Re: capturing user reaction times in msecs
Re: capturing user reaction times in msecs
- Subject: Re: capturing user reaction times in msecs
- From: Scott Ribe <email@hidden>
- Date: Tue, 19 Dec 2006 09:54:12 -0700
- Thread-topic: capturing user reaction times in msecs
> For my purposes, I think that close enough is good enough--especially if the
> error margin is constant. (That is, if every time the display becomes visible
> the system takes the same amount of time to get it onscreen). I'm asking a
> much, much lower level question. What code do I use? I am unable to find a
> simple function or Class that returns the time to the msec. For example, I can
> find a "possible token in the Calendar Format String" that will specify msecs
> (%F), but I have no idea how to use it.
I was going to say years:months:days:hours:minutes:seconds:sinceDate: but I
see it takes an int * for seconds. Wow, it really appears that there may not
be a Cocoa function for this!
You have two options, BSD and Carbon.
#include <sys/time.h>
struct timeval tv;
struct timezone tz;
gettimeofday( &tv, &tz )
#include <Carbon/Carbon.h>
double tm = CFAbsoluteTimeGetCurrent ();
But note that the error will not be constant. From the time you issue
drawing commands until the time they are visible, I would expect will
normally vary from about 0 to 1 full refresh cycle of the display.
--
Scott Ribe
email@hidden
http://www.killerbytes.com/
(303) 722-0567 voice
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