Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!lll-winken!uunet!ficc!cliff
From: cliff@ficc.uu.net (cliff click)
Newsgroups: comp.graphics
Subject: Re: PostScript -> DVI or anything else
Summary: PS->DVI
Message-ID: <4079@ficc.uu.net>
Date: 4 May 89 19:59:21 GMT
References: <808@sunkisd.CS.Concordia.CA> <4054@ficc.uu.net> <170@marvin.moncam.co.uk>
Organization: Ferranti International Controls
Lines: 38

[ Long fruitless response because I hate Postscript, press 'n' quick! ]
In article <170@marvin.moncam.co.uk>, paul@moncam.co.uk (Paul Hudson) writes:
> In article <4054@ficc.uu.net>, cliff@ficc.uu.net (cliff click) writes:
> > In article <808@sunkisd.CS.Concordia.CA>, kiron@db9.CS.Concordia.CA (Kiron Bondale) writes:
> > >I have a PostScript file, that I would like to convert to DVI (or actually
> > The only sure-fire way is to print the page, and read it with a scanner.  
> This is a bit pessimistic. Sure, one would have to write a PS
> interpreter, but that's not too bad (I speak having done just that),
I, too, have written a PS interpreter for a commercially available laser
printer.  What I found was that 90% of the PS producing applications wrote
code that breaks 90% of the PS clones (5 or 6 PS clones we tested against 
our suite of application-produced PS code).  The *interpreter* is fairly easy.
Getting the font machinery, error handling, and special primitives (clippath,
setscreen, settransfer, reversepath, etc) right is a nightmare.  Note:  the
Redbook lies about the required behavior of several primitives, and is mum
about much of the magic that goes on behind the scenes in the font machinery.

How would you handle programs that remap the fonts?  (It looks like:
"100 100 moveto (a) show" but the page is rotated 90 degrees, and "a" in 
the current font produces "Company Foobar Logo" using a combo of Times-Roman
and Times-Bold, and is actually printing a logo up the left margin.  Further
the BuildChar routines are recursively stacked 2 deep.)

How about programs that roll their own fonts, and not using an ASCII ordering?
At least one I know looks to see if he has downloaded that character in the
font in his BuildChar routine, and if not he sends stuff back to the host
which causes the host to send down a series of moveto/lineto commands to 
draw the missing character.  In this case the page output is some complex
interaction between the PS application and the host driver.  *Bleah*.

We also have a suite of programs that break (lockup and/or cold boot) the 
Apple Laserwriter.  I wonder what would happen if we fed them to 
DisplayPostscript on NeXT or Sun?  %-)

-- 
Cliff Click, Software Contractor at Large
Business: uunet.uu.net!ficc!cliff, cliff@ficc.uu.net, +1 713 274 5368 (w).
Disclaimer: lost in the vortices of nilspace...       +1 713 568 3460 (h).