W3C home > Mailing lists > Public > public-bpwg@w3.org > May 2009

Re: [agenda] Agenda for tomorrow's call

From: Alan Chuter <achuter@technosite.es>
Date: Wed, 20 May 2009 09:02:53 +0200
Message-ID: <4A13AB1D.2090002@technosite.es>
To: MWI BPWG Public <public-bpwg@w3.org>
CC: brucel@opera.com
 > We could point to WCAG 2; the "Techniques for WCAG 2" document says
 > "Using CSS to include decorative images":

I think that the WCAG technique is saying "if you want to use images 
that don't require alternative text, you can use CSS," but the BP says 
"use CSS to create sprite images" and should add "if you do this then 
you can't provide alternative text, so don't use sprites for 
non-decorative images."

I think it would be useful to warn people to avoid failure F3: "Failure 
of Success Criterion 1.1.1 due to using CSS to include images that 
convey important information" [1]. I suspect that unfortunately this 
excludes much of the intended scope of the BP.

cheers,

Alan

[1] http://www.w3.org/TR/2008/NOTE-WCAG20-TECHS-20081211/F3


Bruce Lawson wrote:
> On Tue, 19 May 2009 15:24:11 +0100, Alan Chuter <achuter@technosite.es> 
> wrote:
> 
>> Jo Rabin wrote:
>>> A question on sprites: what happens to our bp1 stuff on alt text etc. 
>>> (and what about accessibility aspects).
>>
>> As CSS is necessary for the use of sprites, they should only be used 
>> for decorative images, which by definition do not require a text 
>> alternative. If an image does require a text alternative then it isn't 
>> decorative and shouldn't be done with CSS, so it shouldn't be a sprite 
>> either. So icons or buttons shouldn't be made into sprites if they are 
>> the sole way of conveying information. I think that this should 
>> perhaps be made clear in the BP document [1].
> 
> We could point to WCAG 2; the "Techniques for WCAG 2" document says 
> "Using CSS to include decorative images":
> 
> The objective of this technique is to provide a mechanism to add purely 
> decorative images and images used for visual formatting to Web content 
> without requiring additional markup within the content. This makes it 
> possible for assistive technologies to ignore the non-text content. Some 
> user agents can ignore or turn off CSS at the user's request, so that 
> background images included with CSS simply "disappear" and do not 
> interfere with display settings such as enlarged fonts or high contrast 
> settings.
> 
> http://www.w3.org/TR/WCAG20-TECHS/C9.html
> 
> Hugs,
> 
> Bruce
> 
> 
> 


-- 
Alan Chuter
Departamento de Usabilidad y Accesibilidad
Consultor
Technosite - Grupo Fundosa
FundaciĆ³n ONCE
Tfno.: 91 121 03 30
Fax: 91 375 70 51
achuter@technosite.es
http://www.technosite.es
Received on Wednesday, 20 May 2009 07:05:40 UTC

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