Re: Problems with Gtk::Table

["Erik Ohrnberger" <Erik echohome org>]

Isn't it that once a widget is attached to the table, you can't go and
just attach it again?  I believe that there might be a method to deatch
the widget, but I've not needed or looked for it.

Hope this help,
    Erik.

On Tue, August 9, 2005 12:49, Marcus Lundblad said:
> Hello.
>
> I have a problem with a class derived from Gtk::Table
> In this class I have a method "rearrange" that is called when changing
> the layout of this table:
>
> void
> desks_table::rearrange()
> {
>    int num_cols = (unsigned int)(std::ceil(double(double(num_desks())/
>  						 double(num_rows()))));
>    std::cerr << "resize( " << num_rows() << ", " << num_cols << std::endl;
>    TableList& tl = children();
>    std::cerr << "children size = " << tl.size() << std::endl;
>    int child_size = tl.size();
>    tl.clear();
>
>    resize(num_rows(), num_cols);
>    int desk = 0;
>    for(int i = 0 ; i < num_rows() ; i++) {
>      for(int j = 0 ; j < num_cols && desk < num_desks() ; j++) {
>        std::cerr << "attaching desk " << desk << std::endl;
>        attach(*(desk_widgets[desk]), j, j+1, i, i+1);
>        desk++;
>      }
>    }
> }
>
> The "desk_widgets" is (currently) std::vector<Gtk::Label>, but will be a
> derived class later on, this vector is maintained outside of this method
> (the idea is that this should be usable both when changing number of
> subwidgets and rearraging, columns and rows).
> The first time this is called (as a consequence of the constructor), there
> is no widgets attached and there's 4 widgets allocated in the vector.
>
> The follwing gets printed:
>
> ------------------------------------------------------
>
> resize( 1, 4
> children size = 0
> attaching desk 0
> attaching desk 1
> attaching desk 2
> attaching desk 3
>
> ------------------------------------------------------
>
> and the widgets appear in the table as expected.
>
> The second time the vector has one more element.
> the printout now:
>
> -------------------------------------------------------------------------
>
> resize( 1, 5
> children size = 4
>
> (gov:7206): Gtk-CRITICAL **: gtk_container_remove: assertion
> `GTK_IS_WIDGET (widget)' failed
>
> (gov:7206): Gtk-CRITICAL **: gtk_container_remove: assertion
> `GTK_IS_WIDGET (widget)' failed
>
> (gov:7206): Gtk-CRITICAL **: gtk_container_remove: assertion
> `GTK_IS_WIDGET (widget)' failed
>
> (gov:7206): Gtk-CRITICAL **: gtk_container_remove: assertion
> `GTK_IS_WIDGET (widget)' failed
> attaching desk 0
>
> (gov:7206): Gtk-CRITICAL **: gtk_table_attach: assertion `child->parent ==
> NULL' failed
> attaching desk 1
>
> (gov:7206): Gtk-CRITICAL **: gtk_table_attach: assertion `child->parent ==
> NULL' failed
> attaching desk 2
>
> (gov:7206): Gtk-CRITICAL **: gtk_table_attach: assertion `child->parent ==
> NULL' failed
> attaching desk 3
>
> (gov:7206): Gtk-CRITICAL **: gtk_table_attach: assertion `child->parent ==
> NULL' failed
> attaching desk 4
>
> --------------------------------------------------------------------------
>
> When calling tl.clear() on the children something goes wrong,
> (the exact same thing happens using tl.erase(tl.begin(),tl.end()) )
> the table is resized, but the new slot is empty (even though the last
> attach, on the slot that's new didn't seem to fail.
>
> What am I doing wrong? (I've read the documentation and check sample
> codes, but can't seem to get it right).
>
> //Marcus
>
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