gtk3: support GtkTreeIterCompareFunc

GitHub: fix #596

Reported by Christopher L. Ramsey. Thanks!!!

gtk3/ext/gtk3/rb-gtk3.c

@@ -264,6 +264,37 @@ rb_gtk3_tree_cell_data_func_callback(GtkTreeViewColumn *column,
                rb_iter);
 }
 
+static gint
+rb_gtk3_tree_iter_compare_func_callback(GtkTreeModel *model,
+                                        GtkTreeIter *iter1,
+                                        GtkTreeIter *iter2,
+                                        gpointer user_data)
+{
+    RBGICallbackData *callback_data = user_data;
+    ID id_set_model;
+    VALUE rb_model;
+    VALUE rb_iter1;
+    VALUE rb_iter2;
+    VALUE rb_result;
+
+    CONST_ID(id_set_model, "model=");
+    rb_model = GOBJ2RVAL(model);
+
+    rb_iter1 = BOXED2RVAL(iter1, GTK_TYPE_TREE_ITER);
+    rb_funcall(rb_iter1, id_set_model, 1, rb_model);
+
+    rb_iter2 = BOXED2RVAL(iter2, GTK_TYPE_TREE_ITER);
+    rb_funcall(rb_iter2, id_set_model, 1, rb_model);
+
+    rb_result = rb_funcall(callback_data->rb_callback,
+                           id_call,
+                           3,
+                           rb_model,
+                           rb_iter1,
+                           rb_iter2);
+    return NUM2INT(rb_result);
+}
+
 static void
 rb_gtk3_tree_model_filter_modify_func_callback(GtkTreeModel *model,
                                                GtkTreeIter *iter,
@@ -412,6 +443,8 @@ rb_gtk3_callback_finder(GIArgInfo *info)
         return rb_gtk3_translate_func_callback;
     } else if (name_equal(info, "TreeCellDataFunc")) {
         return rb_gtk3_tree_cell_data_func_callback;
+    } else if (name_equal(info, "TreeIterCompareFunc")) {
+        return rb_gtk3_tree_iter_compare_func_callback;
     } else if (name_equal(info, "TreeModelFilterModifyFunc")) {
         return rb_gtk3_tree_model_filter_modify_func_callback;
     } else if (name_equal(info, "TreeModelFilterVisibleFunc")) {

gtk3/test/test-gtk-tree-sortable.rb

@@ -0,0 +1,35 @@
+# Copyright (C) 2015  Ruby-GNOME2 Project Team
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
+
+class TestGtkTreeSortable < Test::Unit::TestCase
+  include GtkTestUtils
+
+  def setup
+    @model = Gtk::ListStore.new(String)
+  end
+
+  test "#set_sort_func" do
+    @model.append[0] = "abc"
+    @model.append[0] = "xyz"
+    @model.append[0] = "efg"
+    @model.set_sort_column_id(0, :ascending)
+    @model.set_sort_func(0) do |_model, iter1, iter2|
+      iter2[0] <=> iter1[0]
+    end
+    assert_equal(["xyz", "efg", "abc"],
+                 @model.collect {|_model, _path, iter| iter[0]})
+  end
+end