLabelFontSize,this.pointLabelFontStyle,this.pointLabelFontFamily);
			for (i=0;i<this.valuesCount;i++){
				// 5px to space the text slightly out - similar to what we do in the draw function.
				pointPosition = this.getPointPosition(i, largestPossibleRadius);
				textWidth = this.ctx.measureText(template(this.templateString, { value: this.labels[i] })).width + 5;
				if (i === 0 || i === this.valuesCount/2){
					// If we're at index zero, or exactly the middle, we're at exactly the top/bottom
					// of the radar chart, so text will be aligned centrally, so we'll half it and compare
					// w/left and right text sizes
					halfTextWidth = textWidth/2;
					if (pointPosition.x + halfTextWidth > furthestRight) {
						furthestRight = pointPosition.x + halfTextWidth;
						furthestRightIndex = i;
					}
					if (pointPosition.x - halfTextWidth < furthestLeft) {
						furthestLeft = pointPosition.x - halfTextWidth;
						furthestLeftIndex = i;
					}
				}
				else if (i < this.valuesCount/2) {
					// Less than half the values means we'll left align the text
					if (pointPosition.x + textWidth > furthestRight) {
						furthestRight = pointPosition.x + textWidth;
						furthestRightIndex = i;
					}
				}
				else if (i > this.valuesCount/2){
					// More than half the values means we'll right align the text
					if (pointPosition.x - textWidth < furthestLeft) {
						furthestLeft = pointPosition.x - textWidth;
						furthestLeftIndex = i;
					}
				}
			}

			xProtrusionLeft = furthestLeft;

			xProtrusionRight = Math.ceil(furthestRight - this.width);

			furthestRightAngle = this.getIndexAngle(furthestRightIndex);

			furthestLeftAngle = this.getIndexAngle(furthestLeftIndex);

			radiusReductionRight = xProtrusionRight / Math.sin(furthestRightAngle + Math.PI/2);

			radiusReductionLeft = xProtrusionLeft / Math.sin(furthestLeftAngle + Math.PI/2);

			// Ensure we actually need to reduce the size of the chart
			radiusReductionRight = (isNumber(radiusReductionRight)) ? radiusReductionRight : 0;
			radiusReductionLeft = (isNumber(radiusReductionLeft)) ? radiusReductionLeft : 0;

			this.drawingArea = largestPossibleRadius - (radiusReductionLeft + radiusReductionRight)/2;

			//this.drawingArea = min([maxWidthRadius, (this.height - (2 * (this.pointLabelFontSize + 5)))/2])
			this.setCenterPoint(radiusReductionLeft, radiusReductionRight);

		},
		setCenterPoint: function(leftMovement, rightMovement){

			var maxRight = this.width - rightMovement - this.drawingArea,
				maxLeft = leftMovement + this.drawingArea;

			this.xCenter = (maxLeft + maxRight)/2;
			// Always vertically in the centre as the text height doesn't change
			this.yCenter = (this.height/2);
		},

		getIndexAngle : function(index){
			var angleMultiplier = (Math.PI * 2) / this.valuesCount;
			// Start from the top instead of right, so remove a quarter of the circle

			return index * angleMultiplier - (Math.PI/2);
		},
		getPointPosition : function(index, distanceFromCenter){
			var thisAngle = this.getIndexAngle(index);
			return {
				x : (Math.cos(thisAngle) * distanceFromCenter) + this.xCenter,
				y : (Math.sin(thisAngle) * distanceFromCenter) + this.yCenter
			};
		},
		draw: function(){
			if (this.display){
				var ctx = this.ctx;
				each(this.yLabels, function(label, index){
					// Don't draw a centre value
					if (index > 0){
						var yCenterOffset = index * (this.drawingArea/this.steps),
							yHeight = this.yCenter - yCenterOffset,
							pointPosition;

