Spell chord tones from an already chosen root spelling.
This is public for callers that already know the desired root spelling;
spellChord instead derives that spelling from the chord and key.
Letters follow the chord's own tone spellings when it carries a usable set,
and otherwise the diatonic distance each interval implies in a stack of
thirds. Accidentals are always recomputed from the sounding pitch class, so
the tones name exactly the chord's own pitch classes either way.
Spell chord tones from an already chosen root spelling.
This is public for callers that already know the desired root spelling; spellChord instead derives that spelling from the chord and key.
Letters follow the chord's own tone spellings when it carries a usable set, and otherwise the diatonic distance each interval implies in a stack of thirds. Accidentals are always recomputed from the sounding pitch class, so the tones name exactly the chord's own pitch classes either way.