CellularPanel.cpp

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/**********************************************************************
 
  Audacity: A Digital Audio Editor
 
  CellularPanel.cpp
 
  Dominic Mazzoni
  and lots of other contributors
 
  Implements CellularPanel.
 
********************************************************************//*****************************************************************/
 
 
#include "CellularPanel.h"
 
#include <wx/eventfilter.h>
#include <wx/setup.h> // for wxUSE_* macros
#include "KeyboardCapture.h"
#include "UIHandle.h"
#include "TrackPanelMouseEvent.h"
#include "HitTestResult.h"
#include "RefreshCode.h"
#include "TrackPanelCell.h"
 
// A singleton class that intercepts escape key presses when some cellular
// panel is dragging
struct CellularPanel::Filter : wxEventFilter
{
   Filter()
   {
      wxEvtHandler::AddFilter( this );
   }
 
   ~Filter()
   {
      wxEvtHandler::RemoveFilter( this );
   }
 
   static void Create()
   {
      static Filter instance;
   }
 
   int FilterEvent( wxEvent &event ) override
   {
      const auto type = event.GetEventType();
      if (type == wxEVT_KEY_DOWN &&
          static_cast< wxKeyEvent& >( event ).GetKeyCode() == WXK_ESCAPE ) {
         bool eatEvent = false;
         for (const auto &pPanel: {spClickedPanel, spEnteredPanel}) {
            if (pPanel) {
               eatEvent = true;
               // Handle escape either in the clicked panel to abort a drag, or
               // to switch among hit test candidates before button down in the
               // entered (but not yet clicked) panel
               pPanel->HandleEscapeKey( true );
            }
         }
         if (eatEvent)
            return Event_Processed;
      }
      else if ((type == wxEVT_LEFT_DOWN ||
                type == wxEVT_RIGHT_DOWN ||
                type == wxEVT_MIDDLE_DOWN)) {
         if ( spClickedPanel &&
             spClickedPanel != event.GetEventObject() ) {
            // Clicking away from the panel doesn't necessarily change wxWidgets
            // focus, so we use this global filter instead
            spClickedPanel->DoKillFocus();
            // Don't eat the event
         }
      }
      return Event_Skip;
   }
 
   static wxWeakRef< CellularPanel > spClickedPanel;
   static wxWeakRef< CellularPanel > spEnteredPanel;
};
 
wxWeakRef< CellularPanel > CellularPanel::Filter::spClickedPanel = nullptr;
wxWeakRef< CellularPanel > CellularPanel::Filter::spEnteredPanel = nullptr;
 
struct CellularPanel::State
{
   UIHandlePtr mUIHandle;
   
   std::weak_ptr<TrackPanelCell> mLastCell;
   std::vector<UIHandlePtr> mTargets;
   size_t mTarget {};
   unsigned mMouseOverUpdateFlags{};
 
   int mMouseMostRecentX;
   int mMouseMostRecentY;
   
   std::weak_ptr<TrackPanelCell> mpClickedCell;
   
   bool mEnableTab{};
};
 
 
BEGIN_EVENT_TABLE(CellularPanel, OverlayPanel)
    EVT_MOUSE_EVENTS(CellularPanel::OnMouseEvent)
    EVT_MOUSE_CAPTURE_LOST(CellularPanel::OnCaptureLost)
    EVT_COMMAND(wxID_ANY, EVT_CAPTURE_KEY, CellularPanel::OnCaptureKey)
    EVT_KEY_DOWN(CellularPanel::OnKeyDown)
    EVT_KEY_UP(CellularPanel::OnKeyUp)
    EVT_CHAR(CellularPanel::OnChar)
    EVT_SET_FOCUS(CellularPanel::OnSetFocus)
    EVT_KILL_FOCUS(CellularPanel::OnKillFocus)
    EVT_CONTEXT_MENU(CellularPanel::OnContextMenu)
END_EVENT_TABLE()
 
CellularPanel::CellularPanel(
   wxWindow * parent, wxWindowID id,
   const wxPoint & pos, const wxSize & size,
   ViewInfo *viewInfo,
   long style)
: OverlayPanel(parent, id, pos, size, style)
, mViewInfo( viewInfo )
, mState{ std::make_unique<State>() }
{
   // Create the global event filter instance for CellularPanels only when the
   // first CellularPanel is created, not sooner, so that the filter will be
   // invoked before that for the application.
   Filter::Create();
}
 
