W3C home > Mailing lists > Public > www-svg@w3.org > December 2008

Re: Title as attribute or element?

From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
Date: Sat, 6 Dec 2008 13:46:02 +0100
To: www-svg@w3.org, dleeling@comfsm.fm
Message-Id: <200812061346.02318.Dr.O.Hoffmann@gmx.de>

Of course, it would be very nice and helpful both
for users and authors, if such user-agents like
the Geckos, Opera, WebKit, Batik/Squiggle, 
Konqueror+KSVG, the Adobe plugin would have 
some items in the content menu about the 
presentation of text information like the content 
of the elements title, desc and metadata on demand.
For example one button for 'Display text alternative
of the complete document', another one for
'Display text alternatives for the current element'
and 'Display text alternative for the current group'.
Would be even better starting with such a display
to be able to open the text information for parent
elements and children elements, if required.

Unfortunately such accessibility approaches and
approaches for simple educational purposes are
currently not present or not very useful in those
viewers. Opera presents the title elements as
tooltip. Batik/Squiggle title and desc. As already 
noted, this has the tendency to give authors the
idea, that they put content inside the title and 
desc, that is (only) useful as a tooltip, what is
a problem for the variant of an accessibility
alternative text only presentation.  

However, for the given examples, as far as I
understand this, this content fits both for the
title or the desc element and I would work
as intended in Batik/Squiggle, noted as title in
Opera too.
And there is no title attribute. If present without
a prefix and interpreted by Firefox, this indicates
an even bigger problem, because without a 
prefix this should be indicated as an error in
SVG1.1, in SVGT1.2 it should be ignored.
Especially for SVG1.1 there are maybe viewers
having this correct and strict error processing
rules implemented, therefore such documents
should be never published to avoid annoyance
for users of these proper viewers by corrupted
documents.


What works both in Geckos and Opera is SVG1.1 
combined with CSS :hover for groups containing 
text elements, something like this:

CSS:

g text.tooltip
{
display: none
}

g:hover text.tooltip
{
display: inline
}

SVG1.1:

<g fill="violet" stroke="darkmagenta" stroke-width="1">
<text class="tooltip" x="6965" y="-5950" 
font-size="10">Clerodendrum inerme (ilau)</text>
  <circle cx="6970" cy="-5950" r="2"  />
  <circle cx="6960" cy="-5950" r="2"  />
</g>

Discussion:
This does not work in the Adobe plugin or in Batik/Squiggle, 
because they seem not to interprete :hover; 
Konqueror+KSVG1 ignores the CSS completely.
Because it is done with CSS, this pop-up functionality
is decorative only. However because without styling the
text information is visible and related to the group, this 
is a not really bad solution concerning accessibility.
SVGT1.2 has this new attributes to indicate the role
or functionality more precisely, but for this tiny profile
it is explicitly noted, that authors may not rely on 
external stylesheets as required here to note the :hover.
Therefore currently these two methods cannot be
combined.

There are several useful methods in SVG to provide
such text information within a valid SVG document. But 
there is no trivial method making such information accessible
with any user-agent unfortunately.
Received on Saturday, 6 December 2008 12:51:37 GMT

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