boost/gil/bit_aligned_pixel_iterator.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_BIT_ALIGNED_PIXEL_ITERATOR_HPP
   9 #define BOOST_GIL_BIT_ALIGNED_PIXEL_ITERATOR_HPP
  10
  11 #include <boost/gil/bit_aligned_pixel_reference.hpp>
  12 #include <boost/gil/pixel_iterator.hpp>
  13
  14 #include <boost/config.hpp>
  15 #include <boost/iterator/iterator_facade.hpp>
  16
  17 #include <functional>
  18 #include <type_traits>
  19
  20 namespace boost { namespace gil {
  21
  22 /// A model of a heterogeneous pixel that is not byte aligned.
  23 /// Examples are bitmap (1-bit pixels) or 6-bit RGB (222).
  24
  25 /// \defgroup PixelIteratorNonAlignedPixelIterator bit_aligned_pixel_iterator
  26 /// \ingroup PixelIteratorModel
  27 /// \brief An iterator over non-byte-aligned pixels. Models PixelIteratorConcept, PixelBasedConcept, MemoryBasedIteratorConcept, HasDynamicXStepTypeConcept
  28
  29 ////////////////////////////////////////////////////////////////////////////////////////
  30 /// \brief An iterator over non-byte-aligned pixels. Models PixelIteratorConcept, PixelBasedConcept, MemoryBasedIteratorConcept, HasDynamicXStepTypeConcept
  31 ///
  32 /// An iterator over pixels that correspond to non-byte-aligned bit ranges. Examples of such pixels are single bit grayscale pixel, or a 6-bit RGB 222 pixel.
  33 ///
  34 /// \ingroup PixelIteratorNonAlignedPixelIterator PixelBasedModel
  35
  36 template <typename NonAlignedPixelReference>
  37 struct bit_aligned_pixel_iterator : public iterator_facade<bit_aligned_pixel_iterator<NonAlignedPixelReference>,
  38                                                   typename NonAlignedPixelReference::value_type,
  39                                                   std::random_access_iterator_tag,
  40                                                   const NonAlignedPixelReference,
  41                                                   typename NonAlignedPixelReference::bit_range_t::difference_type> {
  42 private:
  43     using parent_t = iterator_facade<bit_aligned_pixel_iterator<NonAlignedPixelReference>,
  44                             typename NonAlignedPixelReference::value_type,
  45                             std::random_access_iterator_tag,
  46                             const NonAlignedPixelReference,
  47                             typename NonAlignedPixelReference::bit_range_t::difference_type>;
  48     template <typename Ref> friend struct bit_aligned_pixel_iterator;
  49
  50     using bit_range_t = typename NonAlignedPixelReference::bit_range_t;
  51 public:
  52     using difference_type = typename parent_t::difference_type;
  53     using reference = typename parent_t::reference;
  54
  55     bit_aligned_pixel_iterator() {}
  56     bit_aligned_pixel_iterator(const bit_aligned_pixel_iterator& p) : _bit_range(p._bit_range) {}
  57     bit_aligned_pixel_iterator& operator=(const bit_aligned_pixel_iterator& p) { _bit_range=p._bit_range; return *this; }
  58
  59     template <typename Ref> bit_aligned_pixel_iterator(const bit_aligned_pixel_iterator<Ref>& p) : _bit_range(p._bit_range) {}
  60
  61     bit_aligned_pixel_iterator(reference* ref) : _bit_range(ref->bit_range()) {}
  62     explicit bit_aligned_pixel_iterator(typename bit_range_t::byte_t* data, int bit_offset=0) : _bit_range(data,bit_offset) {}
  63
  64     /// For some reason operator[] provided by iterator_adaptor returns a custom class that is convertible to reference
  65     /// We require our own reference because it is registered in iterator_traits
  66     reference operator[](difference_type d) const { bit_aligned_pixel_iterator it=*this; it.advance(d); return *it; }
  67
  68     reference operator->()         const { return **this; }
  69     const bit_range_t& bit_range() const { return _bit_range; }
  70           bit_range_t& bit_range()       { return _bit_range; }
  71 private:
  72     bit_range_t _bit_range;
  73     static constexpr int bit_size = NonAlignedPixelReference::bit_size;
  74
  75     friend class boost::iterator_core_access;
  76     reference dereference()     const { return NonAlignedPixelReference(_bit_range); }
  77     void increment()                  { ++_bit_range; }
  78     void decrement()                  { --_bit_range; }
  79     void advance(difference_type d)   { _bit_range.bit_advance(d*bit_size); }
  80
  81     difference_type distance_to(const bit_aligned_pixel_iterator& it) const { return _bit_range.bit_distance_to(it._bit_range) / bit_size; }
  82     bool equal(const bit_aligned_pixel_iterator& it) const { return _bit_range==it._bit_range; }
  83 };
  84
  85 template <typename NonAlignedPixelReference>
  86 struct const_iterator_type<bit_aligned_pixel_iterator<NonAlignedPixelReference>>
  87 {
  88     using type =
  89         bit_aligned_pixel_iterator<typename NonAlignedPixelReference::const_reference>;
  90 };
  91
  92 template <typename NonAlignedPixelReference>
