/**
 * An utility class used to measure frames per second.
 */
export class FPSCallback {
	/**
	 * Initializes a new instance of FPSCallback class.
	 */
	constructor(onFrame: (currentTimeMillis: number) => void);

	/**
	 * Starts the frame per seconds measurement.
	 */
	start(): void;

	/**
	 * Stops the frame per seconds measurement.
	 */
	stop(): void;

	/**
	 * Gets if the current instance of FPSCallback is running.
	 */
	running: boolean;
}