Re: capture "changed" signal for the cell of treeview

[Tristan Van Berkom <tvb gnome org>]

On Sat, May 4, 2013 at 8:02 PM, yu wu <vanii warem gmail com> wrote:
> Since more than one column is changed, row-changed signal will be emitted
> more than once and widgets will be updated more than once. But I just want
> to update other widget once.

This is only more or less true.

When you receive "row-changed" multiple times, then you probably do
something like:

  o gtk_label_set_text()... which is not going to queue a redraw if
the new text is the same as the old text

  o If the text has changed, it will queue a redraw...

So even if a couple things actually changed on a couple different
widgets, that is all happening
synchronously, and then a redraw is queued, things only get painted
once with the new value.

Cheers,
       -Tristan

> This is why I want to know if it is possible to
> know which column is changed in other email. But from your reply to my other
> email, there is no way to know which column to change when row-changed is
> emitted. Then I have to update widgets when cell of column 0 is edited or in
> other functions which result in the change in column 1~3 mentioned above.
>
> As to GtkCellView, I have never used it. I have to read it first and then
> see.
>
>
> 2013/5/4 <tristan van berkom gmail com>
>
> > On 2013-05-04, at 7:00 PM, yu wu <vanii warem gmail com> wrote:
> >
> > As I wrote in my original email, the renderer is ** not ** set editable.
> > Therefore, it can't be connected to ** edited ** signal.
> >
> > Here is the situation for example. Renderer 1 -- column 0 is set editable.
> > Renderer 2-4, i.e., column 1-3, is not set editable. When column 0 is
> > edited, the value of column 1 is set. As to the values for column 2-3, they
> > are set by other functions. Then I would like to capture the changes of
> > column 1-3. After I get the changes, some other widgets (inside treeview or
> > outside treeview) will be updated.
> >
> >
> > I see, well the most efficient way to handle your situation really depends
> > on what you need.
> >
> > For your other display widgets, you might consider using GtkCellView (a
> > widget for rendering a single row from a tree model), or like you mention in
> > the other mail, you could listen to "row-chaned" and update all the widgets
> > which need to display the changed row.
> >
> > You could also implement custom display widgets like GtkCellView, by
> > keeping a GtkTreeRowReference, queuing a redraw when the row changes, and
> > drawing the visual state based of the row data at "draw" time.
> >
> > By the way, I don't know the difference between gtk-list and
> > gtk-devel-list. Now I know it. Could you or someone tell me how to move this
> > post to gtk-list?
> >
> >
> > Don't worry about it, posts can't be "moved", just use the other lists
> > next time ;)
> >
> >
> > 在 2013年5月4日星期六，Tristan Van Berkom 写道：
> > > On Sat, May 4, 2013 at 12:37 PM, yu wu <vanii warem gmail com> wrote:
> > > > I am using the followed to renderer text in cells:
> > > >
> > > > ++++++++++++++++++++++++
> > > >
> > > >   renderer = gtk_cell_renderer_text_new();
> > > >   column = gtk_tree_view_column_new_with_attributes((local =
> > > > char_to_utf8
> > > > ("weight(kg/m)")), renderer, "text", MEM_SEC_WEIGHT_PER_METER, NULL);
> > > >   g_free(local);
> > > >   gtk_tree_view_append_column(treeview, column);
> > > >
> > > > ++++++++++++++++++++++++
> > > >
> > > > I don't set `editable' attribute for the renderer. The value for
> > > > specified
> > > > cell is set by
> > > >
> > > > other sub-function. Then how can I get the `changed' signal for the
> > > > specified cell when its
> > > > value is changed? My purpose is to update other widget when text value
> > > > in
> > > > cell is changed.
> > > > For the text cell renderer, it only has edited signal that is not
> > > > useful for
> > > > my case
> > >
> > > How come the "edited" signal is not useful ?
> > >
> > > You want to catch *every* change while the user is editing a cell ?
> > >
> > > This can be done, but it kind of changes the way cell editing usually
> > > works, i.e. pressing escape, or losing editor focus while editing a text
> > > cell is generally supposed to "cancel" the current edit, hence usually
> > > you wait until the "edited" signal is fired in order to commit any
> > > changes
> > > to the underlying model.
> > >
> > > If you need to handle every keystroke, then connect to the
> > > "editing-started"
> > > signal of a GtkCellRendererText for example, the GtkCellEditable widget
> > > will
> > > in this case be a GtkEntry (which will exist for the duration of the
> > > edit), then
> > > you can connect to the "changed" signal of this entry.
> > >
> > > Note also, this list is about development of GTK+ itself, you should
> > > direct
> > > your questions about using GTK+ to gtk-app-devel-list instead.
> > >
> > > Cheers,
> > >        -Tristan
> > >
> > > > (or maybe I misunderstand some points). When some cell is changed, it
> > > > might
> > > > have no
> > > > any selection. That's, the `changed' signal for selection has no use
> > > > here.
> > > >
> > > > Please help.
> > > >
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