private float getTimingFraction() {
		long currentTime = System.nanoTime() / 1000000;
		long elapsedTime = currentTime - startTime;
		timeToStop = (elapsedTime >= duration);

		float fraction = clampFraction( (float) elapsedTime / duration );
		if( interpolator != null )
			fraction = clampFraction( interpolator.interpolate( fraction ) );
		return fraction;
	}
Returns whether this animation is running.
flatlaf-core/src/main/java/com/formdev/flatlaf/util/Animator.java