X-Git-Url: https://git.donarmstrong.com/?a=blobdiff_plain;f=lily%2Fself-alignment-interface.cc;h=54d4a8ec6f5635e4cf0c1112022510a7261f0ea0;hb=11666bd0847dc1b53de0c558b6d47692c8b5c54a;hp=0c7215233338ebb32c277e2af1a2c88ec154c216;hpb=f93e4199873c91ae32f0e84a610d14853dc379df;p=lilypond.git

diff --git a/lily/self-alignment-interface.cc b/lily/self-alignment-interface.cc
index 0c72152333..54d4a8ec6f 100644
--- a/lily/self-alignment-interface.cc
+++ b/lily/self-alignment-interface.cc
@@ -1,7 +1,7 @@
 /*
   This file is part of LilyPond, the GNU music typesetter.
 
-  Copyright (C) 2004--2011 Han-Wen Nienhuys <hanwen@xs4all.nl>
+  Copyright (C) 2004--2012 Han-Wen Nienhuys <hanwen@xs4all.nl>
 
   LilyPond is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
@@ -20,7 +20,9 @@
 #include "self-alignment-interface.hh"
 
 #include "grob.hh"
+#include "note-column.hh"
 #include "paper-column.hh"
+#include "pointer-group-interface.hh"
 #include "warn.hh"
 
 MAKE_SCHEME_CALLBACK (Self_alignment_interface, y_aligned_on_self, 1);
@@ -54,10 +56,12 @@ Self_alignment_interface::aligned_on_self (Grob *me, Axis a, bool pure, int star
   if (scm_is_number (align))
     {
       Interval ext (me->maybe_pure_extent (me, a, pure, start, end));
-      if (ext.is_empty ())
-        programming_error ("cannot align on self: empty element");
-      else
+      // Empty extent doesn't mean an error - we simply don't align such grobs.
+      // However, empty extent and non-empty stencil would be suspicious.
+      if (!ext.is_empty ())
         return scm_from_double (- ext.linear_combination (scm_to_double (align)));
+      else if (me->get_stencil ())
+        warning (me->name () + " has empty extent and non-empty stencil.");
     }
   return scm_from_double (0.0);
 }
@@ -75,6 +79,27 @@ Self_alignment_interface::centered_on_x_parent (SCM smob)
   return centered_on_object (unsmob_grob (smob)->get_parent (X_AXIS), X_AXIS);
 }
 
+MAKE_SCHEME_CALLBACK (Self_alignment_interface, centered_on_note_columns, 1);
+SCM
+Self_alignment_interface::centered_on_note_columns (SCM smob)
+{
+  Item *it = unsmob_item (smob)->get_column ();
+  if (!it)
+    return scm_from_double (0.0);
+
+  extract_grob_set (it, "elements", elts);
+  vector<Grob *> ncs;
+  Interval centers;
+  for (vsize i = 0; i < elts.size (); i++)
+    if (Note_column::has_interface (elts[i]))
+      centers.add_point (scm_to_double (centered_on_object (elts[i], X_AXIS)));
+
+  if (centers.is_empty ())
+    return scm_from_double (0.0);
+
+  return scm_from_double (centers.center ());
+}
+
 MAKE_SCHEME_CALLBACK (Self_alignment_interface, centered_on_y_parent, 1);
 SCM
 Self_alignment_interface::centered_on_y_parent (SCM smob)
@@ -123,13 +148,19 @@ Self_alignment_interface::aligned_on_parent (Grob *me, Axis a)
   Real align = scm_to_double (align_prop);
 
   Interval ext (me->extent (me, a));
-  if (ext.is_empty ())
-    programming_error ("cannot align on self: empty element");
-  else
+
+  // Empty extent doesn't mean an error - we simply don't align such grobs.
+  // However, empty extent and non-empty stencil would be suspicious.
+  if (!ext.is_empty ())
     x -= ext.linear_combination (align);
+  else if (me->get_stencil ())
+    warning (me->name () + " has empty extent and non-empty stencil.");
 
+  // See comment above.
   if (!he.is_empty ())
     x += he.linear_combination (align);
+  else if (him->get_stencil ())
+    warning (him->name () + " has empty extent and non-empty stencil.");
 
   return scm_from_double (x);
 }