Trouble with graphics display in OS X

Richard Gaskin ambassador at
Sat Jan 15 14:23:03 EST 2005

James Hurley wrote:
 > In OS 9, I get a blur of numbers displayed in the field--this is fine
 > and what I would expect.
 > In OS X I get a discrete sequence of 4 numbers displayed. This is the
 > same kind of herky-jerky behavior I found with graphics display in OS
 > X (but not in OS 9.)
 > (As before, the problem is resolved by adding a line in the repeat
 > loop: wait 0 millisec, or unlock screen. But it runs much more
 > slowly.)

Welcome the to the Quartz rendering engine.

Many apps, including the Finder, have update delays.   These do not 
occur with the Classic or XP versions of the engine.

There may be additional things RunRev could do to force redraw updates, 
but I'm not sure if under the hood it would do much more than "wait 0 
with messages" -- forcing a redraw with Quartz' 16-layer compositing 
will always slow things down.  Sure, you may not actually need 16-layer 
compositing, but gosh isn't it pretty?  After all, it it's too slow 
Apple has an answer:  buy a faster dual-processor machine. ;)

In WebMerge I got a big performance boost by using the mod operator for 
updates during progress-monitoring:

   put 100000 into tMax
   repeat with i = 1 to tMax
      add 1 to i
      if i mod 50 = 0 then
         put "Processing item "&i&" of "& tMax
         wait 0 with messages
      end if
   end repeat

This way I know I'll get an update, but I'm not doing it any more 
frequently than needed to keep the user informed, saving most of those 
clock cyles for use in my stuff rather than Quartz' complexity.

  Richard Gaskin
  Fourth World Media Corporation
  Rev tools and more:

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