millisec test timings and screen refresh rate

[simplsol at aol.com]

Phil,
  LCDs got a bad reputation for speed ten years ago. They are much 
improved now. For instance modern LCD TVs are fast enough to display 
action scenes without blur. To see how much they have improved just 
move your mouse around the screen; you probably won't see any 
"submarining" at all.
  Of course there is some speed difference among screens - at the 
millisecond level.
  Would it work better, for your purposes, to have the test screen 
appear behind a blocking screen, then, instead of making the original 
screen appear, make the blocking screen disappear? Might be faster and 
more predictable.
 Paul Looney

 -----Original Message-----
 From: revdev at pdslabs.net
 To: use-revolution at lists.runrev.com
 Sent: Thu, 19 Apr 2007 5:19 PM
 Subject: millisec test timings and screen refresh rate

  I need some help here. My question is basically this: How do I 
accurately track or calculate the exact moment at which an image 
becomes visible on screen? 
  
  I have a client whose product is a psychological testing app, with a 
battery of canned tests included. I'm reimplementing it in RunRev, 
moving them away from SuperCard + a large handful of XCMDs. All the 
millisecond timing used to be done in the XCMDs, but now RunRev can do 
it natively, and on all platforms... wait, I don't need to sell you... 
sorry. ;o) 
  
  Some tests require the Rev app to track the millisecs elapsed from 
when an image is displayed on screen to when a user-initiated event 
occurs, like a keypress. This means RR needs to know as precisely as 
possible *when* the image became visible on screen. 
  
  (I can already hear some people shifting in their seats, muttering 
"duh! just show the image, unlock screen and put the millisecs into a 
variable!") 
  
  Is it that simple? I assume not. I need to figure out when the image 
became visible, not when I told it to become visible. I'll need to 
factor in screen refresh rate, whether testing is displayed on a CRT or 
on a laptop (the normal delivery medium). This also leads me to ask: Do 
laptop screens refresh the same way CRTs refresh? I doubt it. 
  
  How have you dealt with this in your RunRev experience? I bet 
*someone* has dealt with this before. 
  
 Thanks in advance for all responses. This list is so great! 
  
 Phil Davis 
  
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