Path: utzoo!utgpu!attcan!uunet!mcvax!enea!tut!santra!jmunkki
From: jmunkki@santra.HUT.FI (Juri Munkki)
Newsgroups: comp.sys.mac.programmer
Subject: Re: flicker-free drawing
Message-ID: <15023@santra.UUCP>
Date: 29 Jul 88 19:12:18 GMT
References: <5727@orstcs.CS.ORST.EDU> <12549@agate.BERKELEY.EDU> <424@umn-d-ub.D.UMN.EDU> <14772@apple.Apple.COM>
Sender: jmunkki@santra.UUCP
Reply-To: jmunkki@santra.UUCP (Juri Munkki)
Organization: Helsinki University of Technology, Finland
Lines: 16

In article <14772@Apple.COM> darin@apple.apple.com.UUCP (Darin Adler) writes:
>Off-screen bitmaps are often the best way.

Just a note on off-screen bitmaps: I just wrote a program that uses a 320x320
offscreen bitmap. If I just blit it on the screen with a copybits, the cursor
flashes and is often invisible. The solution that I came to was to draw the
bitmap in 4 parts. The cursor flicker was reduced to a reasonable level.

Of course there are better ways to do this (like synchronizing with a screen),
but they a lot more code than breaking a copybits into four parts. The trap
dispatcher and QD overheads shouldn't be a problem unless your timing is really
critical.

Juri Munkki
jmunkki@santra.hut.fi
jmunkki@fingate.bitnet