CellularPanel::~CellularPanel() = default;
 
void CellularPanel::HandleInterruptedDrag()
{
   auto &state = *mState;
   if (state.mUIHandle &&
       state.mUIHandle->StopsOnKeystroke() ) {
      // The bogus id isn't used anywhere, but may help with debugging.
      // as this is sending a bogus mouse up.  The mouse button is still actually down
      // and may go up again.
      const int idBogusUp = 2;
      wxMouseEvent evt { wxEVT_LEFT_UP };
      evt.SetId( idBogusUp );
      evt.SetPosition(this->ScreenToClient(::wxGetMousePosition()));
      this->ProcessEvent(evt);
   }
}
 
void CellularPanel::Uncapture(bool escaping, wxMouseState *pState)
{
   auto state = ::wxGetMouseState();
   if (!pState) {
      // Remap the position
      state.SetPosition(this->ScreenToClient(state.GetPosition()));
      pState = &state;
   }
 
   if (HasCapture())
      ReleaseMouse();
   HandleMotion( *pState );
 
   if ( escaping || !AcceptsFocus() )
      Filter::spClickedPanel = nullptr;
}
 
bool CellularPanel::CancelDragging( bool escaping )
{
   auto &state = *mState;
   if (state.mUIHandle) {
      // copy shared_ptr for safety, as in HandleClick
      auto handle = state.mUIHandle;
      // UIHANDLE CANCEL
      UIHandle::Result refreshResult = handle->Cancel(GetProject());
      auto pClickedCell = state.mpClickedCell.lock();
      if (pClickedCell)
         ProcessUIHandleResult(
            pClickedCell.get(), {},
            refreshResult | state.mMouseOverUpdateFlags );
      state.mpClickedCell.reset();
      state.mUIHandle.reset(), handle.reset(), ClearTargets();
      Uncapture( escaping );
      return true;
   }
   return false;
}
 
bool CellularPanel::HandleEscapeKey(bool down)
{
   if (!down)
      return false;
 
   {
      auto target = Target();
      const auto pProject = GetProject();
      if (target && target->HasEscape(pProject) && target->Escape(pProject)) {
         HandleCursorForPresentMouseState(false);
         return true;
      }
   }
 
   auto &state = *mState;
   if (state.mUIHandle) {
      CancelDragging( true );
      return true;
   }
 
   if (ChangeTarget(true, false)) {
      HandleCursorForPresentMouseState(false);
      return true;
   }
 
   return false;
}
 
void CellularPanel::UpdateMouseState(const wxMouseState &state)
{
   mLastMouseState = state;
 
   // Simulate a down button if none, so hit test routines can anticipate
   // which button will be clicked
   if (!state.ButtonIsDown(wxMOUSE_BTN_ANY)) {
#ifdef __WXOSX__
      if (state.RawControlDown())
         // On Mac we can distinctly anticipate "right" click (as Control+click)
         mLastMouseState.SetRightDown( true ),
         mLastMouseState.SetLeftDown( false );
      else
#endif
         // Anticipate a left click by default
         mLastMouseState.SetRightDown( false ),
         mLastMouseState.SetLeftDown( true );
   }
}
 
void CellularPanel::HandleModifierKey()
{
   HandleCursorForPresentMouseState();
}
 
void CellularPanel::HandleCursorForPresentMouseState(bool doHit)
{
   // Come here on modifier key or mouse button transitions,
   // or on starting or stopping of play or record,
   // or change of toolbar button,
   // and change the cursor appropriately.
 
   // Get the button and key states
   auto state = ::wxGetMouseState();
   // Remap the position
   state.SetPosition(this->ScreenToClient(state.GetPosition()));
 
   HandleMotion( state, doHit );
}
 
void CellularPanel::HandleMotion( wxMouseState &inState, bool doHit )
{
   UpdateMouseState( inState );
 
   const auto foundCell = FindCell( inState.m_x, inState.m_y );
   auto &rect = foundCell.rect;
   auto &pCell = foundCell.pCell;
   const TrackPanelMouseState tpmState{ mLastMouseState, rect, pCell };
   HandleMotion( tpmState, doHit );
}
 
void CellularPanel::HandleMotion
( const TrackPanelMouseState &tpmState, bool doHit )
{
   auto &state = *mState;
   auto handle = state.mUIHandle;
 
   auto newCell = tpmState.pCell;
   auto oldCell = state.mLastCell.lock();
   auto oldHandle = Target();
 
   TranslatableString status, tooltip;
   wxCursor *pCursor{};
   unsigned refreshCode = 0;
   if ( ! doHit ) {
      // Dragging or not
      handle = Target();
 
      // Assume cell does not change but target does
      refreshCode = state.mMouseOverUpdateFlags;
      state.mMouseOverUpdateFlags = 0;
   }
   else if ( !state.mUIHandle ) {
      // Not yet dragging.
 
      unsigned updateFlags = state.mMouseOverUpdateFlags;
 
