SampleTrackCache.h

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/**********************************************************************
 
Audacity: A Digital Audio Editor
 
SampleTrackCache.h
@brief Buffer results to avoid repeated calls to SampleTrack::Get()
 
Paul Licameli split from WaveTrack.h
 
**********************************************************************/
 
#ifndef __AUDACITY_SAMPLE_TRACK_CACHE__
#define __AUDACITY_SAMPLE_TRACK_CACHE__
 
#include "SampleCount.h"
#include "SampleFormat.h"
#include <memory>
 
class SampleTrack;
 
 
class SAMPLE_TRACK_API SampleTrackCache {
public:
   SampleTrackCache()
      : mBufferSize(0)
      , mOverlapBuffer()
      , mNValidBuffers(0)
   {
   }
 
   explicit SampleTrackCache(const std::shared_ptr<const SampleTrack> &pTrack)
      : mBufferSize(0)
      , mOverlapBuffer()
      , mNValidBuffers(0)
   {
      SetTrack(pTrack);
   }
   ~SampleTrackCache();
 
   const std::shared_ptr<const SampleTrack>& GetTrack() const { return mPTrack; }
   void SetTrack(const std::shared_ptr<const SampleTrack> &pTrack);
 
 
   const float *GetFloats(sampleCount start, size_t len, bool mayThrow);
 
private:
   void Free();
 
   struct Buffer {
      Floats data;
      sampleCount start;
      sampleCount len;
 
      Buffer() : start(0), len(0) {}
      void Free() { data.reset(); start = 0; len = 0; }
      sampleCount end() const { return start + len; }
 
      void swap ( Buffer &other )
      {
         data .swap ( other.data );
         std::swap( start, other.start );
         std::swap( len, other.len );
      }
   };
 
   std::shared_ptr<const SampleTrack> mPTrack;
   size_t mBufferSize;
   Buffer mBuffers[2];
   GrowableSampleBuffer mOverlapBuffer;
   int mNValidBuffers;
};
 
#endif