gtktreeview: Data for all columns is retrieved although only a small subset of 1% is visible - Why?

[Friedrich Beckmann <friedrich beckmann gmx de>]

Hi all,

I posted a question about gtktreeview with 2000 columns on gtk-app-devel-list. 

The question is here:

https://mail.gnome.org/archives/gtk-app-devel-list/2015-December/msg00013.html

This is for the pspp project where a fork from gtktreeview was done about

15 years ago and I did some investigation to reintroduce the gtktreeview

as part of the transition to gtk3. The problem regarding cpu load is described

here: http://lists.gnu.org/archive/html/pspp-dev/2015-12/msg00029.html

In the meantime I looked into the gtktreeview code

and found this comment: 

/* we *need* to set cell data on all cells before the call
 * to _has_can_focus_cell, else _has_can_focus_cell() does not
 * return a correct value.
 */

here: https://git.gnome.org/browse/gtk+/tree/gtk/gtktreeview.c#n5103

I am not sure, but I maybe this is the reason that in our case

the data for 2000 columns is retrieved, although only 16 are visible. Does anybody

remember the reason for this full retrieval? Is this a fundamental problem which

can not be avoided? We at pspp think about the options we have. gtktreeview is

in principle very nice and there is a quite long history now about the alternatives, for

example gtksheet. Of course it is very attractive to use the mechanisms which

are already there, but at the moment I have this performance problem

with a large number of columns. Maybe I can try to help on a patch to improve

on this but some direction and/or background would be nice.

Friedrich