      // First check whether crossing cell to cell
      if ( newCell == oldCell )
         oldCell.reset();
      else {
         // Forget old targets
         ClearTargets();
         // Re-draw any highlighting
         if (oldCell) {
            ProcessUIHandleResult(
               oldCell.get(), oldCell.get(), updateFlags);
         }
      }
 
      auto oldPosition = state.mTarget;
 
      // Now do the
      // UIHANDLE HIT TEST !
      state.mTargets.clear();
      if (newCell)
         state.mTargets = newCell->HitTest(tpmState, GetProject());
      state.mTarget = 0;
 
      // Find the old target's NEW place if we can
      if (oldHandle) {
         auto begin = state.mTargets.begin(), end = state.mTargets.end(),
            iter = std::find(begin, end, oldHandle);
         if (iter != end) {
            size_t newPosition = iter - begin;
            if (newPosition <= oldPosition)
               state.mTarget = newPosition;
            // else, some NEW hit at this position takes priority
         }
      }
 
      handle = Target();
 
      state.mLastCell = newCell;
 
      // These lines caused P2 Bug 2617, repeated refreshing using all CPU.
      // Disabling them might be causing something to not refresh,
      // but so far I have not found a downside to disabling them.  JKC
 
      // VS: https://github.com/audacity/audacity/issues/1363
      // Extensive refresh request fixed by using std::move on 
      // new envelope handle instance
      if (!oldCell && oldHandle != handle)
          // Did not move cell to cell, but did change the target
          refreshCode = updateFlags;
 
 
      if (handle && handle != oldHandle)
         handle->Enter(true, GetProject());
 
      if (oldHandle == handle)
         oldHandle.reset();
   }
 
   // UIHANDLE PREVIEW
   // Update status message and cursor, whether dragging or not
   if (handle) {
      auto preview = handle->Preview( tpmState, GetProject() );
      status = preview.message;
      tooltip = preview.tooltip;
      pCursor = preview.cursor;
      auto code = handle->GetChangeHighlight();
      handle->SetChangeHighlight(RefreshCode::RefreshNone);
      refreshCode |= code;
      state.mMouseOverUpdateFlags |= code;
   }
   if (newCell &&
       (!pCursor || status.empty() || tooltip.empty())) {
      // Defaulting of cursor, tooltip, and status if there is no handle,
      // or if the handle does not specify them
      const auto preview = newCell->DefaultPreview( tpmState, GetProject() );
      if (!pCursor)
         pCursor = preview.cursor;
      if (status.empty())
         status = preview.message;
      if (tooltip.empty())
         tooltip = preview.tooltip;
   }
   if (!pCursor) {
      // Ultimate default cursor
      static wxCursor defaultCursor{ wxCURSOR_DEFAULT };
      pCursor = &defaultCursor;
   }
 
   // Update status, tooltip, and cursor only if we're dragging, or the mouse
   // was in one of our cells and nobody else is dragging
   if (handle || (newCell && !wxWindow::GetCapture())) {
      UpdateStatusMessage(status);
 
#if wxUSE_TOOLTIPS
      if (tooltip.Translation() != GetToolTipText()) {
         // Unset first, by analogy with AButton
         UnsetToolTip();
         if (handle != oldHandle)
            SetToolTip(tooltip);
      }
#endif
 
      if (pCursor)
         SetCursor( *pCursor );
   }
   else if ( oldCell || oldHandle )
      // Leaving a cell or hit test target with no replacement
      UpdateStatusMessage( {} );
 
   if (newCell)
      ProcessUIHandleResult(newCell.get(), newCell.get(), refreshCode);
}
 
void CellularPanel::Leave()
{
   // Make transition into an empty CellularPanel state
   auto state = ::wxGetMouseState();
   const wxRect rect;
   std::shared_ptr<TrackPanelCell> pCell;
   TrackPanelMouseState tpmState{ state, rect, pCell };
   HandleMotion( tpmState );
}
 
bool CellularPanel::HasRotation()
{
   auto &state = *mState;
   // Is there a nontrivial TAB key rotation?
   if ( state.mTargets.size() > 1 )
      return true;
   auto target = Target();
   return target && target->HasRotation();
}
 
bool CellularPanel::HasEscape()
{
   if (IsMouseCaptured())
      return true;
 
   auto &state = *mState;
  if (state.mTarget + 1 == state.mTargets.size() &&
       Target() &&
       !Target()->HasEscape(GetProject()))
       return false;
 
   return state.mTargets.size() > 0;
}
 
bool CellularPanel::ChangeTarget(bool forward, bool cycle)
{
   auto &state = *mState;
   auto size = state.mTargets.size();
 
