Re: Columns vs fields in GtkTreeView

[Murray Cumming <murrayc murrayc com>]

On Wed, 2004-02-11 at 02:30, Dave Malcolm wrote:
> I couldn't see this in the archives, so here goes:
> 
> I believe that the current tree/list API is unnecessarily hard to
> understand because of the potential for confusion between columns in the
> view and columns in the model.

This is a bit easier in gtkmm, because we have Gtk::TreeModel::Column
objects that store the type and index.
 
I also try to always write "model column" and "view column" in the docs,
and never just "column" to avoid confusion.

> So I propose that the "columns" in the model (and the various store
> classes) get renamed to "field".

I think that would just make things more difficult, personally.

>   That way "columns" only refers to
> columns in the view.  I've been using this in my own code, and it
> clarifies things when you have more than one column in the model per
> column in the view, and when you have "hidden columns" - it's suddenly a
> lot clearer that these two concepts called "column" aren't the same
> thing.
> 
> Obviously this would be a pain of an API change (maybe for GTK 3?).  So,
> as a simpler change, we could merely update the docs and sample code to
> use this terminology.
> 
> Here's the sample code from the docs adapted to use the proposed new
> terminology:
> 
> enum
> {
>    TITLE_FIELD,
>    AUTHOR_FIELD,
>    CHECKED_FIELD,
>    N_FIELDS
> };
> 
> void
> populate_tree_model (GtkTreeStore *store)
> {
> 	GtkTreeIter iter1;  /* Parent iter */
> 	GtkTreeIter iter2;  /* Child iter  */
> 
> 	gtk_tree_store_append (store, &iter1, NULL);  /* Acquire a top-level iterator */
> 	gtk_tree_store_set (store, &iter1,
>         	            TITLE_FIELD, "The Art of Computer Programming",
>         	            AUTHOR_FIELD, "Donald E. Knuth",
>         	            CHECKED_FIELD, FALSE,
>         	            -1);
> 
> 	gtk_tree_store_append (store, &iter2, &iter1);  /* Acquire a child iterator */
> 	gtk_tree_store_set (store, &iter2,
>         	            TITLE_FIELD, "Volume 1: Fundamental Algorithms",
> 	                    -1);
> 
> 	gtk_tree_store_append (store, &iter2, &iter1);
> 	gtk_tree_store_set (store, &iter2,
>         	            TITLE_FIELD, "Volume 2: Seminumerical Algorithms",
> 	                    -1);
> 
> 	gtk_tree_store_append (store, &iter2, &iter1);
> 	gtk_tree_store_set (store, &iter2,
>         	            TITLE_FIELD, "Volume 3: Sorting and Searching",
> 	                    -1);
> }
> 
> void
> setup_tree (void)
> {
>    GtkTreeStore *store;
>    GtkWidget *tree;
>    GtkTreeViewColumn *column;
>    GtkCellRenderer *renderer;
> 
>    /* Create a model.  We are using the store model for now, though we
>     * could use any other GtkTreeModel */
>    store = gtk_tree_store_new (N_FIELDS,
>                                G_TYPE_STRING,
>                                G_TYPE_STRING,
>                                G_TYPE_BOOLEAN);
> 
>    /* custom function to fill the model with data */
>    populate_tree_model (store);
> 
>    /* Create a view */
>    tree = gtk_tree_view_new_with_model (GTK_TREE_MODEL (store));
> 
>    /* The view now holds a reference.  We can get rid of our own
>     * reference */
>    g_object_unref (G_OBJECT (store));
> 
>    /* Create a cell render and arbitrarily make it red for demonstration
>     * purposes */
>    renderer = gtk_cell_renderer_text_new ();
>    g_object_set (G_OBJECT (renderer),
>                  "foreground", "red",
>                  NULL);
> 
>    /* Create a column, associating the "text" attribute of the
>     * cell_renderer to the first field of the model */
>    column = gtk_tree_view_column_new_with_attributes ("Author", renderer,
>                                                       "text", AUTHOR_FIELD,
>                                                       NULL);
> 
>    /* Add the column to the view. */
>    gtk_tree_view_append_column (GTK_TREE_VIEW (tree), column);
> 
>    /* Second column.. title of the book. */
>    renderer = gtk_cell_renderer_text_new ();
>    column = gtk_tree_view_column_new_with_attributes ("Title",
>                                                       renderer,
>                                                       "text", TITLE_FIELD,
>                                                       NULL);
>    gtk_tree_view_append_column (GTK_TREE_VIEW (tree), column);
> 
>    /* Last column.. whether a book is checked out. */
>    renderer = gtk_cell_renderer_toggle_new ();
>    column = gtk_tree_view_column_new_with_attributes ("Checked out",
>                                                       renderer,
>                                                       "active", CHECKED_FIELD,
>                                                       NULL);
>    gtk_tree_view_append_column (GTK_TREE_VIEW (tree), column);
> 
>    /* Now we can manipulate the view just like any other GTK widget */
>    ...
> }
> 
> Thoughts?  Do other people think this is better?  Should I make a patch for the docs and samples?  
> 
> 
> 
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-- 
Murray Cumming
www.murrayc.com
murrayc murrayc com