From 1dd946408282051972bc75c849cd406670174da1 Mon Sep 17 00:00:00 2001
From: Mike Solomon <mike@apollinemike.com>
Date: Sat, 2 Jul 2011 23:09:06 +0200
Subject: [PATCH] Fixes the multi-line glissandos to use more intelligent line
 breaks.

---
 input/regression/glissando-broken-multiple.ly |  7 +++
 lily/line-spanner.cc                          |  4 +-
 scm/define-grobs.scm                          |  3 +-
 scm/output-lib.scm                            | 45 +++++++++++--------
 4 files changed, 38 insertions(+), 21 deletions(-)

diff --git a/input/regression/glissando-broken-multiple.ly b/input/regression/glissando-broken-multiple.ly
index 4ef945b427..906f984be4 100644
--- a/input/regression/glissando-broken-multiple.ly
+++ b/input/regression/glissando-broken-multiple.ly
@@ -15,4 +15,11 @@
   \break s1
   \break s1
   c,1^\ff\trill
+  % Subsequent glissando prints correctly instead of
+  % using the Y positions from the previous one.
+  a'1\glissando
+  \break s1
+  \break s1
+  \break s1
+  e1^\ff\trill
 }
diff --git a/lily/line-spanner.cc b/lily/line-spanner.cc
index 69cbc69ce0..d50b94834a 100644
--- a/lily/line-spanner.cc
+++ b/lily/line-spanner.cc
@@ -224,6 +224,9 @@ Line_spanner::print (SCM smob)
 {
   Spanner *me = dynamic_cast<Spanner *> (unsmob_grob (smob));
 
+  // Triggers simple-Y calculations
+  bool simple_y = to_boolean (me->get_property ("simple-Y")) && !to_boolean (me->get_property ("cross-staff"));
+
   Drul_array<SCM> bounds (me->get_property ("left-bound-info"),
 			  me->get_property ("right-bound-info"));
 
@@ -269,7 +272,6 @@ Line_spanner::print (SCM smob)
   while (flip (&d) != LEFT);
 
   Grob *my_common_y = common_y[LEFT]->common_refpoint (common_y[RIGHT], Y_AXIS);
-  bool simple_y = to_boolean (me->get_property ("simple-Y")) && !to_boolean (me->get_property ("cross-staff"));
 
   if (!simple_y)
     {
diff --git a/scm/define-grobs.scm b/scm/define-grobs.scm
index d2162ce587..9a8d14a1c3 100644
--- a/scm/define-grobs.scm
+++ b/scm/define-grobs.scm
@@ -927,7 +927,6 @@
     (Glissando
      . (
 	(after-line-breaking . ,ly:spanner::kill-zero-spanned-time)
-	(before-line-breaking . ,glissando::before-line-breaking)
 	(bound-details . ((right . ((attach-dir .  ,CENTER)
 				    (padding . 1.5)
 				      ))
@@ -939,7 +938,7 @@
 	(left-bound-info . ,ly:line-spanner::calc-left-bound-info)
 	(normalized-endpoints . ,ly:spanner::calc-normalized-endpoints)
 	(right-bound-info . ,ly:line-spanner::calc-right-bound-info)
-	(simple-Y . #t)
+	(simple-Y . ,glissando::make-simple-y)
 	(stencil . ,ly:line-spanner::print)
 	(style . line)
 	(X-extent . #f)
diff --git a/scm/output-lib.scm b/scm/output-lib.scm
index a9581e5e8e..01953a9412 100644
--- a/scm/output-lib.scm
+++ b/scm/output-lib.scm
@@ -795,26 +795,35 @@ between the two text elements."
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;; glissando
 
-(define-public (glissando::before-line-breaking grob)
-  "Establishes the Y terminus points of the glissando based on the pre-broken
-positions of its left and right bounds."
-  (let ((bound-details (ly:grob-property grob 'bound-details))
+(define-public (glissando::make-simple-y grob)
+ "Establishes the Y terminus points of the glissando based on the
+pre-broken positions of its left and right bounds."
+ (let* ((siblings (ly:spanner-broken-into (ly:grob-original grob)))
+        (bound-details (ly:grob-property grob 'bound-details))
         (extra-dy (ly:grob-property grob 'extra-dy 0.0)))
 
-    (for-each (lambda (dir-sym)
-                (let* ((details (assoc-get dir-sym bound-details))
-                       (dir (if (eq? dir-sym 'left) LEFT RIGHT))
-                       (bound (ly:spanner-bound grob dir))
-                       (common-y (ly:grob-common-refpoint grob bound Y))
-                       (y (+ (interval-center (ly:grob-extent bound common-y Y))
-                             (/ (* dir extra-dy)
-                                2))))
-                  (if (not (assoc-get 'Y details))
-                      (set! bound-details (assoc-set! bound-details dir-sym
-                                                      (acons 'Y y details))))))
-              '(left right))
-
-    (set! (ly:grob-property grob 'bound-details) bound-details)))
+   (and (pair? siblings)
+        (for-each (lambda (dir-sym)
+                    (let* ((details (assoc-get dir-sym bound-details))
+                           (dir (if (eq? dir-sym 'left) LEFT RIGHT))
+                           (good-grob (if (eq? dir-sym 'left)
+                                          (first siblings)
+                                          (last siblings)))
+                           (bound (ly:spanner-bound good-grob dir))
+                           (common-y (ly:grob-common-refpoint good-grob
+                                                              bound
+                                                              Y))
+                           (y (+ (interval-center (ly:grob-extent bound
+                                                                 common-y
+                                                                 Y))
+                                 (/ (* dir extra-dy)
+                                    2))))
+                      (if (not (assoc-get 'Y details))
+                          (set! bound-details (assoc-set! bound-details dir-sym
+                                                          (acons 'Y y details))))))
+                  '(left right))
+
+        (set! (ly:grob-property grob 'bound-details) bound-details))))
 
 
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-- 
2.39.2