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

From: Jatinder Mann <jmann@microsoft.com>
Date: Thu, 19 May 2011 00:08:24 +0000
To: "public-web-perf@w3.org" <public-web-perf@w3.org>
Message-ID: <EE4C13A1D11CFA49A58343DE361B0B040683B3BB@TK5EX14MBXC252.redmond.corp.microsoft.com>
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.

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 00:08:51 GMT

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