Group contexts in the Keep_alive_together_engraver (issue 310230043 by address@hidden)

[mark . opus11]

Reviewers: ,

Message:
This patch allows independent sub-groups to operate in the
Keep_alive_together_engraver. For example, it may be desired to display
four instruments in either one tutti staff, two duo staves (I+II,
III+IV), or four solo staves. By labelling the pairs in this situation,
it is possible for the duo-to-solo behaviour of the pairs to operate
independently of each other.

Description:
Group contexts in the Keep_alive_together_engraver

This introduces a `VerticalAxisGroup.keep-alive-group' property
which can be set to a symbol to associate a subset of contexts
under the control of the same Keep_alive_together_engraver. This
group operates only up to the highest `remove-layer` level of its
members.

Please review this at https://codereview.appspot.com/310230043/

Affected files (+38, -0 lines):
  M lily/hara-kiri-group-spanner.cc
  M lily/keep-alive-together-engraver.cc
  M scm/define-grob-properties.scm


Index: lily/hara-kiri-group-spanner.cc
diff --git a/lily/hara-kiri-group-spanner.cc  
b/lily/hara-kiri-group-spanner.cc
index  
76207a5c928abb5dfae0bdb788c063931de21cf2..d721a9642ed72ca953f5733fa4bb5f3e55d855ef  
100644
--- a/lily/hara-kiri-group-spanner.cc
+++ b/lily/hara-kiri-group-spanner.cc
@@ -199,6 +199,7 @@ ADD_INTERFACE (Hara_kiri_group_spanner,
                /* properties */
                "items-worth-living "
                "important-column-ranks "
+               "keep-alive-group "
                "keep-alive-with "
                "make-dead-when "
                "remove-empty "
Index: lily/keep-alive-together-engraver.cc
diff --git a/lily/keep-alive-together-engraver.cc  
b/lily/keep-alive-together-engraver.cc
index  
8931a819c6ff45150ccb229fdec3d06b8c457426..cad55ba1bfe494f74d9bcbd86122985a22011d82  
100644
--- a/lily/keep-alive-together-engraver.cc
+++ b/lily/keep-alive-together-engraver.cc
@@ -26,6 +26,8 @@

 #include "translator.icc"

+#include <map>
+
 class Keep_alive_together_engraver: public Engraver
 {
   vector<Grob *> group_spanners_;
@@ -50,12 +52,30 @@  
Keep_alive_together_engraver::acknowledge_hara_kiri_group_spanner  
(Grob_info i)
 void
 Keep_alive_together_engraver::finalize ()
 {
+  // construct map of maximum remove-layer values in each named  
keep-alive-group
+  map<SCM, int> group_max_map_;
+
+  for (vsize i = 0; i < group_spanners_.size (); ++i)
+    {
+      SCM this_group = group_spanners_[i]->get_property  
("keep-alive-group");
+      SCM this_layer = group_spanners_[i]->get_property ("remove-layer");
+      if (!scm_is_integer (this_layer))
+        continue;
+
+      if (group_max_map_.find (this_group) == group_max_map_.end ())
+        group_max_map_[this_group] = scm_to_int (this_layer);
+      else
+        group_max_map_[this_group] = max (scm_to_int (this_layer),
+                                          group_max_map_[this_group]);
+    }
+
   for (vsize i = 0; i < group_spanners_.size (); ++i)
     {
       SCM this_layer = group_spanners_[i]->get_property ("remove-layer");
       if (scm_is_false (this_layer))
         continue;

+      SCM this_group = group_spanners_[i]->get_property  
("keep-alive-group");
       SCM live_scm = Grob_array::make_array ();
       Grob_array *live = unsmob<Grob_array> (live_scm);
       SCM dead_scm = Grob_array::make_array ();
@@ -96,6 +116,21 @@ Keep_alive_together_engraver::finalize ()
                 }
             }

+          SCM that_group = group_spanners_[j]->get_property  
("keep-alive-group");
+          if (!scm_is_eq (that_group, this_group))
+            {
+              if (scm_is_integer (this_layer) and
+                  group_max_map_[that_group] < scm_to_int (this_layer))
+                {
+                  // layer is killed by a lower level group
+                  dead->add (group_spanners_[j]);
+                  continue;
+                }
+              else
+                // layer ignores a group at undefined, equal or higher  
level
+                continue;
+            }
+
           SCM that_layer = group_spanners_[j]->get_property  
("remove-layer");

           if (scm_is_false (that_layer))
Index: scm/define-grob-properties.scm
diff --git a/scm/define-grob-properties.scm b/scm/define-grob-properties.scm
index  
d55ab4c8c788449af838d45b2afd55b9b1e8247c..ee6d6e042335c26791f873acd3d24975a918580c  
100644
--- a/scm/define-grob-properties.scm
+++ b/scm/define-grob-properties.scm
@@ -547,6 +547,8 @@ slur quants to this position, and print the respective  
scores.")
 ;;;
      (keep-inside-line ,boolean? "If set, this column cannot have
 objects sticking into the margin.")
+     (keep-alive-group ,symbol? "A symbol defining the group to
+which this @code{VerticalAxisGroup} grob belongs.")
      (kern ,ly:dimension? "The space between individual elements
 in any compound bar line, expressed as a multiple of the default
 staff-line thickness (i.e. the visual output is @emph{not}