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From: keith@Apple.COM (Keith Rollin)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Wide offscreen bitmap won't receive draw commands
Message-ID: <34168@apple.Apple.COM>
Date: 21 Aug 89 04:27:33 GMT
References: <22321@andante.UUCP> <30755@ucbvax.BERKELEY.EDU>
Organization: Apple Computer Inc, Cupertino, CA
Lines: 24

In article <30755@ucbvax.BERKELEY.EDU> oster@dewey.soe.berkeley.edu.UUCP (David Phillip Oster) writes:
>In article <22321@andante.UUCP> bwb@andante.UUCP (Bruce Ballard) writes:
>>What am I missing?
>
>If you read QuickDraw in Inside Mac, vol. 1, it will tell you that when
>you create a new grafport, the clipRgn gets initialized to wide open, and
>the visRgn gets initialized to screenBits.bounds. Big off-screen grafports
>should probably do a:
>	ClipRect(&thePort->portRect);
>	RectRgn(thePort->visRgn, &thePort->portRect);
>before drawing on it.

Dave, I think that Bruce also read the line in Inside Mac, page I-149 that
says "The visRgn has no effect on images that aren't displayed on the screen."
I don't know if that warning is correct or not, or if it is what it's supposed
to mean, but it looks to me that people using offscreen bitmaps should indeed
pay attention to what the visRgn is set to, as you pointed out.

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"Argue for your Apple, and sure enough, it's yours" - Keith Rollin, Contusions