Qt dataChanged signal slower then hide/show the view

Question

I implemented my own QAbstractItemModel (for TreeView) and override the setData method, that changes many childrens.

• If I fire one "dataChanged" signal on a big view it is very slow and the ui freezes.
• If I uncomment the signal, it is really fast, but I must interact with the ui (because model did not notify view).
• If I break the Model/View concept, and call the hide and then show method on the TreeView it is fast and all changes are displayed ...

Why does hide/show call work?

Why is the datachanged Signal so slow?

firstIndex = idx.parent().child(firstChangedIndex.row(), 0)
self.dataChanged.emit(firstIndex, firstIndex)

firstChangedIndex = highest parent, that changes, but maybe not column 2

Answer 1

I found my mistake ... The Trolltech modelest was enabled ... Thanks for the hint with the invalid QModelIndex ... work very well