BUG: Fix casting in PeriodicBoundaryCondition

Avoid dynamic_cast failure and use reinterpret_cast for efficiency in
PeriodicBoundaryCondition. The type of ConstNeighborhoodIterator is known to
be compatible with PeriodicBoundaryCondition when used within
PeriodicBoundaryCondition.

Add test that checks for previous segfault that occurred when
ConstNeighborhoodIterator was templated with PeriodicBoundaryCondition.

Co-authored-by: Tobias Wood <[email protected]>

Change-Id: I134a6fc26a565c8405bf579f58cc4a2aee88385f

Author: thewtex

Modules/Core/Common/include/itkConstNeighborhoodIterator.h

@@ -413,7 +413,7 @@ class ITK_TEMPLATE_EXPORT ConstNeighborhoodIterator:
   /** Resets the boundary condition to the internal, default conditions
    * specified by the template parameter. */
   virtual void ResetBoundaryCondition()
-  { m_BoundaryCondition = &m_InternalBoundaryCondition;  }
+  { m_BoundaryCondition = reinterpret_cast< ImageBoundaryConditionPointerType >( &m_InternalBoundaryCondition ); }
 
   /** Sets the internal, default boundary condition. */
   void SetBoundaryCondition(const TBoundaryCondition & c)

Modules/Core/Common/include/itkPeriodicBoundaryCondition.hxx

@@ -29,7 +29,9 @@ PeriodicBoundaryCondition< TInputImage, TOutputImage >
 ::operator()(const OffsetType & point_index, const OffsetType & boundary_offset,
              const NeighborhoodType *data) const
 {
-  const auto * iterator = dynamic_cast< const ConstNeighborhoodIterator< TInputImage, Self > * >( data );
+  // This is guaranteed to be called with an object that is using
+  // PeriodicBoundaryCondition
+  const auto * iterator = reinterpret_cast< const ConstNeighborhoodIterator< TInputImage, Self > * >( data );
   typename TInputImage::PixelType * ptr;
   int          linear_index = 0;
   unsigned int i;
@@ -83,7 +85,9 @@ PeriodicBoundaryCondition< TInputImage, TOutputImage >
              const NeighborhoodType *data,
              const NeighborhoodAccessorFunctorType & neighborhoodAccessorFunctor) const
 {
-  const auto * iterator = dynamic_cast< const ConstNeighborhoodIterator< TInputImage, Self > * >( data );
+  // This is guaranteed to be called with an object that is using
+  // PeriodicBoundaryCondition
+  const auto * iterator = reinterpret_cast< const ConstNeighborhoodIterator< TInputImage, Self > * >( data );
   typename TInputImage::InternalPixelType * ptr;
   int          linear_index = 0;
   unsigned int i;

Modules/Core/Common/test/itkPeriodicBoundaryConditionTest.cxx

@@ -288,5 +288,33 @@ int itkPeriodicBoundaryConditionTest(int, char* [] )
   bc.Print( std::cout );
   vbc.Print( std::cout );
 
+  // Check when ConstNeighborhoodIterator is templated over the
+  // PeriodicBoundaryCondition
+  auto testImage = ImageType::New();
+  ImageType::SizeType testSize = {{ 64, 64 }};
+  ImageType::RegionType testRegion( testSize );
+  testImage->SetRegions(testRegion);
+  testImage->Allocate();
+
+  using BoundaryConditionType = itk::PeriodicBoundaryCondition< ImageType, ImageType >;
+  using IterType = itk::ConstNeighborhoodIterator<ImageType, BoundaryConditionType>;
+  IterType testIter(radius, testImage, testRegion);
+  BoundaryConditionType boundaryCondition;
+  testIter.OverrideBoundaryCondition(&boundaryCondition);
+  std::vector<IterType::OffsetType> back;
+  back.push_back( {{-1, 0 }} );
+  back.push_back( {{ 0,-1 }} );
+  back.push_back( {{ 0, 0 }} );
+  testIter.SetNeedToUseBoundaryCondition(true);
+  testIter.GoToBegin();
+  while (!testIter.IsAtEnd()) {
+      float sum = 0;
+      for (size_t j = 0; j < back.size(); ++j) {
+        const float d = testIter.GetPixel(back[j]);
+        sum += d*d;
+      }
+      ++testIter;
+  }
+
   return EXIT_SUCCESS;
 }