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Re: pause-before property for presentations

From: Dave Raggett <dsr@w3.org>
Date: Fri, 12 Jul 2002 15:02:07 +0100 (BST)
To: Ian Hickson <ian@hixie.ch>
cc: Val Sharp <val@valsharp.co.uk>, <www-style@w3.org>
Message-ID: <Pine.LNX.4.44.0207121428330.1971-100000@hazel>

My suggestion would be to keep things as simple and as declarative 
as possible.  In my experience most people avoid using fancy 
transition or build effects in their slides, with a few exceptions,
e.g. to gradually assemble a complex diagram (which can be handled
via animated SVG). The most common build effect is to reveal the 
next bullet point upon user action (hitting the space bar etc).

Opera supports the @media projection feature, and I hear that work
has started on this for Mozilla. The addition of the progressive
reveal feature would satisfy many people's needs for simple
presentations, and SVG is well suited for more complex ones. Whilst
a progressive reveal feature could be implemented by XHTML + CSS +
scripting, I beleive that a declarative way to express the styling
intent in CSS would be preferable.

In the interest of keeping things simple, and building solidly on
the existing page semantics in CSS, I would suggest something like:

  pause-before:  [auto|avoid|always|inherit]

with a default of "auto". A mechanism for automatically revealing
the next section after a specified delay could be added as a future
extension if there was strong user demand. There may be a better
name for this property, but I can't think of one at this moment. The
semantics of pause is to subdivide pages into visual sections with
the intent of allowing users to progressively reveal sections on an
implementation dependent user action.

-- 
 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 Friday, 12 July 2002 10:01:57 GMT

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