quarter tones in tablature

issue 4643

micro-tones in TabStaff are now printable.  Unless the chosen
string-tuning will allow it, this feature is disabled for
FretBoards.
- changing determine-frets (adding an optional argument) and
  fret-number-tablature-format
- adding a regtest with quarter-tone-string-tuning
- documenting it in Documentation/notation/fretted-strings.itely
  and Documentation/changes.tely

1 files changed, 38 insertions, 0 deletions

diff --git a/Documentation/notation/fretted-strings.itely b/Documentation/notation/fretted-strings.itely
index 3e0a52ae40..d6a97470af 100644
--- a/Documentation/notation/fretted-strings.itely
+++ b/Documentation/notation/fretted-strings.itely
@@ -713,6 +713,44 @@ A modern tab clef can also be used.
 
 The modern tab clef supports tablatures from 4 to 7 strings.
 
+@cindex micro-tones, tab
+@cindex quarter-tones, tab
+@cindex tab micro-tones
+@cindex tab quarter-tones
+
+@code{TabStaff} may support micro-tones like quarter-tones, which
+can be played using bendings.
+@code{noteToFretFunction = #(determine-frets #t)} needs to be set in
+Score-context.  However, micro-tones are not supperted in @code{FretBoards}.
+
+@lilypond[quote,ragged-right,verbatim]
+\layout {
+  \context {
+    \Score
+    noteToFretFunction = #(determine-frets #t)
+  }
+}
+
+custom-tuning = \stringTuning <e, a, d ges beh eeh'>
+
+mus = \relative {
+  eeses'4
+  eeseh
+  ees
+  eeh
+  e
+  eih
+  eis
+  eisih
+  eisis
+}
+
+<<
+  \new Staff << \clef "G_8" \mus >>
+  \new TabStaff \with { stringTunings = \custom-tuning } \mus
+>>
+@end lilypond
+
 @seealso
 Notation Reference:
 @ref{Absolute octave entry},