[Interest] QAbstractItemModel::headerData

andre at familiesomers.nl andre at familiesomers.nl
Fri Nov 22 20:31:47 CET 2013


Bill Crocker schreef op 22.11.2013 20:19:
> Gang:
> 
> I have created my own item model by sub-classing QAbstractItemModel.
> 
> Functions like rowCount take a parent index so the model
> knows for which index it is being asked to return the count.
> This is good.
> 
> My model is hierarchical and different points in the hierarchy
> have a different number of rows and (especially) columns.
> 
> So, how come ::headerData is not passed an index so it knows for
> which parent index it is being asked to return the data?
> 
> I'm using Qt 4.7.1
> 
> Bill
> 
Because Qt does not support vertical headers for tree models (check 
QTreeView, there is no vertical header there!) and it does not support 
different columns for child items either. While theoretically is should 
be possible (after all, QAbstractItemModel really models a nested grid), 
the views simply do not support it. There are 3rd party add ons that 
provide more sofisticated views that can do this sort of thing, but the 
basic Qt model/view system can't handle that. Qt doesn't even handle 
cell spanning (QAbstractItemModel::span is not used.)

André




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