Path: utzoo!attcan!uunet!cbmvax!vu-vlsi!swatsun!jackiw
From: jackiw@cs.swarthmore.edu (Nick Jackiw)
Newsgroups: comp.sys.mac.programmer
Subject: Re: help! large offscreen map
Message-ID: <2328@ilium.cs.swarthmore.edu>
Date: 18 Jan 89 17:15:25 GMT
References: <1105@dogie.edu>
Reply-To: jackiw@ilium.UUCP (Nick Jackiw)
Organization: Visual Geometry Project, Swarthmore College, PA
Lines: 33

In article <1105@dogie.edu> yahnke@vms.macc.wisc.edu (Ross Yahnke, MACC) writes:
> In article <227700002@uxa.cso.uiuc.edu>, wwl90321@uxa.cso.uiuc.edu writes...
> 
> >...Am I missing a mysterious third rect that produces
> >the visible region? The book says never touch visrgn so I guess
> >I won't. 
> 
> The book sez don't touch visrgn but go ahead and do it anyway. 
> So the solution is to go into the grafport and reassign it to an
> infinitely large region.
> 
Now don't forget to save it before hand and restore it either immediately
after drawing to your offscreen map or immediately before copyblitzing from
your map to the screen window/port.

If you're leery about violating the rules (--and I agree with Ross that
this is probably a trivial rule, if you understand the repercussions--),
you can always create a separate grafPort to reference your offscreen
bits (with OpenPort).  This one, never touched by the Window Manager,
is your own baby.  OpenPort() will set its visRgn to "a rectangular
region coincident with screenBits.bounds," which you'll want to dispose-and-
replace (or merely resize) with an infinite region before using as a port.

Peace of mind is only SizeOf(GrafPort) bytes away...

-Nick.


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+-------------------+-jackiw@cs.swarthmore.edu / !rutgers!bpa!swatsun!jackiw-+
|  nicholas jackiw  | jackiw%campus.swarthmore.edu@swarthmr.bitnet           |
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