						// Draw circular lines around the scale
						if (this.lineWidth > 0){
							ctx.strokeStyle = this.lineColor;
							ctx.lineWidth = this.lineWidth;

							if(this.lineArc){
								ctx.beginPath();
								ctx.arc(this.xCenter, this.yCenter, yCenterOffset, 0, Math.PI*2);
								ctx.closePath();
								ctx.stroke();
							} else{
								ctx.beginPath();
								for (var i=0;i<this.valuesCount;i++)
								{
									pointPosition = this.getPointPosition(i, this.calculateCenterOffset(this.min + (index * this.stepValue)));
									if (i === 0){
										ctx.moveTo(pointPosition.x, pointPosition.y);
									} else {
										ctx.lineTo(pointPosition.x, pointPosition.y);
									}
								}
								ctx.closePath();
								ctx.stroke();
							}
						}
						if(this.showLabels){
							ctx.font = fontString(this.fontSize,this.fontStyle,this.fontFamily);
							if (this.showLabelBackdrop){
								var labelWidth = ctx.measureText(label).width;
								ctx.fillStyle = this.backdropColor;
								ctx.fillRect(
									this.xCenter - labelWidth/2 - this.backdropPaddingX,
									yHeight - this.fontSize/2 - this.backdropPaddingY,
									labelWidth + this.backdropPaddingX*2,
									this.fontSize + this.backdropPaddingY*2
								);
							}
							ctx.textAlign = 'center';
							ctx.textBaseline = "middle";
							ctx.fillStyle = this.fontColor;
							ctx.fillText(label, this.xCenter, yHeight);
						}
					}
				}, this);

				if (!this.lineArc){
					ctx.lineWidth = this.angleLineWidth;
					ctx.strokeStyle = this.angleLineColor;
					for (var i = this.valuesCount - 1; i >= 0; i--) {
						if (this.angleLineWidth > 0){
							var outerPosition = this.getPointPosition(i, this.calculateCenterOffset(this.max));
							ctx.beginPath();
							ctx.moveTo(this.xCenter, this.yCenter);
							ctx.lineTo(outerPosition.x, outerPosition.y);
							ctx.stroke();
							ctx.closePath();
						}
						// Extra 3px out for some label spacing
						var pointLabelPosition = this.getPointPosition(i, this.calculateCenterOffset(this.max) + 5);
						ctx.font = fontString(this.pointLabelFontSize,this.pointLabelFontStyle,this.pointLabelFontFamily);
						ctx.fillStyle = this.pointLabelFontColor;

						var labelsCount = this.labels.length,
							halfLabelsCount = this.labels.length/2,
							quarterLabelsCount = halfLabelsCount/2,
							upperHalf = (i < quarterLabelsCount || i > labelsCount - quarterLabelsCount),
							exactQuarter = (i === quarterLabelsCount || i === labelsCount - quarterLabelsCount);
						if (i === 0){
							ctx.textAlign = 'center';
						} else if(i === halfLabelsCount){
							ctx.textAlign = 'center';
						} else if (i < halfLabelsCount){
							ctx.textAlign = 'left';
						} else {
							ctx.textAlign = 'right';
						}

						// Set the correct text baseline based on outer positioning
						if (exactQuarter){
							ctx.textBaseline = 'middle';
						} else if (upperHalf){
							ctx.textBaseline = 'bottom';
						} else {
							ctx.textBaseline = 'top';
						}

						ctx.fillText(this.labels[i], pointLabelPosition.x, pointLabelPosition.y);
					}
				}
			}
		}
	});

	// Attach global event to resize each chart instance when the browser resizes
	helpers.addEvent(window, "resize", (function(){
		// Basic debounce of resize function so it doesn't hurt performance when resizing browser.
		var timeout;
		return function(){
			clearTimeout(timeout);
			timeout = setTimeout(function(){
				each(Chart.instances,function(instance){
					// If the responsive flag is set in the chart instance config
					// Cascade the resize event down to the chart.
					if (instance.options.responsive){
						instance.resize(instance.render, true);
					}
				});
			}, 50);
		};
	})());


	if (amd) {
		define(function(){
			return Chart;
		});
	} else if (typeof module === 'object' && module.exports) {
		module.exports = Chart;
	}

	root.Chart = Chart;

	Chart.noConflict = function(){
		root.Chart = previous;
		return Chart;
	};

}).call(this);