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Re: MAP navbars

From: Charles McCathieNevile <charlesn@srl.rmit.EDU.AU>
Date: Mon, 16 Nov 1998 12:42:02 +1100 (EST)
To: Nir Dagan <nir@dhaame.pair.com>
cc: WAI UA group <w3c-wai-ua@w3.org>, WAI GL <w3c-wai-gl@w3.org>
Message-ID: <Pine.SUN.3.91.981116115644.29986E-100000@sunrise>
OK - what I am thinking is as follows:

A user stylesheet (this relies on CSS2):

...
[USEMAP] { display : none }
MAP, .nav { position: absolute; width: 100%;
        height: 100px;      top: auto;
         right: 0;       bottom: 0;
          left: 0; }
...
(which positions a MAP, or anything of CLASS nav at the bottom of its 
containing block)

Or another possibility:

MAP { display : none }
[USEMAP] { position: fixed;  width: 100%;
        height: 100px;    top: 0;
         right: 0;     bottom: auto;
          left: 0; }

(This fixes the imagemap at the top of the screen, as if it were a frame)


Working with the following HTML:

<BODY>
<IMG SRC="map.gif" USEMAP="mymap" ALT="Imagemap - links repeated at end 
of Page">

...
<P CLASS="nav">
<MAP NAME="mymap">
<A SHAPE="rect" COORDS="0,0,100,100" HREF="some.htm">Somewhere</A> | <A 
SHAPE="rect" COORDS="0,100,200,200" HREF="other.htm">Otherwise</A> | <A 
SHAPE="rect" COORDS="100,0,200,100" HREF="else.htm">Elsewhere</A> 
</MAP>
</P>
</BODY>

(This example is mostly copied from the HTML 4 Specification[2])

I have not, for the moment, included Al's suggestion of naming the start
of the Map. Unfortunately, IMG doesn't allow ALT text to be active so
there is no way to get to the NAMEd point except guess work. A better way
to do this would be to use the content of the OBJECT element, but we're
still waiting for UAs to support that in a stable implementation so I'll 
hold off on that example.

What I think this technique does:

Provides 'redundant' links for UAs which don't support USEMAP.

Enables users to avoid redundant links if they have a fancy browser.

Allows text-only users to have clustered navigation links at the end of
the page, with access to them from the start of the page (via the MAP -
see how Lynx implements imagemaps for an example) in current browsers.

What I am not sure of: 

In a fancy graphic browser, where there is an imagemap with AREAs, and ALT
text is provided for the AREAs, I get a tool-tip telling me what the ALT
text is. I assume that this information is available to a screen reader. 

If I had enlarged the image (for example in Opera) to see it better, and
it was using the example above, would the UA make available in a tool-tip
or similar the content of the Links (in my example Somewhere, Elsewhere,
Otherwise), and/or would it make that available to 3rd party technology.
If it doesn't, should that be a technique included in the UA guidelines? 

Charles McCathieNevile
Received on Sunday, 15 November 1998 20:46:03 GMT

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