Re: Problem with a TreeView - speed

[Milosz Derezynski <internalerror gmail com>]

Sorry, I somehow skipped explicitly stating the point: There is no such thing as "invisible" rows with TreeView, because at least once, they will be visited. Whether you use a cell data func or not practically makes no difference at all, at least for that particular problem.

On Mon, Mar 16, 2009 at 7:48 PM, Milosz Derezynski <internalerror gmail com> wrote:

Treeview will always visit newly added rows, and always visits all rows when setting the model. There is really no way with TreeView to make this very fast.
The only option is fixed width-fixed row height mode, in which TreeView will abstain from visiting all new rows *and* request the renderers to render the data (more precisely, call the size vfunc; it does this only to have the row heights available, but unfortunately for most cell renderers, getting their requested size, similar to a widget, will require them to render the content internally, e.g. CellRendererText will create a PangoLayout with its text, etc.).

The only viable solution that *I* recommend (I do this nowadays on a routine basis because TreeView is just too unflexible) is to write completely own view and model classes not using TreeView at all.

On Mon, Mar 16, 2009 at 5:37 PM, Murray Cumming <murrayc murrayc com> wrote:

On Mon, 2009-03-16 at 17:19 +0100, Dimitri Holz wrote:
> Murray Cumming schrieb:
> > On Mon, 2009-03-16 at 15:00 +0100, Dimitri Holz wrote:
> >
> >> ____I'm programming C++ and Gtkmm since less than one year and I'm a
> >> student without programming-experiences. Because of that I don't
> >> perfectly ____understand what you mean with using of cell_data_func to
> >> show the visible parts of the row.
> >>
> >
> > Sorry. I meant to post a link. Actually, we don't seem to mention this
> > in the book. But it is used in an unrelated example. Search for
> > "ExampleWindow::treeviewcolumn_validated_on_cell_data" here:
> > http://www.gtkmm.org/docs/gtkmm-2.4/docs/tutorial/html/ch08s08.html
> >
> > This is the API reference:
> > http://www.gtkmm.org/docs/gtkmm-2.4/docs/reference/html/classGtk_1_1TreeViewColumn.html#765296845c9e9757ba405becbbc13d96
> >

> > Your callback function will set whatever cellrenderer properties (in the

> > view) that you want to set, and will only be called for visible rows.
> >
>
> I really not understand where in your link a solution for "not showing
> the visible parts of the row" is !?

You _do_ want to show the _visible_ parts. You don't want to waste
processor time or memory on the non visible parts.

>  Can you describe it, please?

I have tried to explain. I think you should try to use
set_cell_data_func() in an example and see when it is called.

--
murrayc murrayc com
www.murrayc.com
www.openismus.com

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Please note that according to the German law on data retention,
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retained for a period of six months.
[Bitte beachten Sie, dass dem Gesetz zur Vorratsdatenspeicherung zufolge
jeder elektronische Kontakt mit mir sechs Monate lang gespeichert wird.]