Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!ucbvax!decwrl!labrea!rutgers!cbmvax!vu-vlsi!swatsun!jackiw
From: jackiw@cs.swarthmore.edu (Nick Jackiw)
Newsgroups: comp.sys.mac.programmer
Subject: Re: SrollRect Hassles
Message-ID: <2525@ilium.cs.swarthmore.edu>
Date: 6 Mar 89 14:37:57 GMT
References: <1733@psu-cs.UUCP>
Reply-To: jackiw@ilium.UUCP (Nick Jackiw)
Distribution: usa
Organization: Visual Geometry Project, Swarthmore College, PA
Lines: 35

In article <1733@psu-cs.UUCP> sagar@psu-cs.UUCP (Arun Sagar) writes:
> 
> When i try the following:
> 
> SetPort(currentPort);
> ScrollRect(&currentPort->portRect,dh,dv,NULL);
> 
> 	it scrolls alright, but doesn't erase the region that it left behind
> like it says in IM-I.
> 
> sagar@psu-cs.

Two possibilities. ScrollRect is supposed to fill in the "scrolled out"
region with the curPort's background pattern&color. Are these set properly
for you?

Second, note that I.M. doesn't say you can pass a null updateRgn as your
last parameter, the way you CAN pass a null maskRgn to copybits. I've had
some difficulties (i. e. crashes) with attempting to pass a NIL handle for
updateRgn.  Try instead to pass an EMPTY rgn:

aRgn:=NewRgn;
ScrollRect(...,aRgn);
DisposeRgn(aRgn);

That might do the trick.




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+-------------------+-jackiw@cs.swarthmore.edu / !rutgers!bpa!swatsun!jackiw-+
|  nicholas jackiw  | jackiw%campus.swarthmore.edu@swarthmr.bitnet           |
+-------------------+-VGP/MathDept/Swarthmore College, Swarthmore, PA 19081--+
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