Attaches bound info to beam for better normalized-endpoint calculations. (issue4605047)

[mtsolo]

Reviewers: ,

Message:
This, in tandem with the modification to spanner_length, leads to better
optical results for feathered beam breaking.

Description:
Attaches bound info to beam for better normalized-endpoint calculations.

Also adds a slight modification to the print function to take into
account
the width of the last stem.

Please review this at http://codereview.appspot.com/4605047/

Affected files:
  M lily/beam.cc


Index: lily/beam.cc
diff --git a/lily/beam.cc b/lily/beam.cc
index  
8a30752c386eccd8294b181c5dd18159c2b492d2..a49b35c98b7a2bbd8d7b9b243abb8f89a899b3ae  
100644
--- a/lily/beam.cc
+++ b/lily/beam.cc
@@ -560,13 +560,15 @@ Beam::print (SCM grob)
   if (normal_stem_count (me))
     {
       span[LEFT] = first_normal_stem (me)->relative_coordinate (commonx,  
X_AXIS);
-      span[RIGHT] = last_normal_stem (me)->relative_coordinate (commonx,  
X_AXIS);
+      span[RIGHT] = last_normal_stem (me)->relative_coordinate (commonx,  
X_AXIS)
+                    + last_normal_stem (me)->extent (commonx,  
X_AXIS).length ();
     }
   else
     {
       extract_grob_set (me, "stems", stems);
       span[LEFT] = stems[0]->relative_coordinate (commonx, X_AXIS);
-      span[RIGHT] = stems.back ()->relative_coordinate (commonx, X_AXIS);
+      span[RIGHT] = stems.back ()->relative_coordinate (commonx, X_AXIS)
+                    + stems.back ()->extent (commonx, X_AXIS).length ();
     }

   Real blot = me->layout ()->get_dimension (ly_symbol2scm  
("blot-diameter"));
@@ -581,6 +583,15 @@ Beam::print (SCM grob)
   else
     pos = ly_scm2realdrul (posns);

+  // allows correct normalized endpoints to be calculated
+  Direction d = LEFT;
+  Drul_array<SCM> bound_info (ly_symbol2scm ("left-bound-info"),  
ly_symbol2scm ("right-bound-info"));
+
+  do
+    me->set_property (bound_info[d], scm_list_2 (scm_cons (ly_symbol2scm  
("X"), scm_from_double (span[d])),
+                                                 scm_cons (ly_symbol2scm  
("Y"), scm_from_double (pos[d]))));
+  while (flip (&d) != LEFT);
+
   scale_drul (&pos, Staff_symbol_referencer::staff_space (me));

   Real dy = pos[RIGHT] - pos[LEFT];
@@ -1862,12 +1873,14 @@ ADD_INTERFACE (Beam,
               "grow-direction "
               "inspect-quants "
               "knee "
+              "left-bound-info "
               "length-fraction "
               "least-squares-dy "
               "neutral-direction "
               "normal-stems "
               "positions "
               "quantized-positions "
+              "right-bound-info "
               "shorten "
               "stems "
               );