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Re: SVG1.1 xlink: can xlink only be used with anchor element?

From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
Date: Fri, 14 Aug 2009 10:55:07 +0200
To: www-svg@w3.org
Message-Id: <200908141055.07098.Dr.O.Hoffmann@gmx.de>
Doug Schepers:
>We also explicitly recommend that UAs display the contents of the 
><title> element as a tooltip (as Opera does).

Well, due to some previous discussions it is noted:
"In this case, authors are encouraged to use the 'role' attribute, with the 
value tooltip ([ARIA], section 4.4.1) to indicate their intent. Future SVG 
specifications may define an explicit mechanism for indicating whether a 
tooltip should be displayed."

and 
"In order to honor authorial intent, it is strongly recommended that when, and 
only when, the appropriate 'role' attribute value is present, user agents 
display the text content of the applicable 'title' and 'desc' elements in a 
highly visible manner supported by the user agent, such as in a tooltip or 
status bar ..."

and this is not what Opera currently does, but a separate tooltip
element as mentioned in the early SVG1.2 draft would be fine to
separate the functionality of a tooltip from that of a title or desc
and would have more semantical meaning as using a metadata
element with role="tooltip".

Of course, within SVG tiny 1.2 Jonathan can set role="tooltip" on
any element he wants to, to indicate, that this is intended as a
tooltip and can use declarative animation to provide the functionality.
With feature strings one can even more check, whether the viewer
already supports animation, if not, one can check, if scripting is
available and provide the tooltip in this way, if not one can provide
a warning, that the viewer is not able to display the document in
the intended way. There are several ways to work around 
implementation gaps in SVG.

If a viewer has too many gaps, there is sometimes no way to
provide a specific functionality at all. Users simply have to use 
another viewer until the gaps are closed.

About xlink:title - even XLink defines some meaning for title and this
is related to the meaning of the link:

"The title attribute is used to describe the meaning of a link or resource 
in a human-readable fashion, along the same lines as the role or arcrole 
attribute."

Without a link it has no meaning.
Does any viewer interprete xlink:role and xlink:arcrole in a meaningful
way?

Jonathan: 
Do the Geckos support the full XLink functionality for
an arbitrary SVG element?
Due to my tests, the Geckos only support a subset of the
XLink functionality in arbitrary XML documents, not even the
functionality for simple links is complete. I think, unfortunately
Opera does not interprete it at all. Therefore not a good idea 
to rely on it in an arbitrary XML document and especially not 
in SVG with some predefined attribute values and definitions 
and special use cases for simple links from XLink.
Received on Friday, 14 August 2009 09:15:46 GMT

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