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Re: ISSUE-3 (monotonic-clock): Animation frame times should be monotonically increasing [Request Animation Frame]

From: James Robinson <jamesr@google.com>
Date: Wed, 18 May 2011 17:17:47 -0700
Message-ID: <BANLkTimQTKZhh2TKBG4DH6MSQVjAUBJ9Rg@mail.gmail.com>
To: Jatinder Mann <jmann@microsoft.com>
Cc: "public-web-perf@w3.org" <public-web-perf@w3.org>
On Wed, May 18, 2011 at 5:08 PM, Jatinder Mann <jmann@microsoft.com> wrote:

> As we have been evaluating this spec, the concept of a
> window.animationStartTime property seems like a very reasonable property to
> standardize. This property will allow all animations to have the same
> starting point. Without standardizing this property, web developers will be
> forced to use Date.now(), which currently is not defined as monotonically
> increasing and may not always have a millisecond resolution.
>
> We feel that both window.animationStartTime and the requestAnimationFrame()
> callback timestamp should be implemented as monotonically increasing clocks,
> in UTC format with millisecond resolution.
>

What does "UTC format with millisecond resolution" mean?  DOMTimeStamps are
defined as numbers, which do not have any sort of format.

- James


>
> Jatinder
>
> -----Original Message-----
> From: public-web-perf-request@w3.org [mailto:
> public-web-perf-request@w3.org] On Behalf Of Web Performance Working Group
> Issue Tracker
> Sent: Wednesday, May 18, 2011 3:18 PM
> To: public-web-perf@w3.org
> Subject: ISSUE-3 (monotonic-clock): Animation frame times should be
> monotonically increasing [Request Animation Frame]
>
>
> ISSUE-3 (monotonic-clock): Animation frame times should be monotonically
> increasing [Request Animation Frame]
>
> http://www.w3.org/2010/webperf/track/issues/3
>
> Raised by: Cameron McCormack
> On product: Request Animation Frame
>
> Having animation frame times run off a monotonic clock would be better for
> authors than a clock that might jump backwards.  Doing this argues for the
> reinclusion of the Window.animationStartTime attribute, so that scripts can
> avoid using Date.now() to record the animation start time, which might bear
> little relation to the monotonic clock values anyway.
>
>
>
>
>
Received on Thursday, 19 May 2011 00:18:13 GMT

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