Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!husc6!bbn!rochester!PT.CS.CMU.EDU!andrew.cmu.edu!ks26+ From: ks26+@andrew.cmu.edu (Kenneth Sykes) Newsgroups: comp.graphics Subject: Re: MacPaint format Message-ID:Date: Tue, 8-Dec-87 17:16:34 EST Article-I.D.: andrew.cVj7d2y00XoGR2g0-1 Posted: Tue Dec 8 17:16:34 1987 Date-Received: Sun, 13-Dec-87 14:49:55 EST Organization: Carnegie Mellon University Lines: 22 In-Reply-To: <518@naucse.UUCP> The file description posted by Warren E. Lewis (8-Dec-87) is complete, with the exception of what the PackBits/UnpackBits procedures do. The packed information consists of a control byte (8 bit signed integer) followed by a set of 'appropriate' data. If the control byte is greater than zero (n = c), then the next n bytes are to be copied directly to the output bitmap (this is called a MIXED block). If the control byte is less than zero, then negate the control byte and add 1 (n = -c + 1). Then make n copies of the next byte in the output bit map (this is called a REPEAT block). After the control byte has been processed and the output bitmap updated, the next control byte is immediately after the data associated with the current control byte. Hope this helps any non-Mac programmers get Mac pictures up-and-running. -- Ken Sykes