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Re: Dropping <input usemap="">

From: Philip Taylor <philip@zaynar.demon.co.uk>
Date: Thu, 16 Aug 2007 01:48:06 +0100
Message-ID: <46C39EC6.3030101@zaynar.demon.co.uk>
To: Robert Burns <rob@robburns.com>
CC: public-html <public-html@w3.org>

Robert Burns wrote:
> On Aug 15, 2007, at 6:18 PM, Philip Taylor wrote:
>> It does work as intended in Firefox and Opera [see below], and it 
>> falls back to the basic server-side image map functionality in IE 
>> (like how <blink> falls back to a CSS-stylable element in IE), so 
>> people can still benefit from its intended functionality by using it now.
> 
> I thought you were saying it doesn't work as intended in those browsers. 
> I thought you said it worked the same as <img usemap> rather than 
> submitting form data. If <input usemap> is exactly the same as <img 
> usemap> then of course there's no reason to maintain it. However, my 
> reading of the HTML 4.01 recommendation is that <input usemap> is 
> supposed to submit form data (with x and y coordinates as well). Since 
> no one implements that (which is what I understand you saying) then it 
> has never been implemented.

What is implemented (in FF and Opera) is that if you click on a part of 
the button that is covered by an <area> from the used <map>, then it 
acts like a link to that <area>'s href, which is the same as with <img 
usemap>. If you click on a part of the button that is not covered by any 
<area>, then it submits the form with x and y coordinates, which is the 
same as with <input type=image>. Try the example I gave earlier 
(<http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C%21DOCTYPE%20html%3E%0D%0A%3Cbody%3E%0D%0A%3Cmap%20name%3Dm%3E%3Carea%20shape%3Drect%20coords%3D0%2C0%2C100%2C100%20href%3Dhttp%3A//google.com%3E%3C/map%3E%0D%0A%3Cform%20action%3D.%3E%3Cinput%20type%3Dimage%20src%3Dimage%20usemap%3D%23m%3E%3C/form%3E>).

That seems like the sensible thing to implement in this case, since it's 
consistent with how the other image maps work, and so I believe it is 
what HTML4 intended, but the HTML4 specification is far too vague for me 
to see whether that's actually the behaviour it's trying to describe 
(unless I'm just missing the part where it says what to do in this case).

> It doesn't submit form data. We have an <input type-'image'> that 
> doesn't submit form data (unless the map is nohrefed or something like 
> that). That doesn't sound like it works as intended to me.

It does submit form data, when you click on a part that's not already 
covered by the client-side image map.

> I'm not sure why you call it an accessibility "hack".

Because (as I understand it) the HTML4 designers started with a 
non-accessible feature (server-side image maps via <input type=image>), 
and then realised they ought to make it accessible, so they added on a 
couple of sentences to include the feature <input usemap>, without 
describing how it should actually work and seemingly without deep design 
thought - it's just a small imprecise fix to plug a perceived hole.

We now have a decade more experience, and the ability to look at how 
HTML has been used in that time, and new technology to help with various 
use cases, so we can have a better perspective on whether that perceived 
hole is a real one that is worth fixing properly for the first time.

> if we think image maps are 
> useful, then client-side form- submission image maps have a clear use too.

<input usemap> doesn't do a client-side form-submission image map - I 
assume you mean that clicking on an <area> would submit the form, 
ignoring the area's href, sending the x,y coordinates of the top-left 
corner of the bounding box of the area's shape, or something like that? 
If you wanted that, it would be an entirely new feature that's 
incompatible with how <input usemap> is currently implemented and used.

> A big benefit of the HTML 4.01 @usemap are that  an author can implement 
> client-side image maps without any server-side scripting, without any 
> knowledge of scripting at all. It can be done in pure HTML markup. That 
> to me is a benefit.

Pure client-side image maps without any server-side scripting are 
already handled by <img usemap>, so <input> doesn't benefit from 
supporting them too. Without server-side scripting, I can't see how you 
would use <form> or <input> at all.

-- 
Philip Taylor
philip@zaynar.demon.co.uk
Received on Thursday, 16 August 2007 00:48:17 UTC

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