Web-ja: update introduction

[lilypond.git] / lily / beaming-pattern.cc

diff --git a/lily/beaming-pattern.cc b/lily/beaming-pattern.cc
index 5510965c31f3fcdcd6e103b5795e6bc0dbf21d30..46a46a5d2ea529aa4c1e09836413f4ee0b708d05 100644 (file)
--- a/lily/beaming-pattern.cc
+++ b/lily/beaming-pattern.cc
@@ -21,8 +21,6 @@
 #include "beaming-pattern.hh"
 #include "misc.hh"
 
-using std::vector;
-
 /*
   Represents a stem belonging to a beam. Sometimes (for example, if the stem
   belongs to a rest and stemlets aren't used) the stem will be invisible.
@@ -134,8 +132,6 @@ Beaming_pattern::beamify (Beaming_options const &options)
   if (infos_.size () <= 1)
     return;
 
-  int subdivide_beam_count = intlog2(options.base_moment_.main_part_.den())-2;
-
   unbeam_invisible_stems ();
 
   if (infos_[0].start_moment_.grace_part_)
@@ -170,12 +166,24 @@ Beaming_pattern::beamify (Beaming_options const &options)
         Direction non_flag_dir = -flag_directions[i];
         if (non_flag_dir)
           {
-            int importance = infos_[i + 1].rhythmic_importance_;
-            int count = (importance < 0 && options.subdivide_beams_) 
-                        ? subdivide_beam_count
-                        : min (min (infos_[i].count (non_flag_dir),
-                                        infos_[i + non_flag_dir].count (-non_flag_dir)),
-                                   infos_[i - non_flag_dir].count (non_flag_dir));
+            int count =
+                (infos_[i + 1].rhythmic_importance_ < 0 &&
+                 options.subdivide_beams_)
+                        // we're left of a subdivision
+                ?  (i != infos_.size () - 2)
+                   // respect the beam count for shortened beams ...
+                   ? max (beam_count_for_rhythmic_position (i + 1),
+                          beam_count_for_length (remaining_length (i + 1)))
+                   // ... except if there's only one trailing stem
+                   : beam_count_for_rhythmic_position (i + 1)
+
+                // we're at any other stem
+                : min (min (infos_[i].count (non_flag_dir),
+                            infos_[i + non_flag_dir].count (-non_flag_dir)),
+                       infos_[i - non_flag_dir].count (non_flag_dir));
+
+            // Ensure at least one beam is left, even for groups longer than 1/8
+            count = max (count, 1);
 
             infos_[i].beam_count_drul_[non_flag_dir] = count;
           }
@@ -365,6 +373,25 @@ Beaming_pattern::end_moment (int i) const
          + infos_.at (i).factor_ * dur.get_length ();
 }
 
+Moment
+Beaming_pattern::remaining_length (int i) const
+{
+    return end_moment (infos_.size () - 1) - infos_[i].start_moment_;
+}
+
+int
+Beaming_pattern::beam_count_for_rhythmic_position (int idx) const
+{
+    // Calculate number of beams representing the rhythmic position of given stem
+    return intlog2(infos_[idx].start_moment_.main_part_.den()) - 2;
+}
+
+int
+Beaming_pattern::beam_count_for_length (Moment len) const
+{
+    return intlog2(len.main_part_.den()) - 2 - intlog2(len.main_part_.num());
+}
+
 bool
 Beaming_pattern::invisibility (int i) const
 {