From 32bbd3a473244d255f8b713516c008a5d3ec6cb4 Mon Sep 17 00:00:00 2001
From: Mike Solomon <mike@apollinemike.com>
Date: Wed, 5 Sep 2012 00:48:43 +0200
Subject: [PATCH] Dynamics do not avoid extremal cross-staff stems in extremal
 directions.

If a cross-staff stem is pointing down and a dynamic is attached below
the stem, for example, it will not be horizontally shifted.
---
 .../dynamics-avoid-cross-staff-stem-2.ly      | 23 +++++++++++++++++++
 lily/self-alignment-interface.cc              | 19 ++++++++++++++-
 2 files changed, 41 insertions(+), 1 deletion(-)
 create mode 100644 input/regression/dynamics-avoid-cross-staff-stem-2.ly

diff --git a/input/regression/dynamics-avoid-cross-staff-stem-2.ly b/input/regression/dynamics-avoid-cross-staff-stem-2.ly
new file mode 100644
index 0000000000..e549646f75
--- /dev/null
+++ b/input/regression/dynamics-avoid-cross-staff-stem-2.ly
@@ -0,0 +1,23 @@
+\version "2.17.2"
+
+\header {
+  texidoc = "Dynamics do not horizontally shift when attached to
+an axis-group extremal cross staff grob that's extremal side
+(UP or DOWN) is the same as its direction.
+"
+}
+
+\new PianoStaff <<
+  \new Staff = "up" {
+    s1 |
+  }
+  \new Staff = "down" {
+    \clef bass
+    \stemDown
+    % keep staff alive
+    <c,, c,>8 [ <c,, c,>8_\f
+    \change Staff = "up"
+    g' g' ]
+    r2 |
+  }
+>>
diff --git a/lily/self-alignment-interface.cc b/lily/self-alignment-interface.cc
index a37b587100..ff2b5bfd59 100644
--- a/lily/self-alignment-interface.cc
+++ b/lily/self-alignment-interface.cc
@@ -199,7 +199,24 @@ Self_alignment_interface::avoid_colliding_grobs (Grob *me, Axis a, Real offset)
 
   Interval iv = me->extent (me, a) + offset;
   for (vsize i = 0; i < colls.size (); i++)
-    ivs.push_back (colls[i]->extent (refp, a));
+    {
+      int my_vai = Grob::get_vertical_axis_group_index (colls[i]);
+      Direction dir = get_grob_direction (colls[i]);
+      // if coll is cross staff but extremal and pointing in the
+      // direction of the extrema, we don't take it into consideration
+      if (Grob *beam = unsmob_grob (colls[i]->get_object ("beam")))
+        {
+          Interval_t<int> vais;
+          extract_grob_set (beam, "normal-stems", stems);
+          for (vsize j = 0; j < stems.size (); j++)
+            vais.add_point (Grob::get_vertical_axis_group_index (stems[j]));
+          // ugh...up and down are different for VerticalAxisGroup order...
+          if ((my_vai == vais[DOWN] && dir == UP)
+              || (my_vai == vais[UP] && dir == DOWN))
+            continue;
+        }
+      ivs.push_back (colls[i]->extent (refp, a));
+    }
 
   Interval_minefield minefield (Interval (iv.center (), iv.center ()), iv.length ());
   for (vsize i = 0; i < ivs.size (); i++)
-- 
2.39.2