StretchHandle.h

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/**********************************************************************
 
Audacity: A Digital Audio Editor
 
StretchHandle.h
 
Paul Licameli split from TrackPanel.cpp
 
**********************************************************************/
 
#ifndef __AUDACITY_STRETCH_HANDLE__
#define __AUDACITY_STRETCH_HANDLE__
 
#include "../../../../UIHandle.h"
 
class Alg_seq;
class Channel;
class NoteTrack;
class Track;
class ViewInfo;
 
class StretchHandle : public UIHandle
{
public:
   enum StretchEnum {
      stretchNone = 0, // false value!
      stretchLeft,
      stretchCenter,
      stretchRight
   };
 
   // Stretching applies to a selected region after quantizing the
   // region to beat boundaries (subbeat stretching is not supported,
   // but maybe it should be enabled with shift or ctrl or something)
   // Stretching can drag the left boundary (the right stays fixed),
   // the right boundary (the left stays fixed), or the center (splits
   // the selection into two parts: when left part grows, the right
   // part shrinks, keeping the leftmost and rightmost boundaries
   // fixed.
   struct StretchState {
      StretchEnum mMode { stretchCenter }; // remembers what to drag
 
      using QuantizedTimeAndBeat = std::pair< double, double >;
 
      QuantizedTimeAndBeat mBeatCenter { 0, 0 };
      QuantizedTimeAndBeat mBeat0 { 0, 0 };
      QuantizedTimeAndBeat mBeat1 { 0, 0 };
      double mLeftBeats {}; // how many beats from left to cursor
      double mRightBeats {}; // how many beats from cursor to right
 
      double mOrigSel0Quantized { -1 }, mOrigSel1Quantized { -1 };
   };
   
private:
   StretchHandle(const StretchHandle&);
   static HitTestPreview HitPreview(StretchEnum stretchMode, bool unsafe);
 
public:
   explicit StretchHandle
      ( const std::shared_ptr<NoteTrack> &pTrack,
        const StretchState &stretchState );
 
   StretchHandle &operator=(const StretchHandle&) = default;
 
   static UIHandlePtr HitTest
      (std::weak_ptr<StretchHandle> &holder,
       const TrackPanelMouseState &state, const AudacityProject *pProject,
       const std::shared_ptr<NoteTrack> &pTrack );
 
   virtual ~StretchHandle();
 
   std::shared_ptr<const Track> FindTrack() const override;
 
   Result Click
      (const TrackPanelMouseEvent &event, AudacityProject *pProject) override;
 
   Result Drag
      (const TrackPanelMouseEvent &event, AudacityProject *pProject) override;
 
   HitTestPreview Preview
      (const TrackPanelMouseState &state, AudacityProject *pProject)
      override;
 
   Result Release
      (const TrackPanelMouseEvent &event, AudacityProject *pProject,
      wxWindow *pParent) override;
 
   Result Cancel(AudacityProject *pProject) override;
 
   bool StopsOnKeystroke() override { return true; }
 
private:
   static double GetT0(const Track &track, const ViewInfo &viewInfo);
   static double GetT1(const Track &track, const ViewInfo &viewInfo);
 
   void Stretch(AudacityProject *pProject, int mouseXCoordinate,
      int trackLeftEdge, Channel *pChannel);
 
   std::shared_ptr<NoteTrack> mpTrack{};
   int mLeftEdge{ -1 };
 
   StretchState mStretchState{};
};
 
#endif