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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;
//! A short-lived object, during whose lifetime, the contents of the WaveTrack are assumed not to change.
/*! It can replace repeated calls to WaveTrack::Get() (each of which opens and closes at least one block).
*/
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);
//! Retrieve samples as floats from the track or from the memory cache
/*! Uses fillZero always
@return null on failure; this object owns the memory; may be invalidated if GetFloats() is called again
*/
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
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