Method ThreadedRequestData

Imaging/Statistics/vtkImageHistogram.cxx:805–957

------------------------------------------------------------------------------ This method is passed a input and output region, and executes the filter algorithm to fill the output from the input. It just executes a switch statement to call the correct function for the regions data types.

// It just executes a switch statement to call the correct function for
// the regions data types.
void vtkImageHistogram::ThreadedRequestData(vtkInformation* vtkNotUsed(request),
  vtkInformationVector** inputVector, vtkInformationVector* vtkNotUsed(outputVector),
  vtkImageData*** vtkNotUsed(inData), vtkImageData** vtkNotUsed(outData), int extent[6],
  int threadId)
{
  vtkInformation* inInfo = inputVector[0]->GetInformationObject(0);
  vtkImageData* inData = vtkImageData::SafeDownCast(inInfo->Get(vtkDataObject::DATA_OBJECT()));
  void* inPtr = inData->GetScalarPointerForExtent(extent);

  vtkImageStencilData* stencil = this->GetStencil();

  double binOrigin = this->BinOrigin;
  double binSpacing = this->BinSpacing;
  int scalarType = inData->GetScalarType();
  int component = this->ActiveComponent;

  // can use faster binning method for int data
  bool useFastExecute = (binSpacing == 1.0 && scalarType != VTK_FLOAT && scalarType != VTK_DOUBLE);

  double scalarRange[2];

  // compute the scalar range of the data unless it is byte data,
  // this allows us to allocate less memory for the histogram
  if (scalarType == VTK_CHAR || scalarType == VTK_UNSIGNED_CHAR || scalarType == VTK_SIGNED_CHAR)
  {
    vtkDataArray::GetDataTypeRange(scalarType, scalarRange);
  }
  else
  {
    switch (scalarType)
    {
      vtkTemplateAliasMacro(vtkImageHistogramExecuteRange(
        inData, stencil, static_cast<VTK_TT*>(inPtr), extent, scalarRange, component));
      default:
        vtkErrorMacro(<< "Execute: Unknown ScalarType");
    }

    // if no voxels (e.g. due to stencil) then return
    if (scalarRange[0] > scalarRange[1])
    {
      return;
    }
  }

  // convert to bin numbers
  int maxBin = this->NumberOfBins - 1;
  double scale = 1.0 / binSpacing;
  double minBinRange = (scalarRange[0] - binOrigin) * scale;
  double maxBinRange = (scalarRange[1] - binOrigin) * scale;
  if (minBinRange < 0 || vtkMath::IsNan(minBinRange))
  {
    minBinRange = 0;
    useFastExecute = false;
  }
  if (maxBinRange > maxBin || vtkMath::IsNan(maxBinRange))
  {
    maxBinRange = maxBin;
    useFastExecute = false;