W3C home > Mailing lists > Public > public-html@w3.org > August 2008

Re: The alt="" attribute

From: Lachlan Hunt <lachlan.hunt@lachy.id.au>
Date: Wed, 27 Aug 2008 23:43:08 +0200
Message-ID: <48B5CA6C.6060402@lachy.id.au>
To: "T.V Raman" <raman@google.com>
Cc: public-html@w3.org

T.V Raman wrote:
> I've taken the liberty of adding in one suggestion of my own as part 
> of this proposal --- namely, add  an img.getEXIFData() DOM method 
> that returns the EXIF metadata for an image as a JSON dictionary.
> 
>       1.5 Enhancing The DOM Methods On _img_
> 
> This might also be a good time to expose one additional DOM method on element 
> _img_ given that :
> 
>     * The majority of the photos uploaded to the Web are from digital cameras.
>     * Digital cameras produce EXIF metadata automatically.
> 
> It would be advantageous to add a _img.getEXIFData()_ method that returns a JSON 
> dictionary containing the EXIF data found at the value of attribute _src_.

Why?  What are the use cases for accessing this information?  Without 
knowing how and why this data is useful, and who it is expected to be 
useful for, it's difficult to evaluate any proposed solutions.  Neither 
your proposal, or the previous proposal in the wiki [1] provide any 
clear use cases, nor describe any problems to be solved.

Also, returning a JSON string from the method doesn't seem particularly 
useful.  JSON is optimised for passing information in the form of 
serialised objects between applications, for example, over a network. 
Unless sending the information to another application is one of the use 
cases, an API that exposes the properties and values in some sort of 
collection object would be better.  But the specifics cannot be 
determined without first knowing how and why it will be used.

> I believe such a DOM method would be extremely useful for mainstream 
applications,
> and is consequently likely to be implemented in the browsers.

Before making any claims about whether browsers would implement a 
feature, you have to explain which "mainstream applications" the method 
would be useful for and why?

> Such a method would be a major win for accessibility over the current status-quo
> of attempting to stuff all image metadata into a single attribute.

Could you also explain how this intended to help accessibility?  Are you 
intending for the metadata to be exposed directly to the end user 
through their browser, or are you expecting authors to provide scripts 
that access and expose the data within the page somehow?  If the former, 
then a DOM API might not be necessary, as the UA can expose this 
information directly via its UI.

[1] http://esw.w3.org/topic/HTML/UANormAndDOMForMediaPropeties

-- 
Lachlan Hunt - Opera Software
http://lachy.id.au/
http://www.opera.com/
Received on Wednesday, 27 August 2008 21:43:51 GMT

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