draw a circle loader

pie.js

createPie : function (game, w, h) {
	console.log("create pie", w, h, this);
	var mask = game.add.bitmapData(w, w),
		bmd = game.add.bitmapData(w, w),
		canvas = bmd.canvas,
		context = bmd.ctx,
		size = 270,
		degreesToRadians = function (degrees) {
			return (degrees * Math.PI) / 180;
		};

	var drawPie = function () {
		bmd.clear();
		context.save();
		var centerX = Math.floor(w / 2);
		var centerY = Math.floor(w / 2);
		var radius = Math.floor(w / 2);

		var startingAngle = degreesToRadians(270);
		var arcSize = degreesToRadians(size);
		var endingAngle = startingAngle + arcSize;

		context.beginPath();
		context.moveTo(centerX, centerY);
		context.arc(centerX, centerY, radius, startingAngle, endingAngle, false);
		context.closePath();

		context.fillStyle = 'rgba(0, 0, 0, 1)';
		context.fill();
		context.restore();

		bmd.render();
	};


	drawPie();

	game.cache.addBitmapData("loaderMaskBMD", bmd);

	var maskImage = game.add.image(348, 221, bmd);
	console.log("maskImage", maskImage);
	// doesn't work
	//game.cache.addImage("loaderMaskImage", maskImage);

	game.load.onFileComplete.add(function (progress) {
		console.log("load", progress);
		size = (360 / 100) * progress;
		drawPie();
	});

	// doesn't work
	//mask.alphaMask('preloaderRingLoaded', maskImage);

	// doesn't work
	//mask.alphaMask('preloaderRingLoaded', game.cache.getBitmapData("loaderMaskBMD"));

	// doesn't work
	//mask.alphaMask('preloaderRingLoaded', game.cache.getImage("loaderMaskImage"));

	var sp = game.add.sprite(348, 221, mask);
	sp.width = w;
	sp.height = h;
	console.log("sp", sp);
},