itkImageHelper.h

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/*=========================================================================
 *
 *  Copyright NumFOCUS
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         https://www.apache.org/licenses/LICENSE-2.0.txt
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 *
 *=========================================================================*/
#ifndef itkImageHelper_h
#define itkImageHelper_h
 
#include "itkMacro.h"  // For ITK_TEMPLATE_EXPORT.
#include <type_traits> // For true_type, false_type, and integral_constant.
 
namespace itk
{
// Forward reference because of circular dependencies
template <unsigned int VImageDimension>
class ITK_TEMPLATE_EXPORT ImageBase;
 
template <unsigned int VImageDimension, unsigned int VLoop>
class ImageHelper
{
public:
  using ImageType = ImageBase<VImageDimension>;
  using IndexType = typename ImageType::IndexType;
  using OffsetType = typename ImageType::OffsetType;
  using OffsetValueType = typename ImageType::OffsetValueType;
  using IndexValueType = typename ImageType::IndexValueType;
 
  inline static void
  ComputeIndex(const IndexType &     bufferedRegionIndex,
               OffsetValueType       offset,
               const OffsetValueType offsetTable[],
               IndexType &           index)
  {
    ImageHelper<VImageDimension, VLoop - 1>::ComputeIndexInner(
      bufferedRegionIndex, offset, offsetTable, index, std::integral_constant<bool, VLoop == 1>{});
  }
  inline static void
  ComputeIndexInner(const IndexType &     bufferedRegionIndex,
                    OffsetValueType &     offset,
                    const OffsetValueType offsetTable[],
                    IndexType &           index,
                    std::false_type)
  {
    index[VLoop] = static_cast<IndexValueType>(offset / offsetTable[VLoop]);
    offset -= (index[VLoop] * offsetTable[VLoop]);
    index[VLoop] += bufferedRegionIndex[VLoop];
    ImageHelper<VImageDimension, VLoop - 1>::ComputeIndexInner(
      bufferedRegionIndex, offset, offsetTable, index, std::integral_constant<bool, VLoop == 1>{});
  }
 
  inline static void
  ComputeIndexInner(const IndexType & bufferedRegionIndex,
                    OffsetValueType & offset,
                    const OffsetValueType[],
                    IndexType & index,
                    std::true_type)
  {
    // Do last
    index[0] = bufferedRegionIndex[0] + static_cast<IndexValueType>(offset);
  }
 
  // ComputeOffset
  //
  inline static void
  ComputeOffset(const IndexType &     bufferedRegionIndex,
                const IndexType &     index,
                const OffsetValueType offsetTable[],
                OffsetValueType &     offset)
  {
    ImageHelper<VImageDimension, VLoop - 1>::ComputeOffsetInner(
      bufferedRegionIndex, index, offsetTable, offset, std::integral_constant<bool, VLoop == 1>{});
  }
 
  inline static void
  ComputeOffsetInner(const IndexType &     bufferedRegionIndex,
                     const IndexType &     index,
                     const OffsetValueType offsetTable[],
                     OffsetValueType &     offset,
                     std::false_type)
  {
    offset += (index[VLoop] - bufferedRegionIndex[VLoop]) * offsetTable[VLoop];
    ImageHelper<VImageDimension, VLoop - 1>::ComputeOffsetInner(
      bufferedRegionIndex, index, offsetTable, offset, std::integral_constant<bool, VLoop == 1>{});
  }
 
  inline static void
  ComputeOffsetInner(const IndexType & bufferedRegionIndex,
                     const IndexType & index,
                     const OffsetValueType[],
                     OffsetValueType & offset,
                     std::true_type)
  {
    // Do last
    offset += index[0] - bufferedRegionIndex[0];
  }
};
} // end namespace itk
 
#endif