Re: a DSSSL typesetter

[Brandon Ibach <bibach@xxxxxxxxxxxxxx>]

Reynolds, Gregg said:
> 
> 
> 
> > -----Original Message-----
> > From:	Brandon Ibach [SMTP:bibach@xxxxxxxxxxxxxx]
> > 
> > has anyone ever thought of implementing TeX's functionality in
> > PostScript?
> >    Has anything like this been thought of, attempted, or done?  Or am
> > I just completely off the wall here?
> > 
> 	[Reynolds, Gregg]  
> 	Brandon:
> 
> 	No, you're not so terribly off the wall, but I think it's more
> complicated than you suspect.  
> 	 
> 	TeX and Postscript are quite different beasts.  Postscript is
> usually categorized as a page-description language, TeX as a typesetting
> language.  Each is extremely good at what it does, and not so well
> suited for other tasks.  Postscript can put ink on paper in whatever
> pattern you desire, but knows next to nothing about typesetting.  There
> is no way to tell it, for example, typeset this footnote at the bottom
> of this page, and if takes up more than 1 inch, chop it off at 1/2 inch,
> and flow the rest to the bottom of the following page(s).  I suppose in
> principle one could write a postscript program to handle such
> compositional tasks, but the language just isn't suited for it, so it
> would be really hard.  TeX on the other hand isn't as powerful as PS for
> simply laying marks on the page (though is it quite powerful in this
> respect in its own right), but it understands typesetting.  Where to
> break lines and pages, for example, or how to handle such traditional
> typesetting conventions as leaders and rules.  Such stuff can get very
> very complicated.  
> 
   Actually, I'm not so convinced that TeX and PostScript are that far
apart.  It's true that TeX knows far more (as PostScript, by it's
essential nature, knows basically nothing) about typesetting, but
that's simply because it was programmed with that knowledge.  The
question is really whether PostScript has the guts to elegantly and
efficiently handle the processing tasks needed to implement the
typesetting process.  I've looked a bit at TeX's general strategy for
typesetting (the "box and glue" idea), and I can't see implementing
something like that in PostScript as being that difficult.  Of course,
there's got to be more to it than that, but...
   Keep in mind, also, that I'm not really suggesting the creation of a
general replacement for TeX.  TeX is an excellent tool for typesetting
*documents*.  What I'm looking to create with PostScript is a good
tool for typesetting a flow object tree.  I really think a reasonable
amount of the work that TeX has to do is already done by the time we
have a flow object tree.  All that needs to be done at that point is
determine the best way to lay the flow objects on the page.  Not that
this isn't probably the hardest part, but how much of that knowledge
of typesetting that TeX is loaded with is used in laying out objects
on the page, and how much is used in determining the characteristics
of those objects to start with?
   Again, I don't know this process well enough to say much of
anything with authority, and I certainly wish I knew TeX better than I
do, but I still think there may be something to this.  *shrug*

-Brandon :)


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