Generic Image Library: iterator_from_2d.hpp Source File

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iterator_from_2d.hpp
1//
2// Copyright 2005-2007 Adobe Systems Incorporated
3//
4// Distributed under the Boost Software License, Version 1.0
5// See accompanying file LICENSE_1_0.txt or copy at
6// http://www.boost.org/LICENSE_1_0.txt
7//
8#ifndef BOOST_GIL_ITERATOR_FROM_2D_HPP
9#define BOOST_GIL_ITERATOR_FROM_2D_HPP
10
11#include <boost/gil/concepts.hpp>
12#include <boost/gil/locator.hpp>
13#include <boost/gil/pixel_iterator.hpp>
14#include <boost/gil/point.hpp>
15
16#include <boost/assert.hpp>
17#include <boost/iterator/iterator_facade.hpp>
18
19namespace boost { namespace gil {
20
22
28
29
33
34
40
41template <typename Loc2> // Models PixelLocatorConcept
42 class iterator_from_2d : public iterator_facade<iterator_from_2d<Loc2>,
43 typename Loc2::value_type,
44 std::random_access_iterator_tag,
45 typename Loc2::reference,
46 typename Loc2::coord_t> {
47 BOOST_GIL_CLASS_REQUIRE(Loc2, boost::gil, PixelLocatorConcept)
48public:
49 using parent_t = iterator_facade<iterator_from_2d<Loc2>,
50 typename Loc2::value_type,
51 std::random_access_iterator_tag,
52 typename Loc2::reference,
53 typename Loc2::coord_t>;
54 using reference = typename parent_t::reference;
55 using difference_type = typename parent_t::difference_type;
56 using x_iterator = typename Loc2::x_iterator;
57 using point_t = typename Loc2::point_t;
58
59 std::ptrdiff_t width() const { return _width; } // number of pixels per image row
60 std::ptrdiff_t x_pos() const { return _coords.x; } // current x position
61 std::ptrdiff_t y_pos() const { return _coords.y; } // current y position
62
65 reference operator[](difference_type d) const { return *(*this+d); }
66
67 bool is_1d_traversable() const { return _p.is_1d_traversable(width()); } // is there no gap at the end of each row?
68 x_iterator& x() { return _p.x(); }
69
70 iterator_from_2d() = default;
71 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) {}
72 iterator_from_2d(const iterator_from_2d& pit) : _coords(pit._coords), _width(pit._width), _p(pit._p) {}
73 template <typename Loc> iterator_from_2d(const iterator_from_2d<Loc>& pit) : _coords(pit._coords), _width(pit._width), _p(pit._p) {}
74 iterator_from_2d& operator=(iterator_from_2d const& other) = default;
75
76private:
77 template <typename Loc> friend class iterator_from_2d;
78 friend class boost::iterator_core_access;
79 reference dereference() const { return *_p; }
80 void increment() {
81 ++_coords.x;
82 ++_p.x();
83 if (_coords.x>=_width) {
84 _coords.x=0;
85 ++_coords.y;
86 _p+=point_t(-_width,1);
87 }
88 }
89 void decrement() {
90 --_coords.x;
91 --_p.x();
92 if (_coords.x<0) {
93 _coords.x=_width-1;
94 --_coords.y;
95 _p+=point_t(_width,-1);
96 }
97 }
98
99 BOOST_FORCEINLINE void advance(difference_type d) {
100 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.
101 point_t delta;
102 if (_coords.x+d>=0) { // not going back to a previous row?
103 delta.x=(_coords.x+(std::ptrdiff_t)d)%_width - _coords.x;
104 delta.y=(_coords.x+(std::ptrdiff_t)d)/_width;
105 } else {
106 delta.x=(_coords.x+(std::ptrdiff_t)d*(1-_width))%_width -_coords.x;
107 delta.y=-(_width-_coords.x-(std::ptrdiff_t)d-1)/_width;
108 }
109 _p+=delta;
110 _coords.x+=delta.x;
111 _coords.y+=delta.y;
112 }
113
114 difference_type distance_to(const iterator_from_2d& it) const {
115 if (_width==0) return 0;
116 return (it.y_pos()-_coords.y)*_width + (it.x_pos()-_coords.x);
117 }
118
119 bool equal(iterator_from_2d const& it) const
120 {
121 BOOST_ASSERT(_width == it.width()); // they must belong to the same image
122 return _coords == it._coords && _p == it._p;
123 }
124
125 point_t _coords;
126 std::ptrdiff_t _width;
127 Loc2 _p;
128};
129
130template <typename Loc> // Models PixelLocatorConcept
131struct const_iterator_type<iterator_from_2d<Loc> > {
132 using type = iterator_from_2d<typename Loc::const_t>;
133};
134
135template <typename Loc> // Models PixelLocatorConcept
136struct iterator_is_mutable<iterator_from_2d<Loc> > : public iterator_is_mutable<typename Loc::x_iterator> {};
137
138
140// HasDynamicXStepTypeConcept
142
143template <typename Loc>
144struct dynamic_x_step_type<iterator_from_2d<Loc> > {
145 using type = iterator_from_2d<typename dynamic_x_step_type<Loc>::type>;
146};
147
148
150// PixelBasedConcept
152
153template <typename Loc> // Models PixelLocatorConcept
154struct color_space_type<iterator_from_2d<Loc> > : public color_space_type<Loc> {};
155
156template <typename Loc> // Models PixelLocatorConcept
157struct channel_mapping_type<iterator_from_2d<Loc> > : public channel_mapping_type<Loc> {};
158
159template <typename Loc> // Models PixelLocatorConcept
160struct is_planar<iterator_from_2d<Loc> > : public is_planar<Loc> {};
161
162template <typename Loc> // Models PixelLocatorConcept
163struct channel_type<iterator_from_2d<Loc> > : public channel_type<Loc> {};
164
165} } // namespace boost::gil
166
167#endif
boost::gil::iterator_from_2d
Provides 1D random-access navigation to the pixels of the image. Models: PixelIteratorConcept,...
Definition: iterator_from_2d.hpp:46
boost::gil::iterator_from_2d::operator[]
reference operator[](difference_type d) const
Definition: iterator_from_2d.hpp:65
boost
defined(BOOST_NO_CXX17_HDR_MEMORY_RESOURCE)
Definition: algorithm.hpp:36
boost::gil::PixelLocatorConcept
GIL's 2-dimensional locator over immutable GIL pixels.
Definition: pixel_locator.hpp:292