Re: Fw: Action-1634: the switch element and <title> and <desc>

You certainly can’t switch which <title>/<desc> applies to a given
element using conditional processing attributes on them.  And I think we
have wording in the spec that describes how <switch> is basically a
control for rendering (as are the conditional processing attributes used
outside a <switch>).

So I think the situation is somewhat similar to a <script> or <style>
element that is a child of a <switch>.  The <switch> itself does not
control whether the <script> or <style> is processed, and they both will
execute/apply.  The same argument could be made for <title> and <desc>
imparting their meanings to the <switch> element.

You could write:

  <switch>
    <g systemLanguage="en">…</g>
    <g systemLanguage="de">…</g>
    <title>…</title>
    <desc>…</title>
  </switch>

and I believe this should mean what you expect.  If you happen to have a
non-English non-German locale, then yes, the <title> element would be
the switch arm that is chosen, though of course you wouldn’t get any
rendering for that element.  But regardless of the locale, the <switch>
would have a title and description.

Richard Schwerdtfeger:
> 
> I am working on the SVG accessibility mapping guide and ran across what we
> believe to be an error in the spec.
> 
> I agree with Amelia on this. Cameron, others do you mind if I modify the
> spec. to remove descriptive elements from the <switch> content model?
> 
> Rich
> 
> 
> Rich Schwerdtfeger
> ----- Forwarded by Richard Schwerdtfeger/Austin/IBM on 05/19/2015 07:38 AM
> -----
> 
> From: Amelia Bellamy-Royds <amelia.bellamy.royds@gmail.com>
> To: Richard Schwerdtfeger/Austin/IBM@IBMUS
> Cc: public-svg-a11y@w3.org
> Date: 05/18/2015 05:06 PM
> Subject: Re: Action-1634: the switch element and <title> and <desc>
> 
> 
> 
> Yes, the spec is wrong.  Or at least inconsistent.  It allows you to do
> something that looks like it would be useful but is actually useless.
> 
> You can put a title and desc inside a switch, just like you can put them
> inside any other container element.  However, you can't put a switch inside
> a shape to switch between titles for that shape.  You can put a switch
> inside a group, and titles inside that switch, but those titles won't be
> associated with the parent group, they'll be associated with the switch.
> So a switch will never be used to select the title or desc for an element.
> 
> And, since titles and descriptions aren't explicitly excluded from the
> switch's switching rules, you can't use them to describe the switch as a
> container element itself.  If you include a title as the first child of a
> switch, that will be the child element that gets selected for the switch,
> and all the other content within the switch construct will be ignored.  If
> something else is included first, the title/desc will be ignored.  So a
> switch will never have a meaningful title or desc itself; if it does, it
> has no content to be named!
> 
> In other words, I should probably recommend that SVG 2 remove "descriptive
> elements" from the content model for <switch>.
> 
> Amelia
> 
> 
> On 18 May 2015 at 15:13, Richard Schwerdtfeger <schwer@us.ibm.com> wrote:
>   Amelia,
> 
>   Perhaps I am reading this wrong but the <switch> element states that it
>   can be a container for a range of different elements including
>   "descriptive elements"
> 
>   When I follow the link for descriptive element i get:
>   http://www.w3.org/TR/SVG2/struct.html#TermDescriptiveElement
> 
>   That text states the following:
>   An element which provides supplementary descriptive information about its
>   parent. Specifically, the following elements are descriptive elements: ‘
>   desc’, ‘metadata’ and‘title’.
> 
>   Is the spec. wrong?
> 
>   Rich
> 
> 
>   Rich Schwerdtfeger
> 
>   Inactive hide details for Amelia Bellamy-Royds ---05/16/2015 07:34:18
>   PM---Hi Richard, You're confusing two issues: language swAmelia
>   Bellamy-Royds ---05/16/2015 07:34:18 PM---Hi Richard, You're confusing
>   two issues: language switching for <title> and <desc>
> 
>   From: Amelia Bellamy-Royds <amelia.bellamy.royds@gmail.com>
>   To: Richard Schwerdtfeger/Austin/IBM@IBMUS, public-svg-a11y@w3.org
>   Date: 05/16/2015 07:34 PM
>   Subject: Re: Action-1634: the switch element and <title> and <desc>
> 
> 
> 
>   Hi Richard,
> 
>   You're confusing two issues: language switching for <title> and <desc>
>   versus content switching with <switch>.  The multi-language alt text
>   options *won't* use <switch> because it wouldn't be backwards
>   compatible.  My response is therefore two parts...
> 
>   ____________________
> 
>   For the accessible text selection:
> 
>   The current text mostly looks good, except that the final sentence seems
>   to be mangled.
> 
>   Here is a light edit:
>         Otherwise, unless the element is marked as presentational
>         (role="presentation" or role="none"):
>               If performing a text alternative computation for an
>               accessible name and the current node provides a descendant
>               <title> element chosen based on the language rules for
>               the SVG specification, return the <title> element's text
>               content as a flat string.
>               If performing a text alternative computation for an
>               accessible description, and the current node provides a
>               descendant <desc> chosen based on the language rules for
>               the SVG specification, return the concatenated text and child
