TrackFocus.h

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/**********************************************************************
 
  Audacity: A Digital Audio Editor
 
  TrackFocus.h
 
  Leland Lucius
 
  Paul Licameli split from TrackPanelAx.h
 
**********************************************************************/
#ifndef __AUDACITY_TRACK_FOCUS__
#define __AUDACITY_TRACK_FOCUS__
 
#include <memory>
 
#include "ClientData.h" // to inherit
#include "Observer.h"
 
class AudacityProject;
class Track;
class TrackList;
 
struct TrackFocusChangeMessage {
   bool focusPanel = false; 
};
 
struct TRACK_SELECTION_API TrackFocusCallbacks {
   virtual ~TrackFocusCallbacks();
 
   virtual void MessageForScreenReader(const TranslatableString& message) = 0;
   virtual void BeginChangeFocus() = 0;
   virtual void EndChangeFocus(const std::shared_ptr<Track> &track) = 0;
   virtual void UpdateAccessibility() = 0;
};
 
class TRACK_SELECTION_API TrackFocus final
   : public ClientData::Base
   , public Observer::Publisher<TrackFocusChangeMessage>
   , public std::enable_shared_from_this<TrackFocus>
{
public:
   static TrackFocus &Get(AudacityProject &project);
   static const TrackFocus &Get(const AudacityProject &project);
 
   explicit TrackFocus(AudacityProject &project);
   ~TrackFocus() final;
 
   TrackFocus(const TrackFocus &) = delete;
   TrackFocus& operator=(const TrackFocus &) = delete;
   
   void SetCallbacks(std::unique_ptr<TrackFocusCallbacks> pCallbacks);
 
   Track *Get();
 
 
   void Set(Track *pTrack, bool focusPanel = false);
 
   void MessageForScreenReader(const TranslatableString& message);
 
   void UpdateAccessibility();
 
   // Returns currently focused track, never changing it
   std::shared_ptr<Track> PeekFocus() const;
 
   int TrackNum(const std::shared_ptr<Track> &track) const;
 
   int NumFocusedTrack() const { return mNumFocusedTrack; }
 
   // Returns currently focused track or first one if none focused
   std::shared_ptr<Track> GetFocus();
 
   const TrackList &GetTracks() const;
 
   std::shared_ptr<Track> FindTrack(int num) const;
 
   // Changes focus to a specified track
   // Return is the actual focused track, which may be different from
   // the argument when that is null
   std::shared_ptr<Track> SetFocus(std::shared_ptr<Track> track = {},
      bool focusPanel = false);
 
private:
   TrackList &GetTracks();
 
   AudacityProject &mProject;
   std::unique_ptr<TrackFocusCallbacks> mpCallbacks;
   std::weak_ptr<Track> mFocusedTrack;
   int mNumFocusedTrack{ 0 };
};
 
#endif // __AUDACITY_TRACK_FOCUS__