   auto target = Target();
   if (target && target->HasRotation()) {
      if(target->Rotate(forward))
         return true;
      else if (cycle && (size == 1 || IsMouseCaptured())) {
         // Rotate through the states of this target only.
         target->Enter(forward, GetProject());
         return true;
      }
   }
 
   if (!cycle &&
       ((forward && state.mTarget + 1 == size) ||
        (!forward && state.mTarget == 0)))
      return false;
 
   if (size > 1) {
      if (forward)
         ++state.mTarget;
      else
         state.mTarget += size - 1;
      state.mTarget %= size;
      if (Target())
         Target()->Enter(forward, GetProject());
      return true;
   }
 
   return false;
}
 
bool CellularPanel::IsMouseCaptured()
{
   auto &state = *mState;
   return state.mUIHandle != NULL;
}
 
void CellularPanel::OnContextMenu(wxContextMenuEvent & WXUNUSED(event))
{
   DoContextMenu({});
}
 
void CellularPanel::HandleWheelRotation( TrackPanelMouseEvent &tpmEvent )
{
   auto pCell = tpmEvent.pCell;
   if (!pCell)
      return;
 
   auto &event = tpmEvent.event;
   double steps {};
#if defined(__WXMAC__) && defined(EVT_MAGNIFY)
   // PRL:
   // Pinch and spread implemented in wxWidgets 3.1.0, or cherry-picked from
   // the future in custom build of 3.0.2
   if (event.Magnify()) {
      event.SetControlDown(true);
      steps = 2 * event.GetMagnification();
   }
   else
#endif
   {
      steps = event.m_wheelRotation /
         (event.m_wheelDelta > 0 ? (double)event.m_wheelDelta : 120.0);
   }
 
   if(event.GetWheelAxis() == wxMOUSE_WHEEL_HORIZONTAL) {
      // Two-fingered horizontal swipe on mac is treated like shift-mousewheel
      event.SetShiftDown(true);
      // This makes the wave move in the same direction as the fingers, and the scrollbar
      // thumb moves oppositely
      steps *= -1;
   }
 
   tpmEvent.steps = steps;
 
   if(!event.HasAnyModifiers()) {
      // We will later un-skip if we do anything, but if we don't,
      // propagate the event up for the sake of the scrubber
      event.Skip();
      event.ResumePropagation(wxEVENT_PROPAGATE_MAX);
   }
 
   unsigned result =
      pCell->HandleWheelRotation( tpmEvent, GetProject() );
   ProcessUIHandleResult(
      pCell.get(), pCell.get(), result);
}
 
void CellularPanel::OnCaptureKey(wxCommandEvent & event)
{
   auto &state = *mState;
   state.mEnableTab = false;
   wxKeyEvent *kevent = static_cast<wxKeyEvent *>(event.GetEventObject());
   const auto code = kevent->GetKeyCode();
   if ( WXK_ESCAPE != code )
      HandleInterruptedDrag();
 
   // Give focused cell precedence
   const auto t = GetFocusedCell();
   if (t) {
      const unsigned refreshResult =
         t->CaptureKey(*kevent, *mViewInfo, this, GetProject());
      ProcessUIHandleResult(t.get(), t.get(), refreshResult);
      event.Skip(kevent->GetSkipped());
   }
 
#if 0
   // Special TAB key handling, but only if the cell didn't capture it
   if ( !(t && !kevent->GetSkipped()) &&
        WXK_TAB == code && HasRotation() ) {
      // Override TAB navigation in wxWidgets, by not skipping
      event.Skip(false);
      mEnableTab = true;
      return;
   }
   else
#endif
   if (!t)
      event.Skip();
}
 
void CellularPanel::OnKeyDown(wxKeyEvent & event)
{
   switch (event.GetKeyCode())
   {
   case WXK_ESCAPE:
      // This switch case is now redundant with the global filter
      if(HandleEscapeKey(true))
         // Don't skip the event, eat it so that
         // AudacityApp does not also stop any playback.
         return;
      else
         break;
 
   case WXK_ALT:
   case WXK_SHIFT:
   case WXK_CONTROL:
#ifdef __WXOSX__
   case WXK_RAW_CONTROL:
#endif
      HandleModifierKey();
      break;
 
