Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!uwm.edu!zaphod.mps.ohio-state.edu!usc!apple!lsr
From: lsr@Apple.COM (Larry Rosenstein)
Newsgroups: comp.sys.mac.programmer
Subject: Re: PICT (version 2) files
Keywords: PICT files
Message-ID: <8897@goofy.Apple.COM>
Date: 27 Jun 90 22:47:34 GMT
References: <9006251132.aa25836@ICS.UCI.EDU> <2582@network.ucsd.edu>
Organization: Apple Computer, Inc.
Lines: 35

In article <2582@network.ucsd.edu> moreland@network.ucsd.edu (John Moreland) writes:

>I thought, perhaps, there might be a "magic number" (0, -1, FFFF, etc..) that
>might tell the Mac to ignore the pictSize field and just read till EOF or
>until it sees the "opEndPic" opcode...

Most program do ignore the pictSize field, because starting with the MacPlus
pictures could be larger than 32K bytes.

>  example), why not just see how many bytes are in the file instead of using
>  the "pictSize" information ?  Even so, files get "munched" and the pictSize

Because some files contain more than 1 picture (like printer spool files).  

>  "after-the-fact" data that "needs" to be generated after all opcodes have
>  been writen out.  This causes great pain on systems like UNIX (with pipes).
>
>  Apple tends to be a little shortsighted about such closed designs. 

Just because you can't stream out a picture without backtracking, doesn't
make it a closed design.  There are lots of file formats that require such
backtracking.  (Usually when the format is designed to be easier for the
reader to process than the writer.)  

QuickDraw pictures are a native Mac format, and if you want to interchange
pictures, then it is best to use a standard interchange format.  The picture
format is completely documented, but it's not intended to be an ANSI
standard.  It has changed a few times in the past, and it will probably
change in the future.

-- 
		 Larry Rosenstein,  Object Specialist
 Apple Computer, Inc.  20525 Mariani Ave, MS 46-B  Cupertino, CA 95014
	    AppleLink:Rosenstein1    domain:lsr@Apple.COM
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