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// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
// SPDX-License-Identifier: BSD-3-Clause
/**
* @class vtkDataCompressor
* @brief Abstract interface for data compression classes.
*
* vtkDataCompressor provides a universal interface for data
* compression. Subclasses provide one compression method and one
* decompression method. The public interface to all compressors
* remains the same, and is defined by this class.
*
* @par Note:
* vtkDataCompressor CompressionLevel maye take on values 1 to 9. With
* values of 1 giving best compression write performance, and a value of 9
* giving best compression ratio. Subclasses of vtkDataCompressor objects
* should be implemented with this in mind to provide a predictable
* compressor interface for vtkDataCompressor users.
*
* @par Thanks:
* Homogeneous CompressionLevel behavior contributed by Quincy Wofford
* (qwofford@lanl.gov) and John Patchett (patchett@lanl.gov)
*
*/
#ifndef vtkDataCompressor_h
#define vtkDataCompressor_h
#include "vtkIOCoreModule.h" // For export macro
#include "vtkObject.h"
VTK_ABI_NAMESPACE_BEGIN
class vtkUnsignedCharArray;
class VTKIOCORE_EXPORT vtkDataCompressor : public vtkObject
{
public:
vtkTypeMacro(vtkDataCompressor, vtkObject);
void PrintSelf(ostream& os, vtkIndent indent) override;
/**
* Get the maximum space that may be needed to store data of the
* given uncompressed size after compression. This is the minimum
* size of the output buffer that can be passed to the four-argument
* Compress method.
*/
virtual size_t GetMaximumCompressionSpace(size_t size) = 0;
/**
* Compress the given input data buffer into the given output
* buffer. The size of the output buffer must be at least as large
* as the value given by GetMaximumCompressionSpace for the given
* input size.
*/
size_t Compress(unsigned char const* uncompressedData, size_t uncompressedSize,
unsigned char* compressedData, size_t compressionSpace);
/**
* Uncompress the given input data into the given output buffer.
* The size of the uncompressed data must be known by the caller.
* It should be transmitted from the compressor by a means outside
* of this class.
*/
size_t Uncompress(unsigned char const* compressedData, size_t compressedSize,
unsigned char* uncompressedData, size_t uncompressedSize);
/**
* Compress the given data. A vtkUnsignedCharArray containing the
* compressed data is returned with a reference count of 1.
*/
vtkUnsignedCharArray* Compress(unsigned char const* uncompressedData, size_t uncompressedSize);
/**
* Uncompress the given data. A vtkUnsignedCharArray containing the
* compressed data is returned with a reference count of 1. The
* size of the uncompressed data must be known by the caller. It
* should be transmitted from the compressor by a means outside of
* this class.
*/
vtkUnsignedCharArray* Uncompress(
unsigned char const* compressedData, size_t compressedSize, size_t uncompressedSize);
/** Compression performance varies greatly with compression level
* Require level setting from any vtkDataCompressor
* Different compressors handle performance parameters differently
* vtkDataCompressors should take a value between 1 and 9
* where 1 is fastest compression, and 9 is best compression.
*/
virtual void SetCompressionLevel(int compressionLevel) = 0;
virtual int GetCompressionLevel() = 0;
protected:
vtkDataCompressor();
~vtkDataCompressor() override;
// Actual compression method. This must be provided by a subclass.
// Must return the size of the compressed data, or zero on error.
virtual size_t CompressBuffer(unsigned char const* uncompressedData, size_t uncompressedSize,
unsigned char* compressedData, size_t compressionSpace) = 0;
// Actual decompression method. This must be provided by a subclass.
// Must return the size of the uncompressed data, or zero on error.
virtual size_t UncompressBuffer(unsigned char const* compressedData, size_t compressedSize,
unsigned char* uncompressedData, size_t uncompressedSize) = 0;
private:
vtkDataCompressor(const vtkDataCompressor&) = delete;
void operator=(const vtkDataCompressor&) = delete;
};
VTK_ABI_NAMESPACE_END
#endif
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