Select most appropriate enharmonic from available chords

Author: miiizen

src/engraving/dom/pitchspelling.cpp

@@ -1168,4 +1168,35 @@ Key clampKey(Key key, PreferSharpFlat prefer)
 
     return key;
 }
+
+int bestEnharmonicFit(const std::vector<int> tpcs, Key key)
+{
+    int keyIndex = int(key) - int(Key::MIN);
+    if (keyIndex < 0 || keyIndex >= int(Key::NUM_OF)) {
+        return tpcs.front();
+    }
+
+    int bestPenalty = INT_MAX;
+    int closestTpc = Tpc::TPC_INVALID;
+
+    for (int tpc : tpcs) {
+        if (tpc == Tpc::TPC_INVALID) {
+            continue;
+        }
+
+        int lof = tpc - Tpc::TPC_MIN;
+        if (lof < 0 || lof >= 34) {
+            continue;
+        }
+
+        int penalty = enharmonicSpelling[keyIndex][lof];
+
+        if (penalty < bestPenalty) {
+            bestPenalty = penalty;
+            closestTpc = tpc;
+        }
+    }
+
+    return closestTpc;
+}
 }

src/engraving/dom/pitchspelling.h

@@ -104,6 +104,7 @@ extern int convertNote(const String& s, NoteSpellingType noteSpelling, NoteCaseT
 extern int clampEnharmonic(int tpc, bool useDoubleSharpsFlats = true);
 extern int clampPitch(int pitch, bool octaved = false);
 extern Key clampKey(Key key, PreferSharpFlat prefer = PreferSharpFlat::NONE);
+extern int bestEnharmonicFit(const std::vector<int> tpcs, Key key);
 
 //---------------------------------------------------------
 //   tpc2alter

src/engraving/editing/transpose.cpp

@@ -599,7 +599,14 @@ void Transpose::transposeFretDiagram(FretDiagram* diagram, Score* score, Interva
         return;
     }
 
-    String name = names.front();
+    Fraction tick = Fraction(0, 1);
+    Segment* seg = diagram->segment();
+    if (seg) {
+        tick = seg->tick();
+    }
+    Key key = !diagram->staff() ? Key::C : diagram->staff()->key(tick);
+
+    String name = findBestEnharmonicFit(names, key, score->style());
 
     diagram->setHarmony(name);
     harmony = diagram->harmony();
@@ -608,17 +615,10 @@ void Transpose::transposeFretDiagram(FretDiagram* diagram, Score* score, Interva
     }
 
     // Transpose harmony without undo
-    Fraction tick = Fraction(0, 1);
-    Segment* seg = harmony->getParentSeg();
-    if (seg) {
-        tick = seg->tick();
-    }
-
     Interval kv = harmony->staff()->transpose(harmony->tick());
     Interval iv = harmony->part()->instrument(harmony->tick())->transpose();
     Interval hInterval((interval.diatonic - kv.diatonic + iv.diatonic), (interval.chromatic - kv.chromatic + iv.chromatic));
 
-    Key key = !harmony->staff() ? Key::C : harmony->staff()->key(tick);
     for (HarmonyInfo* info : harmony->chords()) {
         if (mode == TransposeMode::DIATONICALLY) {
             info->setRootTpc(Transpose::transposeTpcDiatonicByKey(info->rootTpc(), transposeInterval, key, trKeys, useDoubleSharpsFlats));
@@ -646,6 +646,28 @@ void Transpose::transposeFretDiagram(FretDiagram* diagram, Score* score, Interva
     return;
 }
 
+String Transpose::findBestEnharmonicFit(const std::vector<String>& notes, Key key, const MStyle& style)
+{
+    std::vector<int> tpcs;
+    NoteSpellingType harmonySpelling = style.styleV(Sid::chordSymbolSpelling).value<NoteSpellingType>();
+    NoteCaseType harmonyCase = NoteCaseType::AUTO;
+    size_t idx = 0;
+    for (const String& note : notes) {
+        int tpc = convertNote(note, harmonySpelling, harmonyCase, idx);
+        tpcs.push_back(tpc);
+    }
+
+    int tpc = bestEnharmonicFit(tpcs, key);
+
+    if (tpc == Tpc::TPC_INVALID) {
+        return notes.front();
+    }
+
+    String note = tpc2name(tpc, harmonySpelling, harmonyCase);
+
+    return note;
+}
+
 //---------------------------------------------------------
 //   transposeTpcDiatonicByKey
 //

src/engraving/editing/transpose.h

@@ -57,6 +57,8 @@ class Transpose
                                  bool useDoubleSharpsFlats);
     static void transposeFretDiagram(FretDiagram* diagram, Score* score, Interval interval, TransposeMode mode, int transposeInterval,
                                      bool trKeys, bool useDoubleSharpsFlats);
+
+    static String findBestEnharmonicFit(const std::vector<String>& notes, Key key, const MStyle& style);
 };
 
 class TransposeHarmony : public UndoCommand