W3C home > Mailing lists > Public > public-web-perf@w3.org > February 2012

Re: Specifying window.performance.now()

From: Boris Zbarsky <bzbarsky@MIT.EDU>
Date: Wed, 29 Feb 2012 16:40:14 -0500
Message-ID: <4F4E9B3E.4070601@mit.edu>
To: James Robinson <jamesr@google.com>
CC: public-web-perf@w3.org
On 2/29/12 4:20 PM, James Robinson wrote:
> I'm a little more optimistic about requestAnimationFrame.  It's true
> that lots of code is using JS Date.now(), but that code will continue to
> work as-is.  I do not think that there is a large amount of web content
> out there using the callback _parameter_ for timing, most code is just
> ignoring it and grabbing the time out-of-band.

If true, that would make things work ok.  I guess I'd thought people 
would actually use the parameter, since it's there for a reason...

Certainly the demos I've seen using requestAnimationFrame use it.  I 
seem to recall Google Maps doing so too, but maybe they changed that?

> I think we should try changing this and see what happens.  If it turns
> out that we can't change the value of the first parameter to the
> callback, then we can do something uglier like provide a second callback
> parameter.

:(

> I think that we definitely do want to provide a timestamp to
> authors as a callback parameter so that they can synchronize multiple
> animations running on the same logical frame.

Oh, we absolutely do.  That's what Gecko does right now.  The only 
question is what the timestamp's 0-point should be....

-Boris
Received on Wednesday, 29 February 2012 21:40:43 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Wednesday, 29 February 2012 21:40:46 GMT