Rewrite some iterations over tracks and channels in TrackPanel

src/TrackPanel.cpp

@@ -749,34 +749,13 @@ void TrackPanel::UpdateAccessibility()
 // Counts tracks, counting stereo tracks as one track.
 size_t TrackPanel::GetTrackCount() const
 {
-   size_t count = 0;
-   TrackListConstIterator iter(GetTracks());
-   for (auto t = iter.First(); t; t = iter.Next()) {
-      count +=  1;
-      if( t->GetLinked() ){
-         t = iter.Next();
-         if( !t )
-            break;
-      }
-   }
-   return count;
+  return GetTracks()->Leaders().size();
 }
 
 // Counts selected tracks, counting stereo tracks as one track.
 size_t TrackPanel::GetSelectedTrackCount() const
 {
-   size_t count = 0;
-
-   TrackListConstIterator iter(GetTracks());
-   for (auto t = iter.First(); t; t = iter.Next()) {
-      count +=  t->GetSelected() ? 1:0;
-      if( t->GetLinked() ){
-         t = iter.Next();
-         if( !t )
-            break;
-      }
-   }
-   return count;
+   return GetTracks()->SelectedLeaders().size();
 }
 
 void TrackPanel::MessageForScreenReader(const wxString& message)
@@ -1845,10 +1824,8 @@ void TrackPanel::HighlightFocusedTrack(wxDC * dc, const wxRect & rect)
 
 void TrackPanel::UpdateVRulers()
 {
-   TrackListOfKindIterator iter(Track::Wave, GetTracks());
-   for (Track *t = iter.First(); t; t = iter.Next()) {
+   for (auto t : GetTracks()->Any< const WaveTrack >())
       UpdateTrackVRuler(t);
-   }
 
    UpdateVRulerSize();
 }
@@ -1883,14 +1860,12 @@ void TrackPanel::UpdateTrackVRuler(const Track *t)
 
 void TrackPanel::UpdateVRulerSize()
 {
-   TrackListIterator iter(GetTracks());
-   Track *t = iter.First();
-   if (t) {
-      wxSize s = t->vrulerSize;
-      while (t) {
+   auto trackRange = GetTracks()->Any();
+   if (trackRange) {
+      wxSize s { 0, 0 };
+      for (auto t : trackRange)
          s.IncTo(t->vrulerSize);
-         t = iter.Next();
-      }
+
       if (vrulerSize != s) {
          vrulerSize = s;
          mRuler->SetLeftOffset(GetLeftOffset());  // bevel on AdornedRuler
@@ -1927,54 +1902,29 @@ void TrackPanel::OnTrackMenu(Track *t)
 
 Track * TrackPanel::GetFirstSelectedTrack()
 {
-
-   TrackListIterator iter(GetTracks());
-
-   Track * t;
-   for ( t = iter.First();t!=NULL;t=iter.Next())
-      {
-         //Find the first selected track
-         if(t->GetSelected())
-            {
-               return t;
-            }
-
-      }
-   //if nothing is selected, return the first track
-   t = iter.First();
-
-   if(t)
+   auto t = *GetTracks()->Selected().begin();
+   if (t)
       return t;
    else
-      return NULL;
+      //if nothing is selected, return the first track
+      return *GetTracks()->Any().begin();
 }
 
 void TrackPanel::EnsureVisible(Track * t)
 {
-   TrackListIterator iter(GetTracks());
-   Track *it = NULL;
-   Track *nt = NULL;
-
    SetFocusedTrack(t);
 
    int trackTop = 0;
    int trackHeight =0;
 
-   for (it = iter.First(); it; it = iter.Next()) {
+   for (auto it : GetTracks()->Leaders()) {
       trackTop += trackHeight;
-      trackHeight =  it->GetHeight();
 
-      //find the second track if this is stereo
-      if (it->GetLinked()) {
-         nt = iter.Next();
-         trackHeight += nt->GetHeight();
-      }
-      else {
-         nt = it;
-      }
+      auto channels = TrackList::Channels(it);
+      trackHeight = channels.sum( &Track::GetHeight );
 
       //We have found the track we want to ensure is visible.
-      if ((it == t) || (nt == t)) {
+      if (channels.contains(t)) {
 
          //Get the size of the trackpanel.
          int width, height;
@@ -2000,27 +1950,20 @@ void TrackPanel::EnsureVisible(Track * t)
 // 0.0 scrolls to top
 // 1.0 scrolls to bottom.
 void TrackPanel::VerticalScroll( float fracPosition){
-   TrackListIterator iter(GetTracks());
-   Track *it = NULL;
-   Track *nt = NULL;
 
-   // Compute trackHeight
    int trackTop = 0;
-   int trackHeight =0;
+   int trackHeight = 0;
 
-   for (it = iter.First(); it; it = iter.Next()) {
-      trackTop += trackHeight;
-      trackHeight =  it->GetHeight();
+   auto tracks = GetTracks();
+   auto GetHeight =
+      [&]( const Track *t ){ return tracks->GetGroupHeight(t); };
 
