From 56d793a12307e44d79c63a14f72152ba7c664763 Mon Sep 17 00:00:00 2001
From: Kevin Dalley <address@hidden>
Date: Fri, 4 Jul 2008 22:01:31 +0100
Subject: [PATCH] Corrected on_line for better ledger lines for different staves.

---
 input/regression/ledger-lines-varying-staves.ly |   50 +++++++++++++++++++++++
 lily/include/staff-symbol.hh                    |    1 +
 lily/staff-symbol-referencer.cc                 |    3 +-
 lily/staff-symbol.cc                            |   29 +++++++++++++-
 4 files changed, 80 insertions(+), 3 deletions(-)
 create mode 100644 input/regression/ledger-lines-varying-staves.ly

diff --git a/input/regression/ledger-lines-varying-staves.ly b/input/regression/ledger-lines-varying-staves.ly
new file mode 100644
index 0000000..7d9f0e0
--- /dev/null
+++ b/input/regression/ledger-lines-varying-staves.ly
@@ -0,0 +1,50 @@
+\version "2.11.51"
+\header {
+  texidoc = "Ledger lines should appear at every other location
+for a variety of staves using both @code{line-count} and
address@hidden"
+}
+
+notes = \relative c' {
+  c1 | d | e | f
+  g1 | a | b | c
+  d1 | e | f | g
+  a1
+}
+
+\new Staff {
+  % upper and lower lines both odd
+  #(define mylines '(-1 0 1))
+  \override Staff.StaffSymbol #'line-count = #(length mylines)
+  \override Staff.StaffSymbol #'line-positions = #mylines
+  \notes
+}
+
+\new Staff {
+  % upper and lower lines both even
+  #(define mylines '(-2 0 2))
+  \override Staff.StaffSymbol #'line-positions = #mylines
+
+  \override Staff.StaffSymbol #'line-count = #(length mylines)
+  \notes
+}
+
+\new Staff {
+  % lower line odd, upper line even
+  #(define mylines '(-1 0 2))
+  \override Staff.StaffSymbol #'line-positions = #mylines
+  \override Staff.StaffSymbol #'line-count = #(length mylines)
+  \notes
+}
+
+\new Staff {
+  % odd line count
+  \override Staff.StaffSymbol #'line-count = #5
+  \notes
+}
+
+\new Staff {
+  % even line count
+  \override Staff.StaffSymbol #'line-count = #4
+  \notes
+}
diff --git a/lily/include/staff-symbol.hh b/lily/include/staff-symbol.hh
index 4dacde8..6791e7b 100644
--- a/lily/include/staff-symbol.hh
+++ b/lily/include/staff-symbol.hh
@@ -24,6 +24,7 @@ public:
   
   static int get_steps (Grob *);
   static int line_count (Grob *);
+  static bool on_line (Grob *me, int pos);
   DECLARE_SCHEME_CALLBACK (print, (SCM));
   DECLARE_SCHEME_CALLBACK (height, (SCM));  
   DECLARE_GROB_INTERFACE();
diff --git a/lily/staff-symbol-referencer.cc b/lily/staff-symbol-referencer.cc
index e8ef99f..d623bd3 100644
--- a/lily/staff-symbol-referencer.cc
+++ b/lily/staff-symbol-referencer.cc
@@ -35,8 +35,7 @@ Staff_symbol_referencer::on_staff_line (Grob *me)
 bool
 Staff_symbol_referencer::on_line (Grob *me, int pos)
 {
-  int sz = line_count (me) - 1;
-  return ((pos + sz) % 2) == 0;
+  return Staff_symbol::on_line (me, pos);
 }
 
 bool
diff --git a/lily/staff-symbol.cc b/lily/staff-symbol.cc
index d4aa9e1..df441d4 100644
--- a/lily/staff-symbol.cc
+++ b/lily/staff-symbol.cc
@@ -167,8 +167,35 @@ Staff_symbol::height  (SCM smob)
   return ly_interval2scm (y_ext);
 }
 
+bool
+Staff_symbol::on_line (Grob *me, int pos)
+{
+  SCM line_positions = me->get_property ("line-positions");
+  if (scm_is_pair (line_positions))
+    {
+      Real min_line = SCM_FLTMAX;
+      Real max_line = -SCM_FLTMAX;
+      for (SCM s = line_positions; scm_is_pair (s); s = scm_cdr (s))
+	{
+	  Real current_line = scm_to_double (scm_car (s));
+	  if (pos == current_line)
+	    return true;
+	  if (current_line > max_line)
+	    max_line = current_line;
+	  if (current_line < min_line)
+	    min_line = current_line;
+	
+	}
+      if (pos < min_line)
+	return (( (int) (rint (pos - min_line)) % 2) == 0);
+      if (pos > max_line)
+	return (( (int) (rint (pos - max_line)) % 2) == 0);
 
-
+      return false;
+    }
+  else
+    return ((abs (pos + line_count (me)) % 2) == 1);
+}
 
 ADD_INTERFACE (Staff_symbol,
 	       "This spanner draws the lines of a staff.  A staff symbol"
-- 
1.5.4.3