Re: UIEvent timestamp clarification
Re: UIEvent timestamp clarification
- Subject: Re: UIEvent timestamp clarification
- From: Matt Neuburg <email@hidden>
- Date: Fri, 14 Jan 2011 07:56:39 -0800
On Wed, 12 Jan 2011 18:36:56 -0500, Andrew Coad <email@hidden> said:
>
>Reading through the docs, the approximate flow from a user touching an interface component (e.g. a button) to the touch event being processed by the application is:
>
> - User touches (e.g. a UIButton), a "touch" object is created and enqueued on the dispatch thread (main thread)
> - The touch object is dequeued, a UIEvent object is created and dispatched to the target object (for handling)
>
>The docs also state that the timestamp of the UIEvent [event timestamp] is the time that the event was created. From this I assume that [event timestamp] is somewhat later than the actual time that user touched the UIButton - how much later depends on system activity around that time. Is this assumption correct? If so, is there a way to get the time that the user touched the interface? The small number (indeterminate) of milliseconds lag between touch time and event time is important to me. I can tolerate processing the event after an indeterminate lag but I do need to know when the actual touch occurred.
The problem is that the timestamp on the UIEvent is as close to "when the actual touch occurred" as you're going to get - regardless of what it may really indicate. The actual touch is reported to your app from outside the app, i.e. by the system. The system surely puts a timestamp on that report, and that timestamp is probably reproduced as the timestamp on the UIEvent, in which case you are worrying needlessly. But if that timestamp is NOT the timestamp on the UIEvent, you can't access it, so you are still worrying needlessly. :) m.
--
matt neuburg, phd = email@hidden, <http://www.apeth.net/matt/>
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