[Kde-pim] Re: State of KReparentingProxymodel

[Christian Mollekopf]

On Wednesday 10 November 2010 14:04:45 Stephen Kelly wrote:
> Christian Mollekopf wrote:
> > Hi,
> > 
> > I need to create a treemodel based on the hierarchy of kcalendar todos,
> > in the same model i have also other items (notes), which should be left
> > flat.
> > 
> > I found KReparentingProxymodel to be exactly what i need, but i wonder in
> > what state this class is considered. It is not working for me (even the
> > simplest case, to not build any hierarchy with a flat
> > kdescendantsproxymodel as input), but i havent been looking into it yet.
> > 
> > I copied the class from kdelibs/kdeui/tests/proxymodeltestapp/ as it
> > seems to be newer than the one in akonadi_next.
> > 
> > If you tell me that this is the latest version, i will start looking into
> > it.
> 
> Hi Chris,
> 
> The current state of that class is 'highly experimental'. It can be used
> for demos, but I know it has some bugs that I'm not certain how should be
> solved (mostly around new intermediate nodes arriving), but I haven't had
> time to work on it in a long time.
> 
> It looks like the version in proxymodeltestapp is slightly more up to date,
> but I also noticed a difference wrt mapToSource in the akonadi_next version
> which should maybe be in the class.
> 
> It is surprising that it doesn't work for you in even the simplest case.
> Did you try running the proxymodeltestapp and trying the 'reparenting PM'
> tab? That works for me.
> 
> All the best,
> 
> Steve.

Hi Steve,

Sorry for the late reply, I just found your mail, I missed it on the ML =/

I got it working basically, although not all items are correctly mapped. 

I think the cause for the incorrectly mapped items is in 
KReparentingProxyModel::recreateMappings().
The qLowerBound algorithm works only as long, as the items in the model are 
already in the correct order according to the targeted tree structure.

Since we have several items which are on the same level (of tree nesting), it 
is possible that the right parent node is missed and only a remote parent node 
is found.

Testcase, specified parents, proxmodeltestapp:
[1, 2],
[1, 2,3],
[1, 2, 4],
[1, 5],
[1, 2, 6],

which should add 6 in tree below 2 (just after 4),
but instead adds it to 1 (after 5).

The second problem is that all slots are in the private class:

In my subclass i need to build a tree of all items, so i can tell if an item 
is a remote descendant of the given ancestor (otherwise i would have go trough 
all sourcemodel items in  each call of isDescendantOf).

I.e. if the model is reset, i need to rebuild the tree in my subclass before 
endResetProxy rebuilds the internal map. Same for new items which are added 
etc. 
Therfore i propose to make all those private slots protected virtual slots.

I'll provide a patch for both issues, but i don't know on which version of 
kreparentingproxymodel i should work. Atm. I work on the version in 
kdelibs/kdeui/tests/proxymodeltestapp so i can check the test, but as it is 
not installed, i build it directly in my app where i use it...

The version in akonadi_next would be installed, but then i can not test it 
with proxymodeltestapp, so I'm not sure what to do...


Thanks for you help,

Chris

> 
> > Cheers,
> > 
> > Chris
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