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RE: [css3-speech] ISSUE-153 speak: none; usage incompatible with other values of speak

From: Belov, Charles <Charles.Belov@sfmta.com>
Date: Mon, 24 Jan 2011 10:36:24 -0800
Message-ID: <E17F75B6E86AE842A57B4534F82D03769C35D1@MTAMAIL.muni.sfgov.org>
To: "Daniel Weck" <daniel.weck@gmail.com>
Cc: <www-style@w3.org>, "fantasai" <fantasai.lists@inkedblade.net>

> -----Original Message-----
> From: Daniel Weck [mailto:daniel.weck@gmail.com] 
> Sent: Friday, January 21, 2011 11:56 PM
> To: www-style@w3.org; fantasai; Belov, Charles
> Subject: Re: [css3-speech] ISSUE-153 speak: none; usage 
> incompatible with other values of speak
> 
> 
> On 21 Jan 2011, at 18:17, Belov, Charles wrote:
> 
> > Daniel Weck [mailto:daniel.weck@gmail.com] wrote on 
> Wednesday, January 
> > 19, 2011 8:09 AM
> >>
> >> Oops, I apologize for this editorial mistake: I meant 
> "display:none", 
> >> not "visibility:hidden". The former effectively 'deactivates' an 
> >> element (so to speak) whereas the latter is more similar 
> to "voice- 
> >> volume:0%". In other words, "visibility:hidden" preserves 
> the visual 
> >> space that the element would normally occupy if it was visible 
> >> (resulting in an empty or transparent area that still 
> takes part in 
> >> the page layout), and conversely "voice-volume:0%"
> >> results in an audio silence lasting as long as the duration of 
> >> non-silent TTS playback.
> >> Regards, Daniel
> >
> > Actually, that's an argument in favor of speak:none.  It would be 
> > inconvenient to make listeners wait for something that is merely 
> > hidden to sighted readers.
> 
> speak:none is not needed, authors can use display:none instead.  
> Personally I think it makes a lot more sense to reuse 
> existing CSS features, especially when the resulting 
> authoring practice matches accessibility guidelines (e.g. a 
> non-displayed visual element gets ignored by a speech 
> processor, and any visible graphical element gets 
> spoken-out). Is there really a compelling reason to keep 
> speak:none ?  
> I can't think of any. Regards, Daniel

http://www.w3.org/TR/WCAG20/#text-equiv
states:

1.1.1 Non-text Content: All non-text content that is presented to the
user has a text alternative that serves the equivalent purpose, except
for the situations listed below. (Level A) 
....
Decoration, Formatting, Invisible: If non-text content is pure
decoration, is used only for visual formatting, or is not presented to
users, then it is implemented in a way that it can be ignored by
assistive technology.

speak:none (or speakability:none as Fantasai suggested) would allow
exclusion of such displayed content from being read aloud.


Hope this helps,
Charles Belov
SFMTA Webmaster
 
Received on Monday, 24 January 2011 18:55:25 GMT

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