Generic Image Library: scanline_read_iterator.hpp Source File

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scanline_read_iterator.hpp
1//
2// Copyright 2007-2008 Christian Henning
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_IO_SCANLINE_READ_ITERATOR_HPP
9#define BOOST_GIL_IO_SCANLINE_READ_ITERATOR_HPP
10
11#include <boost/gil/io/error.hpp>
12#include <boost/gil/io/typedefs.hpp>
13
14#include <boost/iterator/iterator_facade.hpp>
15
16#include <iterator>
17#include <memory>
18#include <vector>
19
20namespace boost { namespace gil {
21
22#if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
23#pragma warning(push)
24#pragma warning(disable:4512) //assignment operator could not be generated
25#endif
26
28template <typename Reader>
29 class scanline_read_iterator
30 : public boost::iterator_facade<scanline_read_iterator<Reader>, byte_t*, std::input_iterator_tag>
31{
32private:
33 using base_t = boost::iterator_facade
34 <
35 scanline_read_iterator<Reader>,
36 byte_t*,
37 std::input_iterator_tag
38 >;
39public:
40 scanline_read_iterator(Reader& reader, int pos = 0)
41 : reader_(reader), pos_(pos)
42 {
43 buffer_ = std::make_shared<buffer_t>(buffer_t(reader_._scanline_length));
44 buffer_start_ = &buffer_->front();
45 }
46
47private:
48 friend class boost::iterator_core_access;
49
50 void increment()
51 {
52 if (skip_scanline_)
53 {
54 reader_.skip(buffer_start_, pos_);
55 }
56
57 ++pos_;
58
59 skip_scanline_ = true;
60 read_scanline_ = true;
61 }
62
63 bool equal(scanline_read_iterator const& rhs) const
64 {
65 return pos_ == rhs.pos_;
66 }
67
68 typename base_t::reference dereference() const
69 {
70 if (read_scanline_)
71 {
72 reader_.read(buffer_start_, pos_);
73 }
74 skip_scanline_ = false;
75 read_scanline_ = false;
76
77 return buffer_start_;
78 }
79
80private:
81 Reader& reader_;
82
83 mutable int pos_ = 0;
84 mutable bool read_scanline_ = true;
85 mutable bool skip_scanline_ = true;
86
87 using buffer_t = std::vector<byte_t>;
88 using buffer_ptr_t = std::shared_ptr<buffer_t>;
89 buffer_ptr_t buffer_;
90 mutable byte_t* buffer_start_ = nullptr;
91};
92
93#if BOOST_WORKAROUND(BOOST_MSVC, >= 1400)
94#pragma warning(pop)
95#endif
96
97} // namespace gil
98} // namespace boost
99
100#endif
boost::gil::scanline_read_iterator
Input iterator to read images.
Definition: scanline_read_iterator.hpp:31
boost
defined(BOOST_NO_CXX17_HDR_MEMORY_RESOURCE)
Definition: algorithm.hpp:36