[Bug 26868] Incorporate longdesc

https://www.w3.org/Bugs/Public/show_bug.cgi?id=26868

Liam R E Quin <liam@w3.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |faulkner.steve@gmail.com,
                   |                            |mike@w3.org,
                   |                            |public-html-admin@w3.org,
                   |                            |public-html-wg-issue-tracki
                   |                            |ng@w3.org
          Component|CR alt techniques (editor:  |LC1 alt techniques (editor:
                   |Steven Faulkner)            |Steven Faulkner)

--- Comment #1 from Liam R E Quin <liam@w3.org> ---
A good candidate to introduce longdesc might be the diagram example.

We have now,
[[
In the following example we have an image of a pie chart, with text in the alt
attribute representing the data shown in the pie chart
]]

However, since Web browsers don't display alt text if it's too long to fit in
the space allocated for the image (assuming width and height are supplied,
eaither as attributes or from CSS, and default overflow rules), and not all
browsers will even wrap alt text if it's too wide, we can't rely on being able
to describe a pie chart in an alt attribute.

In any case even if we did, it would be extraordinarily irritating to have to
listen to the long image description every time.

So I suggest.
[[
In the following example we have an image of a pie chart, with text in the alt
attribute explaining that it is a pie chart, and the longdesc attribute giving
a link to a full explanation with the colours, percentages and proportions.
Note that a useful alternative representation of a pie chart might be to
include a table of the same data in the document, and to use the ARIA
describedby attribute to point to it, but that technique does not work for most
diagrams, and a detailed description of an image (it's a circle with...) does
not belong in the document itself for most readers.

<img src="piechart.png" alt="Pie chart: Browser Share"
longdesc="browsershare.html">
]]
I think the rest of this example is OK, although use of describedat would help
it considerably.

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Received on Saturday, 24 January 2015 07:10:48 UTC