Change the track view copy function...

... It is const, renamed CopyTo, and invokes the create-on-demand factory in
the destination track; this means Track.cpp doesn't need to do that, and so
does not need TrackView.h

src/Track.cpp

@@ -41,8 +41,6 @@ and TimeTrack.
 
 #include "InconsistencyException.h"
 
-#include "tracks/ui/TrackView.h"
-
 #ifdef _MSC_VER
 //Disable truncation warnings
 #pragma warning( disable : 4786 )
@@ -115,7 +113,7 @@ Track::Holder Track::Duplicate() const
 
    if (mpView)
       // Copy view state that might be important to undo/redo
-      TrackView::Get( *result ).Copy( *mpView );
+      mpView->CopyTo( *result );
 
    return result;
 }

src/tracks/labeltrack/ui/LabelTrackView.cpp

@@ -97,13 +97,14 @@ void LabelTrackView::UnbindFrom( LabelTrack *pParent )
       EVT_LABELTRACK_PERMUTED, &LabelTrackView::OnLabelPermuted, this );
 }
 
-void LabelTrackView::Copy( const CommonTrackCell &other )
+void LabelTrackView::CopyTo( Track &track ) const
 {
-   TrackView::Copy( other );
+   TrackView::CopyTo( track );
+   auto &other = TrackView::Get( track );
 
    if ( const auto pOther = dynamic_cast< const LabelTrackView* >( &other ) ) {
       // only one field is important to preserve in undo/redo history
-      mSelIndex = pOther->mSelIndex;
+      pOther->mSelIndex = mSelIndex;
    }
 }
 

src/tracks/labeltrack/ui/LabelTrackView.h

@@ -82,7 +82,7 @@ private:
    std::shared_ptr<TrackVRulerControls> DoGetVRulerControls() override;
 
    // Preserve some view state too for undo/redo purposes
-   void Copy( const CommonTrackCell &other ) override;
+   void CopyTo( Track &track ) const override;
 
 public:
    static void DoEditLabels(

src/tracks/ui/CommonTrackPanelCell.cpp

@@ -57,7 +57,7 @@ CommonTrackCell::CommonTrackCell( const std::shared_ptr< Track > &parent )
 
 CommonTrackCell::~CommonTrackCell() = default;
 
-void CommonTrackCell::Copy( const CommonTrackCell & )
+void CommonTrackCell::CopyTo( Track& ) const
 {
 }
 

src/tracks/ui/CommonTrackPanelCell.h

@@ -63,7 +63,8 @@ public:
   ~CommonTrackCell();
 
    // Copy state, for undo/redo purposes
-   virtual void Copy( const CommonTrackCell &other );
+   // The default does nothing
+   virtual void CopyTo( Track &track ) const;
 
    std::shared_ptr<Track> DoFindTrack() override;
 

src/tracks/ui/TrackView.cpp

@@ -46,18 +46,15 @@ int TrackView::GetTotalHeight( const TrackList &list )
    return GetCumulativeHeight( *list.Any().rbegin() );
 }
 
-void TrackView::Copy( const CommonTrackCell &otherCell )
+void TrackView::CopyTo( Track &track ) const
 {
-   auto pOther = dynamic_cast< const TrackView* >( &otherCell );
-   if ( !pOther )
-      return;
-   auto &other = *pOther;
+   auto &other = Get( track );
 
-   mMinimized = other.mMinimized;
+   other.mMinimized = mMinimized;
 
    // Let mY remain 0 -- TrackPositioner corrects it later
-   mY = 0;
-   mHeight = other.mHeight;
+   other.mY = 0;
+   other.mHeight = mHeight;
 }
 
 TrackView &TrackView::Get( Track &track )

src/tracks/ui/TrackView.h

@@ -42,7 +42,7 @@ public:
    static int GetTotalHeight( const TrackList &list );
 
    // Copy view state, for undo/redo purposes
-   void Copy( const CommonTrackCell &other ) override;
+   void CopyTo( Track &track ) const override;
 
    static TrackView &Get( Track & );
    static const TrackView &Get( const Track & );