Re: GtkTreeView : why so many "refresh"

["Francois MARTIN" <fmartin caicheuvreux com>]

Hello, and thanks for your answers.
But I still have some questions.


> > 1. I have specified a function 'my_cell_data_func()' using
> > gtk_tree_view_column_set_cell_data_func() on each column of a view.
> > By calling gtk_tree_model_row_changed() on one of the rows of the model,
I
> > am called into my_cell_data_func() for each column of the view for the
> > changed row (it's seem logical).
> > But, if the changed row is  visible (even partially), I am then called
into
> > my_cell_data_func() again: for each visible rows and for each columns of
> > the view (including the changed row itself) ! Are these calls necessary
?
> > Note that there is no auto sort on the view, nor auto-resize on the
> > columns.
>
> To avoid those calls the treeview would have to make a copy of your
> data and store it inside the treeview; which would use a lot of memory
> and time and in most cases would not be useful.

In fact, I don't see why the treeview needs to refresh its whole view
when one of its row has been changed, especially as there is no
auto-sort of the lines nor auto-resize of the columns, and if the size
(especially the height) of the cells does not change.
Can you explain me what those calls are intended to do, and why the
refresh of the changed row, and only of this one, is not enough ?
Is there a way to curb the treeview to refresh/access data only for the
refreshed row and not to all visible lines of the treeview.


> If for some reason your data is too slow to access, you can create
> your own cached copy and return that from the cell data func.

It is exacly what I did !
More over, using an unique 'my_cell_data_func()', I have to distinguish
which cell (i.e., which column) I supposed to render. To do that, I
identify
columns with an id set into their "user-data" property and retreived by
g_object_get_property(column, "user-data", &gvalue_of_type_pointer);
By gprof'ing my program, this access appears in the top ten of the most
cpu eater functions. Is there another quicker way to set and get a client
data into a GtkTreeViewColumn in order to identify it ?



> > 2. Is there a way to prevent 'my_cell_data_func()' from being called
each
> > time the mouse pointer moves over a row (enters and leaves the row area
in
> > fact), while keeping selection enabled ?
>
> If the treeview doesn't copy your data, it has to ask for the data
> each time it wants to display it.
>
> If the treeview copied your data, there would be no point in using the
> model-view architecture.

Ok, perhaps my question was confusing. I think its logical that the
treeview
ask for data of a row about to be selected, as well when a row appears
visible
by scrolling, etc (as you say, to prevent the treeview from storing copy of
data).
But, it is a bit cpu intensive to do that just when the mouse pointer is
simply
hovering over a cell, without selecting it !
Is there a way to deactivate/ignore the "prelit" status without overriding
my
own cell renderer ?


> Note that you can also stuff all your data into one of the prebuilt
> models such as GtkListStore, rather than using a cell_data_func();
> that would give the behavior you're asking for.

I am quite sure all those access are still done, even if we don't see
them since there are "internal".


> Havoc

frmar

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