Re: [docbook-apps] slides: how to balance presentation and content

[Justus-bulk@Piater.name]

Stefan Seefeld <seefeld@sympatico.ca> wrote on Tue, 20 Jan 2009
09:51:23 -0500:

> <foil template="my-two-column-template">
>  <block name="left">
>    <itemizedlist/>
>  </block>
>  <block name="right">
>    <mediaobject/>
>  </block>
>  <block name="footer"/>
> </foil>

I see. Not bad. However, I would prefer to avoid element grammar to
depend on attributes because this is not generally the way DocBook
does it.

This sort of layout can in principle be achieved using DocBook tables
(CALS or HTML style), which is what I do, but it is unwieldy and
cumbersome to adjust.

Perhaps one way forward would be to think about simplified markup for
tabular layouts whose semantics are inspired by tables but whose
markup excludes all the cruft needed for real tables, e.g.:

<foil>
  <twocol>
    <block width="30%">
      <!-- content of left column -->
    </block>
    <block>
      <!-- content of right column -->
    </block>
  </twocol>
</foil>

This would yield intuitive semantics, and stylesheets might reuse much
of the table-related code.

To this end, the first question is: What layout capabilities do we
seek for presentations that cannot be achieved with tables?

And here's my first answer: I'd often like to have a non-grid layout.

Inspired by Stefan's suggestion, how about introducing the notion of a
block that can be freely positioned on a page using CSS semantics,
such as this:

<foil>
  <absolute>
    <block top="2ex" left="10%">
      ...
    </block>
    <block bottom="10ex" right="10em" width="30%">
      ...
    </block>
  </absolute>
</foil>

Here, the first question is: What subset (or adaptation) of CSS is
reasonable, and also expressible in XSL-FO?

Of course, this is a brutal departure from the XML principle of
separation of content from presentation, but as I argued in an earlier
posting, to me the advantages of (ab)using DocBook for presentations
weigh far heavier than purity of principle.

And of course, my two suggestions are meant to be part of a whole, not
mutually exclusive.

Justus


<digression>
I'm going to stay out of the discussion about incremental lists
because I think they should never be used. I've never seen a *good*
presentation that used them. It helps the audience to see the big
picture while the speaker guides them through the details. Slides
should support the talk, not the other way around.
</digression>