[Qt-interest] QAIM::headerData() is not tied to QModelIndex?

[Kishore]

On Monday 16 Aug 2010 4:50:53 pm Andre Somers wrote:
>   Op 16-8-2010 13:01, Andreas Pakulat schreef:
> > On 16.08.10 08:17:09, Kishore wrote:
> >> On Monday 16 Aug 2010 12:39:52 am Andreas Pakulat wrote:
> >>> On 15.08.10 18:01:20, Kishore wrote:
> >>>> Why does the headerData() take section parameter and not a
> >>>> QModelIndex?
> >>>> 
> >>>> I know this is not how QAbstractItemModel is commonly used but QAIM is
> >>>> designed in such a way that every modelindex can again have children
> >>>> and so on... ie. there can be a table within a table. So essentially,
> >>>> in a tree like structure, a child can have more columns than a parent
> >>>> and with a really different set of headerData as well. A more
> >>>> relevant API would be something like:
> >>>> 
> >>>> QAIM::headerData ( const QModelIndex&index, Qt::Orientation
> >>>> orientation, int role = Qt::DisplayRole ) const
> >>>> 
> >>>> just the way it is currently with columnCount().
> >>> 
> >>> This doesn't really make sense display-wise. The header is global so
> >>> you cannot have different strings
> >> 
> >> display-wise, it does not make sense for columnCount either. Still it
> >> exists.
> > 
> > No it completely does, different subtree's may have different number of
> > columns. The header in the view is an optional component, so it might not
> > be shown in such a case where each index has a different number of
> > columns. And having one subtree with less columns than another can also
> > improve performance as the view doesn't have to fetch data for cells
> > that don't exist in the model anyway.
> 
> Still, I think the reasoning of Kishore's question is, by extension of
> what you write above, valid. If you only show a subtree, then you could
> display a header that is valid for that subtree, could you not? It would
> make sense to have the views query for the headers as valid for a
> certain QModelIndex if you have set that index as the root index for
> that view. You just can not, in a standard view, display different
> headers for different levels. That would look confusing, I think. If you
> want something like that, you should just use QicsTable or a widget like
> that. I think the current QAbstractItemModel could even be extended to
> provide that functionality with full backwards compatibility. Simpy make
> the default implemenation call the old function, and change the views to
> query the new method.

Exactly the situation in my use case, where I find such functionality useful.
-- 
Cheers!
Kishore