-      //find the second track if this is stereo
-      if (it->GetLinked()) {
-         nt = iter.Next();
-         trackHeight += nt->GetHeight();
-      }
-      else {
-         nt = it;
-      }
+   auto range = tracks->Leaders();
+   if (!range.empty()) {
+      trackHeight = GetHeight( *range.rbegin() );
+      --range.second;
    }
+   trackTop = range.sum( GetHeight );
 
    int delta;
    

src/TrackPanelAx.cpp

@@ -62,9 +62,7 @@ std::shared_ptr<Track> TrackPanelAx::GetFocus()
          focusedTrack = FindTrack(mNumFocusedTrack);
       }
       if (!focusedTrack) {
-
-         TrackListIterator iter( mTrackPanel->GetTracks() );
-         focusedTrack = Track::Pointer( iter.First() );
+         focusedTrack = Track::Pointer( *mTrackPanel->GetTracks()->Any().first );
          // only call SetFocus if the focus has changed to avoid
          // unnecessary focus events
          if (focusedTrack) 
@@ -99,10 +97,7 @@ std::shared_ptr<Track> TrackPanelAx::SetFocus( std::shared_ptr<Track> track )
 #endif
 
    if( !track )
-   {
-      TrackListIterator iter( mTrackPanel->GetTracks() );
-      track = Track::Pointer( iter.First() );
-   }
+      track = Track::Pointer( *mTrackPanel->GetTracks()->Any().begin() );
 
    mFocusedTrack = track;
    mNumFocusedTrack = TrackNum(track);
@@ -252,24 +247,7 @@ wxAccStatus TrackPanelAx::GetChild( int childId, wxAccessible** child )
 // Gets the number of children.
 wxAccStatus TrackPanelAx::GetChildCount( int* childCount )
 {
-   TrackListIterator iter( mTrackPanel->GetTracks() );
-   Track *t = iter.First();
-   int cnt = 0;
-
-   while( t != NULL )
-   {
-      cnt++;
-
-      if( t->GetLink() != NULL )
-      {
-         t = iter.Next();
-      }
-
-      t = iter.Next();
-   }
-
-   *childCount = cnt;
-
+   *childCount = mTrackPanel->GetTrackCount();
    return wxACC_OK;
 }
 

src/tracks/labeltrack/ui/LabelDefaultClickHandle.cpp

@@ -34,19 +34,10 @@ void LabelDefaultClickHandle::SaveState( AudacityProject *pProject )
    mLabelState = std::make_shared<LabelState>();
    auto &pairs = mLabelState->mPairs;
    TrackList *const tracks = pProject->GetTracks();
-   TrackListIterator iter(tracks);
-   Track *n = iter.First();
 
-   while (n) {
-      if (n->GetKind() == Track::Label) {
-         LabelTrack *const lt = static_cast<LabelTrack*>(n);
+   for (auto lt : tracks->Any<LabelTrack>())
       pairs.push_back( std::make_pair(
-            Track::Pointer<LabelTrack>( lt ),
-            lt->SaveFlags() )
-         );
-      }
-      n = iter.Next();
-   }
+         Track::Pointer<LabelTrack>( lt ), lt->SaveFlags() ) );
 }
 
 void LabelDefaultClickHandle::RestoreState( AudacityProject *pProject )
@@ -70,17 +61,12 @@ UIHandle::Result LabelDefaultClickHandle::Click
    {
       SaveState( pProject );
 
-      TrackList *const tracks = pProject->GetTracks();
-      TrackListIterator iter(tracks);
-      Track *n = iter.First();
-
-      while (n) {
-         if (n->GetKind() == Track::Label && evt.pCell.get() != n) {
-            LabelTrack *const lt = static_cast<LabelTrack*>(n);
+      const auto pLT = evt.pCell.get();
+      for (auto lt : pProject->GetTracks()->Any<LabelTrack>()) {
+         if (pLT != lt) {
             lt->ResetFlags();
             lt->Unselect();
          }
-         n = iter.Next();
       }
    }
 

src/tracks/labeltrack/ui/LabelTextHandle.cpp

@@ -87,27 +87,16 @@ UIHandle::Result LabelTextHandle::Click
    {
       // IF the user clicked a label, THEN select all other tracks by Label
 
-      TrackListIterator iter(tracks);
-      Track *t = iter.First();
-
       //do nothing if at least one other track is selected
-      bool done = false;
-      while (!done && t) {
-         if (t->GetSelected() && t != pLT.get())
-            done = true;
-         t = iter.Next();
-      }
+      bool done = tracks->Selected().any_of(
+         [&](const Track *pTrack){ return pTrack != pLT.get(); }
+      );
 
       if (!done) {
          //otherwise, select all tracks
-         t = iter.First();
-         while (t)
-         {
+         for (auto t : tracks->Any())
             selectionState.SelectTrack
-               ( *t, true, true,
-                 pProject->GetMixerBoard() );
-            t = iter.Next();
-         }
+               ( *t, true, true, pProject->GetMixerBoard() );
       }
 
       // Do this after, for its effect on TrackPanel's memory of last selected

src/tracks/ui/TimeShiftHandle.cpp

@@ -229,13 +229,9 @@ void TimeShiftHandle::CreateListOfCapturedClips
 
    // First, if click was in selection, capture selected clips; otherwise
    // just the clicked-on clip
-   if ( state.capturedClipIsSelection ) {
-      TrackListIterator iter( &trackList );
-      for (Track *t = iter.First(); t; t = iter.Next()) {
-         if (t->GetSelected())
+   if ( state.capturedClipIsSelection )
+      for (auto t : trackList.Selected())
          AddClipsToCaptured( state, viewInfo, t, true );
-      }
-   }
    else {
       state.capturedClipArray.push_back
          (TrackClip( &capturedTrack, state.capturedClip ));