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Re: Where does flicker come from?

From: Wendy A Chisholm <chisholm@trace.wisc.edu>
Date: Mon, 24 May 1999 16:22:58 -0500
Message-Id: <199905242125.QAA155258@mail1.doit.wisc.edu>
To: Ian Jacobs <ij@w3.org>, w3c-wai-gl@w3.org
Cc: w3c-wai-ua@w3.org
Flicker and other visual events that may cause a seizure (such as quick
changes from light to dark) may be created by the following 4 ways (there
may be more):
1.  scripting
2.  animated images
3.  applets
4.  embedded multimedia objects

possible suggestions for UA:
1.  allow users to disable scripting, applets, and multimedia objects 
2.  allow the user to control the rate of change (of scripts, applets, and
multimedia objects).
3.  allows users to pause animated images (i.e. only show first or last
frame, or step through frames at user request)


At 01:49 PM 5/24/99 , Ian Jacobs wrote:
>We say in checkpoint 7.1 of the Web Content Accessibility Guidelines
> Until user agents allow users to control flickering, 
> avoid causing the screen to flicker.
>I'd like to tell the UA WG how flicker may be caused so
>that UAs can prevent it. Can someone explain what markup
>or settings lead to flicker?
>Thank you,
> - Ian
>[1] http://www.w3.org/TR/WAI-WEBCONTENT/#gl-movement
>Ian Jacobs (jacobs@w3.org)   http://www.w3.org/People/Jacobs
>Telephone May 1999 only:     (212) 688-4489
>Cell phone May 1999:         (917) 450-8783
>Otherwise Tel/Fax:           (212) 684-1814
Received on Monday, 24 May 1999 17:26:01 GMT

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