/*=========================================================================
 *
 *  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 itkImageScanlineConstIterator_hxx
#define itkImageScanlineConstIterator_hxx


namespace itk
{

template <typename TImage>
void
ImageScanlineConstIterator<TImage>::NextLine()
{
  // increment to the next scanline

  // Get the index of the last pixel on the span (row)
  IndexType ind = this->m_Image->ComputeIndex(static_cast<OffsetValueType>(m_SpanEndOffset - 1));

  const IndexType & startIndex = this->m_Region.GetIndex();
  const SizeType &  size = this->m_Region.GetSize();

  // Check to see if we are past the last pixel in the region
  // Note that ++ind[0] moves to the next pixel along the row.
  ++ind[0];
  bool done = (ind[0] == startIndex[0] + static_cast<IndexValueType>(size[0]));
  for (unsigned int i = 1; done && i < ImageIteratorDimension; ++i)
  {
    done = (ind[i] == startIndex[i] + static_cast<IndexValueType>(size[i]) - 1);
  }

  // if the iterator is outside the region (but not past region begin) then
  // we need to wrap around the region
  unsigned int dim = 0;
  if (!done)
  {
    while (((dim + 1) < ImageIteratorDimension) &&
           (ind[dim] > startIndex[dim] + static_cast<IndexValueType>(size[dim]) - 1))
    {
      ind[dim] = startIndex[dim];
      ind[++dim]++;
    }
  }

  this->m_Offset = this->m_Image->ComputeOffset(ind);
  m_SpanEndOffset = this->m_Offset + static_cast<OffsetValueType>(size[0]);
  m_SpanBeginOffset = this->m_Offset;
}

} // end namespace itk

#endif
