[Qt-interest] QTreeView and custom QAbstractItemModel performance problem

[Sean Harmer]

On Friday 09 July 2010 14:01:59 Felix Brack wrote:
> You mean move from TreeView to TableView, right? 

No we meant moving to a model that inherits from QAbstractTableModel since 
this takes care of implementing the table-like semantics on top of 
QAbstractItemModel for you.

> I can (and probably
> will) do that but it's really the last resort. Furthermore when looking
> at what the TableView can do I will have to switch off about everything.
> For what I want the TableView is like taking sledgehammer to crack a
> nut. I just want a protocol, say 200 lines, first column shows an icon
> and when it's full the oldest data gets discarded.
> 
> As already stated: I don't think (I might be wrong of course) it is
> performance problem of any function in the data model (including
> hasChildren). The problem is the view requesting the same information
> again and again from the data model. I have been able to prove this with
> a very stupid data() function in an earlier post.
> Of course this could be wrong; that would be the case if I missed to
> implement a function in my data model that stops the view from queering
> the same values again and again; that function however is not yet known
> to me.

Hence my request for you to produce a small compilable example that shows the 
issue. We are willing to help you but we do not have time to write test cases 
from scratch. We do not need to see your actual application - just a dummy 
model that does something similar to the model in the app but which does show 
the same symptoms. Ideally the sample app should be of order 200 lines of 
code.

You often find that you stumble upon the problem whilst preparing such 
examples.

Good luck,

Sean