reactfx/src/main/java/org/reactfx/EventStreams.java
public static EventStream<Long> animationTicks() {
        return new EventStreamBase<Long>() {
            private final AnimationTimer timer = new AnimationTimer() {
                @Override
                public void handle(long now) {
                    emit(now);
                }
            };

            @Override
            protected Subscription observeInputs() {
                timer.start();
                return timer::stop;
            }
        };
    }
public static EventStream<Long> animationTicks() {
        return new EventStreamBase<Long>() {
            private final AnimationTimer timer = new AnimationTimer() {
                @Override
                public void handle(long now) {
                    emit(now);
                }
            };

            @Override
            protected Subscription observeInputs() {
                timer.start();
                return timer::stop;
            }
        };
    }
Returns an event stream that emits a timestamp of the current frame in
nanoseconds on every frame. The timestamp has the same meaning as the
argument of the {@link AnimationTimer#handle(long)} method.