breadth_first_thinning.hh

// Copyright (C) 2009, 2010 EPITA Research and Development Laboratory (LRDE)
//
// This file is part of Olena.
//
// Olena is free software: you can redistribute it and/or modify it under
// the terms of the GNU General Public License as published by the Free
// Software Foundation, version 2 of the License.
//
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Olena.  If not, see <http://www.gnu.org/licenses/>.
//
// As a special exception, you may use this file as part of a free
// software project without restriction.  Specifically, if other files
// instantiate templates or use macros or inline functions from this
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// an executable, this file does not by itself cause the resulting
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// exception does not however invalidate any other reasons why the
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#ifndef MLN_TOPO_SKELETON_BREADTH_FIRST_THINNING_HH
# define MLN_TOPO_SKELETON_BREADTH_FIRST_THINNING_HH

/// \file
/// \brief Computing a skeleton by using breadth-first thinning on a
/// binary image.

# include <algorithm>

# include <mln/core/routine/duplicate.hh>

# include <mln/core/concept/image.hh>
# include <mln/core/concept/neighborhood.hh>

# include <mln/core/site_set/p_set.hh>

# include <mln/fun/p2b/tautology.hh>

namespace mln
{

  namespace topo
  {

    namespace skeleton
    {

      /** \brief Skeleton by Breadth-First Thinning.

	  A generic implementation of the computation of a skeleton
	  using a breadth-first thinning on a binary.

          \param input      The input image.
          \param nbh        The adjacency relation between triangles.
          \param is_simple  The predicate on the simplicity of points
                            (sites).  This functor must provide a method
                            <tt>void set_image(const Image<I>&)</tt>.
	  \param detach     A function used to detach a cell from \a input.
          \param constraint A constraint on point (site); if it
       	                    returns \c false for a point, this point
                            will not be removed.  */
      template <typename I, typename N, typename F, typename G, typename H>
      mln_concrete(I)
      breadth_first_thinning(const Image<I>& input,
			     const Neighborhood<N>& nbh,
			     Function_v2b<F>& is_simple,
			     G detach,
			     const Function_v2b<H>& constraint =
			       fun::p2b::tautology());


# ifndef MLN_INCLUDE_ONLY

      template <typename I, typename N, typename F, typename G, typename H>
      inline
      mln_concrete(I)
      breadth_first_thinning(const Image<I>& input_,
			     const Neighborhood<N>& nbh_,
			     Function_v2b<F>& is_simple_,
			     G detach,
			     const Function_v2b<H>& constraint_)
      {
	const I& input = exact(input_);
	const N& nbh = exact(nbh_);
	F& is_simple = exact(is_simple_);
	const H& constraint = exact(constraint_);

	mln_concrete(I) output = duplicate(input);
	// Attach the work image to IS_SIMPLE.
	is_simple.set_image(output);

	typedef mln_psite(I) psite;
	typedef p_set<psite> set_t;
	set_t set;
	// Populate SET with candidate simple points.
	mln_piter(I) p_(output.domain());
	for_all(p_)
	{
	  /* CONSTRAINTS and IS_SIMPLE are site-to-boolean (p2b)
	     predicate functors; passing an iterator as argument might
	     not be possible (C++ cannot resolve template routines if
	     an implicit conversion of the argument is needed).  Help
	     the compiler and pass an actual, explicit psite.  */
	  psite p = p_;
	  if (output(p) && constraint(p) && is_simple(p))
	    set.insert(p);
	}

	while (!set.is_empty())
	  {
	    set_t next_set;

	    mln_piter(set_t) ps(set);
	    for_all(ps)
	    {
	      // Same remark as above.
	      psite p = ps;

	      /* FIXME: We compute the cell and attachment of P twice:
		 during the call to is_simple() and within detach().
		 How could we reuse this elegantly, without breaking
		 the genericity of the skeleton algorithm?
		 Also, keep in mind that functors can maintain an
		 internal state and make side effects, meaning that
		 e.g. constraint(p) might not be constant for a
		 given p during the thinning.  */
	      if (constraint(p) && is_simple(p))
		{
		  detach(p, output);
		  mln_niter(N) n_(nbh, p);
		  for_all(n_)
		  {
		    // Same remark as above regarding P and P_.
		    psite n = n_;
		    if (output.domain().has(n)
			&& output(n) && constraint(n) && is_simple(n))
		      next_set.insert(n);
		  }
		}
	    }
	    set.clear();
	    std::swap(set, next_set);
	  }
	return output;
      }

# endif // MLN_INCLUDE_ONLY

    } // end of namespace mln::topo::skeleton

  } // end of namespace mln::topo

} // end of namespace mln

#endif // ! MLN_TOPO_SKELETON_BREADTH_FIRST_THINNING_HH