Method SeekFile

IO/Image/vtkImageReader2.cxx:557–595

------------------------------------------------------------------------------

//------------------------------------------------------------------------------
void vtkImageReader2::SeekFile(int i, int j, int k)
{
  std::streamoff startOffset;

  // convert data extent into constants that can be used to seek.
  startOffset = static_cast<std::streamoff>(i - this->DataExtent[0]) * this->DataIncrements[0];

  if (this->FileLowerLeft)
  {
    startOffset += static_cast<std::streamoff>(j - this->DataExtent[2]) * this->DataIncrements[1];
  }
  else
  {
    startOffset += static_cast<std::streamoff>(this->DataExtent[3] - this->DataExtent[2] - j) *
      this->DataIncrements[1];
  }

  // handle three and four dimensional files
  if (this->GetFileDimensionality() >= 3)
  {
    startOffset += static_cast<std::streamoff>(k - this->DataExtent[4]) * this->DataIncrements[2];
  }

  startOffset += this->GetHeaderSize(k);

  // error checking
  if (!this->File)
  {
    vtkWarningMacro(<< "File must be specified.");
    return;
  }

  this->File->seekg(startOffset, ios::beg);
  if (this->File->fail())
  {
    vtkWarningMacro("File operation failed.");
    return;
  }
}

//------------------------------------------------------------------------------
// This function reads in one data of data.