Fix updating the measure/beat field in PlaybackToolBar

PlaybackToolbarModel emitted a "playback position changed" signal in response to notifications on the `playbackState->playbackPositionChanged()` channel. `PlaybackController` also listens to this channel, and uses it to update its `m_currentTick` value. The value is used to determine the current measure/beat position in PlaybackToolbar.

The problem: the order in which channel listeners are invoked is undefined. And in this case we are unlucky: PlaybackToolbarModel's listener is invoked first, so it updates the QML view; and only after that, PlaybackController's listener is invoked, so its `m_currentTick` is updated too late. So, the QML view is updated based on the old `m_currentTick`.

Solution: don't listen to `playbackState->playbackPositionChanged()` directly, but listen to a channel from PlaybackController. This channel sends the notification after updating `m_currentTick`.

This commit also updates the name and signature of this channel, to better reflect its purpose.

This problem was a regression, maybe caused by 8b95896, but that is an unverified conjecture.

src/notation/view/abstractnotationpaintview.cpp

@@ -622,7 +622,7 @@ void AbstractNotationPaintView::onNotationSetup()
         onPlayingChanged();
     });
 
-    playbackController()->midiTickPlayed().onReceive(this, [this](uint32_t tick) {
+    playbackController()->currentPlaybackPositionChanged().onReceive(this, [this](audio::secs_t, midi::tick_t tick) {
         movePlaybackCursor(tick);
     });
 

src/playback/internal/playbackcontroller.cpp

@@ -227,9 +227,9 @@ void PlaybackController::seek(const audio::secs_t secs)
     currentPlayer()->seek(secs);
 }
 
-Channel<uint32_t> PlaybackController::midiTickPlayed() const
+muse::async::Channel<secs_t, tick_t> PlaybackController::currentPlaybackPositionChanged() const
 {
-    return m_tickPlayed;
+    return m_currentPlaybackPositionChanged;
 }
 
 TrackSequenceId PlaybackController::currentTrackSequenceId() const
@@ -1264,7 +1264,7 @@ void PlaybackController::setupSequencePlayer()
 {
     currentPlayer()->playbackPositionChanged().onReceive(this, [this](const audio::secs_t pos) {
         m_currentTick = notationPlayback()->secToTick(pos);
-        m_tickPlayed.send(m_currentTick);
+        m_currentPlaybackPositionChanged.send(pos, m_currentTick);
 
         updateCurrentTempo();
 

src/playback/internal/playbackcontroller.h

@@ -63,7 +63,7 @@ class PlaybackController : public IPlaybackController, public muse::actions::Act
 
     void reset() override;
 
-    muse::async::Channel<uint32_t> midiTickPlayed() const override;
+    muse::async::Channel<muse::audio::secs_t, muse::midi::tick_t> currentPlaybackPositionChanged() const override;
 
     muse::audio::TrackSequenceId currentTrackSequenceId() const override;
     muse::async::Notification currentTrackSequenceIdChanged() const override;
@@ -212,7 +212,7 @@ class PlaybackController : public IPlaybackController, public muse::actions::Act
     muse::async::Notification m_isPlayingChanged;
     muse::async::Notification m_totalPlayTimeChanged;
     muse::async::Notification m_currentTempoChanged;
-    muse::async::Channel<uint32_t> m_tickPlayed;
+    muse::async::Channel<muse::audio::secs_t, muse::midi::tick_t> m_currentPlaybackPositionChanged;
     muse::async::Channel<muse::actions::ActionCode> m_actionCheckedChanged;
 
     muse::audio::TrackSequenceId m_currentSequenceId = -1;

src/playback/iplaybackcontroller.h

@@ -50,7 +50,7 @@ class IPlaybackController : MODULE_EXPORT_INTERFACE
 
     virtual void reset() = 0;
 
-    virtual muse::async::Channel<uint32_t> midiTickPlayed() const = 0;
+    virtual muse::async::Channel<muse::audio::secs_t, muse::midi::tick_t> currentPlaybackPositionChanged() const = 0;
 
     virtual muse::audio::TrackSequenceId currentTrackSequenceId() const = 0;
     virtual muse::async::Notification currentTrackSequenceIdChanged() const = 0;

src/playback/tests/mocks/playbackcontrollermock.h

@@ -38,7 +38,7 @@ class PlaybackControllerMock : public IPlaybackController
 
     MOCK_METHOD(void, reset, (), (override));
 
-    MOCK_METHOD(muse::async::Channel<uint32_t>, midiTickPlayed, (), (const, override));
+    MOCK_METHOD((muse::async::Channel<muse::audio::secs_t, muse::midi::tick_t>), currentPlaybackPositionChanged, (), (const, override));
 
     MOCK_METHOD(muse::audio::TrackSequenceId, currentTrackSequenceId, (), (const, override));
     MOCK_METHOD(muse::async::Notification, currentTrackSequenceIdChanged, (), (const, override));

src/playback/view/playbacktoolbarmodel.cpp

@@ -67,8 +67,6 @@ void PlaybackToolBarModel::load()
 
 void PlaybackToolBarModel::setupConnections()
 {
-    context::IPlaybackStatePtr playbackState = globalContext()->playbackState();
-
     playbackController()->isPlayAllowedChanged().onNotify(this, [this]() {
         emit isPlayAllowedChanged();
     });
@@ -77,7 +75,7 @@ void PlaybackToolBarModel::setupConnections()
         onActionsStateChanges({ PLAY_ACTION_CODE });
     });
 
-    playbackState->playbackPositionChanged().onReceive(this, [this](secs_t secs) {
+    playbackController()->currentPlaybackPositionChanged().onReceive(this, [this](secs_t secs, midi::tick_t) {
         updatePlayPosition(secs);
     });
 

src/stubs/playback/playbackcontrollerstub.cpp

@@ -48,9 +48,9 @@ void PlaybackControllerStub::reset()
 {
 }
 
-muse::async::Channel<uint32_t> PlaybackControllerStub::midiTickPlayed() const
+muse::async::Channel<muse::audio::secs_t, muse::midi::tick_t> PlaybackControllerStub::currentPlaybackPositionChanged() const
 {
-    return muse::async::Channel<uint32_t>();
+    return muse::async::Channel<muse::audio::secs_t, muse::midi::tick_t>();
 }
 
 muse::audio::TrackSequenceId PlaybackControllerStub::currentTrackSequenceId() const

src/stubs/playback/playbackcontrollerstub.h

@@ -36,7 +36,7 @@ class PlaybackControllerStub : public IPlaybackController
 
     void reset() override;
 
-    muse::async::Channel<uint32_t> midiTickPlayed() const override;
+    muse::async::Channel<muse::audio::secs_t, muse::midi::tick_t> currentPlaybackPositionChanged() const override;
 
     muse::audio::TrackSequenceId currentTrackSequenceId() const override;
     muse::async::Notification currentTrackSequenceIdChanged() const override;