- From: Doug Schepers <schepers@w3.org>
- Date: Sat, 26 Jul 2008 10:15:17 -0400
- To: www-svg <www-svg@w3.org>
Hi, Jonathan- You're right, this is not adequately defined in the spec, particularly in the case where a <use> references an element that isn't there. I made a number of clarifications to the spec in particular places, which you can read and see if you think this behavior suits your use cases: http://lists.w3.org/Archives/Public/public-svg-wg/2008JulSep/0091.html Keep in mind that these changes are not yet approved by the SVG WG, but I am confident that we will make some clarification, even if it's different than my suggested changes. Regards- -Doug Schepers W3C Team Contact, WebApps, SVG, and CDF Jonathan Chetwynd wrote (on 7/26/08 8:16 AM): > Helder, > > thanks once again, I'm content to file bugs with the UAs, however this > wasn't my intent. > > Rather that the description given is not sufficient. > Graphics are a complex area, and describing what is missing and where, > will be hard if it is to be consistent across UA. > which users expect, perhaps demand... > > as you indicate there appears to be no guidance on the author providing > 'alt' content, nor a method or technique. > > a test case is here: http://www.openicon.org/feeds/exResReq.svg > > > What is the rationale for the default being false? > this must inherently be confusing for the user, as they will not be > aware of the issue. > and the author too who has not considered this matter, does not refer to > the specs or uses a tool that does not require or automate this matter. > > regards > > > > Jonathan Chetwynd > > j.chetwynd@btinternet.com > http://www.openicon.org/ > > +44 (0) 20 7978 1764 > > > On 26 Jul 2008, at 11:43, Helder Magalhães wrote: > >> >>> current UA do not indicate missing content either with graphic or text. >>> iirc batik wont display at all, others ignore. >>> Is there a recommendation on this issue? >> [...] >>> html UA generally provide an empty box with a cross or similar and alt >>> content >> >> The external resources property [1] seems to imply a recommendation on >> this: error processing notes [2] states that: >> «A highly perceivable indication of error shall occur. For visual >> rendering situations, an example of an indication of error would be to >> render a translucent colored pattern such as a checkerboard on top of >> the area where the SVG content is rendered.» >> >> I'd interpret the whole as: if a document portion is marked with >> "externalResourcesRequired" set to "true" and the external resource(s) >> is(are) not available, then mark that portion with a checkerboard (or >> similar). Please correct me if this sounds naive! >> >> So, if your findings are correct (didn't check implementations >> myself), user agents seem to be the ones which need to catch up. ;-) >> >> As an implementation suggestion, one might use conditional processing >> [3] to achieve a desired fall back. Using a "switch" containing >> external resources required feature string [4] for UA which support >> external resource loading (with proper error processing) and >> alternative content for cases (where the UA doesn't contain the >> feature string) might do the trick! :-) >> >> >> >>> I recognise the SVGWG may not be chartered to consider UA issues, >>> however >>> and there does not seem to be another suitable public space to raise >>> this. >> >> I believe the SVGWG is the proper place for discussing user agent >> matter (which relates to SVG, of course). For instance, there are >> guidelines for user agent behavior spread over the specification (for >> example, in implementation notes section [5]). >> >> >> >> Hope this helps, >> >> Helder Magalhães >> >> [1] http://www.w3.org/TR/SVG/struct.html#ExternalResourcesRequired >> [2] http://www.w3.org/TR/SVG/implnote.html#ErrorProcessing >> [3] http://www.w3.org/TR/SVG/struct.html#ConditionalProcessing >> [4] http://www.w3.org/TR/SVG/feature.html#ExternalResourcesRequired >> [5] http://www.w3.org/TR/SVG/implnote.html >> > > --
Received on Saturday, 26 July 2008 14:15:53 UTC