Export stem styles on notes with implicit stem directions

cuthbertLab · Aug 3, 2024 · b9861ad · b9861ad
1 parent 204e9d0
commit b9861ad
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Showing 2 changed files with 24 additions and 7 deletions.
diff --git a/music21/musicxml/m21ToXml.py b/music21/musicxml/m21ToXml.py
@@ -4103,17 +4103,26 @@ def noteToXml(self, n: note.GeneralNote, noteIndexInChord=0, chordParent=None):
             n = t.cast(note.NotRest, n)
             stemDirection = n.stemDirection
 
-        if stemDirection is not None:
+        if stem_has_style := (chordOrN.hasStyleInformation
+                                and isinstance(chordOrN.style, style.NoteStyle)
+                                and chordOrN.style.stemStyle is not None):
+            note_style = chordOrN.style
+
+        if stemDirection is not None or stem_has_style:
             mxStem = SubElement(mxNote, 'stem')
-            sdText = stemDirection
+            if stemDirection is None:
+                if closest_clef := chordOrN.getContextByClass(clef.Clef):
+                    sdText = closest_clef.getStemDirectionForPitches(chordOrN.pitches)
+                else:
+                    sdText = 'up'
+            else:
+                sdText = stemDirection
             if sdText == 'noStem':
                 sdText = 'none'
             mxStem.text = sdText
-            if (chordOrN.hasStyleInformation
-                    and isinstance(chordOrN.style, style.NoteStyle)
-                    and chordOrN.style.stemStyle is not None):
-                self.setColor(mxStem, chordOrN.style.stemStyle)
-                self.setPosition(mxStem, chordOrN.style.stemStyle)
+            if stem_has_style:
+                self.setColor(mxStem, note_style.stemStyle)
+                self.setPosition(mxStem, note_style.stemStyle)
 
         # end Stem
 

diff --git a/music21/musicxml/test_m21ToXml.py b/music21/musicxml/test_m21ToXml.py
@@ -27,6 +27,7 @@
 from music21 import repeat
 from music21 import spanner
 from music21 import stream
+from music21 import style
 from music21 import tempo
 
 from music21.musicxml import helpers
@@ -921,6 +922,13 @@ def test_roman_musicxml_two_kinds(self):
         self.assertIn('<rest', xmlOut)
         self.assertNotIn('<forward>', xmlOut)
 
+    def test_stem_style_without_direction(self):
+        one_note_tune = converter.parse('tinyNotation: 2/4 c2')
+        half_note = one_note_tune.recurse().notes.first()
+        half_note.style.stemStyle = style.Style()
+        half_note.style.stemStyle.color = 'red'
+        xmlOut = GeneralObjectExporter().parse(one_note_tune).decode('utf-8')
+        self.assertIn('<stem color="#FF0000">up</stem>', xmlOut)
 
 
 class TestExternal(unittest.TestCase):