Method HDRReaderUpdateSlice

IO/Image/vtkHDRReader.cxx:217–347

------------------------------------------------------------------------------ This function reads in one data of data. templated to handle different data types.

// This function reads in one data of data.
// templated to handle different data types.
bool vtkHDRReader::HDRReaderUpdateSlice(float* outPtr, int* outExt)
{
  vtkResourceStream* stream = this->GetStream();
  vtkNew<vtkFileResourceStream> fileStream;
  if (!stream)
  {
    if (!fileStream->Open(this->InternalFileName))
    {
      vtkErrorMacro("Could not open file " << this->InternalFileName);
      return false;
    }
    stream = fileStream;
  }

  // Ignore header
  stream->Seek(this->HeaderSize, vtkResourceStream::SeekDirection::Begin);

  // Even if we have a smaller extent, the RLE encoding forces us to read all the line width
  const int width = this->GetWidth();

  const int extentWidth = outExt[1] - outExt[0] + 1;

  // We read only lines that we need (depending on outExt[2] and outExt[3]);
  int nbLinesLeft = outExt[3] - outExt[2] + 1;
  const int totalNbLines = nbLinesLeft;

  float* outPtr2 = outPtr;
  // decrPtr is the number of byte needed to go to the previous line
  int decrPtr = 0;
  if (this->FileLowerLeft)
  {
    // Start at the end of outPtr and go up
    outPtr2 = outPtr + (nbLinesLeft - 1) * extentWidth * 3;
    decrPtr = 2 * extentWidth * 3;
  }

  if ((width < 8) || (width > 0x7fff))
  {
    // File not run length encoded
    this->ReadAllFileNoRLE(stream, outPtr2, decrPtr, outExt);
    this->CloseFile();
    return true;
  }

  // We need to skip some lines
  int nbSkipLines = outExt[2];

  // Store the position in case of a non RLE encoded file
  vtkTypeInt64 afterHeader = stream->Tell();

  // rgbe will hold the value of each channels
  unsigned char rgbe[4];
  // lineBuffer will contain data read from the file
  // 4 uchar for each pixel of a line
  std::vector<unsigned char> lineBuffer(width * 4);
  while (nbLinesLeft > 0)
  {
    stream->Read(rgbe, sizeof(unsigned char) * 4);