Remove more uses of Track::SetLinked() and Track::SetChannel()

src/Menus.cpp

@@ -7819,6 +7819,7 @@ void MenuCommandHandler::HandleMixAndRender
    WaveTrack::Holder uNewLeft, uNewRight;
    ::MixAndRender(
       tracks, trackFactory, rate, defaultFormat, 0.0, 0.0, uNewLeft, uNewRight);
+   tracks->GroupChannels(*uNewLeft, uNewRight ? 2 : 1);
 
    if (uNewLeft) {
       // Remove originals, get stats on what tracks were mixed
@@ -8769,22 +8770,20 @@ void MenuCommandHandler::OnNewStereoTrack(const CommandContext &context)
    auto defaultFormat = project.GetDefaultFormat();
    auto rate = project.GetRate();
 
-   auto t = tracks->Add(trackFactory->NewWaveTrack(defaultFormat, rate));
-   t->SetChannel(Track::LeftChannel);
    project.SelectNone();
 
-   t->SetSelected(true);
-   t->SetLinked (true);
+   auto left = tracks->Add(trackFactory->NewWaveTrack(defaultFormat, rate));
+   left->SetSelected(true);
 
-   t = tracks->Add(trackFactory->NewWaveTrack(defaultFormat, rate));
-   t->SetChannel(Track::RightChannel);
+   auto right = tracks->Add(trackFactory->NewWaveTrack(defaultFormat, rate));
+   right->SetSelected(true);
 
-   t->SetSelected(true);
+   tracks->GroupChannels(*left, 2);
 
    project.PushState(_("Created new stereo audio track"), _("New Track"));
 
    project.RedrawProject();
-   trackPanel->EnsureVisible(t);
+   trackPanel->EnsureVisible(left);
 }
 
 void MenuCommandHandler::OnNewLabelTrack(const CommandContext &context)

src/Mix.cpp

@@ -120,10 +120,7 @@ void MixAndRender(TrackList *tracks, TrackFactory *trackFactory,
 
    // TODO: more-than-two-channels
    decltype(mixLeft) mixRight{};
-   if (mono) {
-      mixLeft->SetChannel(Track::MonoChannel);
-   }
-   else {
+   if ( !mono ) {
       mixRight = trackFactory->NewWaveTrack(format, rate);
       if (oneinput) {
          auto channels = TrackList::Channels(first);
@@ -134,14 +131,10 @@ void MixAndRender(TrackList *tracks, TrackFactory *trackFactory,
       }
       else
          mixRight->SetName(_("Mix"));
-      mixLeft->SetChannel(Track::LeftChannel);
-      mixRight->SetChannel(Track::RightChannel);
       mixRight->SetOffset(mixStartTime);
-      mixLeft->SetLinked(true);
    }
 
 
-
    auto maxBlockLen = mixLeft->GetIdealBlockSize();
 
    // If the caller didn't specify a time range, use the whole range in which

src/effects/Effect.cpp

@@ -2543,6 +2543,7 @@ void Effect::Preview(bool dryOnly)
          mixRight->SetSelected(true);
          mTracks->Add(std::move(mixRight));
       }
+      mTracks->GroupChannels(*mixLeft, mixRight ? 2 : 1);
    }
    else {
       for (auto src : saveTracks->Any< const WaveTrack >()) {

src/effects/StereoToMono.cpp

@@ -157,9 +157,7 @@ bool EffectStereoToMono::ProcessOne(int count)
    mLeftTrack->Clear(mLeftTrack->GetStartTime(), mLeftTrack->GetEndTime());
    outTrack->Flush();
    mLeftTrack->Paste(minStart, outTrack.get());
-   mLeftTrack->SetLinked(false);
-   mRightTrack->SetLinked(false);
-   mLeftTrack->SetChannel(Track::MonoChannel);
+   mOutputTracks->GroupChannels( *mLeftTrack,  1 );
    mOutputTracks->Remove(mRightTrack);
 
    return bResult;

src/toolbars/ControlToolBar.cpp

@@ -1164,10 +1164,13 @@ bool ControlToolBar::DoRecord(AudacityProject &project,
 
          wxString baseTrackName = recordingNameCustom? defaultRecordingTrackName : defaultTrackName;
 
+         Track *first {};
          for (int c = 0; c < recordingChannels; c++) {
             std::shared_ptr<WaveTrack> newTrack{
                p->GetTrackFactory()->NewWaveTrack().release()
             };
+            if (!first)
+               first = newTrack.get();
 
             // Quantize bounds to the rate of the new track.
             if (c == 0) {
@@ -1215,26 +1218,14 @@ bool ControlToolBar::DoRecord(AudacityProject &project,
                newTrack->SetMinimized(true);
             }
 
-            if (recordingChannels == 2) {
-               if (c == 0) {
-                  newTrack->SetChannel(Track::LeftChannel);
-                  newTrack->SetLinked(true);
-               }
-               else {
-                  newTrack->SetChannel(Track::RightChannel);
-               }
-            }
-            else {
-               newTrack->SetChannel( Track::MonoChannel );
-            }
-
             p->GetTracks()->RegisterPendingNewTrack( newTrack );
             transportTracks.captureTracks.push_back(newTrack);
             // Bug 1548.  New track needs the focus.
             p->GetTrackPanel()->SetFocusedTrack( newTrack.get() );
          }
+         p->GetTracks()->GroupChannels(*first, recordingChannels);
       }
-
+      
       //Automated Input Level Adjustment Initialization
       #ifdef EXPERIMENTAL_AUTOMATED_INPUT_LEVEL_ADJUSTMENT
          gAudioIO->AILAInitialize();

src/tracks/playabletrack/wavetrack/ui/WaveTrackControls.cpp

@@ -847,46 +847,39 @@ void WaveTrackMenuTable::OnMergeStereo(wxCommandEvent &)
    auto partner = static_cast< WaveTrack * >
       ( *tracks->Find( pTrack ).advance( 1 ) );
 