>               content of that <desc> element.
> 
>   I've moved the "unless the element" bit to the top to make it clear that
>   we're talking about the element being named, not the title/desc element.
>   There should be no role on title/desc, and its obligatory role is none,
>   but that doesn't prevent it from being used as the name for its parent.
> 
>   I've used "the concatenated text and child content of that <desc>
>   element" because the SVG 1.1 specifications allow complex content within
>   <desc>, including content from other namespaces.  This has been used in
>   practice to include HTML markup within the description, although the
>   specs don't specifically say what to do with it.  Feel free to replace
>   with a better wording. It really should be the same wording as for
>   aria-describedby; there is an editorial note in ACC-Name saying that they
>   need to come up with explicit wording for aria-describedby, so we would
>   want to pass our wording by them!
> 
>   __________________
> 
>   For <switch>:
> 
>   A <switch> changes which elements are rendered to the screen, so it
>   should be addressed when building the accessibility tree.  A switch
>   should never have any title/desc of its own.  The SVG 1 specs didn't
>   specifically say that I can't have them, but they also don't exclude
>   title/desc children from the switching mechanism, so including them never
>   has the intended consequence!
> 
>   I would therefore lean towards making <switch> an obligatory
>   role="none" / no role may be applied.  It's not quite presentational in
>   the sense that using tables for layout is presentational, but it's only
>   impact is on which other elements get displayed.  Does anyone think that
>   is too strict?  It would mean ignoring any aria-label or other
>   attributes.  Authors might add these if they are treating the <switch> as
>   a group containing multiple presentations of the same content.
> 
>   As far as dealing with the switch behavior, that should go in section
>   5.1, which currently just references CORE-AAM (
>   http://www.w3.org/TR/core-aam-1.1/#mapping_general).  In that spec, there
>   are rules for excluding or including elements in the accessibility tree.
>   I think we need a paragraph (possibly more informative than normative)
>   about how those rules should apply to SVG: how they apply to non-rendered
>   graphical elements, as well as how they apply to switch-ed content.
> 
>   I'll read over the CORE-AAM section and put together a draft text for the
>   SVG doc.
>   __________________
> 
>   There are two other SVG elements that I think need special treatment:
>   <view> and <use>.  I'll send separate notes on them.
> 
>   Best,
>   Amelia
> 
> 
>   On 14 May 2015 at 09:51, Richard Schwerdtfeger <schwer@us.ibm.com> wrote:
>         https://www.w3.org/WAI/PF/Group/track/actions/1634
> 
>         I am proposing a modification to the text of the accessible name
>         and description computation to better address the <switch> element.
>         Please review:
> 
>         Here is the current text for step F of the SVG name and description
>         computation (
>         http://www.w3.org/TR/svg-aam-1.0/#mapping_additional_nd):
> 
>         Otherwise, if performing a text alternative computation for an
>         accessible name and the current node provides a descendant <title>
>         element chosen based on the language rules for the SVG
>         specification, return the title text alternative as a flat string,
>         unless the element is marked as presentational (role="presentation"
>         or role="none"). If performing a text alternative computation for
>         an accessible description, and the current node provides a
>         descendant <desc> chosen based on the language rules for the SVG
>         specification; return the description text alternative an
>         accessible description computation attribute as presentational
>         (role="presentation" or role="none").
> 
>         Proposed Text:
> 
>         Otherwise, if performing a text alternative computation for an
>         accessible name and the current node provides a descendant <switch>
>         element with one or more descendant <title>s return the title text
>         alternative as a flat text string determined by the switch, unless
>         the element is marked (role="presentation" or role="none");
>         otherwise if the current node does not provide a descendant switch
>         element, but it does provide a descendant <text>, return the title
>         text of the first descendant <title> element as a flat text string,
>         unless the element is marked (role="presentation" or role="none").
>         If performing a text alternative computation for an accessible
>         description and the current node provides a descendant <switch>
>         element with one or more descendant <desc>s return the description
>         text alternative as a flat text string determined by the switch,
>         unless the element is marked (role="presentation" or role="none");
>         otherwise if the current node does not provide a descendant switch
>         element, but it does provide a descendant <desc>, return the
>         description text of the first descendant <desc> element as a flat
>         text string, unless the element is marked (role="presentation" or
>         role="none").
> 
> 
> 
>         Rich Schwerdtfeger
> 
> 
> 
> 
> 



-- 
Cameron McCormack ≝ http://mcc.id.au/

Received on Tuesday, 19 May 2015 23:07:29 UTC