11.4. Item Factory Example

Here is an example using the GTK item factory.

#include <gtk/gtk.h>
#include <strings.h>

/* Obligatory basic callback */
static void print_hello( GtkWidget *w,
                         gpointer   data )
{
  g_message ("Hello, World!\n");
}

/* This is the GtkItemFactoryEntry structure used to generate new menus.
   Item 1: The menu path. The letter after the underscore indicates an
           accelerator key once the menu is open.
   Item 2: The accelerator key for the entry
   Item 3: The callback function.
   Item 4: The callback action.  This changes the parameters with
           which the function is called.  The default is 0.
   Item 5: The item type, used to define what kind of an item it is.
           Here are the possible values:

           NULL               -> "<Item>"
           ""                 -> "<Item>"
           "<Title>"          -> create a title item
           "<Item>"           -> create a simple item
           "<CheckItem>"      -> create a check item
           "<ToggleItem>"     -> create a toggle item
           "<RadioItem>"      -> create a radio item
           <path>             -> path of a radio item to link against
           "<Separator>"      -> create a separator
           "<Branch>"         -> create an item to hold sub items (optional)
           "<LastBranch>"     -> create a right justified branch 
*/

static GtkItemFactoryEntry menu_items[] = {
  { "/_File",         NULL,         NULL, 0, "<Branch>" },
  { "/File/_New",     "<control>N", print_hello, 0, NULL },
  { "/File/_Open",    "<control>O", print_hello, 0, NULL },
  { "/File/_Save",    "<control>S", print_hello, 0, NULL },
  { "/File/Save _As", NULL,         NULL, 0, NULL },
  { "/File/sep1",     NULL,         NULL, 0, "<Separator>" },
  { "/File/Quit",     "<control>Q", gtk_main_quit, 0, NULL },
  { "/_Options",      NULL,         NULL, 0, "<Branch>" },
  { "/Options/Test",  NULL,         NULL, 0, NULL },
  { "/_Help",         NULL,         NULL, 0, "<LastBranch>" },
  { "/_Help/About",   NULL,         NULL, 0, NULL },
};


void get_main_menu( GtkWidget  *window,
                    GtkWidget **menubar )
{
  GtkItemFactory *item_factory;
  GtkAccelGroup *accel_group;
  gint nmenu_items = sizeof (menu_items) / sizeof (menu_items[0]);

  accel_group = gtk_accel_group_new ();

  /* This function initializes the item factory.
     Param 1: The type of menu - can be GTK_TYPE_MENU_BAR, GTK_TYPE_MENU,
              or GTK_TYPE_OPTION_MENU.
     Param 2: The path of the menu.
     Param 3: A pointer to a gtk_accel_group.  The item factory sets up
              the accelerator table while generating menus.
  */

  item_factory = gtk_item_factory_new (GTK_TYPE_MENU_BAR, "<main>", 
				       accel_group);

  /* This function generates the menu items. Pass the item factory,
     the number of items in the array, the array itself, and any
     callback data for the the menu items. */
  gtk_item_factory_create_items (item_factory, nmenu_items, menu_items, NULL);

  /* Attach the new accelerator group to the window. */
  gtk_window_add_accel_group (GTK_WINDOW (window), accel_group);

  if (menubar)
    /* Finally, return the actual menu bar created by the item factory. */ 
    *menubar = gtk_item_factory_get_widget (item_factory, "<main>");
}

int main( int argc,
          char *argv[] )
{
  GtkWidget *window;
  GtkWidget *main_vbox;
  GtkWidget *menubar;
  
  gtk_init (&argc, &argv);
  
  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
  g_signal_connect (G_OBJECT (window), "destroy", 
		    G_CALLBACK (gtk_main_quit), 
		    NULL);
  gtk_window_set_title (GTK_WINDOW (window), "Item Factory");
  gtk_widget_set_size_request (GTK_WIDGET (window), 300, 200);
  
  main_vbox = gtk_vbox_new (FALSE, 1);
  gtk_container_set_border_width (GTK_CONTAINER (main_vbox), 1);
  gtk_container_add (GTK_CONTAINER (window), main_vbox);
  gtk_widget_show (main_vbox);
  
  get_main_menu (window, &menubar);
  gtk_box_pack_start (GTK_BOX (main_vbox), menubar, FALSE, TRUE, 0);
  gtk_widget_show (menubar);
  
  gtk_widget_show (window);

  gtk_main ();
  
  return 0;
}

For now, there's only this example. An explanation and lots 'o' comments will follow later.