Low impact FPS counter

FPSCounter.hx

class FPSCounter extends TextField
{
	public var currentFPS (default, null):Float;

	private var cacheCount:Int;
	private var times:Array <Float>;
	private var lastUIUpdate:Float;

	public function new(x:Float = 10, y:Float = 10, color:Int = 0x000000, fontSize:Int=24) {

		super ();

		this.x = x;
		this.y = y;

		currentFPS = 0;
		lastUIUpdate = 0;
		selectable = false;
		defaultTextFormat = new TextFormat("_sans", fontSize, color, true);
		text = "";

		cacheCount = 0;
		times = [];

		addEventListener(Event.ENTER_FRAME, onEnterFrame);
	}

	// Event Handlers
	private function onEnterFrame (event:Event):Void {

		var currentTime = Timer.stamp ();
		times.push(currentTime);

		while (times[0] < currentTime - 1) {
			times.shift();
		}

		var currentCount = times.length;
		currentFPS = Math.round ((currentCount + cacheCount) / 2);

		if (currentCount != cacheCount && visible) {
			var sinceLastUpdate = currentTime - lastUIUpdate;

			if (sinceLastUpdate > 3)
			{
				text = "" + currentFPS + " fps";
				lastUIUpdate = currentTime;
			}
		}
		cacheCount = currentCount;
	}
}