new file: perform drum notes.

[lilypond.git] / lily / pitch-squash-engraver.cc

diff --git a/lily/pitch-squash-engraver.cc b/lily/pitch-squash-engraver.cc
index 4961e70f19112469f3787417da59a46e4286c370..197b589fa4a665cddb284170c1750a12d14315c3 100644 (file)
--- a/lily/pitch-squash-engraver.cc
+++ b/lily/pitch-squash-engraver.cc
@@ -3,7 +3,7 @@
   
   source file of the GNU LilyPond music typesetter
   
-  (c)  1997--2002 Han-Wen Nienhuys <hanwen@cs.uu.nl>
+  (c) 1997--2004 Han-Wen Nienhuys <hanwen@cs.uu.nl>
   
  */
 #include "staff-symbol-referencer.hh"
@@ -22,7 +22,8 @@ void
 Pitch_squash_engraver::acknowledge_grob (Grob_info i)
 {
   SCM newpos = get_property ("squashedPosition");
-  if (Note_head::has_interface (i.grob_))
+  if (gh_number_p (newpos)
+      && Note_head::has_interface (i.grob_))
     {
       i.grob_->set_grob_property ("staff-position", newpos);
     }
@@ -35,10 +36,13 @@ Pitch_squash_engraver::Pitch_squash_engraver()
 }
 
 ENTER_DESCRIPTION(Pitch_squash_engraver,
-/* descr */       "Treat all pitches as middle C.  Note that the notes move, but
-the locations of accidentals stay the same. 
-Set the position field of all note heads to zero. This useful for
-making a single line staff that demonstrates the rhythm of a melody.",
+/* descr */       
+                 "Set the vertical position of noteheads to "
+                 "@code{squashedPosition}, if that "
+                 "property is set. "
+                 "This can be used to make  a single line staff "
+                 "demonstrating the rhythm of a melody.",
+
 /* creats*/       "",
 /* accepts */     "",
 /* acks  */      "note-head-interface",