Using a treeview with a dynamic number of columns

["Thiago Guzella" <thiago guzella gmail com>]

Greetings everyone,


I am writing a Gtkmm app that contains a treeview, composed of a given
number of columns that are always visible, followed by columns that
are dynamically handled. Depending on user actions, a "dynamic" column
in the treeview needs to be added or removed. I have been implementing
this pattern in the following way:

class TreeViewColumns : public Gtk::TreeModel::ColumnRecord {

   Gtk::TreeModelColumn<Glib::ustring> constant_column_1;
   Gtk::TreeModelColumn<Glib::ustring> constant_column_2;
   Gtk::TreeModelColumn<Glib::ustring> constant_column_3;

   vector< Gtk::TreeModelColumn<Glib::ustring> > dynamic_columns;

   ...

   TreeViewColumns() {

      // Add the constant columns
      add(constant_column_1);
      add(constant_column_1);
      add(constant_column_1);
   }

   void addDynamicColumn() {

      // Insert the column
      dynamic_columns.push_back(Gtk::TreeModelColumn<Glib::ustring> ());
      // Add the new, dynamic, column
      add(dynamic_columns.back());
   }

};

class MyTreeView : public Gtk::TreeView {

   TreeViewColumns m_cols;
   Glib::RefPtr<Gtk::ListStore> m_ref_tree_model;


   MyTreeView() /* m_cols initialized; constant columns added */ {

      // Create list store
      m_ref_tree_model = Gtk::ListStore::create(*m_cols);
      // Set the tree model
      set_model(m_ref_tree_model);
   }
};

But, after experimenting, I have come to the conclusion that I can't
just add a column (by calling TreeViewColumns::addDynamicColumn) and
using MyTreeView::append_column.

After reading a previous thread
(http://mail.gnome.org/archives/gtkmm-list/2002-July/msg00367.html), I
tried to, when adding a new column, clear the columns, add the dynamic
column, running Gtk::TreeModel::ColumnRecord::add for each column to
be displayed, recreating the list store and updating the tree model.
But that doesn't seem to work. So, I would like to ask, how should
this scheme be implemented?


--
Thiago dos Santos Guzella
Electrical Enginnering Student - UFMG (www.ufmg.br), Brazil
Linux User #354160
UIN: 13465286. Jabber: tguzella At jabber Dot org

"Faith: not wanting to know what is true."
Friedrich Nietzsche