W3C home > Mailing lists > Public > www-svg@w3.org > November 2004

Re: SVGAccessibilityWG: has-been-clicked or a:visited

From: Philippe Lhoste <PhiLho@GMX.net>
Date: Wed, 10 Nov 2004 00:39:18 +0100
Message-ID: <41915526.9090006@GMX.net>
CC: www-svg@w3.org

Will Pearson wrote:
> However, I don't know whether SVG is truely accessible to some users.  The
> problem comes down to how the semantic meaning encoded within diagrams is
> visually extracted.  It isn't a problem unique to SVG, but a problem with
> diagrams in general.  The technique of providing a textual equivalent for
> elements of a drawing is fine up to a point, but problems arise due to other
> semantic encoding techniques being used within diagrams.  Spatial
> relationships between diagram elements, colors, etc. can provide as much
> meaning as the lines themselves do, and this is often either not conveyed or
> not conveyed with any clarity by textual descriptions for a single diagram
> element without the context of other diagram elements.  Therefore, having
> things like LongDesc assigned to a <LINE> tag really don't make a drawing
> 100% accessible to someone who has no means of extracting the meaning
> visually.

Some (general) remarks and various thoughts by somebody not in the 
accessibility "business" but interested by the issues:

- Accessibility isn't just about people with trouble with reading or 
viewing. Problem which you address correctly by using "to some users". 
Some parts of the art may be perceived, but can be hard to distinguish. 
So textual equivalent are only part of the accessibility, of course.

- Ultimately, an accessible viewer would read the SVG code... That's the 
advantage of SVG over bitmap images, they have semantics. Without going 
so far, it could be interesting to hover over a line (or any other 
shape) and extract some information, like exact color (named one even if 
#hhh is used) or thickness. Since these data can be used to convey 
information, like you mention, it could be a useful feature. Of course, 
for drawings conveying some information, like diagrams. It would be less 
useful for artistic drawings.

- I remember having seen a mouse with "force feedback", ie. that provide 
feedback on the environment where the cursor goes. To transpose examples 
to SVG, it would tickle when going over a stroke, or go sluggish over a 
given color. I wonder if this mouse is still sold.

Jonathan wrote:
 > To raise another issue,
 >
 >     It isn't clear why alt isn't included as well as title, they have
 > different functions perhaps one describing the image, and the other
 > the linked resource, surely essential accessibility for SVG?

I am not sure about what you are saying here. AFAIK, alt is used only in 
img tags (OK, area and input too). alt is here to provide a short 
description, in case of text-only browsers (or editors showing raw 
HTML...), or graphical browsers with images disabled, or even when the 
link to the image is broken.
It doesn't make much sense in SVG where the images are part of the 
document, so are not likely to be absent or not displayed. Of course, 
there is the image element which refers to external images, and where 
links can be broken, but it is not obvious how to use such alt attribute 
(if displayed inside the drawing, it can break it more than the current 
behavior of just ignoring the element with broken link).

-- 
Philippe Lhoste
--  (near) Paris -- France
--  Professional programmer and amateur artist
--  http://Phi.Lho.free.fr
--  --  --  --  --  --  --  --  --  --  --  --  --  --
Received on Tuesday, 9 November 2004 23:41:27 UTC

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