JavaScript

var canvas = document.querySelector('#canvas');
var ctx = canvas.getContext('2d');
var w = canvas.width;
var h = canvas.height;
	ctx.clearRect(0,0,w,h);
var image = new Image();
var r = 100;
image.onload = function() {
var pattern = ctx.createPattern(image,'no-repeat');
	ctx.fillStyle=pattern;
	ctx.arc(100,100,r,0,Math.PI*2,false);
	ctx.fill();
};
image.src = 'http://jewellslinks.com/site/wp-content/uploads/2012/03/bg-blinking-star-background.gif';