[gegl] buffer: make direct access in GeglBufferIterator more picky

[Øyvind Kolås <ok src gnome org>]

commit ddbf61815fc11663ef12d6ec142cbceb7102ae31
Author: Øyvind Kolås <pippin gimp org>
Date:   Wed Jun 4 20:15:26 2014 +0200

    buffer: make direct access in GeglBufferIterator more picky

 gegl/buffer/gegl-buffer-iterator.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletions(-)
---
diff --git a/gegl/buffer/gegl-buffer-iterator.c b/gegl/buffer/gegl-buffer-iterator.c
index 969561f..a6c6cc8 100644
--- a/gegl/buffer/gegl-buffer-iterator.c
+++ b/gegl/buffer/gegl-buffer-iterator.c
@@ -585,7 +585,10 @@ gegl_buffer_iterator_next (GeglBufferIterator *iter)
           && priv->sub_iter[0].full_rect.width == primary->tile_width 
           && priv->sub_iter[0].full_rect.height == primary->tile_height
           && priv->sub_iter[0].full_rect.x == primary->extent.x
-          && priv->sub_iter[0].full_rect.y == primary->extent.y)
+          && priv->sub_iter[0].full_rect.y == primary->extent.y
+          && priv->sub_iter[0].buffer->extent.x == iter->roi[0].x
+          && priv->sub_iter[0].buffer->extent.y == iter->roi[0].y
+          )
       {
         if (gegl_cl_is_accelerated ())
           for (index = 0; index < priv->num_buffers; index++)