[Xy-pic] Tip sizes when using the slides class

Ross Moore ross@ics.mq.edu.au
Mon, 30 Sep 2002 19:38:51 +1000 (EST)

> > To get a good result with slides, you need to do either:
> >
> >   1.  use the PostScript extensions, with a suitable driver;
> >      e.g.  \usepackage[ps,dvips,rotate,frame,all]{xy}
> >      and  \UsePSspecials   (if necessary)
> >      and \UsePSframes, etc.
> Well, I've tried:
> \documentclass{slides}
> \usepackage[ps,dvips,all]{xy}
> \SelectTips{cm}{}   % To compare like with like below
> \begin{document}
> \begin{slide}
> Compare $\xymatrix{A \ar[r] & B}$ with $A\rightarrow B$.
> \end{slide}
> \end{document}
> and it makes no difference; the arrowhead is still far too small.

> >      You will need a PostScript based viewer to see the results.
> >

With Xy-pic PostScript support, you can use the  xyline  extension,
which allows for thicker lines and arrow-heads.
(Consult the Xy-pic Reference manual; chapter 11.)

> Well, I'm glad of your response, but: can I ask you to be a little more
> explicit, please?  For example, can you modify my eight lines of TeX to
> work?

\SelectTips{cm}{}   % To compare like with like below
Compare $\xymatrix{A \ar @*{[|(4)]}[r] & B}$ with $A\rightarrow B$.
%%                       ^^^^^^^^^^

The extra marked bit causes the arrow to be constructed with lines 
that are 4 x thicker than usual. 
Use whatever factor you think is best for your slides.

You will have to add such an adjustment to every \ar command
to have this working throughout all of your slides.

If, however, you were using \xygraph instead of \xymatrix to layout
your diagrams, then you can ajust the style for all arrows in a diagram,
using the  - and : shorthand notations (see Xy-picRM, \S24, note 24j);

> > OR
> >   2.  layout your slides on a paper-size reduced sufficiently
> >       to look good with 10pt fonts; e.g.  B7 or A6 size.
> >       Then view the results magnified to fill the window/screen.
> Umm.  This is a whole new can of worms, in particular I'll need to create
> a whole new style for this.  I can't believe that no-one has solve the
> problem of creating slides for presentations with XyPic.

Not really.
It's mainly just a matter of changing the \textheight and \textwidth
and some margins, and continue using LaTeX default styles,
rather than having to redefine all font-sizes to be scaled-up for slides.
The  geometry  package is *very good* for setting page-size and margins.

Overall it's less work, I'd say.
But of course that depends upon your starting point. 

It also assumes that scaling by a factor of close to 4 will produce
acceptable visual quality; hence you'll need all fonts to be scaleable.

> >      This is the best with pdfTeX/pdfLaTeX, which is currently not
> >      compatible with Xy-pic's PostScript extensions.
> Well, unfortunately I *will* need to use the PostScript extensions, as
> XyPic's drawing of circles is somewhat inaccurate otherwise.

This should help you get over those last hurdles.
	Ross Moore

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