From 780a425fafbc0f67a6682ad93c58f18d56580971 Mon Sep 17 00:00:00 2001
From: Louis Bigo <louis.bigo@univ-lille.fr>
Date: Thu, 18 Nov 2021 13:11:51 +0100
Subject: [PATCH] solves #778

---
 music21/musicxml/m21ToXml.py | 10 ++++++++++
 music21/musicxml/xmlToM21.py | 13 +++++++++++++
 music21/tablature.py         | 18 ++++++++++++++++++
 3 files changed, 41 insertions(+)

diff --git a/music21/musicxml/m21ToXml.py b/music21/musicxml/m21ToXml.py
index 48bcc35b5a..e9d87851d5 100644
--- a/music21/musicxml/m21ToXml.py
+++ b/music21/musicxml/m21ToXml.py
@@ -6062,6 +6062,16 @@ def staffLayoutToXmlStaffDetails(self, staffLayout):
             mxStaffLines.text = str(staffLayout.staffLines)
 
         # TODO: staff-tuning
+        if hasattr(staffLayout, 'fretboard'):
+            tuning_pitches = staffLayout.fretboard.tuning
+            for i in range(len(tuning_pitches)):
+                mxStaffTuning = SubElement(mxStaffDetails, 'staff-tuning')
+                mxStaffTuning.set('line', str(i + 1))
+                mxTuningStep = SubElement(mxStaffTuning, 'tuning-step')
+                mxTuningStep.text = tuning_pitches[i].name
+                mxTuningOctave = SubElement(mxStaffTuning, 'tuning-octave')
+                mxTuningOctave.text = str(tuning_pitches[i].octave)
+
         # TODO: capo
         # TODO: staff-size
         return mxStaffDetails
diff --git a/music21/musicxml/xmlToM21.py b/music21/musicxml/xmlToM21.py
index e0b02c7135..ba262e9354 100644
--- a/music21/musicxml/xmlToM21.py
+++ b/music21/musicxml/xmlToM21.py
@@ -5691,7 +5691,20 @@ def xmlStaffLayoutFromStaffDetails(
                 stl.staffType = stream.enums.StaffType(xmlText)
             except ValueError:
                 environLocal.warn(f'Got an incorrect staff-type in details: {mxStaffType}')
+
         # TODO: staff-tuning*
+        mxStaffTuning = mxDetails.findall('staff-tuning')
+        if mxStaffTuning is not None:
+            tuning_pitches = []
+            for i in range(len(mxStaffTuning)):
+                staff_tuning = mxStaffTuning[i]
+                line = int(staff_tuning.get('line'))
+                tuning_step = staff_tuning.find('tuning-step').text
+                tuning_octave = int(staff_tuning.find('tuning-octave').text)
+                tuning_pitches.append(pitch.Pitch(tuning_step + str(tuning_octave)))
+            fretboard = tablature.FretBoard.getFretBoardFromTuning(tuning_pitches)
+            setattr(stl, 'fretboard', fretboard)
+
         # TODO: capo
         # TODO: show-frets
         # TODO: print-spacing
diff --git a/music21/tablature.py b/music21/tablature.py
index e96b64eb0c..5d0aa58743 100644
--- a/music21/tablature.py
+++ b/music21/tablature.py
@@ -244,6 +244,13 @@ def getPitches(self):
 
         return pitchList
 
+    @staticmethod
+    def getFretBoardFromTuning(pitches):
+        standard_fret_boards = [GuitarFretBoard, UkeleleFretBoard, BassGuitarFretBoard, MandolinFretBoard]
+        for standard_fret_board in standard_fret_boards:
+            if pitches == standard_fret_board().tuning:
+                return standard_fret_board()
+        return CustomFretBoard(pitches)
 
 class FirstFret:
     '''
@@ -344,6 +351,17 @@ def __init__(self, fretNotes=None, displayFrets=4):
         super().__init__(numStrings, fretNotes, displayFrets)
 
         self.tuning = [pitch.Pitch('G3'), pitch.Pitch('D4'), pitch.Pitch('A4'), pitch.Pitch('E5')]
+
+class CustomFretBoard(FretBoard):
+    '''
+    A custom fretboard tuned with any list of pitches
+    '''
+
+    def __init__(self, pitches, fretNotes=None, displayFrets=4):
+        numStrings = len(pitches)
+        super().__init__(numStrings, fretNotes, displayFrets)
+
+        self.tuning = pitches.copy()
 # ------------------------------------------------------------------------------