vtkX3DExporterFIWriterHelper.h

Go to the documentation of this file.

// SPDX-FileCopyrightText: Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
// SPDX-License-Identifier: BSD-3-Clause
#ifndef vtkX3DExporterFIWriterHelper_h
#define vtkX3DExporterFIWriterHelper_h
 
// #include "vtkX3DExporterFIByteWriter.h"
#include "vtkZLibDataCompressor.h"
#include <cassert>
 
#define EXPONENT_MASK_32 0x7f800000
#define MANTISSA_MASK_32 0x007fffff
 
#ifndef max
#define max(a, b) (((a) > (b)) ? (a) : (b))
#endif
VTK_ABI_NAMESPACE_BEGIN
class vtkX3DExporterFIWriterHelper
{
public:
  union float_to_unsigned_int_to_bytes
  {
    float f;
    unsigned int ui;
    unsigned char ub[4]; // unsigned bytes
  };
 
  template <typename T>
  static void EncodeFloatFI(vtkX3DExporterFIByteWriter* writer, T* value, size_t size)
  {
    // We want to start at position 3
    assert(writer->CurrentBytePos == 2);
 
    // ITU C.19.3.4: If the alternative encoding-algorithm is present,
    // then the two bits '11' (discriminant) are appended
    writer->PutBits("11");
    // ITU 10.8.1: This encoding algorithm has a vocabulary table index of 7,
    writer->PutBits(7 - 1, 8);
 
    std::string bytes;
    char byte[4];
    for (size_t i = 0; i < size; i++)
    {
      float_to_unsigned_int_to_bytes v;
      v.f = value[i];
 
      // Avoid -0
      if (v.ui == 0x80000000)
      {
        v.f = 0;
      }
 
      byte[0] = v.ub[3];
      byte[1] = v.ub[2];
      byte[2] = v.ub[1];
      byte[3] = v.ub[0];
 
      bytes.append(byte, 4);
    }
    EncodeNonEmptyByteString5(writer, bytes);
  }
 
  template <typename T>
  static void EncodeIntegerFI(vtkX3DExporterFIByteWriter* writer, T* value, size_t size)
  {
    // We want to start at position 3
    assert(writer->CurrentBytePos == 2);
 
    // ITU C.19.3.4: If the alternative encoding-algorithm is present,
    // then the two bits '11' (discriminant) are appended
    writer->PutBits("11");
    // ITU 10.8.1: This encoding algorithm has a vocabulary table index of 4,
    writer->PutBits(4 - 1, 8);
    std::string bytes;
    for (size_t i = 0; i < size; i++)
    {
      int v = value[i];
      int f = ReverseBytes(&v);
      char* p = reinterpret_cast<char*>(&f);
      bytes.append(p, 4);
    }
    EncodeNonEmptyByteString5(writer, bytes);
  }
 
  static void EncodeCharacterString3(vtkX3DExporterFIByteWriter* writer, const std::string& value)
  {
    // We want to start at position 3
    assert(writer->CurrentBytePos == 2);
 
    // ITU C.19.3.1 If the alternative utf-8 is present, then the two bits '00'
    // are appended to the bit stream.
    writer->PutBits("00");
    // ITU C.19.4: The component bytes is encoded as described in C.23.
    EncodeNonEmptyByteString5(writer, value);
  }
 
  // ITU C.23: Encoding of the NonEmptyByteString starting
  // on the fifth bit of an byte
  static void EncodeNonEmptyByteString5(
    vtkX3DExporterFIByteWriter* writer, const std::string& value)
  {
    int length = static_cast<int>(value.length());
    if (length <= 8)
    {
      writer->PutBit(false);
      writer->PutBits(length - 1, 3);
    }
    else if (length <= 264)
    {
      writer->PutBits("1000");
      writer->PutBits(length - 9, 8);
    }
    else
    {
      writer->PutBits("1100");
      writer->PutBits(length - 265, 32);
    }
    writer->PutBytes(value.c_str(), length);
  }
 
