Slow screen lock/unlock

Michael J. Lew michaell at unimelb.edu.au
Wed Mar 16 18:22:28 EST 2005


At 5:41 PM -0500 16/3/05, Jonathan Lynch wrote:
>How long does it take if you comment out the lock screen line?

Well, I thought I had answered that before you asked it, but a typo 
got in the way! When I comment out the lock screen line it takes less 
than one millisecond.

Unfortunately, simply omitting the lock and unlock screen commands 
doesn't get rid of my problem. The reason I ran the test of 
lock/unlock speed is that the following test script animates the 
points at an unacceptably slow (and somewhat erratic) rate:

on mouseUp
   --initialise some convenience variables
   put the left of grc 1 into l
   put the width of grc 1 into w
   put the top of grc 1 into t
   put the height of grc 1 into h

   repeat
     --make randomly placed points
     put empty into myPoints
     repeat 100
       put l + random(w) into x
       put t + random(h) into y
       put x&","&y & return after mypoints
     end repeat

     --display them
     lock screen
     set the points of grc 2 to myPoints
     unlock screen

     if the mouse is down then exit repeat
   end repeat
end mouseUp

Graphic 2 is set to be a polygon with its markers shown (2 by 2 
squares) and its line thickness set to zero.

No combination of lock and unlock or no locks makes it any better. 
The making of the points and the setting of the points take almost no 
time. The slowness is in getting it onto the screen.

...and before someone asks, no, the slowness is not related to 
polling the mouse: commenting out that line doesn't change the update 
rates.


>
>At 10:08 AM +1100 17/3/05, Michael J. Lew wrote:
>>
>>Subject: Slow screen lock/unlock
>>
>>It takes about 260 milliseconds to lock and unlock the screen (OS X
>>10.3, slowish G4). Here is my test script that takes 2680
>>milliseconds to run:
>>
>>on mouseUp
>>    put the milliseconds into startTime
>>    repeat 10
>>      lock screen
>>      unlock screen
>>    end repeat
>>    put the milliseconds-startTime
>>end mouseUp
>>
>>If I comment out either the lock screen or the unlock screen then the
>>whole thing takes 2 milliseconds and if I comment out the unlock
>>screen line then it takes less than one millisecond.
>>
>>Is it slow on other systems?
>>Is this some Quartz "feature"?
>>Is there something wrong with the way that Rev does screen locking or
>>unlocking?
>>How can I get around slow screen updates for animating lots of points?

-- 
Michael J. Lew

Senior Lecturer
Department of Pharmacology
The University of Melbourne
Parkville 3010
Victoria
Australia

Phone +613 8344 8304

**
New email address: michaell at unimelb.edu.au
**


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