Implement Multi View checkbox menu item in wave track TCP...

... When it's off (default), Spectrum and Waveform buttons behave as before,
and dragging of the sub-view separator is disabled.

When it transitions to off, and the view is split, then the top sub-view takes
up the whole view.

When it transitions on, nothing visible happens.

When it is on, and you choose Spectrum or Waveform, then the corrsponding
sub-view toggles visibility.

When a sub-view is turned on by the menu item, it appears lowest.

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

@@ -120,6 +120,7 @@ enum {
    On24BitID,              //    |
    OnFloatID,              // <---
 
+   OnMultiViewID,
    OnWaveformID,
    OnSpectrumID,
    OnSpectrogramSettingsID,
@@ -567,6 +568,7 @@ protected:
 
    PlayableTrackControls::InitMenuData *mpData;
 
+   void OnMultiView(wxCommandEvent & event);
    void OnSetDisplay(wxCommandEvent & event);
    void OnSpectrogramSettings(wxCommandEvent & event);
 
@@ -602,7 +604,11 @@ void WaveTrackMenuTable::InitMenu(Menu *pMenu, void *pUserData)
 
    std::vector<int> checkedIds;
 
-   const auto displays = WaveTrackView::Get( *pTrack ).GetDisplays();
+   const auto &view = WaveTrackView::Get( *pTrack );
+   if (view.GetMultiView())
+      checkedIds.push_back( OnMultiViewID );
+
+   const auto displays = view.GetDisplays();
    for ( auto display : displays ) {
       checkedIds.push_back(
          display == WaveTrackViewConstants::Waveform
@@ -687,18 +693,28 @@ void WaveTrackMenuTable::InitMenu(Menu *pMenu, void *pUserData)
 }
 
 BEGIN_POPUP_MENU(WaveTrackMenuTable)
+
+   WaveTrack *const pTrack = static_cast<WaveTrack*>(mpTrack);
+   const auto &view = WaveTrackView::Get( *pTrack );
+
    POPUP_MENU_SEPARATOR()
 
-   // View types are now a non-exclusive choice.  The first two are mutually
-   // exclusive, but the view may be in a state with either of those, and also
-   // spectrogram, after a mouse drag.  Clicking any of these three makes that
-   // view take up all the height.
-   POPUP_MENU_CHECK_ITEM(OnWaveformID, XO("Wa&veform"), OnSetDisplay)
-   POPUP_MENU_CHECK_ITEM(OnSpectrumID, XO("&Spectrogram"), OnSetDisplay)
+   POPUP_MENU_CHECK_ITEM(OnMultiViewID, XO("&Multi View"), OnMultiView)
+
+   if ( view.GetMultiView() ) {
+      POPUP_MENU_CHECK_ITEM(OnWaveformID, XO("Wa&veform"), OnSetDisplay)
+      POPUP_MENU_CHECK_ITEM(OnSpectrumID, XO("&Spectrogram"), OnSetDisplay)
+   }
+   else {
+      POPUP_MENU_RADIO_ITEM(OnWaveformID, XO("Wa&veform"), OnSetDisplay)
+      POPUP_MENU_RADIO_ITEM(OnSpectrumID, XO("&Spectrogram"), OnSetDisplay)
+   }
 
    POPUP_MENU_ITEM(OnSpectrogramSettingsID, XO("S&pectrogram Settings..."), OnSpectrogramSettings)
    POPUP_MENU_SEPARATOR()
 
+// If these are enabled again, choose a hot key for Mono that does not conflict
+// with Multi View
 //   POPUP_MENU_RADIO_ITEM(OnChannelMonoID, XO("&Mono"), OnChannelChange)
 //   POPUP_MENU_RADIO_ITEM(OnChannelLeftID, XO("&Left Channel"), OnChannelChange)
 //   POPUP_MENU_RADIO_ITEM(OnChannelRightID, XO("R&ight Channel"), OnChannelChange)
@@ -711,9 +727,8 @@ BEGIN_POPUP_MENU(WaveTrackMenuTable)
    POPUP_MENU_ITEM(OnSplitStereoMonoID, XO("Split Stereo to Mo&no"), OnSplitStereoMono)
 #endif
 
-   WaveTrack *const pTrack = static_cast<WaveTrack*>(mpTrack);
    if ( pTrack ) {
-      const auto displays = WaveTrackView::Get( *pTrack ).GetDisplays();
+      const auto displays = view.GetDisplays();
       bool hasWaveform =
          make_iterator_range( displays.begin(), displays.end() )
             .contains( WaveTrackViewConstants::Waveform );
@@ -730,6 +745,23 @@ BEGIN_POPUP_MENU(WaveTrackMenuTable)
 END_POPUP_MENU()
 
 
+void WaveTrackMenuTable::OnMultiView(wxCommandEvent & event)
+{
+   const auto pTrack = static_cast<WaveTrack*>(mpData->pTrack);
+   const auto &view = WaveTrackView::Get( *pTrack );
+   bool multi = !view.GetMultiView();
+   WaveTrackView::WaveTrackDisplay display;
+   if ( !multi )
+      display = *view.GetDisplays().begin();
+   for (const auto channel : TrackList::Channels(pTrack)) {
+      auto &channelView = WaveTrackView::Get( *channel );
+      channelView.SetMultiView( multi );
+      if ( !multi )
+         // Whichever sub-view was on top will take up all
+         channelView.SetDisplay( display );
+   }
+}
+
 ///  Set the Display mode based on the menu choice in the Track Menu.
 void WaveTrackMenuTable::OnSetDisplay(wxCommandEvent & event)
 {
@@ -747,20 +779,28 @@ void WaveTrackMenuTable::OnSetDisplay(wxCommandEvent & event)
       id = Spectrum; break;
    }
 
