mems/performance.html

## performance.html
<!DOCTYPE html PUBLIC>
<html>
	<head>
		<title></title>
	</head>
	<body>
		<script>
			// Polyfill
			window.performance = (window.performance || {
				offset: Date.now(),
				now: function now(){
					return Date.now() - this.offset;
				}
			});

			var canvas = document.createElement("CANVAS");
			canvas.width = canvas.height = 1000;
			var context = canvas.getContext("2d");
			var t0 = performance.now();
			// first call drawImage twice. Required by Chrome, Opera, IE and Safari Mobile: it take time at cold start, not in next reloads
			context.drawImage(canvas, 0, 0, 1, 1);
			context.drawImage(canvas, 0, 0, 1, 1);
			var t1 = performance.now();
			for(var iter = 0; iter < 50; iter++){
				context.translate(-10, -10);
				context.rotate(Math.PI/2);
				context.translate(10, 10);
				context.drawImage(canvas, 0, 0, 20, 20, 0, 0, 19, 19);
			}
			var t2 = performance.now();
			document.body.textContent = "\ncanvas stress test: "+(t2 - t1).toFixed(4)+"ms (init: "+(t1 - t0).toFixed(4)+"ms)";
		</script>
	</body>
</html>
	<!DOCTYPE html PUBLIC>
	<html>
	<head>
	<title></title>
	</head>
	<body>
	<script>
	// Polyfill
	window.performance = (window.performance \|\| {
	offset: Date.now(),
	now: function now(){
	return Date.now() - this.offset;
	}
	});

	var canvas = document.createElement("CANVAS");
	canvas.width = canvas.height = 1000;
	var context = canvas.getContext("2d");
	var t0 = performance.now();
	// first call drawImage twice. Required by Chrome, Opera, IE and Safari Mobile: it take time at cold start, not in next reloads
	context.drawImage(canvas, 0, 0, 1, 1);
	context.drawImage(canvas, 0, 0, 1, 1);
	var t1 = performance.now();
	for(var iter = 0; iter < 50; iter++){
	context.translate(-10, -10);
	context.rotate(Math.PI/2);
	context.translate(10, 10);
	context.drawImage(canvas, 0, 0, 20, 20, 0, 0, 19, 19);
	}
	var t2 = performance.now();
	document.body.textContent = "\ncanvas stress test: "+(t2 - t1).toFixed(4)+"ms (init: "+(t1 - t0).toFixed(4)+"ms)";
	</script>
	</body>
	</html>