Path: utzoo!utgpu!water!watmath!clyde!att!ucbvax!decwrl!asente
From: asente@decwrl.dec.com (Paul Asente)
Newsgroups: comp.windows.news
Subject: Re: Is NeWS UseABLE?
Message-ID: <730@bacchus.DEC.COM>
Date: 22 Aug 88 17:42:34 GMT
References: <229.8808111329@jura.ritd.co.uk> <3499@encore.UUCP>
Reply-To: asente@decwrl.UUCP (Paul Asente)
Organization: DEC Western Software Lab
Lines: 36

In article <3499@encore.UUCP> bzs@encore.UUCP (Barry Shein) writes:
>Does there exist any graphics editor which can take a postscript image
>description and let you edit it visually in some useful way?
>
>Is this hard? I think it's possible, but my intuitions say it's very
>hard, not sure why exactly other than that such editors tend to want
>object descriptions and postscript doesn't particularly lend itself to
>that (it could be enforced as a discipline of course, I mean that
>given some random graphic image from someone it won't likely be
>structured in any particularly useful way.)
>...
>What would it have taken to have made postscript also appropropriate
>for graphical editing? Not sure. This is just a bunch of questions.

Funny you should ask this question.  I spent the last few years of my life
doing a thesis on this very subject.  You are right; it's very hard.  My
solution was to design a new language that was very close to PostScript
but had the idea of objects.  It would be possible to imbed this in
PostScript by defining new operators, but it was still a new language.
There are reasons that you don't want to do this by imbedding --
PostScript is so flexible that it's impossible to statically analyze a
program and deduce anything interesting about it.  In order to make
editing fast you have to do some reasoning about the program, so I gave up
some of PostScript's flexibility.  PostScript programs that are "well
behaved" can mechanically be translated into my language, but others
cannot.

If you want all the details, you can order report 87/6 from DEC WRL:

	Carmen Rouse	
	DEC Western Research Laboratory
	100 Hamilton Avenue
	Palo Alto, CA 94301

	-paul asente
	    asente@decwrl.dec.com	decwrl!asente