Xref: utzoo comp.sys.mac.misc:5246 comp.sys.mac.programmer:18755 comp.lang.postscript:6612 comp.graphics:14236
Path: utzoo!attcan!uunet!zaphod.mps.ohio-state.edu!usc!apple!well!shiva
From: shiva@well.sf.ca.us (Kenneth Porter)
Newsgroups: comp.sys.mac.misc,comp.sys.mac.programmer,comp.lang.postscript,comp.graphics
Subject: Re: Interpreting Postscript on Mac || Tools to generate MacDraw file ??
Summary: Converting from PostScript
Keywords: MsWord MacDraw Postscript Macrolanguage
Message-ID: <21495@well.sf.ca.us>
Date: 5 Nov 90 17:24:18 GMT
References: <2170@tnoibbc.UUCP>
Lines: 39



Your description of MacDraw suggests that it is a descriptive
graphic format.  PostScript is a procedural language, like C
and Forth. Imagine what would be involved in converting a C
program to a MacDraw file.  Even a C or Forth program that
consisted mostly of drawing primitives would be quite difficult
to parse and convert.  The models are just too different.
 
This is a general problem associated with converting PostScript
to other graphics formats.  Because PostScript is procedural,
the graphics operators are normally embedded within quite a bit
of control structure (loops and conditionals).  Unless the
PostScript source restricts itself to a well-defined set of
operators, it is essentially impossible to convert the source
to an object description. 
 
Illustrator can parse PostScript files and recover objects
provided that the PostScript uses a specific set of procedures
defined in Illustrator's prolog (see the Illustrator file
format document available from ps-file-server@adobe.com). 
These procedures are designed to represent objects.  An
Illustrator object is represented by a call to a procedure with
appropriate parameters.
 
If your PostScript file was generated mechanically by an
application, it's possible that it uses a prolog to encapsulate
the application's object descriptions into PostScript
procedures (as Illustrator does). If this is the case, your
parsing job gets considerably easier because you just have to
parse the application's pseudo-object-language (ie. the
PostScript script containing calls to the application's object
procedures).
 
If what you want is PostScript to raster, you should use
Ghostscript or one of the commercial host-based PostScript
clones like Go-Script or Freedom of Press.
 
Ken (shiva@well.sf.ca.us)