-   const auto displays = WaveTrackView::Get( *pTrack ).GetDisplays();
-   const bool wrongType = !(displays.size() == 1 && displays[0] == id);
-   if (wrongType) {
+   auto &view = WaveTrackView::Get( *pTrack );
+   if ( view.GetMultiView() ) {
       for (auto channel : TrackList::Channels(pTrack)) {
-         channel->SetLastScaleType();
-         WaveTrackView::Get( *channel )
-            .SetDisplay(WaveTrackView::WaveTrackDisplay(id));
+         WaveTrackView::Get( *channel ).ToggleSubView( id );
       }
+   }
+   else {
+      const auto displays = view.GetDisplays();
+      const bool wrongType = !(displays.size() == 1 && displays[0] == id);
+      if (wrongType) {
+         for (auto channel : TrackList::Channels(pTrack)) {
+            channel->SetLastScaleType();
+            WaveTrackView::Get( *channel )
+               .SetDisplay(WaveTrackView::WaveTrackDisplay(id));
+         }
 
-      AudacityProject *const project = ::GetActiveProject();
-      ProjectHistory::Get( *project ).ModifyState(true);
+         AudacityProject *const project = ::GetActiveProject();
+         ProjectHistory::Get( *project ).ModifyState(true);
 
-      using namespace RefreshCode;
-      mpData->result = RefreshAll | UpdateVRuler;
+         using namespace RefreshCode;
+         mpData->result = RefreshAll | UpdateVRuler;
+      }
    }
 }
 
@@ -896,6 +936,7 @@ void WaveTrackMenuTable::OnMergeStereo(wxCommandEvent &)
    partnerView.SetMinimized(bBothMinimizedp);
 
    partnerView.RestorePlacements( view.SavePlacements() );
+   partnerView.SetMultiView( view.GetMultiView() );
 
    //On Demand - join the queues together.
    if (ODManager::IsInstanceCreated())

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

@@ -197,6 +197,9 @@ public:
       WaveTrackView &view, WaveTrackSubView &subView,
       const TrackPanelMouseState &state )
    {
+      if ( !view.GetMultiView() )
+         return {};
+
       SubViewAdjuster adjuster{ view };
       auto hit = adjuster.HitTest( subView,
          state.state.GetY(), state.rect.GetTop(), state.rect.GetHeight() );
@@ -470,8 +473,9 @@ void WaveTrackView::CopyTo( Track &track ) const
    auto &other = TrackView::Get( track );
 
    if ( const auto pOther = dynamic_cast< WaveTrackView* >( &other ) ) {
-      // only one field is important to preserve in undo/redo history
+      // only these fields are important to preserve in undo/redo history
       pOther->RestorePlacements( SavePlacements() );
+      pOther->mMultiView = mMultiView;
    }
 }
 
@@ -542,6 +546,47 @@ void WaveTrackView::SetDisplay(WaveTrackDisplay display)
    DoSetDisplay( display );
 }
 
+void WaveTrackView::ToggleSubView(WaveTrackDisplay display)
+{
+   size_t ii = 0;
+   size_t found = 0;
+   if ( WaveTrackSubViews::FindIf( [&]( const WaveTrackSubView &subView ) {
+      if ( subView.SubViewType() == display ) {
+         found = ii;
+         return true;
+      }
+      ++ii;
+      return false;
+   } ) ) {
+      auto &foundPlacement = mPlacements[found];
+      if ( foundPlacement.fraction > 0.0 ) {
+         auto index = foundPlacement.index;
+         foundPlacement = { -1, 0.0 };
+         if (index >= 0) {
+            for ( auto &placement : mPlacements ) {
+               if ( placement.index > index )
+                  --placement.index;
+            }
+         }
+      }
+      else {
+         float total = 0;
+         int greatest = -1;
+         unsigned nn = 0;
+         for ( const auto &placement : mPlacements ) {
+            if ( placement.fraction >= 0.0 && placement.index >= 0 ) {
+               total += placement.fraction;
+               greatest = std::max( greatest, placement.index );
+               ++nn;
+            }
+         }
+         // Turn on the sub-view, putting it lowest, and with average of the
+         // heights of the other sub-views
+         foundPlacement = { greatest + 1, total / nn };
+      }
+   }
+}
+
 void WaveTrackView::DoSetDisplay(WaveTrackDisplay display)
 {
    size_t ii = 0;

src/tracks/playabletrack/wavetrack/ui/WaveTrackView.h

@@ -91,6 +91,8 @@ public:
    void RestorePlacements( const WaveTrackSubViewPlacements &placements )
       { mPlacements = placements; }
 
+   void ToggleSubView( WaveTrackDisplay id );
+
    // Get all the sub-views, in a sequence that is unspecified but in
    // correspondence with the result of SavePlacements
    std::vector< std::shared_ptr< WaveTrackSubView > > GetAllSubViews();
@@ -98,6 +100,9 @@ public:
    // Return cached height of rect in last call of GetSubViews
    wxCoord GetLastHeight() const { return mLastHeight; }
 
+   bool GetMultiView() const { return mMultiView; }
+   void SetMultiView( bool value ) { mMultiView = value; }
+
 private:
    void BuildSubViews() const;
    void DoSetDisplay(WaveTrackDisplay display);
@@ -121,6 +126,8 @@ protected:
 
    WaveTrackSubViewPlacements mPlacements;
    mutable wxCoord mLastHeight{};
+
+   bool mMultiView{ false };
 };
 
 // Helper for drawing routines