Method RequestData

Imaging/Core/vtkImageDifference.cxx:418–482

------------------------------------------------------------------------------ Create thread-local objects before initiating the multithreading

//------------------------------------------------------------------------------
// Create thread-local objects before initiating the multithreading
int vtkImageDifference::RequestData(
  vtkInformation* request, vtkInformationVector** inputVector, vtkInformationVector* outputVector)
{
  int ret = 1;

  if (this->EnableSMP) // For vtkSMPTools implementation.
  {
    // Get the input and output data objects
    vtkImageData* inDataPointer[2];
    vtkImageData** inData[2] = { &inDataPointer[0], &inDataPointer[1] };
    vtkImageData* outData[1];
    this->PrepareImageData(inputVector, outputVector, inData, outData);

    // Get the extent
    int extent[6];
    outData[0]->GetExtent(extent);

    // Do a dummy execution of SplitExtent to compute the number of pieces
    vtkIdType pieces = this->SplitExtent(nullptr, extent, 0, this->NumberOfThreads);

    // Use vtkSMPTools to multithread the functor
    vtkImageDifferenceSMPThreadLocal threadData;
    vtkImageDifferenceSMPFunctor functor(this, inData, outData, extent, pieces);
    this->SMPThreadData = &threadData;
    vtkSMPTools::For(0, pieces, functor);
    this->SMPThreadData = nullptr;
  }
  else
  {
    // For vtkMultiThreader implementation.
    this->ThreadData = new vtkImageDifferenceThreadData[this->NumberOfThreads];

    // The superclass will call ThreadedRequestData
    ret = this->Superclass::RequestData(request, inputVector, outputVector);

    // Compute error sums here.
    this->Error = 0.0;
    this->ThresholdedError = 0.0;
    for (int i = 0; i < this->NumberOfThreads; i++)
    {
      this->Error += this->ThreadData[i].Error;
      this->ThresholdedError += this->ThreadData[i].ThresholdedError;
      this->ErrorMessage = this->ThreadData[i].ErrorMessage;
      if (this->ErrorMessage)
      {
        break;
      }
    }

    delete[] this->ThreadData;
    this->ThreadData = nullptr;
  }

  if (this->ErrorMessage)
  {
    // Report errors here, do not report errors while multithreading!
    vtkErrorMacro("RequestData: " << this->ErrorMessage);
    this->ErrorMessage = nullptr;