Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!mips!apple!dlyons
From: dlyons@Apple.COM (David A. Lyons)
Newsgroups: comp.sys.apple2
Subject: Re: supporting better graphics on the gs
Message-ID: <51812@apple.Apple.COM>
Date: 22 Apr 91 10:16:49 GMT
References: <1991Apr20.070832.24635@ux1.cso.uiuc.edu>
Organization: Apple Computer Inc., Cupertino, CA
Lines: 45

In article <1991Apr20.070832.24635@ux1.cso.uiuc.edu> wogg0743@uxa.cso.uiuc.edu (William Shakespeare) writes:
>Actually, it would be easier to support larger bitmaps than one would at
>first imagine.  Actually, I should say better resolution on a large bitmap.
>If one were to put a large video buffer in, for instance, bank $E2, filling
>the entire bank (ie., the buffer is twice normal SHR size), and assuming
>the hardware to support the buffer existed, the ROM graphics routines could
>be used to draw to it, with some minor complications.

All true, given the appropriate hardware.  In fact, a third party could
-easily- patch QuickDraw to work with a larger screen buffer, given that
the buffer is still linear, still 2 or 4 bits per pixel (BTW, the VOC
does not provide a linear buffer for 640x400).  InitPort and OpenPort
are probably the only routines you'd have to patch.  There would be a
performance hit because (1) you're dealing with more memory and (2) parts
of QuickDraw are optimized for the $x12000 160-bytes-per-scanline screen,
but with a fast accelerator it would be usable (with applications that
use QuickDraw).

>[...] I assume that there is a practical limitation of 64k for
>such a buffer

If there is, it's news to me!  QD is actually supposed to work with >64K
pixel maps without problems.  This has not been tested as well as the
normal case of a 32K screen; maybe there are problems.

>There is a hitch involved with toolset which expect the screen to be in
>specific place (didn't someone says something about the menu manager?)

Yes, the Menu Manager currently "knows" where the screen is.  I'm not
happy with that, and I expect someday the Menu Manager will be more
friendly to QuickDraw.

Oh, the other thing is cursor tracking--QuickDraw's cursor handling code
also knows where the screen is and would have to be patched out.

>William ("Shakespeare") Gulstad          /  So where are the C.S. babes?
>wogg0743@uxa.cso.uiuc.edu                /  Joni Mitchell for President!
-- 
David A. Lyons, Apple Computer, Inc.      |   DAL Systems
Apple II System Software Engineer         |   P.O. Box 875
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