Custom cell_data_func for treeviewcolumn warnings.

[Germán Diago]

Hello. I'm having problems with this code. The problem is that I get a
lot of warnings
when I try to insert rows in my TreeModel from the main function.
My TreeColumnRecord has a pointer type, but it's not derived from
Glib::Object. Is this the problem?
And if it is, is there any workaround to not require my class to
inherit from Glib::Object without
splitting MisCols class into separate fields. Thanks in advance.



struct MiClase {
        std::string a;
public:
        MiClase() {}
        MiClase(std::string aa) : a(aa) {}
};

struct MisCols : TreeModelColumnRecord {
        Gtk::TreeModelColumn<MiClase *> entero_;
public:

        MisCols() {
                add(entero_);
        }
};

void funcCol(CellRenderer * r, const Gtk::TreeModel::iterator& iter)
{
        CellRendererText * re = (CellRendererText *)r;
        Gtk::TreeModelColumn<MiClase *> col;
        re->property_text() = (iter->get_value(col)->a);
       
// re->property_text() = iter->get_value(col)->a;
}


int main(int argc, char * argv[]) {
        Main m(argc, argv);
        TreeView tv;
        Window w;
        MisCols cols;
       
        vector<MiClase> mc = {MiClase("hola"), MiClase("adios") };
               
        auto l = ListStore::create(cols);
        tv.set_model(l);

        auto row = *l->append();

        row[cols.entero_] = &mc[0];
       
        //row = *l->append();
        //row[cols.entero_] = &mc[1];
       
        TreeViewColumn viewcol("MiClase", cols.entero_);
        viewcol.set_cell_data_func(*viewcol.get_first_cell_renderer(), &funcCol);
               
        tv.append_column(viewcol);
       
       
       
        w.add(tv);
        w.show_all();
        Main::run(w);
}
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[Daniel Elstner]

Am Sonntag, den 21.06.2009, 23:44 +0200 schrieb Germán Diago:
> Hello. I'm having problems with this code. The problem is that I get a
> lot of warnings
> when I try to insert rows in my TreeModel from the main function.
> My TreeColumnRecord has a pointer type, but it's not derived from
> Glib::Object. Is this the problem?

No.

> Gtk::TreeModelColumn<MiClase *> col;
> re->property_text() = (iter->get_value(col)->a);

This is the problem.  That TreeModelColumn is not assigned to any tree
model column.  You need to use a direct reference to the TreeModelColumn
instance you added to the TreeModelColumnRecord.

For background, a TreeModelColumn stores two things: The C GType that
corresponds to the C++ template argument, and the model column index.
The model column index is assigned by the add() method, starting from
zero and incremented by one with each add() call.

The idea behind the TreeModelColumn and TreeModelColumnRecord classes is
to tie the dynamic type information of the C API and the static type
information of the C++ API together.  This makes it possible to have all
the flexibility offered by the GtkTreeModel API without sacrificing
compile-time type-safety.

> // re->property_text() = iter->get_value(col)->a;

Hm, get_value() is sort of half-internal API.  It is preferable to write

    MiClase* value = (*iter)[columns.entero];
    re->property_text() = value->a;

instead.

--Daniel


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