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Re: Strangeness with ScrollRect and QDFlushPortBuffer

Eric's correct. All flushes are beam synced. Different graphics drivers have different implementation of the beamsync functionality. e.g. flush when beam is not in region of update, flush when beam is below region of update or even vbl sync'ing. The second is very likely going to cause slow downs as you move closer to the bottom of the screen.

haroon

On Friday, May 16, 2003, at 7:27 AM, Eric Schlegel wrote:

On Friday, May 16, 2003, at 12:42 AM, Larry Gerndt wrote:

Now here's the strangeness: When the window is located near the top of the
screen, the slide is seen to be nice and zippy. But if I move the window
close to the bottom of the screen, it is much slower. In fact, there is a
continuum: the closer the window is to the bottom of the screen, the slower
the slide effect is.

It's probably because CoreGraphics synchronizes flushes to the screen with the CRT beam, and it takes longer for the beam to get to the bottom of the screen, so you have to wait longer between each flush for the beam to pass by that location before the next flush can occur.

I'm not sure if there's a way to avoid this, maybe Haroon or Joseph can comment.

-eric
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References: 
 >Re: Strangeness with ScrollRect and QDFlushPortBuffer (From: Eric Schlegel <email@hidden>)



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