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From: acmfiu@serss0.fiu.edu (ACMFIU)
Newsgroups: comp.sys.apple2
Subject: fast screen updates on the GS
Message-ID: <2556@kluge.fiu.edu>
Date: 21 Feb 91 04:59:08 GMT
Sender: news@kluge.fiu.edu
Organization: Florida International University, Miami
Lines: 28

In an effort to figure out how in the world to do this (and it is driving
me up the wall) i did the following:

when you create a window, a GrafPort is created. So, i allocated memory
for 32K of memory for the screen and changed the pixel map pointer in the
LocInfo record int he GrafPort data structure to this area of memory
thinking that QuickDraw would "know" that it is NOT the same address as
the screen ($e12000) and thus not add the extra overhead for writing directly
to the screen.

I then copied the contents of the screen to my pointer (PtrToHand) and
then did the updates to the window and then copied the info back to the
screen (HandToPtr). I was hoping this would speed things up but it did
absolutely nothing for speed.

It seems that QuickDraw is not "smart" enough to figure this out. What in
the world is so darn hard about making an off-screen GrafPort? Any Apple
DTS people out there want to answer this, please! Maybe I don't fully
understand QuickDraw because the manuals don't seem too enlightening
to me. I tried OpenPort once and moved the portInfo rectangle off the
screen but that didn't seem to help at all. When the portInfo rectangle
moves, does the pixelmap move with it? I also tried SetOrigin but who knows
what this does. Aren't tools suppose to make things easier. Right now I
just feel like writing my own graphic tools and say goodbye to compatibility
with all the other desktop programs. But then when this thing is finally
figured out I'll say, "now wasn't that easy?".

albert


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