Bugzilla – Bug 20220
hwTimestamp should be interoperable with the high resolution time spec
Last modified: 2013-01-07 23:30:37 UTC
PointerEvent has a hwTimestamp field, currently defined as:
A timestamp, in microseconds, of the pointer event as reported by hardware. The origin time (e.g. hwTimestamp equals 0) is hardware and/or operating system dependent. If the hardware does not provide a high resolution timestamp, then the value must be 0.
However, for this value to be really useful it must be comparable to the high-resolution time returned by other APIs. In particular, the High Resolution Time spec (http://dvcs.w3.org/hg/webperf/raw-file/tip/specs/HighResolutionTime/Overview.html) defines specific semantics for such a value. Can we just match those?
In fact, it sounds like 'systemTime' is going to be added to the DOM Event type for this purpose (http://lists.w3.org/Archives/Public/www-dom/2012OctDec/0022.html, http://lists.w3.org/Archives/Public/public-web-perf/2012Oct/0046.html). Perhaps we should just remove hwTimestamp from pointer events, and rely on the pending addition for all types of Event.
Per 12/18 WG meeting resolution, removing hwTimestamp from spec. We will follow-up with DOM4/UI-EVENTS to pursue a general high-res timestamp on all events (not just pointer.