Imported Upstream version 2.16.0

[lilypond.git] / scm / auto-beam.scm

diff --git a/scm/auto-beam.scm b/scm/auto-beam.scm
index 82b5917d1c2730bc8b88d9adaa2621806e45e7f0..b77022f2fca1cb2e24a164cdf4e2f7e8d1628f87 100644 (file)
--- a/scm/auto-beam.scm
+++ b/scm/auto-beam.scm
@@ -1,6 +1,6 @@
 ;;;; This file is part of LilyPond, the GNU music typesetter.
 ;;;;
-;;;; Copyright (C) 2000--2011 Jan Nieuwenhuizen <janneke@gnu.org>
+;;;; Copyright (C) 2000--2012 Jan Nieuwenhuizen <janneke@gnu.org>
 ;;;;
 ;;;; LilyPond is free software: you can redistribute it and/or modify
 ;;;; it under the terms of the GNU General Public License as published by
@@ -16,9 +16,9 @@
 ;;;; along with LilyPond.  If not, see <http://www.gnu.org/licenses/>.
 
 ;;  Determine whether an auto beam should be extended to the right
-;;  of the current stem.  We start anywhere except on the last note
-;;  of a beat.  We end according to the follwing rules, in order
-;;  of decreasing priority:
+;;  of the current stem.  We start anywhere, except mid-measure in
+;;  3/4 time. We end according to the follwing rules, in order of
+;;  decreasing priority:
 ;;
 ;;  1. end <type>
 ;;  2. end <greater type>
@@ -79,6 +79,7 @@
                                           '())
                                beaming<?))
              (function (if (= dir START) 'begin 'end))
+             (beam-half-measure (get 'beamHalfMeasure #t))
              (type (moment->fraction test-beam))
              (non-grace (ly:make-moment
                           (ly:moment-main-numerator measure-pos)
@@ -106,15 +107,13 @@
                                   exception-grouping 0 grouping-moment)))
 
        (if (= dir START)
-            ;; Start rules
-            (or (not (equal? time-signature-fraction '(3 . 4))) ;; start anywhere if not 3/4
-                (= (ly:moment-main-numerator pos) 0) ;; start at beginning of measure
-               (not (null? exception-grouping)) ;; don't use special rules if exception
-               (beat-end? pos beat-endings)  ;; are we at start of beat?
-               (and (not (equal? test-beam base-moment)) ;; is beat split?
-                     (not (beat-end? (ly:moment-add pos test-beam)
-                                     beat-endings))))  ;; will this note end the beat
-            ;; End rules
+            ;; Start rules -- #t if beam is allowed to start
+            (or beam-half-measure ;; Start anywhere, but option for mid-measure
+                (not (equal? (ly:moment-add pos pos) measure-length))
+                (not (= 3 (car time-signature-fraction))) ;; in triple meter
+                (not (= (cdr type) ;; when the beamed note is 1/6 of a measure
+                        (* 2 (cdr time-signature-fraction)))))
+            ;; End rules -- #t if beam is required to end
             (or (= (ly:moment-main-numerator pos) 0) ;; end at measure beginning
                 (if (null? exception-grouping)
                     (beat-end? pos beat-endings) ;; no exception, so check beat ending