Re: Using a treeview with a dynamic number of columns

[Ed Leaver <eleaver sterlingseismic com>]

On Wed, 2006-03-01 at 19:51, Thiago Guzella wrote:
> Greetings everyone,
I guess my first question is whether or not your "dynamic" columns really
need to be removed from the TreeModel, or whether merely selectively hiding their visibility from the user will suffice. While I will be interested if someone has an answer to your actuall question, what I do in my application is add all the columns I'll ever need to the TreeModel when I create it, then choose which of those columns I want to display when I set the treeview for that model. For example, given an appropriate definition for class C_Columns:

void showTreeView(TreeView & treeview, const C_Columns & Columns, bool show_type){
    Glib::RefPtr<TreeModel> treemodel = treeview.get_model();
    treeview.remove_all_columns();
    treeview.set_model(treemodel);
    treeview.append_column("Path",Columns.m_display_name);
    if(show_type) treeview.append_column("Type",Columns.m_row_type_str); 
    treeview.append_column("Owner",Columns.m_owner);
    treeview.append_column("Date",Columns.m_date);
    treeview.append_column("Size",Columns.m_size_str);
    treeview.get_selection()->set_mode(Gtk::SELECTION_MULTIPLE);
    treeview.show();
}

> 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
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