From 62def686e9dda3a058e216f647eb62a21ba2d35c Mon Sep 17 00:00:00 2001
From: Martin Kronbichler <kronbichler@lnm.mw.tum.de>
Date: Wed, 8 Mar 2017 11:10:16 +0100
Subject: [PATCH] Add additional listener to grid movement

---
 include/deal.II/grid/grid_tools.h | 2 +-
 include/deal.II/grid/tria.h       | 9 +++++++++
 source/fe/fe_values.cc            | 4 ++++
 source/grid/tria.cc               | 1 +
 4 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/include/deal.II/grid/grid_tools.h b/include/deal.II/grid/grid_tools.h
index 7b1f2e9369..fb8341a644 100644
--- a/include/deal.II/grid/grid_tools.h
+++ b/include/deal.II/grid/grid_tools.h
@@ -1729,7 +1729,7 @@ namespace GridTools
       }
 
     // Make sure FEValues notices that the mesh has changed
-    triangulation.signals.post_refinement();
+    triangulation.signals.mesh_movement();
   }
 
 
diff --git a/include/deal.II/grid/tria.h b/include/deal.II/grid/tria.h
index b1380ae512..c1ddaf5764 100644
--- a/include/deal.II/grid/tria.h
+++ b/include/deal.II/grid/tria.h
@@ -2090,6 +2090,15 @@ public:
      */
     boost::signals2::signal<void ()> post_refinement;
 
+    /**
+     * This signal is triggered when a function in deal.II moves the grid
+     * points of a mesh, e.g. GridTools::transform. Unfortunately,
+     * modification of a vertex in user code through
+     * <code>cell_iterator->vertex(v) = xxxx</code> cannot be detected by this
+     * method.
+     */
+    boost::signals2::signal<void ()> mesh_movement;
+
     /**
      * This signal is triggered for each cell that is going to be coarsened.
      *
diff --git a/source/fe/fe_values.cc b/source/fe/fe_values.cc
index 9736e93d30..f94e2cc106 100644
--- a/source/fe/fe_values.cc
+++ b/source/fe/fe_values.cc
@@ -3492,6 +3492,10 @@ maybe_invalidate_previous_present_cell (const typename Triangulation<dim,spacedi
       // if this FEValues has never been set to any cell at all, then
       // at least subscribe to the triangulation to get notified of
       // changes
+      tria_listener =
+        cell->get_triangulation().signals.mesh_movement.connect
+        (std_cxx11::bind (&FEValuesBase<dim,spacedim>::invalidate_present_cell,
+                          std_cxx11::ref(static_cast<FEValuesBase<dim,spacedim>&>(*this))));
       tria_listener =
         cell->get_triangulation().signals.post_refinement.connect
         (std_cxx11::bind (&FEValuesBase<dim,spacedim>::invalidate_present_cell,
diff --git a/source/grid/tria.cc b/source/grid/tria.cc
index 6a5ac44105..a52cde1fd4 100644
--- a/source/grid/tria.cc
+++ b/source/grid/tria.cc
@@ -8968,6 +8968,7 @@ Triangulation (const MeshSmoothing smooth_grid,
   signals.create.connect (signals.any_change);
   signals.post_refinement.connect (signals.any_change);
   signals.clear.connect (signals.any_change);
+  signals.mesh_movement.connect (signals.any_change);
 }
 
 
-- 
2.39.5