From c23257e11e29845598281ec0e6acabdc8b281b7e Mon Sep 17 00:00:00 2001
From: Han-Wen Nienhuys <hanwen@xs4all.nl>
Date: Mon, 20 Aug 2007 01:19:15 -0300
Subject: [PATCH] Calculate vertical extent of arpeggio via positions property.

This eliminates duplicate code, and allows manual override of
arpeggio(bracket) extents.
---
 lily/arpeggio.cc               | 58 ++++++++++++++++++----------------
 lily/include/arpeggio.hh       |  2 ++
 scm/define-grob-properties.scm |  9 +++---
 scm/define-grobs.scm           |  1 +
 4 files changed, 39 insertions(+), 31 deletions(-)

diff --git a/lily/arpeggio.cc b/lily/arpeggio.cc
index b501117624..6773b846e9 100644
--- a/lily/arpeggio.cc
+++ b/lily/arpeggio.cc
@@ -18,12 +18,9 @@
 #include "lookup.hh"
 #include "pointer-group-interface.hh"
 
-MAKE_SCHEME_CALLBACK (Arpeggio, print, 1);
-SCM
-Arpeggio::print (SCM smob)
+Grob *
+Arpeggio::get_common_y (Grob *me)
 {
-  Grob *me = unsmob_grob (smob);
-
   Grob *common = me;
 
   extract_grob_set (me, "stems", stems);
@@ -34,17 +31,27 @@ Arpeggio::print (SCM smob)
 					Y_AXIS);
     }
 
+  return common;
+}
+
+MAKE_SCHEME_CALLBACK(Arpeggio, calc_positions, 1);
+SCM
+Arpeggio::calc_positions (SCM grob)
+{
+  Grob *me = unsmob_grob (grob);
+  Grob *common = get_common_y (me);
+  
   /*
     TODO:
 
     Using stems here is not very convenient; should store noteheads
     instead, and also put them into the support. Now we will mess up
     in vicinity of a collision.
-
   */
   Interval heads;
   Real my_y = me->relative_coordinate (common, Y_AXIS);
 
+  extract_grob_set (me, "stems", stems);
   for (vsize i = 0; i < stems.size (); i++)
     {
       Grob *stem = stems[i];
@@ -56,6 +63,20 @@ Arpeggio::print (SCM smob)
 		   - my_y);
     }
 
+  heads *= 1/Staff_symbol_referencer::staff_space(me);
+
+  return ly_interval2scm (heads);
+}
+
+MAKE_SCHEME_CALLBACK (Arpeggio, print, 1);
+SCM
+Arpeggio::print (SCM smob)
+{
+  Grob *me = unsmob_grob (smob);
+  Interval heads = robust_scm2interval (me->get_property ("positions"),
+					Interval())
+    * Staff_symbol_referencer::staff_space (me);
+  
   if (heads.is_empty () || heads.length () < 0.5)
     {
       if (!to_boolean (me->get_property ("transparent")))
@@ -101,27 +122,9 @@ SCM
 Arpeggio::brew_chord_bracket (SCM smob)
 {
   Grob *me = unsmob_grob (smob);
-  Grob *common = me;
-
-  extract_grob_set (me, "stems", stems);
-  for (vsize i = 0; i < stems.size (); i++)
-    {
-      Grob *stem = stems[i];
-      common = common->common_refpoint (Staff_symbol_referencer::get_staff_symbol (stem),
-					Y_AXIS);
-    }
-
-  Interval heads;
-  Real my_y = me->relative_coordinate (common, Y_AXIS);
-
-  for (vsize i = 0; i < stems.size (); i++)
-    {
-      Grob *stem = stems[i];
-      Grob *ss = Staff_symbol_referencer::get_staff_symbol (stem);
-      Interval iv = Stem::head_positions (stem);
-      iv *= Staff_symbol::staff_space (ss) / 2.0;
-      heads.unite (iv + ss->relative_coordinate (common, Y_AXIS) - my_y);
-    }
+  Interval heads = robust_scm2interval (me->get_property ("positions"),
+					Interval())
+    * Staff_symbol_referencer::staff_space (me);
 
   Real lt = me->layout ()->get_dimension (ly_symbol2scm ("line-thickness"));
   Real sp = 1.5 * Staff_symbol_referencer::staff_space (me);
@@ -170,6 +173,7 @@ ADD_INTERFACE (Arpeggio,
 
 	       /* properties */
 	       "arpeggio-direction "
+	       "positions "
 	       "stems "
 	       "script-priority " // TODO: make around-note-interface
 	       );
diff --git a/lily/include/arpeggio.hh b/lily/include/arpeggio.hh
index c18eb10c3e..7db201bb00 100644
--- a/lily/include/arpeggio.hh
+++ b/lily/include/arpeggio.hh
@@ -16,7 +16,9 @@
 class Arpeggio
 {
 public:
+  static Grob *get_common_y (Grob *);
   DECLARE_SCHEME_CALLBACK (print, (SCM));
+  DECLARE_SCHEME_CALLBACK (calc_positions, (SCM));
   DECLARE_SCHEME_CALLBACK (brew_chord_bracket, (SCM));
   DECLARE_SCHEME_CALLBACK (width, (SCM));
   DECLARE_SCHEME_CALLBACK (height, (SCM));
diff --git a/scm/define-grob-properties.scm b/scm/define-grob-properties.scm
index 1319cf645d..754ebcb00e 100644
--- a/scm/define-grob-properties.scm
+++ b/scm/define-grob-properties.scm
@@ -406,11 +406,12 @@ at a column with a negative penalty.")
 whether to put a page turn at this column.  Can be @code{force} or
 @code{allow}.")
      (parenthesized ,boolean? "Parenthesize this grob.")
-     (positions ,pair? "Pair of staff coordinates @code{(@var{left}
+     (positions ,number-pair? "Pair of staff coordinates @code{(@var{left}
 . @var{right})}, where both @var{left} and @var{right} are in
-@code{staff-space} units of the current staff.  LilyPond uses these
-values to select which slur candidate positions to use; if extreme
-positions are requested, LilyPond selects the closest positions.")
+@code{staff-space} units of the current staff.
+
+For slurs, this value selects which slur candidate
+to use; if extreme positions are requested, the closest one is taken.")
 
      (ratio ,number? "Parameter for slur shape.  The higher this
 number, the quicker the slur attains its @code{height-limit}.")
diff --git a/scm/define-grobs.scm b/scm/define-grobs.scm
index ce76c346f8..caf1947323 100644
--- a/scm/define-grobs.scm
+++ b/scm/define-grobs.scm
@@ -150,6 +150,7 @@
 	(Y-offset . ,ly:staff-symbol-referencer::callback)
 	(X-offset . ,ly:side-position-interface::x-aligned-side)
 	(direction . ,LEFT)
+	(positions . ,ly:arpeggio::calc-positions)
 	(padding . 0.5)
 	(script-priority . 0)
 	(side-axis . ,X)
-- 
2.39.2