W3C home > Mailing lists > Public > wai-tech-comments@w3.org > September 2001

Height/Width/Aspect?

From: Sean B. Palmer <sean@mysterylights.com>
Date: Sun, 23 Sep 2001 02:03:58 +0100
Message-ID: <013801c143cb$a3c67940$cfec93c3@y0r1d9>
To: <wai-tech-comments@w3.org>
I have always maintained that important structural and semantic information
must be retained in the first class instance, and not relegated to a
stylesheet. For example, one shouldn't use CSS to add comments using the
"content" property, because that's information that should be renderable no
matter what the user's style settings. It's content, not style.

However, I'm wondering just how much the "height" and "width" attributes
are part of the content. Heights and widths in XHTML are generally pixel
based absolute units that are based on screen rendering. That's not device
independent, but OTOH it is information which can be skipped by other user
agents. It's unlike (for example) embedded color presentation in that the
color is often a manifestiation of some semantic element (in the non-XML
sense). A height and a width are generally based on some distinct absolute
physical property of the visual media object.

However, with raster image formats such as SVG, we have to move our
attention to user override of absolute display characteristics, now that
the override is actually useful (pixellated images being pretty pointless
to enlarge). When one sets heght and width properties on an <object> in
XHTML for an image/svg+xml media object, it should be merely a suggestion
that the user can easily override, by selecting the object in real time and
resizing it in the display frame, and/or by setting a user stylesheet.

So I suggest that the most important structural detail of media objects
that are erndered visually is their aspect ratios, and that the height and
width indicator attributes in XHTML are merely methods of deriving that
aspect ratio *and* of providing a default absolute display box for the
object. The question is as to just what extent this mechanism is preserved
in XHTML 2.0.

Should XHTML 2.0 offer both a mere non-unit based aspect ratio attribute,
e.g. 'aspect="3:2"', as well as a set of height and width attributes (with
optional unit indicators, I guess)?

--
Kindest Regards,
Sean B. Palmer
@prefix : <http://webns.net/roughterms/> .
:Sean :hasHomepage <http://purl.org/net/sbp/> .
Received on Saturday, 22 September 2001 21:04:41 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Thursday, 22 March 2007 18:09:35 GMT