[WebODF] Foreign elements & cursor positioning

[Friedrich W. H. Kossebau]

Am Mittwoch, 14. August 2013, 09:51:00 schrieb Friedrich W. H. Kossebau:
> Hi,
> 
> sorry for ignoring this email for so long, but priorities, well...
> 
> Am Donnerstag, 1. August 2013, 01:37:50 schrieb Philip Peitsch:
> > Hi everyone,
> > 
> > I have been looking at some funky "valid" ODT documents and discovering
> > some fun behaviours around cursor positioning. I thought this was a good
> > time to bring up some potential changes, as I noticed on IRC the other
> > night that Friedrich had also discovered sometimes the user is unable to
> > place the cursor inside a text:a block.
> > 
> > The existing rules for valid cursor positions only allow placing the
> > cursor
> > inside what is known as a "grouping element", which is either a span, p or
> > h. This has already caused me some challenges, because for one of the
> > highlight overlays I'm doing on top of webodf I need to wrap document text
> > in a normal HTML span, which then prevents the cursor from entering.
> > 
> > In the situation Friedrich found, there is actually no requirement saying
> > the text content within a text:a element must be placed in a span.
> > 
> > The suggestion on IRC yesterday was to just add text:a into the grouping
> > element definitions (a reasonable one), but I got to thinking a little
> > more
> > about whether this is the best long-term solution. Especially as there are
> > other elements that could possible contain character data. And for
> > extensibility purposes, ideally we don't want to have to redo this core
> > cursor positioning logic every time the UI requires some extra containers
> > and wrappers to help display things :).
> > 
> > Re-reading the ODF specs[1], the preferred approach laid out is actually a
> > blacklist, not a whitelist as we're currently doing. The blacklist as
> > required for processing is already defined & used in
> > StyleHelper.isAcceptedNode, is used for OpRemoveText and
> > OpApplyDirectStyling.
> > 
> > Would anyone have any problems if I changed OdtDocument.TestPositionFilter
> > to use the blacklist approach instead? The blacklist will need an
> > additional entry to exclude the cursor as well, so I'll put that in also.
> > 
> > From my testing with this, it appears to function identically to the
> > existing approach, with the added bonus of being able to navigate within
> > text:a tags that don't contain a span :)
> > 
> > Cheers,
> > 
> > Philip
> > 
> > P.S., sorry for all the list spam lately! Apparently I have too much time
> > for philosophy :)
> 
> (if only more spam would be philosophical ;) )
> 
> > [1]
> > http://docs.oasis-open.org/office/v1.2/os/OpenDocument-v1.2-os-part1.html#
> > F
> > oreignElementsAndAttributes
> 
> Having now read the referenced §3.17 Foreign Elements and Attributes I would
> agree that this code needs to be turned into rather blacklist-based.
> 
> I might have missed/forgotten the content of related discussions on irc/in
> real life, but I recall there has been some.
> 
> So Jos & Aditya, do you remember any reasons you had for staying with the
> white-list (besides not needing any new coding effort ;) )?

Turned into redmine issue http://webodf.org/redmine/issues/82 to track this 
problem.

Cheers
Friedrich
-- 
Friedrich W. H. Kossebau // KO GmbH
http://kogmbh.com/legal/