iterator_from_2d.hpp

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00001 /*
00002     Copyright 2005-2007 Adobe Systems Incorporated
00003    
00004     Use, modification and distribution are subject to the Boost Software License,
00005     Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
00006     http://www.boost.org/LICENSE_1_0.txt).
00007 
00008     See http://opensource.adobe.com/gil for most recent version including documentation.
00009 */
00010 /*************************************************************************************************/
00011 
00012 #ifndef GIL_ITERATOR_FROM_2D_H
00013 #define GIL_ITERATOR_FROM_2D_H
00014 
00023 
00024 #include <cassert>
00025 #include <boost/iterator/iterator_facade.hpp>
00026 #include "gil_concept.hpp"
00027 #include "gil_config.hpp"
00028 #include "pixel_iterator.hpp"
00029 #include "locator.hpp"
00030 
00031 namespace boost { namespace gil {
00032 
00038 
00039 
00043 
00044 
00050 
00051 template <typename Loc2>    // Models PixelLocatorConcept
00052 class iterator_from_2d : public iterator_facade<iterator_from_2d<Loc2>,
00053                                                 typename Loc2::value_type,
00054                                                 random_access_traversal_tag,
00055                                                 typename Loc2::reference,
00056                                                 typename Loc2::coord_t> {
00057     GIL_CLASS_REQUIRE(Loc2, boost::gil, PixelLocatorConcept)
00058 public:
00059     typedef iterator_facade<iterator_from_2d<Loc2>,
00060                             typename Loc2::value_type,
00061                             random_access_traversal_tag,
00062                             typename Loc2::reference,
00063                             typename Loc2::coord_t> parent_t;
00064     typedef typename parent_t::reference       reference;
00065     typedef typename parent_t::difference_type difference_type;
00066     typedef typename Loc2::x_iterator          x_iterator;
00067     typedef typename Loc2::point_t             point_t;
00068 
00069     std::ptrdiff_t width()         const { return _width; }            // number of pixels per image row
00070     std::ptrdiff_t x_pos()         const { return _coords.x; }         // current x position
00071     std::ptrdiff_t y_pos()         const { return _coords.y; }         // current y position
00072 
00075     reference operator[](difference_type d) const { return *(*this+d); }
00076 
00077     bool            is_1d_traversable() const { return _p.is_1d_traversable(width()); }   // is there no gap at the end of each row?
00078     x_iterator&     x()                   { return _p.x(); }
00079 
00080     iterator_from_2d(){}
00081     iterator_from_2d(const Loc2& p, std::ptrdiff_t width, std::ptrdiff_t x=0, std::ptrdiff_t y=0) : _coords(x,y), _width(width), _p(p) {}
00082     iterator_from_2d(const iterator_from_2d& pit) : _coords(pit._coords), _width(pit._width), _p(pit._p) {}
00083     template <typename Loc> iterator_from_2d(const iterator_from_2d<Loc>& pit) : _coords(pit._coords), _width(pit._width), _p(pit._p) {}
00084 
00085 private:
00086     template <typename Loc> friend class iterator_from_2d;
00087     friend class boost::iterator_core_access;
00088     reference dereference() const { return *_p; }
00089     void increment() {
00090         ++_coords.x;
00091         ++_p.x();
00092         if (_coords.x>=_width) {
00093             _coords.x=0;
00094             ++_coords.y;
00095             _p+=point_t(-_width,1);
00096         }           
00097     }
00098     void decrement() {
00099         --_coords.x;
00100         --_p.x();
00101         if (_coords.x<0) {
00102             _coords.x=_width-1;
00103             --_coords.y;
00104             _p+=point_t(_width,-1);
00105         }
00106     }
00107 
00108     GIL_FORCEINLINE void advance(difference_type d) {  
00109         if (_width==0) return;  // unfortunately we need to check for that. Default-constructed images have width of 0 and the code below will throw if executed.
00110         point_t delta;
00111         if (_coords.x+d>=0) {  // not going back to a previous row?
00112             delta.x=(_coords.x+(std::ptrdiff_t)d)%_width - _coords.x;
00113             delta.y=(_coords.x+(std::ptrdiff_t)d)/_width;
00114         } else {
00115             delta.x=(_coords.x+(std::ptrdiff_t)d*(1-_width))%_width -_coords.x;
00116             delta.y=-(_width-_coords.x-(std::ptrdiff_t)d-1)/_width;
00117         }   
00118         _p+=delta;
00119         _coords.x+=delta.x;
00120         _coords.y+=delta.y;
00121     }
00122 
00123     difference_type distance_to(const iterator_from_2d& it) const { 
00124         if (_width==0) return 0;
00125         return (it.y_pos()-_coords.y)*_width + (it.x_pos()-_coords.x);
00126     }
00127 
00128     bool equal(const iterator_from_2d& it) const {
00129         assert(_width==it.width());     // they must belong to the same image
00130         return _coords==it._coords && _p==it._p;
00131     }
00132 
00133     point2<std::ptrdiff_t> _coords;
00134     std::ptrdiff_t _width;
00135     Loc2 _p;
00136 };
00137 
00138 template <typename Loc> // Models PixelLocatorConcept
00139 struct const_iterator_type<iterator_from_2d<Loc> > {
00140     typedef iterator_from_2d<typename Loc::const_t> type;
00141 };
00142 
00143 template <typename Loc> // Models PixelLocatorConcept
00144 struct iterator_is_mutable<iterator_from_2d<Loc> > : public iterator_is_mutable<typename Loc::x_iterator> {};
00145 
00146 
00148 //  HasDynamicXStepTypeConcept
00150 
00151 template <typename Loc>
00152 struct dynamic_x_step_type<iterator_from_2d<Loc> > {
00153     typedef iterator_from_2d<typename dynamic_x_step_type<Loc>::type>  type;
00154 };
00155 
00156 
00158 //  PixelBasedConcept
00160 
00161 template <typename Loc> // Models PixelLocatorConcept
00162 struct color_space_type<iterator_from_2d<Loc> > : public color_space_type<Loc> {};
00163 
00164 template <typename Loc> // Models PixelLocatorConcept
00165 struct channel_mapping_type<iterator_from_2d<Loc> > : public channel_mapping_type<Loc> {};
00166 
00167 template <typename Loc> // Models PixelLocatorConcept
00168 struct is_planar<iterator_from_2d<Loc> > : public is_planar<Loc> {};
00169 
00170 template <typename Loc> // Models PixelLocatorConcept
00171 struct channel_type<iterator_from_2d<Loc> > : public channel_type<Loc> {};
00172 
00173 } }  // namespace boost::gil
00174 
00175 #endif

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