Imported Upstream version 2.14.2

[lilypond.git] / lily / keep-alive-together-engraver.cc

diff --git a/lily/keep-alive-together-engraver.cc b/lily/keep-alive-together-engraver.cc
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+/*
+  This file is part of LilyPond, the GNU music typesetter.
+
+  Copyright (C) 2010--2011 Joe Neeman <joeneeman@gmail.com>
+
+  LilyPond is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  LilyPond 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 General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with LilyPond.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "context.hh"
+#include "dispatcher.hh"
+#include "engraver.hh"
+#include "grob.hh"
+#include "grob-array.hh"
+
+#include "translator.icc"
+
+class Keep_alive_together_engraver: public Engraver
+{
+  vector<Grob*> group_spanners_;
+
+public:
+  TRANSLATOR_DECLARATIONS (Keep_alive_together_engraver);
+  DECLARE_ACKNOWLEDGER (hara_kiri_group_spanner);
+
+  virtual void finalize ();
+};
+
+Keep_alive_together_engraver::Keep_alive_together_engraver ()
+{
+}
+
+void
+Keep_alive_together_engraver::acknowledge_hara_kiri_group_spanner (Grob_info i)
+{
+  group_spanners_.push_back (i.grob ());
+}
+
+void
+Keep_alive_together_engraver::finalize ()
+{
+  for (vsize i = 0; i < group_spanners_.size (); ++i)
+    {
+      SCM grob_array_scm = Grob_array::make_array ();
+      Grob_array *ga = unsmob_grob_array (grob_array_scm);
+
+      // It would make Hara_kiri_group_spanner::request_suicide a _little_
+      // faster if we removed each grob from its own array. It seems
+      // unnecessary for now, though.
+      ga->set_array (group_spanners_);
+      group_spanners_[i]->set_object ("keep-alive-with", grob_array_scm);
+    }
+}
+
+ADD_ACKNOWLEDGER (Keep_alive_together_engraver, hara_kiri_group_spanner);
+
+ADD_TRANSLATOR (Keep_alive_together_engraver,
+               /* doc */
+               "This engraver collects all @code{Hara_kiri_group_spanner}s "
+               "that are created in contexts at or below its own.  "
+               "These spanners are then tied together so that one will "
+               "be removed only if all are removed.  For example, "
+               "if a @code{StaffGroup} uses this engraver, then the staves "
+               "in the group will all be visible as long as there is a note "
+               "in at least one of them.",
+
+               /* create */
+               "",
+
+               /* read */
+               "",
+
+               /* write */
+               ""
+               );