#if 0
   case WXK_TAB:
      if ( mEnableTab && HasRotation() ) {
         ChangeTarget( !event.ShiftDown(), true );
         HandleCursorForPresentMouseState(false);
         return;
      }
      else
         break;
#endif
   }
 
   const auto t = GetFocusedCell();
   if (t) {
      const unsigned refreshResult =
         t->KeyDown(event, *mViewInfo, this, GetProject());
      ProcessUIHandleResult(t.get(), t.get(), refreshResult);
   }
   else
      event.Skip();
}
 
void CellularPanel::OnChar(wxKeyEvent & event)
{
   switch (event.GetKeyCode())
   {
   case WXK_ESCAPE:
   case WXK_ALT:
   case WXK_SHIFT:
   case WXK_CONTROL:
   case WXK_PAGEUP:
   case WXK_PAGEDOWN:
      return;
   }
 
   const auto t = GetFocusedCell();
   if (t) {
      const unsigned refreshResult =
         t->Char(event, *mViewInfo, this, GetProject());
      ProcessUIHandleResult(t.get(), t.get(), refreshResult);
   }
   else
      event.Skip();
}
 
void CellularPanel::OnKeyUp(wxKeyEvent & event)
{
   bool didSomething = false;
   switch (event.GetKeyCode())
   {
   case WXK_ESCAPE:
      didSomething = HandleEscapeKey(false);
      break;
 
   case WXK_ALT:
   case WXK_SHIFT:
   case WXK_CONTROL:
#ifdef __WXOSX__
   case WXK_RAW_CONTROL:
#endif
      HandleModifierKey();
      break;
   }
 
   if (didSomething)
      return;
 
   const auto t = GetFocusedCell();
   if (t) {
      const unsigned refreshResult =
         t->KeyUp(event, *mViewInfo, this, GetProject());
      ProcessUIHandleResult(t.get(), t.get(), refreshResult);
      return;
   }
 
   event.Skip();
}
 
void CellularPanel::OnCaptureLost(wxMouseCaptureLostEvent & WXUNUSED(event))
{
   auto &state = *mState;
   state.mUIHandle.reset();
   Leave();
 
   // This is bad.  We are lying abou the event by saying it is a mouse up.
   wxMouseEvent e(wxEVT_LEFT_UP);
   e.SetId( kCaptureLostEventId );
 
   e.m_x = state.mMouseMostRecentX;
   e.m_y = state.mMouseMostRecentY;
 
   OnMouseEvent(e);
}
 
void CellularPanel::OnMouseEvent(wxMouseEvent & event)
try
{
   const auto foundCell = FindCell( event.m_x, event.m_y );
   auto &rect = foundCell.rect;
   auto &pCell = foundCell.pCell;
 
   const auto size = GetSize();
   TrackPanelMouseEvent tpmEvent{ event, rect, size, pCell };
 
#if defined(__WXMAC__) && defined(EVT_MAGNIFY)
   // PRL:
   // Pinch and spread implemented in wxWidgets 3.1.0, or cherry-picked from
   // the future in custom build of 3.0.2
   if (event.Magnify()) {
      HandleWheelRotation( tpmEvent );
   }
#endif
 
   // If a mouse event originates from a keyboard context menu event then
   // event.GetPosition() == wxDefaultPosition. wxContextMenu events are handled in
   // CellularPanel::OnContextMenu(), and therefore associated mouse events are ignored here.
   // Not ignoring them was causing bug 613: the mouse events were interpreted as clicking
   // outside the tracks.
   if (event.GetPosition() == wxDefaultPosition && (event.RightDown() || event.RightUp())) {
      event.Skip();
      return;
   }
 
   if (event.m_wheelRotation != 0)
      HandleWheelRotation( tpmEvent );
 
   if (event.LeftDown() || event.LeftIsDown() || event.Moving()) {
      // Skip, even if we do something, so that the left click or drag
      // may have an additional effect in the scrubber.
      event.Skip();
      event.ResumePropagation(wxEVENT_PROPAGATE_MAX);
   }
 
   auto &state = *mState;
   state.mMouseMostRecentX = event.m_x;
   state.mMouseMostRecentY = event.m_y;
 
   if (event.LeftDown()) {
      // The activate event is used to make the
      // parent window 'come alive' if it didn't have focus.
      wxActivateEvent e;
      GetParent()->GetEventHandler()->ProcessEvent(e);
   }
 
   if (event.Entering())
   {
      Filter::spEnteredPanel = this;
   }
   else if (event.Leaving())
   {
      if (Filter::spEnteredPanel == this)
         Filter::spEnteredPanel = nullptr;
      Leave();
 
      auto buttons =
         // Bug 1325: button state in Leaving events is unreliable on Mac.
         // Poll the global state instead.
         // event.ButtonIsDown(wxMOUSE_BTN_ANY);
         ::wxGetMouseState().ButtonIsDown(wxMOUSE_BTN_ANY);
 
      if (!buttons) {
         CancelDragging( false );
 
#if defined(__WXMAC__)
 
