Fix GH#9779 beam stem direction flip

Update chord's set stem direction method to set the beam's direction
to Direction::AUTO if applicable.

Update the beam's set direction method to update its notes' stem
direction.

When a beam's direction is set with the "x" keyboard key, the
"_direction" member of the beam class is no longer equal to
"Direction::AUTO". So, in the beam's layout code the final beam
direction is not taken from the first note in the note group
(of the beam) but from the "_direction" member.

The problem is that if the user tries to set the beam's direction
with a note stem direction (in the property panel), it will be
ignored in the beam's layout code.

Backport of musescore#9800, resp. duplicate of musescore#9851

libmscore/beam.cpp

@@ -2228,8 +2228,14 @@ std::vector<QPointF> Beam::gripsPositions(const EditData& ed) const
 void Beam::setBeamDirection(Direction d)
       {
       _direction = d;
-      if (d != Direction::AUTO)
+      if (d != Direction::AUTO) {
             _up = d == Direction::UP;
+            if (!_elements.empty()) {
+                  Chord* c = toChord(_elements.first());
+                  if (c)
+                        c->setStemDirection(d, d);
+                  }
+            }
       }
 
 //---------------------------------------------------------

libmscore/chord.cpp

@@ -2762,7 +2762,7 @@ qreal Chord::dotPosX() const
 //   setStemDirection
 //---------------------------------------------------------
 
-void Chord::setStemDirection(Direction d)
+void Chord::setStemDirection(Direction d, Direction beamDir)
       {
       _stemDirection = d;
       if (beam()) {
@@ -2771,6 +2771,8 @@ void Chord::setStemDirection(Direction d)
                   if (c)
                         c->_stemDirection = d;
                   }
+            if (beamDir == Direction::AUTO)
+                  beam()->setBeamDirection(beamDir);
             }
       }
 

libmscore/chord.h

@@ -106,7 +106,7 @@ class Chord final : public ChordRest {
       bool readProperties(XmlReader&) override;
       Element* drop(EditData&) override;
 
-      void setStemDirection(Direction d);
+      void setStemDirection(Direction d, Direction beamDir = Direction::AUTO);
       Direction stemDirection() const    { return _stemDirection; }
 
       LedgerLine* ledgerLines()                  { return _ledgerLines; }