[gtk+] gtktreemodelfilter: fix corner case in rows-reordered handling

[Kristian Rietveld <kristian src gnome org>]

commit 9ed76387fa2d91d7ac063ff1ce6d2cace84d7688
Author: Kristian Rietveld <kris gtk org>
Date:   Sun Sep 11 12:00:00 2011 +0200

    gtktreemodelfilter: fix corner case in rows-reordered handling
    
    If the level to be reordered did not contain an elt with offset == 0
    (for example if that node was hidden), the first reference was not
    correctly transferred.
    
    A unit test for this has been added in a previous commit.

 gtk/gtktreemodelfilter.c |   16 +++++++---------
 1 files changed, 7 insertions(+), 9 deletions(-)
---
diff --git a/gtk/gtktreemodelfilter.c b/gtk/gtktreemodelfilter.c
index bf954e1..a8795fb 100644
--- a/gtk/gtktreemodelfilter.c
+++ b/gtk/gtktreemodelfilter.c
@@ -2698,7 +2698,7 @@ gtk_tree_model_filter_rows_reordered (GtkTreeModel *c_model,
 
   GSequence *tmp_seq;
   GSequenceIter *tmp_end_iter;
-  GSequenceIter *old_first_elt = NULL;
+  GSequenceIter *old_first_siter = NULL;
   gint *tmp_array;
   gint i, elt_count;
   gint length;
@@ -2818,6 +2818,8 @@ gtk_tree_model_filter_rows_reordered (GtkTreeModel *c_model,
   tmp_array = g_new (gint, g_sequence_get_length (level->visible_seq));
   elt_count = 0;
 
+  old_first_siter = g_sequence_get_iter_at_pos (level->seq, 0);
+
   for (i = 0; i < length; i++)
     {
       FilterElt *elt;
@@ -2827,10 +2829,6 @@ gtk_tree_model_filter_rows_reordered (GtkTreeModel *c_model,
       if (elt == NULL)
         continue;
 
-      /* Keep a reference if this elt has old_pos == 0 */
-      if (new_order[i] == 0)
-        old_first_elt = siter;
-
       /* Only for visible items an entry should be present in the order array
        * to be emitted.
        */
@@ -2848,15 +2846,15 @@ gtk_tree_model_filter_rows_reordered (GtkTreeModel *c_model,
   g_sequence_sort (level->visible_seq, filter_elt_cmp, NULL);
 
   /* Transfer the reference from the old item at position 0 to the
-   * new item at position 0.
+   * new item at position 0, unless the old item at position 0 is also
+   * at position 0 in the new sequence.
    */
-  if (old_first_elt && g_sequence_iter_get_position (old_first_elt))
+  if (g_sequence_iter_get_position (old_first_siter) != 0)
     gtk_tree_model_filter_level_transfer_first_ref (filter,
                                                     level,
-                                                    old_first_elt,
+                                                    old_first_siter,
                                                     g_sequence_get_iter_at_pos (level->seq, 0));
 
-
   /* emit rows_reordered */
   if (g_sequence_get_length (level->visible_seq) > 0)
     {