1/*
2 Copyright 2005-2007 Adobe Systems Incorporated
3
4 Use, modification and distribution are subject to the Boost Software License,
5 Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
6 http://www.boost.org/LICENSE_1_0.txt).
7
8 See http://opensource.adobe.com/gil for most recent version including documentation.
9*/
10
11/*************************************************************************************************/
12
13#ifndef GIL_PIXEL_ITERATOR_H
14#define GIL_PIXEL_ITERATOR_H
15
16////////////////////////////////////////////////////////////////////////////////////////
17/// \file
18/// \brief pixel iterator support
19/// \author Lubomir Bourdev and Hailin Jin \n
20/// Adobe Systems Incorporated
21/// \date 2005-2007 \n May 16, 2006
22///
23////////////////////////////////////////////////////////////////////////////////////////
24
25#include <cassert>
26#include <iterator>
27#include "gil_config.hpp"
28#include "gil_concept.hpp"
29#include "utilities.hpp"
30#include "pixel.hpp"
31
32namespace boost { namespace gil {
33
34//forwarded declaration (as this file is included in step_iterator.hpp)
35template <typename Iterator>
36class memory_based_step_iterator;
37
38template <typename Iterator> struct dynamic_x_step_type;
39
40/// \brief metafunction predicate determining whether the given iterator is a plain one or an adaptor over another iterator.
41/// Examples of adaptors are the step iterator and the dereference iterator adaptor.
42template <typename It>
43struct is_iterator_adaptor : public mpl::false_{};
44
45/// \brief returns the base iterator for a given iterator adaptor. Provide an specialization when introducing new iterator adaptors
46template <typename It>
47struct iterator_adaptor_get_base;
48
49/// \brief Changes the base iterator of an iterator adaptor. Provide an specialization when introducing new iterator adaptors
50template <typename It, typename NewBaseIt>
51struct iterator_adaptor_rebind;
52
53/// \brief Returns the type of an iterator just like the input iterator, except operating over immutable values
54template <typename It>
55struct const_iterator_type;
56
57// The default implementation when the iterator is a C pointer is to use the standard constness semantics
58template <typename T> struct const_iterator_type< T*> { typedef const T* type; };
59template <typename T> struct const_iterator_type<const T*> { typedef const T* type; };
60
61/// \brief Metafunction predicate returning whether the given iterator allows for changing its values
62/// \ingroup GILIsMutable
63template <typename It>
64struct iterator_is_mutable{};
65
66// The default implementation when the iterator is a C pointer is to use the standard constness semantics
67template <typename T> struct iterator_is_mutable< T*> : public mpl::true_{};
68template <typename T> struct iterator_is_mutable<const T*> : public mpl::false_{};
69
70/// \defgroup PixelIteratorModelInterleavedPtr C pointer to a pixel
71/// \ingroup PixelIteratorModel
72/// \brief Iterators over interleaved pixels.
73/// A C pointer to a model of PixelValueConcept is used as an iterator over interleaved pixels. Models PixelIteratorConcept, HomogeneousPixelBasedConcept, HasDynamicXStepTypeConcept, MemoryBasedIteratorConcept
74
75
76
77/////////////////////////////
78// HasDynamicXStepTypeConcept
79/////////////////////////////
80
81/// \ingroup PixelIteratorModelInterleavedPtr
82template <typename Pixel>
83struct dynamic_x_step_type<Pixel*> {
84 typedef memory_based_step_iterator<Pixel*> type;
85};
86
87/// \ingroup PixelIteratorModelInterleavedPtr
88template <typename Pixel>
89struct dynamic_x_step_type<const Pixel*> {
90 typedef memory_based_step_iterator<const Pixel*> type;
91};
92
93
94/////////////////////////////
95// PixelBasedConcept
96/////////////////////////////
97
98template <typename Pixel> struct color_space_type< Pixel*> : public color_space_type<Pixel> {};
99template <typename Pixel> struct color_space_type<const Pixel*> : public color_space_type<Pixel> {};
100
101template <typename Pixel> struct channel_mapping_type< Pixel*> : public channel_mapping_type<Pixel> {};
102template <typename Pixel> struct channel_mapping_type<const Pixel*> : public channel_mapping_type<Pixel> {};
103
104template <typename Pixel> struct is_planar< Pixel*> : public is_planar<Pixel> {};
105template <typename Pixel> struct is_planar<const Pixel*> : public is_planar<Pixel> {};
106
107/////////////////////////////
108// HomogeneousPixelBasedConcept
109/////////////////////////////
110
111template <typename Pixel> struct channel_type<Pixel*> : public channel_type<Pixel> {};
112template <typename Pixel> struct channel_type<const Pixel*> : public channel_type<Pixel> {};
113
114////////////////////////////////////////////////////////////////////////////////////////
115///
116/// Support for pixel iterator movement measured in memory units (bytes or bits) as opposed to pixel type. \n
117/// Necessary to handle image row alignment and channel plane alignment.
118///
119////////////////////////////////////////////////////////////////////////////////////////
120
121/////////////////////////////
122// MemoryBasedIteratorConcept
123/////////////////////////////
124
125template <typename T>
126struct byte_to_memunit : public mpl::int_<1> {};
127
128template <typename P>
129inline std::ptrdiff_t memunit_step(const P*) { return sizeof(P); }
130
131template <typename P>
132inline std::ptrdiff_t memunit_distance(const P* p1, const P* p2) {
133 return (gil_reinterpret_cast_c<const unsigned char*>(p2)-gil_reinterpret_cast_c<const unsigned char*>(p1));
134}
135
136template <typename P>
137inline void memunit_advance(P* &p, std::ptrdiff_t diff) {
138 p=(P*)((unsigned char*)(p)+diff);
139}
140
141template <typename P>
142inline P* memunit_advanced(const P* p, std::ptrdiff_t diff) {
143 return (P*)((char*)(p)+diff);
144}
145
146// memunit_advanced_ref
147// (shortcut to advancing a pointer by a given number of memunits and taking the reference in case the compiler is not smart enough)
148
149template <typename P>
150inline P& memunit_advanced_ref(P* p, std::ptrdiff_t diff) {
151 return *memunit_advanced(p,diff);
152}
153
154} } // namespace boost::gil
155
156#endif
157

source code of boost/boost/gil/pixel_iterator.hpp