= The Tree View Widget
{{link nil, "tut-gtk2-treev-cbbr", nil, nil}}

== Problem With Combo Box Renderers

== C GTK+ version of "Spin Button Renderers" example program

{{image_right("dialog-warning.png")}}
Unfortunately neither GtkCellRendererCombo nor Gtk::CellRendererCombo classes currently (as of Ruby 1.8.6 and Ruby-GNOME2 rel.: 2-0.17.0-rc1) work as expected. Following is the C incarnation of this example. You can compile and run it to see for yourself, that the problem is not in GTK+ but rather in ...

You can compile this program with the following command:

gcc -Wall iterators.c -o iterators \
`pkg-config --cflags gtk+-2.0` \
`pkg-config --libs gtk+-2.0`

Note the backticks surrounding the last two parameters which are the commands supplying flags, include options, and required libraries to gcc. Indeed you should have all this GTK+ stuff installed in order for gcc to compile this program.



{{image_left("treev-trees-ok.png")}}

{{image_right("dialog-warning.png")}}

This program  does not display Combo Boxes!



{{br}}

Following is the ((*treestore-combob.c*)) program in C that also does not work:

#include <gtk/gtk.h>

enum
{
   BUY_IT = 0,
   QUANTITY,
   PRODUCT,
   COLUMNS
};

enum
{
   PRODUCT_CATEGORY,
   PRODUCT_CHILD
};

typedef struct
{
   gint product_type;
   gboolean buy;
   gint quantity;
   gchar *product;
} GroceryItem;

GroceryItem list[] =
{
   { PRODUCT_CATEGORY, TRUE, 0, "Cleaning Supplies" },
   { PRODUCT_CHILD, TRUE, 1, "Paper Towels" },
   { PRODUCT_CHILD, TRUE, 3, "Toilet Paper" },
   { PRODUCT_CATEGORY, TRUE, 0, "Food" },
   { PRODUCT_CHILD, TRUE, 2, "Bread" },
   { PRODUCT_CHILD, FALSE, 1, "Butter" },
   { PRODUCT_CHILD, TRUE, 1, "Milk" },
   { PRODUCT_CHILD, FALSE, 3, "Chips" },
   { PRODUCT_CHILD, TRUE, 4, "Soda" },
   { PRODUCT_CATEGORY, FALSE, 0, NULL }
};

static void setup_tree_view (GtkWidget*);
static void cell_edited (GtkCellRendererText*, gchar*, gchar*, GtkTreeView*);

int main (int argc,
           char *argv[])
{
   GtkWidget *window, *treeview, *scrolled_win;
   GtkTreeStore *store;
   GtkTreeIter iter, child;
   guint i = 0, j;
  
   gtk_init (&argc, &argv);
  
   window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
   gtk_window_set_title (GTK_WINDOW (window), "Grocery List");
   gtk_container_set_border_width (GTK_CONTAINER (window), 10);
   gtk_widget_set_size_request (window, 275, 300);
  
   g_signal_connect (G_OBJECT (window), "destroy",
                     G_CALLBACK (gtk_main_quit), NULL);
  
   treeview = gtk_tree_view_new ();  
   setup_tree_view (treeview);
  
   store = gtk_tree_store_new (COLUMNS, G_TYPE_BOOLEAN, G_TYPE_INT, G_TYPE_STRING);
  
   while (list[i].product != NULL)
   {
     /* If the product type is a category, count the quantity of all of the products
      * in the category that are going to be boughty. */
     if (list[i].product_type == PRODUCT_CATEGORY)
     {
       j = i + 1;
      
       /* Calculate how many products will be bought in the category. */
       while (list[j].product != NULL && list[j].product_type != PRODUCT_CATEGORY)
       {
         if (list[j].buy)
           list[i].quantity += list[j].quantity;
         j++;
       }
      
