SampleBlock.h

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/**********************************************************************
 
Audacity: A Digital Audio Editor
 
SampleBlock.h
 
**********************************************************************/
 
#ifndef __AUDACITY_SAMPLE_BLOCK__
#define __AUDACITY_SAMPLE_BLOCK__
 
#include "GlobalVariable.h"
#include "SampleFormat.h"
#include "AudioSegmentSampleView.h"
 
#include <functional>
#include <memory>
#include <unordered_set>
 
#include "Observer.h"
#include "XMLTagHandler.h"
 
class AudacityProject;
class ProjectFileIO;
class XMLWriter;
 
class SampleBlock;
using SampleBlockPtr = std::shared_ptr<SampleBlock>;
using SampleBlockConstPtr = std::shared_ptr<const SampleBlock>;
class SampleBlockFactory;
using SampleBlockFactoryPtr = std::shared_ptr<SampleBlockFactory>;
 
using SampleBlockID = long long;
 
class MinMaxRMS
{
public:
   float min = 0;
   float max = 0;
   float RMS = 0;
};
 
class WAVE_TRACK_API SampleBlock
{
public:
   virtual ~SampleBlock();
 
   virtual void CloseLock() noexcept = 0;
 
   virtual SampleBlockID GetBlockID() const = 0;
 
   // If !mayThrow and there is an error, ignores it and returns zero.
   // That may be appropriate when only attempting to display samples, not edit.
   size_t GetSamples(samplePtr dest,
                     sampleFormat destformat,
                     size_t sampleoffset,
                     size_t numsamples, bool mayThrow = true);
 
   virtual BlockSampleView GetFloatSampleView(bool mayThrow) = 0;
 
   virtual sampleFormat GetSampleFormat() const = 0;
 
   virtual size_t GetSampleCount() const = 0;
 
   virtual bool
      GetSummary256(float *dest, size_t frameoffset, size_t numframes) = 0;
   virtual bool
      GetSummary64k(float *dest, size_t frameoffset, size_t numframes) = 0;
 
   // If !mayThrow and there is an error, ignores it and returns zeroes.
   // That may be appropriate when only attempting to display samples, not edit.
   MinMaxRMS GetMinMaxRMS(
      size_t start, size_t len, bool mayThrow = true);
 
   // If !mayThrow and there is an error, ignores it and returns zeroes.
   // That may be appropriate when only attempting to display samples, not edit.
   MinMaxRMS GetMinMaxRMS(bool mayThrow = true) const;
 
   virtual size_t GetSpaceUsage() const = 0;
 
   virtual void SaveXML(XMLWriter &xmlFile) = 0;
 
protected:
   virtual size_t DoGetSamples(samplePtr dest,
                     sampleFormat destformat,
                     size_t sampleoffset,
                     size_t numsamples) = 0;
 
   virtual MinMaxRMS DoGetMinMaxRMS(size_t start, size_t len) = 0;
 
   virtual MinMaxRMS DoGetMinMaxRMS() const = 0;
};
 
// Makes a useful function object
inline std::function< void(SampleBlockConstPtr) >
BlockSpaceUsageAccumulator (unsigned long long &total)
{
   return [&total](SampleBlockConstPtr pBlock){
      total += pBlock->GetSpaceUsage();
   };
};
 
struct SampleBlockCreateMessage { };
 
class WAVE_TRACK_API SampleBlockFactory
   : public Observer::Publisher<SampleBlockCreateMessage>
{
public:
   struct WAVE_TRACK_API Factory : GlobalHook<Factory,
      SampleBlockFactoryPtr( AudacityProject& )
   >{};
 
   // Invoke the installed factory (throw an exception if none was installed)
   static SampleBlockFactoryPtr New( AudacityProject &project );
 
   virtual ~SampleBlockFactory();
 
   // Returns a non-null pointer or else throws an exception
   SampleBlockPtr Create(constSamplePtr src,
      size_t numsamples,
      sampleFormat srcformat);
 
   // Returns a non-null pointer or else throws an exception
   SampleBlockPtr CreateSilent(
      size_t numsamples,
      sampleFormat srcformat);
 
   // Returns a non-null pointer or else throws an exception
   SampleBlockPtr CreateFromXML(
      sampleFormat srcformat,
      const AttributesList &attrs);
 
   // Potentially returns a null pointer
   SampleBlockPtr CreateFromId(sampleFormat srcformat, SampleBlockID id);
 
   using SampleBlockIDs = std::unordered_set<SampleBlockID>;
   virtual SampleBlockIDs GetActiveBlockIDs() = 0;
 
protected:
   // The override should throw more informative exceptions on error than the
   // default InconsistencyException thrown by Create
   virtual SampleBlockPtr DoCreate(constSamplePtr src,
      size_t numsamples,
      sampleFormat srcformat) = 0;
 
   // The override should throw more informative exceptions on error than the
   // default InconsistencyException thrown by CreateSilent
   virtual SampleBlockPtr DoCreateSilent(
      size_t numsamples,
      sampleFormat srcformat) = 0;
 
   // The override should throw more informative exceptions on error than the
   // default InconsistencyException thrown by CreateFromXML
   virtual SampleBlockPtr DoCreateFromXML(
      sampleFormat srcformat,
      const AttributesList &attrs) = 0;
 
   virtual SampleBlockPtr
   DoCreateFromId(sampleFormat srcformat, SampleBlockID id) = 0;
};
 
#endif