From: Lei Qiao <qiaol618@gmail.com>
Date: Tue, 13 Oct 2015 00:19:45 +0000 (-0500)
Subject: add signal pre_coarsening_on_cell to Triangulation.
X-Git-Tag: v8.4.0-rc2~285^2~9
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4ed6457454dc867969c63ad18bd57b4d78f6d769;p=dealii.git

add signal pre_coarsening_on_cell to Triangulation.
---

diff --git a/include/deal.II/grid/tria.h b/include/deal.II/grid/tria.h
index a4dfba2c24..52a81a6a9a 100644
--- a/include/deal.II/grid/tria.h
+++ b/include/deal.II/grid/tria.h
@@ -1921,6 +1921,13 @@ public:
     boost::signals2::signal<void ()> create;
     boost::signals2::signal<void ()> pre_refinement;
     boost::signals2::signal<void ()> post_refinement;
+    /**
+     * @note the signal parameter @p cell is correspond to the new active cell
+     * after coarsening is done rather than a current active cell.
+     * In another word, all children of @p cell will be deleted after coarsening
+     * and @p cell will become the new active cell then.
+     */
+    boost::signals2::signal<void (const Triangulation<dim, spacedim>::cell_iterator &cell)> pre_coarsening_on_cell;
     boost::signals2::signal<void (const Triangulation<dim, spacedim>::cell_iterator &cell)> post_refinement_on_cell;
     boost::signals2::signal<void (const Triangulation<dim, spacedim> &original_tria)> copy;
     boost::signals2::signal<void ()> clear;
diff --git a/source/grid/tria.cc b/source/grid/tria.cc
index a68cf0a8ff..be2f5b234e 100644
--- a/source/grid/tria.cc
+++ b/source/grid/tria.cc
@@ -11669,11 +11669,15 @@ void Triangulation<dim, spacedim>::execute_coarsening ()
   if (levels.size() >= 2)
     for (cell = last(); cell!=endc; --cell)
       if (cell->level()<=static_cast<int>(levels.size()-2) && cell->user_flag_set())
-        // use a separate function,
-        // since this is dimension
-        // specific
-        internal::Triangulation::Implementation
-        ::delete_children (*this, cell, line_cell_count, quad_cell_count);
+        {
+          // inform all listeners that cell coarsening is going to happen
+          signals.pre_coarsening_on_cell(cell);
+          // use a separate function,
+          // since this is dimension
+          // specific
+          internal::Triangulation::Implementation
+          ::delete_children (*this, cell, line_cell_count, quad_cell_count);
+        }
 
   // re-compute number of lines and
   // quads