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Re: advice on alt text for image maps

From: Steve Faulkner <faulkner.steve@gmail.com>
Date: Sat, 4 Jan 2014 16:49:23 +0000
Message-ID: <CA+ri+V=Z1xCgcNkQCEzB3C9KkxoZ9N3fi5HkzmmWyNUzzdxVNQ@mail.gmail.com>
To: Leif Halvard Silli <xn--mlform-iua@xn--mlform-iua.no>
Cc: "Jukka K. Korpela" <jukka.k.korpela@kolumbus.fi>, HTMLWG WG <public-html@w3.org>, HTML Accessibility Task Force <public-html-a11y@w3.org>
hi leif,

will think on your comments, agree as Jukka pointed out there needs to be
better advice for alt text for images used as image maps.



HTML 5.1 <http://www.w3.org/html/wg/drafts/html/master/>

On 28 December 2013 05:29, Leif Halvard Silli <
xn--mlform-iua@xn--mlform-iua.no> wrote:

> Jukka K. Korpela, Thu, 26 Dec 2013 23:34:57 +0200:
> > 2013-12-24 19:26, Steve Faulkner wrote:
> >> I have made some modifications to the example:
> >>
> >>
> http://www.w3.org/html/wg/drafts/html/master/embedded-content-0.html#image-maps-0
> > There's no general guideline for writing the alt attribute,
> > though. [...]
> Great stuff, Jukka. You’ve gotten me to think. I hope Steve considers
> your ideas, which I hereby wish to expand on a little.
>   [ Snipping to the general guideline you propose: ]
> >> If an img element has a usemap attribute  [ … ] it acts as a
> >> caption for the collection of the alt attributes of the area elements
> Put that in the spec! To view the alternative text of the usemap image
> as a caption for the line of area elements, is a good, general
> authoring guideline.
> > How does the text "Map of Katoomba" help [...]
> > In this case, alt="" would seem to be the appropriate
> That the alternative text can be set to empty whenever a caption for
> the area element links is unnecessary, is an intriguing part of your
> proposal. Some supportive observations:
> A) Two, slightly different, presentation modes appear to exist:
>    1. Image-map-mode is triggered by alt-text presence. Image-map-
>       mode is characterized by an ”Image map!” + alt-text
>       announcement that precedes presentation of the <area> links.
>    2. Line-of-links-mode is triggered by empty as well as omitted
>       alt-text. Line-of-links-mode is characterized by the lack
>       of any Image Map announcment (e.g. check VoiceOver+Safari)
>       Unique for this mode, Lynx generates its own text ([USEMAP])
>       regardless of whether the alt-text is empty or omitted.
> B) HTML5’s WAI-ARIA section specifies that empty @alt triggers
>    presentation role. Use of @usemap attribute does not matter.
> C) Use cases for not announcing a usemap image as an image
>    map do exist. E.g. image maps used for site navigation as
>    well as the example Jukka described.
> D) An image-map image may be as varied as a non-image-map image -
>    it could be a logo, text, portrait - even decorative. One might
>    as well use <figure> with image maps, and supposedly omit @alt.
>    Which justifies more than just a ”always use alt-text” advice.
> E) WAI-ARIA gives us a third mode - image mode:
>      *  <img role="img" src="file" alt="Text" usemap=#map />
>    Here, the area elements get presented as a line of consecutive
>    links without preceding image-map announcement. But, instead of
>    being silent about the image, role="img" causes the image to be
>    announced as an image (vs announced as image map or not at all).
> F) It seems that image-map images could be viewed as having their
>    own, non-ARIA defined ”role”, much like e.g. <table> have no
>    corresponding ARIA role. By setting the alternative text to
>    empty, the role is changed to role="presentation". By setting
>    role="img", the image-map image is set to image. Again, much
>    like the <table> may be changed from its native, non-ARIA-
>    defined role to e.g. presentation role (via role=presentation)
>    as well as to other, specific roles (like grid).
> As a conclusion, the advice on how to author alt text for usemap images
> could be split in 3 parts based on whether the usemap image should have
> native role (when alternative text is present), presentation role (when
> the native role is overruled by empty or omitted alternative text or
> role="presentation") or image role (when the native role is overruled
> via role="img").
> --
> leif halvard silli
Received on Saturday, 4 January 2014 16:50:34 UTC

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