  // ITU C.27: Encoding of integers in the range 1 to 2^20
  // starting on the third bit of an byte
  static void EncodeInteger3(vtkX3DExporterFIByteWriter* writer, unsigned int value)
  {
    // We want to start at position 3
    assert(writer->CurrentBytePos == 2);
 
    if (value <= 32) // ITU  C.27.2
    {
      writer->PutBit(false);
      writer->PutBits(value - 1, 5);
    }
    else if (value <= 2080) // ITU C.27.3
    {
      writer->PutBits("100");
      writer->PutBits(value - 33, 11);
    }
    else if (value < 526368) // ITU C.27.4
    {
      writer->PutBits("101");
      writer->PutBits(value - 2081, 19);
    }
    else // ITU C.27.5
    {
      writer->PutBits("1100000000");
      writer->PutBits(value - 526369, 20);
    }
  }
 
  // ITU C.25: Encoding of integers in the range 1 to 2^20
  // starting on the second bit of an byte
  static void EncodeInteger2(vtkX3DExporterFIByteWriter* writer, unsigned int value)
  {
    // We want to start at position 2
    assert(writer->CurrentBytePos == 1);
 
    if (value <= 64) // ITU  C.25.2
    {
      writer->PutBits("0");
      writer->PutBits(value - 1, 6);
    }
    else if (value <= 8256) // ITU C.25.3
    {
      writer->PutBits("10");
      writer->PutBits(value - 65, 13);
    }
    else // ITU C.25.4
    {
      writer->PutBits("110");
      writer->PutBits(value - 8257, 20);
    }
  }
 
private:
  static int ReverseBytes(int* x)
  {
    /* break x apart, then put it back together backwards */
    int part1 = (*x) & 0xFF;
    int part2 = ((*x) >> 8) & 0xFF;
    int part3 = ((*x) >> 16) & 0xFF;
    int part4 = ((*x) >> 24) & 0xFF;
    return (part1 << 24) | (part2 << 16) | (part3 << 8) | part4;
  }
 
  friend class X3DEncoderFunctions;
};
 
class X3DEncoderFunctions
{
 
public:
  template <typename T>
  static void EncodeIntegerDeltaZ(vtkX3DExporterFIByteWriter* writer, T* value, size_t size,
    vtkZLibDataCompressor* compressor, bool image = false)
  {
    // We want to start at position 3
    assert(writer->CurrentBytePos == 2);
 
    // ITU C.19.3.4: If the alternative encoding-algorithm is present,
    // then the two bits '11' (discriminant) are appended
    writer->PutBits("11");
    // ITU 10.8.1: This encoding algorithm has a vocabulary table index of 33
    writer->PutBits(34 - 1, 8);
 
    // compute delta
    char span = 0;
    size_t i = 0;
    int f;
    unsigned char* p;
    std::vector<unsigned char> deltas;
 
    if (image)
    {
      span = 0;
      for (i = 0; i < size; i++)
      {
        int v = 1 + (value[i]);
        int* vp = &v;
        f = vtkX3DExporterFIWriterHelper::ReverseBytes(vp);
        p = reinterpret_cast<unsigned char*>(&f);
        deltas.push_back(p[0]);
        deltas.push_back(p[1]);
        deltas.push_back(p[2]);
        deltas.push_back(p[3]);
      }
      compressor->SetCompressionLevel(9);
    }
    else
    {
      for (i = 0; i < 20; i++)
      {
        if (value[i] == -1)
        {
          span = static_cast<char>(i) + 1;
          break;
        }
      }
      if (!span)
        span = 4;
 
      for (i = 0; i < static_cast<size_t>(span); i++)
      {
        int v = 1 + value[i];
        int* vp = &v;
        f = vtkX3DExporterFIWriterHelper::ReverseBytes(vp);
 
        p = reinterpret_cast<unsigned char*>(&f);
        deltas.push_back(p[0]);
        deltas.push_back(p[1]);
        deltas.push_back(p[2]);
        deltas.push_back(p[3]);
      }
      for (i = span; i < size; i++)
      {
        int v = 1 + (value[i] - value[i - span]);
        f = vtkX3DExporterFIWriterHelper::ReverseBytes(&v);
 
        p = reinterpret_cast<unsigned char*>(&f);
        deltas.push_back(p[0]);
        deltas.push_back(p[1]);
        deltas.push_back(p[2]);
        deltas.push_back(p[3]);
      }
    }
 
