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pause-before property for presentations

From: Dave Raggett <dsr@w3.org>
Date: Wed, 10 Jul 2002 17:46:52 +0100 (BST)
To: www-style@w3.org
Message-ID: <Pine.LNX.4.44.0207101719240.3374-100000@hazel>


I am currently using Linux and would very much like to be able to 
use XHTML and CSS for presentations. The @media projection {...}
feature provides the basic mechanism for dividing an XHTML document 
into slides when used with the page-break-before property. What's
missing is a means to hide sections until the presenter hits the
space bar or clicks the mouse etc.

The Magic Point (mgp) utility approaches this feature by allowing 
you to define pauses with the %pause command. It therefore occurred
to me that CSS could readily provide this feature by a pause-before
property. This would be interpreted in a similar way to how Opera
interprets the page-break-before, with the exception that instead
of a page flip, you just reveal the section including and following
the pause-before property, and upto but not including the next
pause-before, or page-break-before, which ever comes first.

The CSS spec wouldn't need to specify what user action is needed
to reveal the next section, and this is the same situation as now
for the page-break-before in the projection mode. Likewise the
semantics of sections defined by the pause-before property would
be defined in essentially the same way that pages are now.

I am hoping that implementers would also support a means to use
CSS to provide page headers and footers for projections.

The current alternatives for presentations include:

 - split your XHTML into separate files (e.g. with a perl script)
   and hack the pause effect with JavaScript

 - use mgp (on Linux)

 - use LaTeX and pdfscreen or PPower4 to generate PDF slides

 - use SVG

 - use Open Office

 - use Windows and the ubiquitous PowerPoint utility

Of the above choices, XHTML+CSS looks to me like the cleanest
and the most accessible.

-- 
 Dave Raggett <dsr@w3.org> or <dave.raggett@openwave.com>
 W3C lead for voice/multimodal. http://www.w3.org/People/Raggett 
 tel/fax: +44 1225 866240 (or 867351) +44 771 213 7629 (GSM)
Received on Wednesday, 10 July 2002 12:46:44 GMT

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