-   pTrack->SetLinked(true);
+   tracks->GroupChannels( *pTrack, 2 );
 
-   if (partner) {
-      // Set partner's parameters to match target.
-      partner->Merge(*pTrack);
+   // Set partner's parameters to match target.
+   partner->Merge(*pTrack);
 
-      pTrack->SetPan( 0.0f );
-      pTrack->SetChannel(Track::LeftChannel);
-      partner->SetPan( 0.0f );
-      partner->SetChannel(Track::RightChannel);
+   pTrack->SetPan( 0.0f );
+   partner->SetPan( 0.0f );
 
-      // Set NEW track heights and minimized state
-      bool bBothMinimizedp = ((pTrack->GetMinimized()) && (partner->GetMinimized()));
-      pTrack->SetMinimized(false);
-      partner->SetMinimized(false);
-      int AverageHeight = (pTrack->GetHeight() + partner->GetHeight()) / 2;
-      pTrack->SetHeight(AverageHeight);
-      partner->SetHeight(AverageHeight);
-      pTrack->SetMinimized(bBothMinimizedp);
-      partner->SetMinimized(bBothMinimizedp);
+   // Set NEW track heights and minimized state
+   bool bBothMinimizedp = ((pTrack->GetMinimized()) && (partner->GetMinimized()));
+   pTrack->SetMinimized(false);
+   partner->SetMinimized(false);
+   int AverageHeight = (pTrack->GetHeight() + partner->GetHeight()) / 2;
+   pTrack->SetHeight(AverageHeight);
+   partner->SetHeight(AverageHeight);
+   pTrack->SetMinimized(bBothMinimizedp);
+   partner->SetMinimized(bBothMinimizedp);
 
-      //On Demand - join the queues together.
-      if (ODManager::IsInstanceCreated())
-         if (!ODManager::Instance()->MakeWaveTrackDependent(partner, pTrack))
-         {
-            ;
-            //TODO: in the future, we will have to check the return value of MakeWaveTrackDependent -
-            //if the tracks cannot merge, it returns false, and in that case we should not allow a merging.
-            //for example it returns false when there are two different types of ODTasks on each track's queue.
-            //we will need to display this to the user.
-         }
+   //On Demand - join the queues together.
+   if (ODManager::IsInstanceCreated())
+      if (!ODManager::Instance()->MakeWaveTrackDependent(partner, pTrack))
+      {
+         ;
+         //TODO: in the future, we will have to check the return value of MakeWaveTrackDependent -
+         //if the tracks cannot merge, it returns false, and in that case we should not allow a merging.
+         //for example it returns false when there are two different types of ODTasks on each track's queue.
+         //we will need to display this to the user.
+      }
 
-      AudacityProject *const project = ::GetActiveProject();
-      /* i18n-hint: The string names a track */
-      project->PushState(wxString::Format(_("Made '%s' a stereo track"),
-         pTrack->GetName()),
-         _("Make Stereo"));
-   }
-   else
-      pTrack->SetLinked(false);
+   /* i18n-hint: The string names a track */
+   project->PushState(wxString::Format(_("Made '%s' a stereo track"),
+      pTrack->GetName()),
+      _("Make Stereo"));
 
    mpData->result = RefreshCode::RefreshAll;
 }
@@ -899,7 +892,6 @@ void WaveTrackMenuTable::SplitStereo(bool stereo)
    AudacityProject *const project = ::GetActiveProject();
    auto channels = TrackList::Channels( pTrack );
 
-
    int totalHeight = 0;
    int nChannels = 0;
    for (auto channel : channels) {
@@ -907,7 +899,6 @@ void WaveTrackMenuTable::SplitStereo(bool stereo)
       channel->SetName(pTrack->GetName());
       if (stereo)
          channel->SetPanFromChannelType();
-      channel->SetChannel(Track::MonoChannel);
 
       //On Demand - have each channel add its own.
       if (ODManager::IsInstanceCreated())
@@ -919,7 +910,7 @@ void WaveTrackMenuTable::SplitStereo(bool stereo)
       ++nChannels;
    }
 
-   pTrack->SetLinked(false);
+   project->GetTracks()->GroupChannels( *pTrack, 1 );
    int averageHeight = totalHeight / nChannels;
 
    for (auto channel : channels)
@@ -947,12 +938,9 @@ void WaveTrackMenuTable::OnSwapChannels(wxCommandEvent &)
 
    SplitStereo(false);
 
-   first->SetChannel(Track::RightChannel);
-   partner->SetChannel(Track::LeftChannel);
-
    TrackList *const tracks = project->GetTracks();
-   (tracks->MoveUp(partner));
-   partner->SetLinked(true);
+   tracks->MoveUp( partner );
+   tracks->GroupChannels( *partner, 2 );
 
    MixerBoard* pMixerBoard = project->GetMixerBoard();
    if (pMixerBoard)