AnimationTimer and actual frame rate

Markus KARG markus at
Fri Dec 23 17:18:49 UTC 2016

I assume it is OK for you to use internal APIs? Then you could go with:


and let a timer fire one per second to request tracker.getAverageFPS().

Beware not to use any AnimationTimer handlers, as it will reduce FPS, even if the handler method is short.


-----Original Message-----
From: openjfx-dev [mailto:openjfx-dev-bounces at] On Behalf Of Michael Paus
Sent: Freitag, 23. Dezember 2016 17:04
To: openjfx-dev at
Subject: Re: AnimationTimer and actual frame rate

Thank you. That explains a lot of what I am observing but it also makes me wonder how you could effectively measure the actual frame rate because that's what you are normally interested in.

Am 23.12.16 um 09:15 schrieb Markus KARG:
> AnimationTimer is fired once per "planned" frame (i. e. running at maximum possible FPS), not per "actually rendered" frame. JavaFX contains a lot of optimizations. For example, a boolean property animated over time to switch from false to true will only imply a single modification, hence only one frame is actually rendered.
> -Markus
> -----Original Message-----
> From: openjfx-dev [mailto:openjfx-dev-bounces at] On 
> Behalf Of Michael Paus
> Sent: Donnerstag, 22. Dezember 2016 17:29
> To: openjfx-dev at
> Subject: AnimationTimer and actual frame rate
> Hi all,
> for quite a while now I am observing a strange behavior when running 
> some
> JavaFX graphics tests. The scenario is very simple. I am running some 
> animation
> which puts some load onto the graphics engine and I am trying to 
> measure the
> frame rate via an instance of an AnimationTimer. When I increase the 
> load high
> enough I reach a point where the indicated frame rate is just 60FPS or 
> even a bit
> lower but the observed frame rate on screen has already dropped to 
> something
> like 1-2 FPS. So what I observe is that the AnimationTimer is running 
> much faster
> than the updates of the graphics. How can that be? Does anybody have 
> an explanation
> under which circumstances this can happen? Or is this behavior a bug which I should report?
> Just some puzzle for the boring Christmas holidays :-)
> Merry Christmas to all of you
> Michael
> PS: My system is a MacBook Pro with NVidia graphic card.

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