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Re: SC failure for using pixel font size

From: Christophe Strobbe <strobbe@hdm-stuttgart.de>
Date: Thu, 17 Jul 2014 11:24:58 +0200
Message-ID: <53C7966A.2010402@hdm-stuttgart.de>
To: w3c-wai-gl@w3.org

On 17/07/2014 10:26, Aurélien Levy wrote:
> Le 17/07/2014 09:26, Ramón Corominas a écrit :
>> This is an interesting point. Since "accessibility supported" is
>> defined as "compatible with AT that users use", I think that SC 1.4.4
>> should take into account the reality that most low vision users who
>> rely on browser's zoom don't use the "full zoom" option, but
>> text-only increase.

Can you explain which browsers you have in mind here? On Windows 7, IE
11, Google Chrome 35, Opera 12.17 (Presto-based), Opera 22
(Webkit-based) and SeaMonkey 2.26.1 offer no text-resize mechanism other
than zooming. Only Firefox 30 seems to offer a "zoom text only" option
for its zoom function.  So are "most low vision users" working with this
Firefox option?

>> (...)
>> In any case, normally the use of absolute units is only problematic
>> in -some- containers and certain positioning properties, but not for
>> the text size.
> Even without using the zoom sufficient technique or another one listed
> as so, it's still not a failure in regard of the current failures we
> got except for text based form controls (F80). The F69 can't apply
> because it's about having content clipped, truncated or obscured when
> text is resized at 200% and in our case in browser not increasing
> pixel based font size we haven't that kinds of problems.
> Furthermore as far a I know browser isn't considered as an AT and the
> SC text say "without assistive technology" so basically any user of AT
> is outside of the scope for this SC.


A browser is not an AT but that does not mean that AT users are out of
scope. Rather, they must be able to resize text using just a browser,
regardless whether they use AT or not.

> The only thing left is the intent of the
> SC http://www.w3.org/TR/UNDERSTANDING-WCAG20/visual-audio-contrast-scale.html
> that say :
> "The scaling of content is primarily a user agent responsibility. User
> agents that satisfy UAAG 1.0 Checkpoint 4.1
> <http://www.w3.org/TR/WAI-USERAGENT/guidelines.html#tech-configure-text-scale>
> allow users to configure text scale. The author's responsibility is to
> create Web content that does not prevent the user agent from scaling
> the content effectively. Authors may satisfy this Success Criterion by
> verifying that content does not interfere with user agent support for
> resizing text, including text-based controls, or by providing direct
> support for resizing text or changing the layout. "
> and
> "If the author is using a technology whose user agents do not provide
> zoom support, the author is responsible to provide this type of
> functionality directly or to provide content that works with the type
> of functionality provided by the user agent. If the user agent doesn't
> provide zoom functionality but does let the the user change the text
> size, the author is responsible for ensuring that the content remains
> usable when the text is resized."
> So, the real question I think WCAG must give an answer on is :
> Is it a failure or not to use pixel font size in an environment where :
> - user may have a browser that doesn't scale it and don't provide a
> zoom feature (IE6 for example + I'm not sure every mobile browser out
> there do it )

Microsoft's own ie6countdown.com site now redirects to
<https://www.modern.ie/en-us/ie6countdown>, which says that Internet
Explorer 6 usage is down to 4.2%, mostly due China, where 22.2% of
internet users still use this prehistoric browser.
I don't know how mobile browsers deal with px fonts.

> - no others sufficient technique is used

In an environment where user agents do not support zooming and cannot
resize text when font size is defined in pixels, SC 1.4.4 would not be
met unless the content provides a text resizing mechanism. That's my
reading of the SC.

Best regards,


> Regards,
> -- 
> Aurélien Levy
> ----
> Temesis

Christophe Strobbe
Akademischer Mitarbeiter
Adaptive User Interfaces Research Group
Hochschule der Medien
Nobelstraße 10
70569 Stuttgart
Tel. +49 711 8923 2749

"La vie est courte, hélas! et je n'ai pas encore lu tous mes livres!" (d'après Mallarmé).
Received on Thursday, 17 July 2014 09:25:19 UTC

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