         // We must install the cursor ourselves since the window under
         // the mouse is no longer this one and wx2.8.12 makes that check.
         // Should re-evaluate with wx3.
         wxSTANDARD_CURSOR->MacInstall();
#endif
      }
   }
 
   if (state.mUIHandle) {
      auto pClickedCell = state.mpClickedCell.lock();
      if (event.Dragging()) {
         // UIHANDLE DRAG
         // copy shared_ptr for safety, as in HandleClick
         auto handle = state.mUIHandle;
         const UIHandle::Result refreshResult =
            handle->Drag( tpmEvent, GetProject() );
         ProcessUIHandleResult
            (pClickedCell.get(), pCell.get(), refreshResult);
         state.mMouseOverUpdateFlags |= refreshResult;
         if (refreshResult & RefreshCode::Cancelled) {
            // Drag decided to abort itself
            state.mUIHandle.reset(), handle.reset(), ClearTargets();
            state.mpClickedCell.reset();
            Uncapture( false, &event );
         }
         else {
            UpdateMouseState(event);
            TrackPanelMouseState tpmState{ mLastMouseState, rect, pCell };
            HandleMotion( tpmState );
         }
      }
      else if (event.ButtonUp()) {
         // UIHANDLE RELEASE
         // copy shared_ptr for safety, as in HandleClick
         auto handle = state.mUIHandle;
         unsigned moreFlags = state.mMouseOverUpdateFlags;
         UIHandle::Result refreshResult =
            handle->Release( tpmEvent, GetProject(), this );
         ProcessUIHandleResult
            (pClickedCell.get(), pCell.get(),
             refreshResult | moreFlags);
         state.mUIHandle.reset(), handle.reset(), ClearTargets();
         state.mpClickedCell.reset();
         // will also Uncapture() below
      }
   }
   else if ( event.GetEventType() == wxEVT_MOTION )
      // Update status message and cursor, not during drag
      // consider it not a drag, even if button is down during motion, if
      // mUIHandle is null, as it becomes during interrupted drag
      // (e.g. by hitting space to play while dragging an envelope point)
      HandleMotion( event );
   else if ( event.ButtonDown() || event.ButtonDClick() )
      HandleClick( tpmEvent );
 
   if (event.ButtonDown() && IsMouseCaptured()) {
      if (!HasCapture())
         CaptureMouse();
   }
 
   if (event.ButtonUp())
      Uncapture( false );
}
catch( ... )
{
   // Abort any dragging, as if by hitting Esc
   if ( CancelDragging( true ) )
      ;
   else {
      Uncapture( true );
      Refresh(false);
   }
   throw;
}
 
namespace {
 
class DefaultRightButtonHandler : public UIHandle {
public:
   explicit DefaultRightButtonHandler(
      const std::shared_ptr<TrackPanelCell> &pCell )
      : mwCell{ pCell }
   {}
 
   ~DefaultRightButtonHandler() override;
 
   std::shared_ptr<const Track> FindTrack() const override
   { return nullptr; }
 
   virtual Result Click
      (const TrackPanelMouseEvent &event, AudacityProject *pProject) override
   {
      return RefreshCode::RefreshNone;
   }
 
   virtual Result Drag
      (const TrackPanelMouseEvent &event, AudacityProject *pProject) override
   {
      return RefreshCode::RefreshNone;
   }
 
   virtual HitTestPreview Preview
      (const TrackPanelMouseState &state, AudacityProject *pProject) override
   {
      return {};
   }
 
   virtual Result Release
      (const TrackPanelMouseEvent &event, AudacityProject *pProject,
       wxWindow *pParent) override
   {
      if (auto pCell = mwCell.lock()) {
         auto point = event.event.GetPosition();
         return pCell->DoContextMenu(event.rect, pParent, &point, pProject);
      }
      return RefreshCode::RefreshNone;
   }
 
   virtual Result Cancel(AudacityProject *pProject) override
   {
      return RefreshCode::RefreshNone;
   }
 
private:
   std::weak_ptr<TrackPanelCell> mwCell;
};
 
DefaultRightButtonHandler::~DefaultRightButtonHandler()
{
}
 
}
 
void CellularPanel::HandleClick( const TrackPanelMouseEvent &tpmEvent )
{
   auto pCell = tpmEvent.pCell;
   // Do hit test once more, in case the button really pressed was not the
   // one "anticipated."
   {
      TrackPanelMouseState tpmState{
         tpmEvent.event,
         tpmEvent.rect,
         tpmEvent.pCell
      };
      HandleMotion( tpmState );
   }
 
   auto &state = *mState;
   state.mUIHandle = Target();
   if (tpmEvent.event.RightDown() &&
       !(state.mUIHandle && state.mUIHandle->HandlesRightClick())) {
      if (auto pCell = state.mLastCell.lock())
         state.mUIHandle = std::make_shared<DefaultRightButtonHandler>(pCell);
   }
 
   if (state.mUIHandle) {
      // UIHANDLE CLICK
      // Make another shared pointer to the handle, in case recursive
      // event dispatching otherwise tries to delete the handle.
      auto handle = state.mUIHandle;
      UIHandle::Result refreshResult =
         handle->Click( tpmEvent, GetProject() );
      if (refreshResult & RefreshCode::Cancelled)
         state.mUIHandle.reset(), handle.reset(), ClearTargets();
      else {
         Filter::spClickedPanel = this;
 
