GtkTreeView: displaying structures and sorting

[martine cs washington edu]

I have what seems to be a pretty common situation:
I have a struct with a few fields.  I get an array of these structs and
I want to display them in a list-like form.  

It seems there are a few ways of doing this:
 - create a list store with the appropriate fields:
     gtk_list_store_new(n, ...);
   where n is the number of fields I'm trying to display. 
   Then, I iterate through the list of structs and call
   gtk_list_store_append() and gtk_list_store_set() to fill in these
   fields.  This is undesireable because I am copying the data from my
   structures to the list widget, and changing the data in the
   structures will not affect the data displayed in the list.

 - or, I can make my structure into a boxed type, as was done in the
   gtk stock demonstration.  However, this again appears to copy the structure
   to the list whenever I append.

 - or, I can create a list store that stores a pointer to the structures:
     gtk_list_store_new(1, G_TYPE_POINTER)
   and write code similar to the boxed type code; for example, here I
   supply the data to display the "username" field of the "Friend"
   structure.

        static void
        user_name_data_func(GtkTreeViewColumn *tree_column,
                            GtkCellRenderer   *cell,
                            GtkTreeModel      *model,
                            GtkTreeIter       *iter,
                            gpointer           data)
        {
            Friend *friend;
            gtk_tree_model_get(model, iter,
                    0, &friend,
                    -1);
            g_object_set(cell,
                    "text", friend->username,
                    NULL);
        }

   this function is attached to the column like so:

        gtk_tree_view_column_set_cell_data_func(column, cell_renderer,
            user_name_data_func, NULL, NULL);

   and when I destroy my list, I free all of the structures:

        static gboolean
        model_free_friend(GtkTreeModel *model, GtkTreePath *path, GtkTreeIter
        *iter, gpointer data) {
            Friend *friend;
            gtk_tree_model_get(model, iter,
                    0, &friend,
                    -1);
            friend_free(friend);
            return FALSE;
        }

        .../* destroying */...
        gtk_tree_model_foreach([the list store],
            model_free_friend, NULL);


This final solution seems ideal; however, this completely loses the
advantage of the first solution: GTK doesn't know how to properly sort
each of my display columns.


I've scoured the documentation and glanced over the mailing list, and
I'm surprised this isn't a FAQ.  At least in the context of this
program, there are many different places where I want to display some
sort of list of structures, and I imagine that most other programs would
too.

So how should I be doing it?  (Assume that my structure is sorta
heavyweight and I'd like to avoid copying the data needlessly if at all
possible.)



And, finally, while I have your attention: even if I pick the first
option, accepting that the list store will duplicate all of my data and
I'm careful to refresh the data when it changes, how can I sort data
that is displayed by a Pixbuf?  (For example, I have a "type" column,
which displays an icon representing the type; sorting on it should at
least group the rows by their type, and I'd like to choose the order
myself.)


Thanks!

-- 
      Evan Martin
martine cs washington edu
  http://neugierig.org