otbMergeLabelObjectFunctor.h

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/*
 * Copyright (C) 2005-2022 Centre National d'Etudes Spatiales (CNES)
 *
 * This file is part of Orfeo Toolbox
 *
 *     https://www.orfeo-toolbox.org/
 *
 * 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
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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 otbMergeLabelObjectFunctor_h
#define otbMergeLabelObjectFunctor_h
 
#include <algorithm>
 
namespace otb
{
 
namespace Functor
{
 
template <class TLabelObject>
class MergeLabelObjectFunctor
{
public:
  typedef TLabelObject                                LabelObjectType;
  typedef typename LabelObjectType::Pointer           LabelObjectPointerType;
  typedef typename LabelObjectType::LineContainerType LineContainerType;
  typedef typename LabelObjectType::LineType          LineType;
  typedef typename LineType::IndexType                IndexType;
 
 
  inline LabelObjectPointerType operator()(const LabelObjectType* l1, const LabelObjectType* l2) const
  {
    // Retrieve the two input line containers
    LineContainerType lines1 = l1->GetLineContainer();
    LineContainerType lines2 = l2->GetLineContainer();
 
    // Ensure they are sorted according to our criterion
    stable_sort(lines1.begin(), lines1.end(), &LexicographicalLineCompare);
    stable_sort(lines2.begin(), lines2.end(), &LexicographicalLineCompare);
 
    // Merge the two containers
    LineContainerType linesOut1(lines1.size() + lines2.size());
    merge(lines1.begin(), lines1.end(), lines2.begin(), lines2.end(), linesOut1.begin(), &LexicographicalLineCompare);
 
    // Merge consecutive and overlapping lines
    LineContainerType linesOut2;
 
    // Initialize output final container
    typename LineContainerType::const_iterator lit = linesOut1.begin();
    linesOut2.push_back(*lit);
    ++lit;
 
    // Walk the merged line container
    while (lit != linesOut1.end())
    {
      // Test if next line overlaps with current
      if (LinesOverlap(linesOut2.back(), *lit))
      {
        // Merge lines
        LineType mline = MergesLines(linesOut2.back(), *lit);
 
        // Replace the last line by the merged line
        linesOut2.pop_back();
        linesOut2.push_back(mline);
      }
      else
      {
        // Push back the new line
        linesOut2.push_back(*lit);
      }
 
      // fetch next line
      ++lit;
    }
 
    // Create the output label object
    LabelObjectPointerType resp = LabelObjectType::New();
    resp->CopyAllFrom(l1);
    resp->GetLineContainer() = linesOut2;
 
    // Return the output label object
    return resp;
  }
 
private:
  static bool LexicographicalLineCompare(const LineType& l1, const LineType& l2)
  {
    bool resp = l2.GetIndex()[1] > l1.GetIndex()[1];
    resp      = resp || (l2.GetIndex()[1] == l1.GetIndex()[1] && (l1.GetIndex()[0] < l2.GetIndex()[0]));
    return resp;
  }
 
  static bool LinesOverlap(const LineType& l1, const LineType& l2)
  {
    // Test if we are in same row
    bool sameRow        = l2.GetIndex()[1] == l1.GetIndex()[1];
    bool leftEndInside  = (l2.GetIndex()[0] >= l1.GetIndex()[0] && l2.GetIndex()[0] <= l1.GetIndex()[0] + static_cast<long>(l1.GetLength()));
    bool rightEndInside = (l1.GetIndex()[0] >= l2.GetIndex()[0] && l1.GetIndex()[0] <= l2.GetIndex()[0] + static_cast<long>(l2.GetLength()));
 
    return (sameRow && (leftEndInside || rightEndInside));
  }
 
  static const LineType MergesLines(const LineType& l1, const LineType& l2)
  {
    LineType resp;
    resp.SetIndex(l1.GetIndex());
    unsigned long length = std::max(l1.GetLength(), l2.GetIndex()[0] + l2.GetLength() - l1.GetIndex()[0]);
    resp.SetLength(length);
    return resp;
  }
 
}; // end class MergeLabelObjectFunctor
 
} // end namespace Functor
 
} // end namespace otb
 
#endif