[css3-images] [Fwd: RE: CSS Image Values and Replaced Content Module Level 3 - very brief review]

Below is some unvetted review by members of PFWG of CSS Image Values and
Replaced Content Module Level 3
http://www.w3.org/TR/2012/WD-css3-images-20120112/. We appreciate your
accommodating us on a review extension but unfortunately were not able
to process a full group review on time. The comments below were proposed
by members of the group and we decided it was best to send you this as
is sooner than a full formal review later.

-------- Original Message --------

I gave this a brief review and while the overall concept of image
replacement is widely abused I couldn't find much in this spec to
specifically comment about.

I agree.  This spec deals with ways to reference and create images.  The
primary issue with CSS images is that there is no concept of a
foreground-image, which seems to be outside the scope of this spec.


      3.3 Using Elements as Images

A note should probably be added here to note that the element referenced
will contain none of the structural content of the element which is
referenced. It should note that while there are uses for this technique
there are also many places where using this will result in accessibility
issues.


      EXAMPLE 8


This example does not meet accessibility requirements. When background
images are disabled the next/previous buttons will no longer be visible.
Also - there is no text alternative provided for screen reader users.
The example should be refined so it meets all accessibility requirements.

the example also suggests using click handlers to make the previews
navigable.  These should be links, or at least use ARIA with the click
handlers.


      EXAMPLE 11


It should probably be stated that this silly example would result in
accessibility issues. Normally, anywhere text appears in a background
image is a problem.


      4. Gradients


It should probably be stated that gradients can cause subtle issues with
maintaining a sufficient luminosity contrast ratio between the text and
its background. (an informative note about making sure to meet WCAG2
1.4.3 is probably good)
it might also be a good idea to advise against animating repeating
radial gradients, as they may cause flashing and seizure issues. 


-- 

Michael Cooper
Web Accessibility Specialist
World Wide Web Consortium, Web Accessibility Initiative
E-mail cooper@w3.org <mailto:cooper@w3.org>
Information Page <http://www.w3.org/People/cooper/>