X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=scm%2Fauto-beam.scm;h=85ff3c65a1db9ef07a8dfb3b88a55eb569bbda12;hb=b27579f3a9b2311232f8eb1f11403f560dcc9b17;hp=3cb350867b18265f1f240f2527bd28d1961e30f4;hpb=17183f4a9696f2187128490a669895964959fa84;p=lilypond.git

diff --git a/scm/auto-beam.scm b/scm/auto-beam.scm
index 3cb350867b..85ff3c65a1 100644
--- a/scm/auto-beam.scm
+++ b/scm/auto-beam.scm
@@ -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.   In general, we start anywhere except on
+;;  the last note of a beat. We end according to the follwing rules,
+;;  in order of decreasing priority:
 ;;
 ;;  1. end <type>
 ;;  2. end <greater type>
@@ -61,6 +61,12 @@
   (define (beat-end? moment beat-structure)
     (pair? (member moment beat-structure)))  ;; member returns a list if found, not #t
 
+  (define (use-special-3-4-rules? fraction base-moment exceptions)
+    "Should we use special 3/4 time signature beaming rules?"
+     (and (equal? fraction '(3 . 4))
+          (equal? base-moment (ly:make-moment 1 4))
+          (null? (assoc-get '(1 . 8) exceptions '()))))
+
   ;; Start of actual auto-beam test routine
   ;;
   ;;
@@ -79,6 +85,8 @@
                                           '())
                                beaming<?))
              (function (if (= dir START) 'begin 'end))
+             (beam-whole-measure (get 'beamWholeMeasure #t))
+             (beam-half-measure (get 'beamHalfMeasure #f))
              (type (moment->fraction test-beam))
              (non-grace (ly:make-moment
                           (ly:moment-main-numerator measure-pos)
@@ -106,17 +114,35 @@
                                   exception-grouping 0 grouping-moment)))
 
 	(if (= dir START)
-            ;; Start rules
-            (or (not (equal? time-signature-fraction '(3 . 4))) ;; start anywhere if not 3/4
+            ;; Start rules -- start anywhere unless 3/4 with default rules
+            ;; #t if beam is to start
+            (or (not (use-special-3-4-rules?
+                       time-signature-fraction
+                       base-moment
+                       exceptions)) ;; start anywhere if not default 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 beam-half-measure
+                     (equal? type '(1 . 8))
+                     (equal? pos (ly:make-moment 3 8))) ;; start at mid-measure if 1/8 note beam
+                (beat-end? pos beat-endings)  ;; start if 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
+            ;; End rules -- #t if beam is 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
-                    (member pos exception-moments))))))) ;; check exception rule
+                (if (use-special-3-4-rules?
+                      time-signature-fraction
+                      base-moment
+                      exceptions)
+                    ;; special rule for default 3/4 beaming
+                    (if (and (equal? type '(1 . 8))
+                             (or beam-whole-measure
+                                 (and beam-half-measure
+                                      (not (equal? pos (ly:make-moment 3 8))))))
+                        #f
+                        (beat-end? pos beat-endings))
+                    ;; rules for all other cases -- check for applicable exception
+                    (if (null? exception-grouping)
+                        (beat-end? pos beat-endings) ;; no exception, so check beat ending
+                        (member pos exception-moments)))))))) ;; check exception rule