radio-menu-item: Add join_group()

The other Radio* widgets have this convenience method that removes the
memory management of the opaque GSList used to handle the group from the
API usable from language bindings (especially the ones not based on
introspection).

This commit adds gtk_radio_menu_item_join_group().

https://bugzilla.gnome.org/show_bug.cgi?id=671362

1 files changed, 56 insertions, 0 deletions

diff --git a/gtk/gtkradiomenuitem.c b/gtk/gtkradiomenuitem.c
index da37120431..27320f0078 100644
--- a/gtk/gtkradiomenuitem.c
+++ b/gtk/gtkradiomenuitem.c
@@ -558,3 +558,59 @@ gtk_radio_menu_item_activate (GtkMenuItem *menu_item)
 
   gtk_widget_queue_draw (GTK_WIDGET (radio_menu_item));
 }
+
+/**
+ * gtk_radio_menu_item_join_group:
+ * @radio_menu_item: a #GtkRadioMenuItem
+ * @group_source: (allow-none): a #GtkRadioMenuItem whose group we are
+ *   joining, or %NULL to remove the @radio_menu_item from its current
+ *   group
+ *
+ * Joins a #GtkRadioMenuItem object to the group of another #GtkRadioMenuItem
+ * object.
+ *
+ * This function should be used by language bindings to avoid the memory
+ * manangement of the opaque #GSList of gtk_radio_menu_item_get_group()
+ * and gtk_radio_menu_item_set_group().
+ *
+ * A common way to set up a group of #GtkRadioMenuItem instances is:
+ *
+ * |[
+ *   GtkRadioMenuItem *last_item = NULL;
+ *
+ *   while ( ...more items to add... )
+ *     {
+ *       GtkRadioMenuItem *radio_item;
+ *
+ *       radio_item = gtk_radio_menu_item_new (...);
+ *
+ *       gtk_radio_menu_item_join_group (radio_item, last_item);
+ *       last_item = radio_item;
+ *     }
+ * ]|
+ *
+ * Since: 3.18
+ */
+void
+gtk_radio_menu_item_join_group (GtkRadioMenuItem *radio_menu_item,
+                                GtkRadioMenuItem *group_source)
+{
+  g_return_if_fail (GTK_IS_RADIO_MENU_ITEM (radio_menu_item));
+  g_return_if_fail (group_source == NULL || GTK_IS_RADIO_MENU_ITEM (group_source));
+
+  if (group_source != NULL)
+    {
+      GSList *group = gtk_radio_menu_item_get_group (group_source);
+
+      if (group == NULL)
+        {
+          /* if the group source does not have a group, we force one */
+          gtk_radio_menu_item_set_group (group_source, NULL);
+          group = gtk_radio_menu_item_get_group (group_source);
+        }
+
+      gtk_radio_menu_item_set_group (radio_menu_item, group);
+    }
+  else
+    gtk_radio_menu_item_set_group (radio_menu_item, NULL);
+}