Re: liststore issue 1 - iter points to wrong row after sort of column with cellrenderercombo

[Mike Martin <redtux1 gmail com>]

On Thu, 28 Feb 2019 at 18:05, Nicolas Soubeiran <nicolas soubeiran gmail com>
wrote:

> As you noticed "editing-started" is used at the beginning of editing a
> cell as the documentation states and is defined on the base class
> GtkCellRenderer:
>
> This signal gets emitted when a cell starts to be edited. The intended use
> of this signal is to do special setup on *editable* , e.g. adding a
> GtkEntryCompletion
> <https://developer.gnome.org/gtk3/stable/GtkEntryCompletion.html> or
> setting up additional columns in a GtkComboBox
> <https://developer.gnome.org/gtk3/stable/GtkComboBox.html>.
> https://developer.gnome.org/gtk3/stable/GtkCellRenderer.html#GtkCellRenderer-editing-started
>
> While "edited" is only available on  GtkCellRendererText and is mainly to
> be used for "simple" edition of text (called when user validates
> https://developer.gnome.org/gtk3/stable/GtkCellRendererText.html#GtkCellRendererText-edited
> In case you have a GtkCellRendererText the signals will be called like
> this:
> - editing-started
> if user validates
>    - edited with new_text the string the user entered
> else (user cancel edition)
>    - editing-canceled
> In all cases you only have the path of the edited row, since the
> cellrenderer does not "know" the model it is displaying : you have to pass
> it through the signal user_data (then you can build the iter and do your
> edition code)
>
>
> Le jeu. 28 févr. 2019 à 18:43, Mike Martin <redtux1 gmail com> a écrit :
>
> > Thanks
> > Though what I don't quite get is the difference in behaviour between
> > editing-started and edited (both using path to get the ITER)
> > On my particular scenario I use editing-started to setup some stuff so I
> > can use the iter created
> >
> > On Thu, 28 Feb 2019, 12:30 Nicolas Soubeiran via gtk-app-devel-list, <
> > gtk-app-devel-list gnome org> wrote:
> >
> > > Hello,
> > > after you sort the model, you shall consider that all iter and path
> > > previously stored are wrong :
> > > A path is a representation of the position of the row in the current case
> > > (which you can read by using gtk_tree_path_to_string).
> > >
> > > https://developer.gnome.org/gtk3/stable/GtkTreeModel.html#gtk-tree-path-to-string
> > >
> > >  Iter are quite the same (but link to a particular GtkTreeModel), such as
> > > list::iterator of C++ STL : they are pointer to row that you can use to
> > > access to data or walk through the models.  You can make an iter from a
> > > path and a model :
> > >
> > > GtkTreePath *path;GtkTreeIter iter;
> > >
> > > GtkTreeModel* model;
> > >
> > > GtkListStore store = gtk_list_store_new(3, G_TYPE_INT,
> > > G_TYPE_STRING,G_TYPE_STRING)
> > >
> > > model = GTK_TREE_MODEL(store);
> > >
> > > path = gtk_tree_path_new_from_string
> > > <
> > > https://developer.gnome.org/gtk3/stable/GtkTreeModel.html#gtk-tree-path-new-from-string
> > > >
> > > ("3"); // third rowgtk_tree_model_get_iter
> > > <
> > > https://developer.gnome.org/gtk3/stable/GtkTreeModel.html#gtk-tree-model-get-iter
> > > >
> > > (model, &iter, path); // may be invalid (check return value)
> > >
> > >  If you really want to keep track of a particular row, you have to use
> > > GtkTreeRowReference
> > >
> > > https://developer.gnome.org/gtk3/stable/GtkTreeModel.html#GtkTreeRowReference
> > > But GTK will have to keep the reference up to date, so each time your
> > > model change (inserting, deleting, sorting...)
> > > GTK will triggered signal to update your GtkTreeRowReference which may
> > > cause an overhead in your application
> > >
> > > Hope this helps you to understand better the GtkTreeModel paradigm
> > > _______________________________________________
> > > gtk-app-devel-list mailing list
> > > gtk-app-devel-list gnome org
> > > https://mail.gnome.org/mailman/listinfo/gtk-app-devel-list

What I suspect is happening is that once a column is sorted, the column is
resorted as soon as a change is made so path never points to the current
row. Though doesn't happen with a plain text renderer.

I have tested this with my code, and this is exactly what is happening

Before the edited function is called, the liststore is sorted again, so the
path string points to the row that is now at the previous position (ie:the
next row)

If the change made does not mean the row is sorted to a different position
then the same row is referenced, example
(where the first is value in column 0 and second is a fixed row indicator)
in both cases this the first row

Sort reorders the rows
/data/staging -> /data/staging2
/data/1staging       2

Sort does not reorder row
/data/staging -> /data/1staging
/data/1staging       1


Mike