       /* Add the category as a new root element. */
       gtk_tree_store_append (store, &iter, NULL);
       gtk_tree_store_set (store, &iter, BUY_IT, list[i].buy,
                           QUANTITY, list[i].quantity, PRODUCT, list[i].product, -1);
     }
     /* Otherwise, add the product as a child of the category. */
     else
     {
       gtk_tree_store_append (store, &child, &iter);
       gtk_tree_store_set (store, &child, BUY_IT, list[i].buy,
                           QUANTITY, list[i].quantity, PRODUCT, list[i].product, -1);
     }
    
     i++;
   }
  
   gtk_tree_view_set_model (GTK_TREE_VIEW (treeview), GTK_TREE_MODEL (store));
   gtk_tree_view_expand_all (GTK_TREE_VIEW (treeview));
   g_object_unref (store);
  
   scrolled_win = gtk_scrolled_window_new (NULL, NULL);
   gtk_scrolled_window_set_policy (GTK_SCROLLED_WINDOW (scrolled_win),
                                   GTK_POLICY_AUTOMATIC, GTK_POLICY_AUTOMATIC);
  
   gtk_container_add (GTK_CONTAINER (scrolled_win), treeview);
   gtk_container_add (GTK_CONTAINER (window), scrolled_win);
   gtk_widget_show_all (window);
  
   gtk_main ();
   return 0;
}

/* Add three columns to the GtkTreeView. All three of the columns will be
  * displayed as text, although one is a gboolean value and another is
  * an integer. */
static void
setup_tree_view (GtkWidget *treeview)
{
   GtkCellRenderer *renderer;
   GtkTreeViewColumn *column;
   GtkListStore *model;
   GtkTreeIter iter;
  
   /* Create a GtkListStore that will be used for the combo box renderer. */
   model = gtk_list_store_new (1, G_TYPE_STRING);
  
   gtk_list_store_append (model, &iter);
   gtk_list_store_set (model, &iter, 0, "None", -1);
   gtk_list_store_append (model, &iter);
   gtk_list_store_set (model, &iter, 0, "One", -1);
   gtk_list_store_append (model, &iter);
   gtk_list_store_set (model, &iter, 0, "Half a Dozen", -1);
   gtk_list_store_append (model, &iter);
   gtk_list_store_set (model, &iter, 0, "Dozen", -1);
   gtk_list_store_append (model, &iter);
   gtk_list_store_set (model, &iter, 0, "Two Dozen", -1);

   renderer = gtk_cell_renderer_text_new ();
   column = gtk_tree_view_column_new_with_attributes
                          ("Buy", renderer, "text", BUY_IT, NULL);
   gtk_tree_view_append_column (GTK_TREE_VIEW (treeview), column);
  
   /* Create the GtkCellRendererCombo and add the tree model. Then add the
    * renderer to a new column and add the column to the GtkTreeView */
  
   renderer = gtk_cell_renderer_combo_new ();
   g_object_set (renderer, "text-column", 0, "editable", TRUE,
                 "has-entry", TRUE, "model", model, NULL);
   column =  gtk_tree_view_column_new_with_attributes
                          ("Count", renderer, "text", QUANTITY, NULL);
   gtk_tree_view_append_column (GTK_TREE_VIEW (treeview), column);
  
   g_signal_connect (G_OBJECT (renderer), "edited",
                     G_CALLBACK (cell_edited),
                     (gpointer) treeview);

   renderer = gtk_cell_renderer_text_new ();
   column = gtk_tree_view_column_new_with_attributes
                          ("Product", renderer,  "text", PRODUCT, NULL);
   gtk_tree_view_append_column (GTK_TREE_VIEW (treeview), column);
}

/* Apply the changed text to the cell */
static void
cell_edited (GtkCellRendererText *renderer,
             gchar *path,
             gchar *new_text,
             GtkTreeView *treeview)
{
   GtkTreeIter iter;
   GtkTreeModel *model;
  
   /* Make sure the text is not empty. If not, apply it to the tree view cell */
   if (g_ascii_strcasecmp (new_text, "") != 0)
   {
       model = gtk_tree_view_get_model (treeview);
       if (gtk_tree_model_get_iter_from_string (model, &iter, path))
         gtk_list_store_set (GTK_LIST_STORE (model), &iter, QUANTITY, new_text, -1);
   }
}