#if wxUSE_TOOLTIPS
         // Remove any outstanding tooltip
         UnsetToolTip();
#endif
 
         if( !HasFocus() && AcceptsFocus() )
            SetFocusIgnoringChildren();
 
         state.mpClickedCell = pCell;
 
         // Perhaps the clicked handle wants to update cursor and state message
         // after a click.
         TrackPanelMouseState tpmState{
            tpmEvent.event,
            tpmEvent.rect,
            tpmEvent.pCell
         };
         HandleMotion( tpmState );
      }
      ProcessUIHandleResult(
         pCell.get(), pCell.get(), refreshResult);
      state.mMouseOverUpdateFlags |= refreshResult;
   }
}
 
void CellularPanel::DoContextMenu( std::shared_ptr<TrackPanelCell> pCell )
{
   if( !pCell ) {
      pCell = GetFocusedCell();
      if( !pCell )
         return;
   }
 
   std::weak_ptr<TrackPanelCell> wCell = pCell;
 
   const auto delegate = pCell->ContextMenuDelegate();
   if (!delegate)
      return;
 
   auto rect = FindRect( *delegate );
   const UIHandle::Result refreshResult =
      delegate->DoContextMenu(rect, this, nullptr, GetProject());
   pCell.reset();
 
   ProcessUIHandleResult(wCell.lock().get(), wCell.lock().get(), refreshResult);
}
 
void CellularPanel::OnSetFocus(wxFocusEvent &event)
{
   SetFocusedCell();
   Refresh( false);
}
 
void CellularPanel::DoKillFocus()
{
   if (auto pCell = GetFocusedCell()) {
      auto refreshResult = pCell->LoseFocus(GetProject());
      auto &state = *mState;
      auto pClickedCell = state.mpClickedCell.lock();
      if (pClickedCell)
         ProcessUIHandleResult( pClickedCell.get(), {}, refreshResult );
   }
   Refresh( false);
}
 
void CellularPanel::OnKillFocus(wxFocusEvent & WXUNUSED(event))
{
   DoKillFocus();
   if (KeyboardCapture::IsHandler(this))
   {
      KeyboardCapture::Release(this);
   }
}
 
// Empty out-of-line default functions to fill Visitor's vtable
CellularPanel::Visitor::~Visitor() {}
void CellularPanel::Visitor::VisitCell(
   const wxRect &rect, TrackPanelCell &cell ) {}
void CellularPanel::Visitor::BeginGroup(
   const wxRect &rect, TrackPanelGroup &group ) {}
void CellularPanel::Visitor::EndGroup(
   const wxRect &rect, TrackPanelGroup &group ) {}
 
// Public, top-level entry for generalized Visit
void CellularPanel::Visit( Visitor &visitor )
{
   Visit( GetClientRect(), Root(), visitor );
}
 
// Common utility class for the functions that follow
namespace {
   struct Adaptor : CellularPanel::Visitor {
      using SimpleCellVisitor = CellularPanel::SimpleCellVisitor;
      using SimpleNodeVisitor = CellularPanel::SimpleNodeVisitor;
 
      // Visit cells only
      Adaptor( const SimpleCellVisitor& function_ )
      : function{ [&](const wxRect &rect, TrackPanelNode &cell) {
         return function_( rect, static_cast<TrackPanelCell&>(cell) );
      } }
      {}
 
      // Visit cells and groups, each once only, choosing pre- or post- ordering
      // for the groups
      Adaptor( const SimpleNodeVisitor &function_, bool pre_ )
         : function{ function_ }, pre{ pre_ }, post{ ! pre_ } {}
 
      void VisitCell( const wxRect &rect, TrackPanelCell &cell ) override
         { return function( rect, cell ); }
      void BeginGroup( const wxRect &rect, TrackPanelGroup &group ) override
         { if (pre) return function( rect, group ); }
      void EndGroup( const wxRect &rect, TrackPanelGroup &group ) override
         { if (post) return function( rect, group ); }
 
      SimpleNodeVisitor function;
      const bool pre{ false }, post{ false };
   };
}
 
