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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 itkImageRegionConstIterator_hxx
#define itkImageRegionConstIterator_hxx
namespace itk
{
//----------------------------------------------------------------------------
// Increment when the fastest moving direction has reached its bound.
// This method should *ONLY* be invoked from the operator++() method.
template <typename TImage>
void
ImageRegionConstIterator<TImage>::Increment()
{
// We have reached the end of the span (row), need to wrap around.
// First back up one pixel, because we are going to use a different
// algorithm to compute the next pixel
--this->m_Offset;
// Get the index of the last pixel on the span (row)
typename ImageIterator<TImage>::IndexType ind =
this->m_Image->ComputeIndex(static_cast<OffsetValueType>(this->m_Offset));
const typename ImageIterator<TImage>::IndexType & startIndex = this->m_Region.GetIndex();
const typename ImageIterator<TImage>::SizeType & size = this->m_Region.GetSize();
// Increment along a row, then wrap at the end of the region row.
// 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 end) then
// we need to wrap around the region
unsigned int d = 0;
if (!done)
{
while (((d + 1) < ImageIteratorDimension) && static_cast<SizeValueType>(ind[d] - startIndex[d]) >= size[d])
{
ind[d] = startIndex[d];
ind[++d]++;
}
}
this->m_Offset = this->m_Image->ComputeOffset(ind);
m_SpanEndOffset = this->m_Offset + static_cast<OffsetValueType>(size[0]);
m_SpanBeginOffset = this->m_Offset;
}
//----------------------------------------------------------------------------
// Decrement when the fastest moving direction has reached its bound.
// This method should *ONLY* be invoked from the operator--() method.
template <typename TImage>
void
ImageRegionConstIterator<TImage>::Decrement()
{
// We have pasted the beginning of the span (row), need to wrap around.
// First move forward one pixel, because we are going to use a different
// algorithm to compute the next pixel
this->m_Offset++;
// Get the index of the first pixel on the span (row)
typename ImageIterator<TImage>::IndexType ind =
this->m_Image->ComputeIndex(static_cast<IndexValueType>(this->m_Offset));
const typename ImageIterator<TImage>::IndexType & startIndex = this->m_Region.GetIndex();
const typename ImageIterator<TImage>::SizeType & size = this->m_Region.GetSize();
// Decrement along a row, then wrap at the beginning of the region row.
// Check to see if we are past the first pixel in the region
// Note that --ind[0] moves to the previous pixel along the row.
bool done = (--ind[0] == startIndex[0] - 1);
for (unsigned int i = 1; done && i < ImageIteratorDimension; ++i)
{
done = (ind[i] == startIndex[i]);
}
// 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]))
{
ind[dim] = startIndex[dim] + static_cast<IndexValueType>(size[dim]) - 1;
ind[++dim]--;
}
}
this->m_Offset = this->m_Image->ComputeOffset(ind);
m_SpanEndOffset = this->m_Offset + 1;
m_SpanBeginOffset = m_SpanEndOffset - static_cast<OffsetValueType>(size[0]);
}
} // end namespace itk
#endif
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