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