// Simplified entry points for visits that don't need all the generality of
// CellularPanel::Visitor
void CellularPanel::VisitCells( const SimpleCellVisitor &visitor )
{
   Adaptor adaptor{ visitor };
   Visit( adaptor );
}
 
void CellularPanel::VisitPreorder( const SimpleNodeVisitor &visitor )
{
   Adaptor adaptor{ visitor, true };
   Visit( adaptor );
}
 
void CellularPanel::VisitPostorder( const SimpleNodeVisitor &visitor )
{
   Adaptor adaptor{ visitor, false };
   Visit( adaptor );
}
 
namespace {
   wxRect Subdivide(
      const wxRect &rect, bool divideX,
      const TrackPanelGroup::Refinement &children,
      const TrackPanelGroup::Refinement::const_iterator iter)
   {
      const auto next = iter + 1;
      const auto end = children.end();
      wxCoord nextCoord;
      if (next == end)
         nextCoord = std::max( iter->first,
            divideX ? rect.GetRight() : rect.GetBottom() );
      else
         nextCoord = next->first - 1;
 
      auto lesser = iter->first;
      auto greater = nextCoord;
 
      auto result = rect;
      if (divideX)
         result.SetLeft(lesser), result.SetRight(greater);
      else
         result.SetTop(lesser), result.SetBottom(greater);
 
      return result;
   };
}
 
// Private, recursive implementation function of Visit
void CellularPanel::Visit(
   const wxRect &rect, const std::shared_ptr<TrackPanelNode> &node,
   Visitor &visitor )
{
   if (auto pCell = dynamic_cast<TrackPanelCell*>(node.get()))
      visitor.VisitCell( rect, *pCell );
   else if (auto pGroup = dynamic_cast<TrackPanelGroup*>(node.get())) {
      visitor.BeginGroup( rect, *pGroup );
 
      // Recur on children
      const auto results = pGroup->Children( rect );
      const bool divideX = results.first == TrackPanelGroup::Axis::X;
      const auto &children = results.second;
      const auto begin = children.begin(), end = children.end();
      for (auto iter = begin; iter != end; ++iter)
         Visit(
            Subdivide(rect, divideX, children, iter), iter->second, visitor );
 
      visitor.EndGroup( rect, *pGroup );
   }
   else
      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 { {}, {} };
}
 
wxRect CellularPanel::FindRect( const TrackPanelCell &cell )
{
   wxRect result;
 
   struct Stop{};
   try { VisitCells( [&]( const wxRect &rect, TrackPanelCell &visited ) {
      if ( &visited == &cell )
         result = rect, throw Stop{};
   } ); }
   catch ( const Stop& ) {}
 
   return result;
}
 
wxRect CellularPanel::FindRect(
   const std::function< bool( TrackPanelNode& ) > &pred)
{
   wxRect result;
 
   struct Stop{};
   try { VisitPreorder( [&]( const wxRect &rect, TrackPanelNode &visited ) {
      if ( pred( visited ) )
         result = rect, throw Stop{};
   } ); }
   catch ( const Stop& ) {}
 
   return result;
}
 
UIHandlePtr CellularPanel::Target()
{
   auto &state = *mState;
   if (state.mTargets.size())
      return state.mTargets[state.mTarget];
   else
      return {};
}
 
wxCoord CellularPanel::MostRecentXCoord() const
{
   auto &state = *mState;
   return state.mMouseMostRecentX;
}
 
void CellularPanel::ClearTargets()
{
   auto &state = *mState;
   // Forget the rotation of hit test candidates when the mouse moves from
   // cell to cell or outside of the panel entirely.
   state.mLastCell.reset();
   state.mTargets.clear();
   state.mTarget = 0;
   state.mMouseOverUpdateFlags = 0;
}
 
std::shared_ptr<TrackPanelCell> CellularPanel::LastCell() const
{
   auto &state = *mState;
   return state.mLastCell.lock();
}
 
void CellularPanel::Draw( TrackPanelDrawingContext &context, unsigned nPasses )
{
   const auto panelRect = GetClientRect();
   auto lastCell = LastCell();
   for ( unsigned iPass = 0; iPass < nPasses; ++iPass ) {
 
      VisitPostorder( [&]( const wxRect &rect, TrackPanelNode &node ) {
 
         // Draw the node
         const auto newRect = node.DrawingArea(
            context, rect, panelRect, iPass );
         if ( newRect.Intersects( panelRect ) )
            node.Draw( context, newRect, iPass );
 
         // Draw the current handle if it is associated with the node
         if ( &node == lastCell.get() ) {
            auto target = Target();
            if ( target ) {
               const auto targetRect =
                  target->DrawingArea( context, rect, panelRect, iPass );
               if ( targetRect.Intersects( panelRect ) )
                  target->Draw( context, targetRect, iPass );
            }
         }
 
      } ); // nodes
 
   } // passes
}