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Re: guideline 7.1 about screen flickering (fwd)

From: Charles McCathieNevile <charles@w3.org>
Date: Thu, 26 Jul 2001 21:55:36 -0400 (EDT)
To: Matt May <mcmay@bestkungfu.com>
cc: <jasonw@ariel.ucs.unimelb.edu.au>, Kynn Bartlett <kynn@reef.com>, WAI GL <w3c-wai-gl@w3.org>
Message-ID: <Pine.LNX.4.30.0107262146581.22852-100000@tux.w3.org>
Hmmm. It seems that  thre are about 3 things that we could say.

User agents ought to make it clear that a stopped animation is in fact an
animation. (Until they do, I guess we would like authors to do it. <sigh/>)

User agents (iCab, Opera, Explorer, various external viewers taht I use with
lynx) allow some animations to be stopped, and proxying tools available allow
them to be stopped as well (do any of those provide an option to go fetch the
thing and show the animation?). Should we describe how this is done in the
techniques, or in the browser support page?

So in the case of animated gif content I propose that the until user agents
condition has been met. As far as I know this is not the case for other
formats (I know of one example where the animation is done by a java applet,
and can be stopped by clicking on the applet, but I found that out by
accident.  The example is still in the left hand frame of
http://www.wendyrule.com and there are probably a bunnch of accessibiltiy
problems with the site.)

We should look at the way that alternative equivalents for dynamic content
are required, to ensure that the case Matt outlines below is covered, even if
that will only ever be a second-rate solution (it is better than none, which
seems our current answer).



On Thu, 26 Jul 2001, Matt May wrote:

  ----- Original Message -----
  From: "Jason White" <jasonw@ariel.ucs.unimelb.edu.au>
  > While agreeing with Kynn, I would add that the user agent (or software
  > operating in conjunction with it) is in an excellent position to block
  > these effects if the user so wishes. That is, if one wants to take
  > steps to prevent certain effects that might be distracting, one is
  > entirely free to do so (it is merely a case of overriding the author's
  > presentation).

  But when one does override the presentation, one loses the ability to view
  animations that actually _do_ aid their comprehension, doesn't one? There's
  no way of determining whether a given image is animated, and no way to start
  an animation when it's disabled.

  I browse with images but without animation, and it's very common for the
  first frame of a given animated GIF to communicate little to nothing. (For
  example, a banner ad for Snickers candy bars, with no Snickers logo
  anywhere, and only the word "Hungry?" Or nothing at all, on a black
  background.) Here, the user receives none of the content of the image, and
  alt text is not visible. Turning off images completely and relying on alt
  text is the only real solution involving the user agent, and I find that to
  be really excessive in context.

  At the least, I'd like to see a requirement that animated GIFs degrade to
  something meaningful when animations are turned off (e.g., displaying the
  last frame of the animation first, in the case of banners, since they
  usually represent the payoff). The current 4.4 (design content so that when
  presentation effects are turned off or not supported the content is still
  usable) seems to require that.


Charles McCathieNevile    http://www.w3.org/People/Charles  phone: +61 409 134 136
W3C Web Accessibility Initiative     http://www.w3.org/WAI    fax: +1 617 258 5999
Location: 21 Mitchell street FOOTSCRAY Vic 3011, Australia
(or W3C INRIA, Route des Lucioles, BP 93, 06902 Sophia Antipolis Cedex, France)
Received on Thursday, 26 July 2001 21:55:42 UTC

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