Re: [xsl] Swing-style Glue and Struts

[Wendell Piez <wapiez at mulberrytech dot com>]

James,

What you describe is, as you apparently suspect, very ambitious. It is 
perilously close to constraint-based, layout-driven formatting, which is 
still a ways out.

For example, you're bound to find that "count[ing] lines within the 
template match block that were copied through" will be a bear. What's a 
"line"? Will it be a structure in your source (say a <line> element) you 
can count, or will you have to resort to other means to count them?

Another problem you'll have is that HTML is *not* well-suited to support 
this design paradigm: you are bound to require many kluges, browser 
dependencies etc. if you try to get at all complex. (For example, you need 
to go to CSS ... still unevenly supported ... before you can get a notion 
of "vertical line spacing" in HTML.) Trying to teach a dog to dance, etc. 
(Now, *eventually* it is to be hoped that XSL-FO may do this kind of thing 
fairly gracefully. But not soon: let's get v.1 first. Some SVG people are 
beginning to make noises about constraint-based processing for their v.2. I 
hope they try it: it seems a natural place to take a first stab at the 
problem.)

Now, this is not to say the task you describe is impossible, if (as you 
stipulate) your "layout manager" is rudimentary enough. Just don't try to 
get too ambitious: go one tiny step at a time.

Just my impressions. I hope someone whose hands are deeper in the guts of 
the technologies is willing to weigh in. (I'm just a "user".)

Cheers,
Wendell

At 10:03 AM 8/1/01, you wrote:
>  In Java Swing, you can nudge components around within a GUI
>  layout by adding Glue and Strut components.
>  I would like to implement something similar using XSLT with my
>  servlet's XML output, resulting in HTML table cells that
>  incorporate a rudimentary layout manager...
>
>  I would like to guarentee vertical table cell size, without
>  knowing until XML generation time, how many text lines will be in
>  the cell.
>
>  I suppose that I would have to generate a tag/value combination
>  that would specify the desired vertical line spacing, then I
>  would have to count lines within the template match block that
>  were copied through, and then take the difference (if one
>  existed...) and send that value as a parameter to a subroutine
>  that generated lines with just whitespace...
>
>  Before I embark on this XSLT Odyssey, do the experienced XSLTers
>  on this list think this is viable? Or are there hidden perils in
>  this task that come to mind?
>
>  -Jim Parsons, ArsDigita Corp.
>  -jparsons@arsdigita.com
>
>  XSL-List info and archive:  http://www.mulberrytech.com/xsl/xsl-list


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Wendell Piez                            mailto:wapiez@mulberrytech.com
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