    size_t bufferSize = deltas.size() + static_cast<unsigned int>(ceil(deltas.size() * 0.001)) + 12;
    unsigned char* buffer = new unsigned char[bufferSize];
    size_t newSize = compressor->Compress(deltas.data(), static_cast<unsigned long>(deltas.size()),
      buffer, static_cast<unsigned long>(bufferSize));
 
    std::string bytes;
    int size32 = static_cast<int>(size);
    int size32_reversed = vtkX3DExporterFIWriterHelper::ReverseBytes(&size32);
    char* s = reinterpret_cast<char*>(&size32_reversed);
    bytes.append(s, 4);
    bytes.append(&span, 1);
 
    for (i = 0; i < newSize; i++)
    {
      unsigned char c = buffer[i];
      bytes += c;
    }
    delete[] buffer;
 
    vtkX3DExporterFIWriterHelper::EncodeNonEmptyByteString5(writer, bytes);
    if (image)
    {
      compressor->SetCompressionLevel(5);
    }
  }
 
  static void EncodeQuantizedzlibFloatArray(vtkX3DExporterFIByteWriter* writer, const double* value,
    size_t size, vtkZLibDataCompressor* compressor)
  {
    // We want to start at position 3
    assert(writer->CurrentBytePos == 2);
 
    // ITU C.19.3.4: If the alternative encoding-algorithm is present,
    // then the two bits '11' (discriminant) are appended
    writer->PutBits("11");
    // ITU 10.8.1: This encoding algorithm has a vocabulary table index of 33
    writer->PutBits(34, 8);
 
    unsigned char* bytes = new unsigned char[size * 4];
    unsigned char* bytepos = bytes;
    std::string bytesCompressed;
    size_t i;
 
    const double* vd = value;
    for (i = 0; i < size; i++)
    {
      union float_to_unsigned_int_to_bytes
      {
        float f;
        unsigned int ui;
        unsigned char ub[4]; // unsigned bytes
      };
      float_to_unsigned_int_to_bytes v;
      v.f = (*vd) * 2.0;
 
      // Avoid -0
      if (v.ui == 0x80000000)
      {
        v.f = 0.0f;
      }
      // vtkGenericWarningMacro(<< "value: " << v << " bytes: " << (int)s[0] << " " << (int)s[1] <<
      // " " << (int)s[2] << " " << (int)s[3]);
      *bytepos++ = v.ub[3];
      *bytepos++ = v.ub[2];
      *bytepos++ = v.ub[1];
      *bytepos++ = v.ub[0];
      vd++;
    }
 
    // Compress the data
    size_t bufferSize = (size * 4) + static_cast<size_t>(ceil((size * 4) * 0.001)) + 12;
    unsigned char* buffer = new unsigned char[bufferSize];
    size_t newSize = compressor->Compress(
      bytes, static_cast<unsigned long>(size * 4), buffer, static_cast<unsigned long>(bufferSize));
 
    char* s;
    // Put the number of bits for exponent
    bytesCompressed += static_cast<char>(8);
    // Put the number of bits for mantissa
    bytesCompressed += static_cast<char>(23);
    // Put the length
    int length = static_cast<int>(size * 4);
    int length_reversed = vtkX3DExporterFIWriterHelper::ReverseBytes(&length);
    s = reinterpret_cast<char*>(&length_reversed);
    bytesCompressed.append(s, 4);
 
    // Put the number of floats
    int numFloats = static_cast<int>(size);
    int numFloats_reversed = vtkX3DExporterFIWriterHelper::ReverseBytes(&numFloats);
    s = reinterpret_cast<char*>(&numFloats_reversed);
    bytesCompressed.append(s, 4);
 
    for (i = 0; i < newSize; i++)
    {
      unsigned char c = buffer[i];
      bytesCompressed += c;
    }
    vtkX3DExporterFIWriterHelper::EncodeNonEmptyByteString5(writer, bytesCompressed);
    delete[] buffer;
    delete[] bytes;
  }
};
 
VTK_ABI_NAMESPACE_END
#endif
// VTK-HeaderTest-Exclude: vtkX3DExporterFIWriterHelper.h