- From: Dominic Mazzoni <dmazzoni@google.com>
- Date: Thu, 30 Apr 2015 08:29:07 -0700
- To: Joseph Scheuhammer <clown@alum.mit.edu>
- Cc: "W3C WAI Protocols & Formats" <public-pfwg@w3.org>
- Message-ID: <CAFz-FYynOjhV4pt4Rqd0zLDNidZybF_W7nKNVuHt_9-jD04eCA@mail.gmail.com>
Thanks for the longer explanation! Makes sense now. On Thu, Apr 30, 2015 at 7:44 AM, Joseph Scheuhammer <clown@alum.mit.edu> wrote: > On 2015-04-29 5:55 PM, Dominic Mazzoni wrote: > >> It's clear that we don't have consensus on how to interpret the spec. >> Does anyone know what was actually intended? >> > > The interpretation that only the first aria-labelledby is followed is > correct. There is an explanatory example at the end of step 2B, repeated > below[1]: > > The following example shows the meaning of the clause "… and the current >> node is not already part of an aria-labelledby traversal …" . >> >> * element1's accessible name is "hello" because this is a first traversal >> of its aria-labelledby, leading to element3. >> * element2 has no accessible name. The computation involves a first >> traversal of its aria-labelledby leading to element1, but element1's >> aria-labelledby is not subsequently followed. >> >> <element1 id="el1" aria-labelledby="el3" /> >> <element2 id="el2" aria-labelledby="el1" /> >> <element3 id="el3"> hello </element3> >> > > I think the restriction has to do with reverse relationships[2]. Like > aria-controls and aria-flowto, aria-labelledby creates a > 'label-for/labelled-by' relationship structure in some accessibility APIs > (in addition to a name string). That's simple to do if there are only two > accessible nodes in the relationship. But, if aria-labelledby references > are followed indefinitely, it's not clear how to create the > label-for/labelledby relationship(s). Is there only one such > relationship? Or a flat chain of relationships? Or is it a many-to-one > relationship with one label-for with many labelled-bys? Or, one-to-many > and hierarchical? My head hurts just thinking about how the relationship > could be represented. > > Also, FWIW, I think it it's simpler for authors if only the first > aria-labelledby is followed. They know what they have to work with, and > don't have to worry about indefinitely long chains of aria-labelledbys. > > Regarding the credit card example: > > <input aria-labelledby="label1"> >> <div id="label1"> >> Enter your >> <img src="visa.png" aria-labelledby="visa"> >> or >> <img src="mastercard.png" aria-labelledby="mastercard"> >> credit card number now. >> </div> >> <div hidden id="visa">Visa</div> >> <div hidden id="mastercard">Mastercard</div> >> > > The desired result could be accomplished using @aria-label or @alt on the > <img> elements. Since that doesn't involve following a second > aria-labelledby reference, the alternative text of the images is captured > by the recursion at step 2B: > > <input aria-labelledby="label1"> > <div id="label1"> > Enter your > <img src="visa.png" aria-label="Visa"> > or > <img src="mastercard.png" aria-label="Mastercard"> > credit card number now. > </div> > > or: > > <input aria-labelledby="label1"> > <div id="label1"> > Enter your > <img src="visa.png" alt="Visa"> > or > <img src="mastercard.png" alt="Mastercard"> > credit card number now. > </div> > > Those work in FireFox. > > [1] http://www.w3.org/TR/accname-aam-1.1/#step2B > [2] > http://www.w3.org/TR/core-aam-1.1/#mapping_additional_relations_reverse_relations > > -- > ;;;;joseph. > > 'Array(16).join("wat" - 1) + " Batman!"' > - G. Bernhardt - > > >
Received on Thursday, 30 April 2015 15:29:35 UTC