nonvirtual reimplementation of CellularPanel::FindCell using nodes

src/AdornedRulerPanel.cpp

@@ -2141,19 +2141,6 @@ std::shared_ptr<TrackPanelNode> AdornedRulerPanel::Root()
    return std::make_shared< MainGroup >( *this );
 }
 
-auto AdornedRulerPanel::FindCell(int mouseX, int mouseY) -> FoundCell
-{
-   bool mayScrub = mProject->GetScrubber().CanScrub() &&
-      mShowScrubbing;
-   if (mayScrub && mScrubZone.Contains(mouseX, mouseY))
-      return { mScrubbingCell, mScrubZone };
-
-   if (mInner.Contains(mouseX, mouseY))
-      return { mQPCell, mInner };
-
-   return {};
-}
-
 wxRect AdornedRulerPanel::FindRect(const TrackPanelCell &cell)
 {
    if (&cell == mScrubbingCell.get())

src/AdornedRulerPanel.h

@@ -177,7 +177,6 @@ private:
    // area into cells
    std::shared_ptr<TrackPanelNode> Root() override;
 
-   FoundCell FindCell(int mouseX, int mouseY) override;
    wxRect FindRect(const TrackPanelCell &cell) override;
 public:
    AudacityProject * GetProject() const override;

src/CellularPanel.cpp

@@ -937,7 +937,6 @@ namespace {
       const auto end = children.end();
       const auto nextCoord = ((next == end) ? upperBound : next->first - 1);
 
-      // Some defense against bad overrides of TrackPanelGroup::Children
       auto lesser = std::max(lowerBound, std::min(upperBound, iter->first));
       auto greater = std::max(lesser, std::min(upperBound, nextCoord));
 
@@ -976,6 +975,45 @@ void CellularPanel::Visit(
       return;
 }
 
+auto CellularPanel::FindCell(int mouseX, int mouseY) -> FoundCell
+{
+   auto rect = this->GetClientRect();
+   auto node = Root();
+   while (node) {
+      if ( auto pCell = std::dynamic_pointer_cast< TrackPanelCell >( node ) )
+         // Found the bottom of the hierarchy
+         return { pCell, rect };
+      else if ( auto pGroup = dynamic_cast< TrackPanelGroup* >( node.get() ) ) {
+         // Ask node for its subdivision
+         const auto results = pGroup->Children( rect );
+         const bool divideX = results.first == TrackPanelGroup::Axis::X;
+         const auto &children = results.second;
+
+         // Find the correct child
+         const auto begin = children.begin(), end = children.end();
+         auto iter = std::upper_bound( begin, end,
+            (divideX ? mouseX : mouseY),
+            [&]( wxCoord coord, const TrackPanelGroup::Child &child ) {
+               return coord < child.first;
+            }
+         );
+         if (iter == begin)
+            break;
+         --iter;
+
+         // Descend the hierarchy of nodes
+         rect = Subdivide(rect, divideX, children, iter);
+         node = iter->second;
+      }
+      else
+         // Nulls in the array of children are allowed, to define a void with
+         // no cell
+         break;
+   }
+
+   return { {}, {} };
+}
+
 UIHandlePtr CellularPanel::Target()
 {
    auto &state = *mState;

src/CellularPanel.h

@@ -44,17 +44,10 @@ public:
    
    virtual AudacityProject *GetProject() const = 0;
    
-   // Find track info by coordinate
-   struct FoundCell {
-      std::shared_ptr<TrackPanelCell> pCell;
-      wxRect rect;
-   };
-
    // Get the root object defining a recursive subdivision of the panel's
    // area into cells
    virtual std::shared_ptr<TrackPanelNode> Root() = 0;
 
-   virtual FoundCell FindCell(int mouseX, int mouseY) = 0;
    virtual wxRect FindRect(const TrackPanelCell &cell) = 0;
 
    // Structure and functions for generalized visitation of the subdivision
@@ -93,6 +86,14 @@ public:
    virtual bool TakesFocus() const = 0;
    
 public:
+   // Find cell by coordinate
+   struct FoundCell {
+      std::shared_ptr< TrackPanelCell > pCell;
+      wxRect rect;
+   };
+
+   FoundCell FindCell(int mouseX, int mouseY);
+
    UIHandlePtr Target();
    
    std::shared_ptr<TrackPanelCell> LastCell() const;

src/TrackPanel.cpp

@@ -126,13 +126,13 @@ time, but that width may be adjusted when tracks change their vertical scales.
 GetLabelWidth() counts columns up to and including the VRuler.
 GetLeftOffset() is yet one more -- it counts the "one pixel" column.
 
-FindCell() for label returns a rectangle that OMITS left, top, and bottom
+Cell for label has a rectangle that OMITS left, top, and bottom
 margins
 
-FindCell() for vruler returns a rectangle right of the label,
+Cell for vruler has a rectangle right of the label,
 up to and including the One Pixel column, and OMITS top and bottom margins
 
-FindCell() for track returns a rectangle with x == GetLeftOffset(), and OMITS
+Cell() for track returns a rectangle with x == GetLeftOffset(), and OMITS
 right, top, and bottom margins
 
 +--------------- ... ------ ... --------------------- ...       ... -------------+
@@ -2088,27 +2088,6 @@ std::shared_ptr<TrackPanelNode> TrackPanel::Root()
    return std::make_shared< MainGroup >( *this );
 }
 
-/// Determines which cell is under the mouse
-///  @param mouseX - mouse X position.
-///  @param mouseY - mouse Y position.
-auto TrackPanel::FindCell(int mouseX, int mouseY) -> FoundCell
-{
-   auto range = Cells();
-   auto &iter = range.first, &end = range.second;
-   while
-      ( iter != end &&
-        !(*iter).second.Contains( mouseX, mouseY ) )
-      ++iter;
-   if (iter == end)
-      return {};
-
-   auto found = *iter;
-   return {
-      found.first,
-      found.second
-   };
-}
-
 wxRect TrackPanel::FindRect( const TrackPanelCell &cell )
 {
    auto range = Cells();

src/TrackPanel.h

@@ -341,9 +341,6 @@ protected:
    // area into cells
    std::shared_ptr<TrackPanelNode> Root() override;
 
-   // Find track info by coordinate
-   FoundCell FindCell(int mouseX, int mouseY) override;
-
    // Find rectangle of the given cell
    wxRect FindRect(const TrackPanelCell &cell) override;