  93 struct iterator_is_mutable<bit_aligned_pixel_iterator<NonAlignedPixelReference>>
  94     : std::integral_constant<bool, NonAlignedPixelReference::is_mutable>
  95 {};
  96
  97 template <typename NonAlignedPixelReference>
  98 struct is_iterator_adaptor<bit_aligned_pixel_iterator<NonAlignedPixelReference>>
  99     : std::false_type
 100 {};
 101
 102 /////////////////////////////
 103 //  PixelBasedConcept
 104 /////////////////////////////
 105
 106 template <typename NonAlignedPixelReference>
 107 struct color_space_type<bit_aligned_pixel_iterator<NonAlignedPixelReference> > : public color_space_type<NonAlignedPixelReference> {};
 108
 109 template <typename NonAlignedPixelReference>
 110 struct channel_mapping_type<bit_aligned_pixel_iterator<NonAlignedPixelReference> > : public channel_mapping_type<NonAlignedPixelReference> {};
 111
 112 template <typename NonAlignedPixelReference>
 113 struct is_planar<bit_aligned_pixel_iterator<NonAlignedPixelReference> > : public is_planar<NonAlignedPixelReference> {}; // == false
 114
 115 /////////////////////////////
 116 //  MemoryBasedIteratorConcept
 117 /////////////////////////////
 118
 119 template <typename NonAlignedPixelReference>
 120 struct byte_to_memunit<bit_aligned_pixel_iterator<NonAlignedPixelReference>>
 121     : std::integral_constant<int, 8>
 122 {};
 123
 124 template <typename NonAlignedPixelReference>
 125 inline std::ptrdiff_t memunit_step(const bit_aligned_pixel_iterator<NonAlignedPixelReference>&) {
 126     return NonAlignedPixelReference::bit_size;
 127 }
 128
 129 template <typename NonAlignedPixelReference>
 130 inline std::ptrdiff_t memunit_distance(const bit_aligned_pixel_iterator<NonAlignedPixelReference>& p1, const bit_aligned_pixel_iterator<NonAlignedPixelReference>& p2) {
 131     return (p2.bit_range().current_byte() - p1.bit_range().current_byte())*8 + p2.bit_range().bit_offset() - p1.bit_range().bit_offset();
 132 }
 133
 134 template <typename NonAlignedPixelReference>
 135 inline void memunit_advance(bit_aligned_pixel_iterator<NonAlignedPixelReference>& p, std::ptrdiff_t diff) {
 136     p.bit_range().bit_advance(diff);
 137 }
 138
 139 template <typename NonAlignedPixelReference>
 140 inline bit_aligned_pixel_iterator<NonAlignedPixelReference> memunit_advanced(const bit_aligned_pixel_iterator<NonAlignedPixelReference>& p, std::ptrdiff_t diff) {
 141     bit_aligned_pixel_iterator<NonAlignedPixelReference> ret=p;
 142     memunit_advance(ret, diff);
 143     return ret;
 144 }
 145
 146 template <typename NonAlignedPixelReference> inline
 147 NonAlignedPixelReference memunit_advanced_ref(bit_aligned_pixel_iterator<NonAlignedPixelReference> it, std::ptrdiff_t diff) {
 148     return *memunit_advanced(it,diff);
 149 }
 150 /////////////////////////////
 151 //  HasDynamicXStepTypeConcept
 152 /////////////////////////////
 153
 154 template <typename NonAlignedPixelReference>
 155 struct dynamic_x_step_type<bit_aligned_pixel_iterator<NonAlignedPixelReference> > {
 156     using type = memory_based_step_iterator<bit_aligned_pixel_iterator<NonAlignedPixelReference> >;
 157 };
 158
 159 /////////////////////////////
 160 //  iterator_type_from_pixel
 161 /////////////////////////////
 162
 163 template <typename B, typename C, typename L, bool M>
 164 struct iterator_type_from_pixel<const bit_aligned_pixel_reference<B,C,L,M>,false,false,false>
 165 {
 166     using type = bit_aligned_pixel_iterator<bit_aligned_pixel_reference<B,C,L,false>> ;
 167 };
 168
 169 template <typename B, typename C, typename L, bool M>
 170 struct iterator_type_from_pixel<const bit_aligned_pixel_reference<B,C,L,M>,false,false,true>
 171 {
 172     using type = bit_aligned_pixel_iterator<bit_aligned_pixel_reference<B,C,L,true>>;
 173 };
 174
 175 template <typename B, typename C, typename L, bool M, bool IsPlanar, bool IsStep, bool IsMutable>
 176 struct iterator_type_from_pixel<bit_aligned_pixel_reference<B,C,L,M>,IsPlanar,IsStep,IsMutable>
 177     : public iterator_type_from_pixel<const bit_aligned_pixel_reference<B,C,L,M>,IsPlanar,IsStep,IsMutable> {};
 178
 179 } }  // namespace boost::gil
 180
 181 namespace std {
 182
 183 // It is important to provide an overload of uninitialized_copy for bit_aligned_pixel_iterator. The default STL implementation calls placement new,
 184 // which is not defined for bit_aligned_pixel_iterator.
 185 template <typename NonAlignedPixelReference>
 186 boost::gil::bit_aligned_pixel_iterator<NonAlignedPixelReference> uninitialized_copy(boost::gil::bit_aligned_pixel_iterator<NonAlignedPixelReference> first,
 187                                                                                    boost::gil::bit_aligned_pixel_iterator<NonAlignedPixelReference> last,
 188                                                                                    boost::gil::bit_aligned_pixel_iterator<NonAlignedPixelReference> dst) {
 189     return std::copy(first,last,dst);
 190 }
 191
 192 }   // namespace std
 193 #endif