Re: capturing user reaction times in msecs
Re: capturing user reaction times in msecs
- Subject: Re: capturing user reaction times in msecs
- From: Ronny Reichmann <email@hidden>
- Date: Tue, 19 Dec 2006 18:04:36 +0100
Thats wrong NSDate does!!!
double elapsed = [[NSDate date] timeIntervalSinceDate:startDate]
Am 19.12.2006 um 17:54 schrieb Scott Ribe:
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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