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// Copyright (c) 2006 Fernando Luis Cacciola Carballal. All rights reserved.
//
// This file is part of CGAL (www.cgal.org); you may redistribute it under
// the terms of the Q Public License version 1.0.
// See the file LICENSE.QPL distributed with CGAL.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL: svn+ssh://scm.gforge.inria.fr/svn/cgal/branches/CGAL-3.2-branch/Straight_skeleton_2/include/CGAL/compute_outer_frame_margin.h $
// $Id: compute_outer_frame_margin.h 31990 2006-06-20 18:56:09Z fcacciola $
//
// Author(s) : Fernando Cacciola <fernando_cacciola@ciudad.com.ar>
//
#ifndef CGAL_COMPUTE_OUTER_FRAME_MARGIN_H
#define CGAL_COMPUTE_OUTER_FRAME_MARGIN_H
#include <vector>
#include <algorithm>
#include <boost/shared_ptr.hpp>
#include <boost/optional/optional.hpp>
#include <CGAL/algorithm.h>
#include <CGAL/Polygon_offset_builder_traits_2.h>
CGAL_BEGIN_NAMESPACE
template<class ForwardPointIterator, class Traits>
boost::optional< typename Traits::FT > compute_outer_frame_margin ( ForwardPointIterator aBegin
, ForwardPointIterator aEnd
, typename Traits::FT aOffset
, Traits const& aTraits
)
{
typedef typename Traits::Kernel Kernel ;
typedef typename Traits::FT FT ;
typedef typename Traits::Point_2 Point_2 ;
typedef typename Traits::Segment_2 Segment_2 ;
Kernel kernel ;
typename Kernel::Equal_2 equal = kernel.equal_2_object();
typename Kernel::Collinear_2 collinear = kernel.collinear_2_object();
typename Kernel::Compute_squared_distance_2 squared_distance = kernel.compute_squared_distance_2_object();
typename Kernel::Construct_segment_2 construct_segment = kernel.construct_segment_2_object();
typedef boost::optional<Point_2> OptionalPoint_2 ;
FT lMaxSDist(0.0) ;
ForwardPointIterator lLast = CGAL::predecessor(aEnd) ;
bool lOverflow = false ;
for ( ForwardPointIterator lCurr = aBegin ; lCurr < aEnd ; ++ lCurr )
{
ForwardPointIterator lPrev = ( lCurr == aBegin ? lLast : CGAL::predecessor(lCurr) ) ;
ForwardPointIterator lNext = ( lCurr == lLast ? aBegin : CGAL::successor (lCurr) ) ;
if ( !equal(*lPrev,*lCurr) && !equal(*lCurr,*lNext) && !collinear(*lPrev,*lCurr,*lNext) )
{
Segment_2 lLEdge = construct_segment(*lPrev,*lCurr);
Segment_2 lREdge = construct_segment(*lCurr,*lNext);
OptionalPoint_2 lP = Construct_offset_point_2(aTraits)(aOffset,lLEdge,lREdge);
if ( !lP )
{
lOverflow = true ;
break ;
}
FT lSDist = CGAL::squared_distance(*lCurr,*lP);
if ( ! CGAL_NTS is_finite(lSDist) )
{
lOverflow = true ;
break ;
}
if ( lSDist > lMaxSDist )
lMaxSDist = lSDist ;
}
}
if ( ! lOverflow )
{
FT lDist = CGAL_NTS sqrt(lMaxSDist) ;
return boost::optional<FT>( lDist + ( aOffset * FT(1.05) ) ) ; // Add a %5 gap
}
else
return boost::optional<FT>();
}
template<class ForwardPointIterator, class FT>
boost::optional<FT> compute_outer_frame_margin ( ForwardPointIterator aBegin, ForwardPointIterator aEnd, FT aOffset )
{
typedef typename std::iterator_traits<ForwardPointIterator>::value_type Point_2 ;
typedef typename Kernel_traits<Point_2>::Kernel K;
Polygon_offset_builder_traits_2<K> traits ;
return compute_outer_frame_margin(aBegin,aEnd,aOffset,traits);
}
CGAL_END_NAMESPACE
#endif // CGAL_COMPUTE_OUTER_FRAME_MARGIN_H //
// EOF //
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