Merge pull request #1068 from nnnick/animation-refactory

Animation refactory

src/Chart.Core.js

@@ -915,7 +915,7 @@
 		},
 		stop : function(){
 			// Stops any current animation loop occuring
-			cancelAnimFrame(this.animationFrame);
+			Chart.animationService.cancelAnimation(this);
 			return this;
 		},
 		resize : function(callback){
@@ -939,15 +939,26 @@
 			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
-				);
+				var animation = new Chart.Animation();
+				animation.numSteps = this.options.animationSteps;
+				animation.easing = this.options.animationEasing;
+				
+				// render function
+				animation.render = function(chartInstance, animationObject) {
+					var easingFunction = helpers.easingEffects[animationObject.easing];
+					var stepDecimal = animationObject.currentStep / animationObject.numSteps;
+					var easeDecimal = easingFunction(stepDecimal);
+					
+					chartInstance.draw(easeDecimal, stepDecimal, animationObject.currentStep);
+				};
+				
+				// user events
+				animation.onAnimationProgress = this.options.onAnimationProgress;
+				animation.onAnimationComplete = this.options.onAnimationComplete;
+				
+				Chart.animationService.addAnimation(this, animation);
 			}
 			else{
 				this.draw();
@@ -1354,6 +1365,16 @@
 		}
 	});
 
+	Chart.Animation = Chart.Element.extend({
+		currentStep: null, // the current animation step
+		numSteps: 60, // default number of steps
+		easing: "", // the easing to use for this animation
+		render: null, // render function used by the animation service
+		
+		onAnimationProgress: null, // user specified callback to fire on each step of the animation 
+		onAnimationComplete: null, // user specified callback to fire when the animation finishes
+	});
+	
 	Chart.Tooltip = Chart.Element.extend({
 		draw : function(){
 
@@ -2059,6 +2080,90 @@
 		}
 	});
 
+	Chart.animationService = {
+		frameDuration: 17,
+		animations: [],
+		dropFrames: 0,
+		addAnimation: function(chartInstance, animationObject) {
+			for (var index = 0; index < this.animations.length; ++ index){
+				if (this.animations[index].chartInstance === chartInstance){
+					// replacing an in progress animation
+					this.animations[index].animationObject = animationObject;
+					return;
+				}
+			}
+			
+			this.animations.push({
+				chartInstance: chartInstance,
+				animationObject: animationObject
+			});
+
+			// If there are no animations queued, manually kickstart a digest, for lack of a better word
+			if (this.animations.length == 1) {
+				helpers.requestAnimFrame.call(window, this.digestWrapper);
+			}
+		},
+		// Cancel the animation for a given chart instance
+		cancelAnimation: function(chartInstance) {
+			var index = helpers.findNextWhere(this.animations, function(animationWrapper) {
+				return animationWrapper.chartInstance === chartInstance;
+			});
+			
+			if (index)
+			{
+				this.animations.splice(index, 1);
+			}
+		},
+		// calls startDigest with the proper context
+		digestWrapper: function() {
+			Chart.animationService.startDigest.call(Chart.animationService);
+		},
+		startDigest: function() {
+
+			var startTime = Date.now();
+			var framesToDrop = 0;
+
+			if(this.dropFrames > 1){
+				framesToDrop = Math.floor(this.dropFrames);
+				this.dropFrames -= framesToDrop;
+			}
+
+			for (var i = 0; i < this.animations.length; i++) {
+
+				if (this.animations[i].animationObject.currentStep === null){
+					this.animations[i].animationObject.currentStep = 0;
+				}
+
+				this.animations[i].animationObject.currentStep += 1 + framesToDrop;
+				if(this.animations[i].animationObject.currentStep > this.animations[i].animationObject.numSteps){
+					this.animations[i].animationObject.currentStep = this.animations[i].animationObject.numSteps;
+				}
+				
+				this.animations[i].animationObject.render(this.animations[i].chartInstance, this.animations[i].animationObject);
+				
+				if (this.animations[i].animationObject.currentStep == this.animations[i].animationObject.numSteps){
+					// executed the last frame. Remove the animation.
+					this.animations.splice(i, 1);
+					// Keep the index in place to offset the splice
+					i--;
+				}
+			}
+
+			var endTime = Date.now();
+			var delay = endTime - startTime - this.frameDuration;
+			var frameDelay = delay / this.frameDuration;
+
+			if(frameDelay > 1){
+				this.dropFrames += frameDelay;
+			}
+
+			// Do we have more stuff to animate?
+			if (this.animations.length > 0){
+				helpers.requestAnimFrame.call(window, this.digestWrapper);
+			}
+		}
+	};
+
 	// 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.