2 // Copyright 2005-2007 Adobe Systems Incorporated
3 // Copyright 2019 Mateusz Loskot <mateusz at loskot dot net>
5 // Distributed under the Boost Software License, Version 1.0
6 // See accompanying file LICENSE_1_0.txt or copy at
7 // http://www.boost.org/LICENSE_1_0.txt
9 #ifndef BOOST_GIL_BIT_ALIGNED_PIXEL_REFERENCE_HPP
10 #define BOOST_GIL_BIT_ALIGNED_PIXEL_REFERENCE_HPP
12 #include <boost/gil/pixel.hpp>
13 #include <boost/gil/channel.hpp>
14 #include <boost/gil/detail/mp11.hpp>
16 #include <boost/assert.hpp>
17 #include <boost/config.hpp>
20 #include <type_traits>
22 namespace boost { namespace gil {
24 /// A model of a heterogeneous pixel that is not byte aligned.
25 /// Examples are bitmap (1-bit pixels) or 6-bit RGB (222).
27 /////////////////////////////
30 // Represents a range of bits that can span multiple consecutive bytes. The range has a size fixed at compile time, but the offset is specified at run time.
31 /////////////////////////////
33 template <int RangeSize, bool IsMutable>
36 using byte_t = mp11::mp_if_c<IsMutable, unsigned char, unsigned char const>;
37 using difference_type = std::ptrdiff_t;
38 template <int RS, bool M> friend class bit_range;
40 byte_t* _current_byte; // the starting byte of the bit range
41 int _bit_offset; // offset from the beginning of the current byte. 0<=_bit_offset<=7
44 bit_range() : _current_byte(nullptr), _bit_offset(0) {}
45 bit_range(byte_t* current_byte, int bit_offset)
46 : _current_byte(current_byte)
47 , _bit_offset(bit_offset)
49 BOOST_ASSERT(bit_offset >= 0 && bit_offset < 8);
52 bit_range(const bit_range& br) : _current_byte(br._current_byte), _bit_offset(br._bit_offset) {}
53 template <bool M> bit_range(const bit_range<RangeSize,M>& br) : _current_byte(br._current_byte), _bit_offset(br._bit_offset) {}
55 bit_range& operator=(const bit_range& br) { _current_byte = br._current_byte; _bit_offset=br._bit_offset; return *this; }
56 bool operator==(const bit_range& br) const { return _current_byte==br._current_byte && _bit_offset==br._bit_offset; }
58 bit_range& operator++() {
59 _current_byte += (_bit_offset+RangeSize) / 8;
60 _bit_offset = (_bit_offset+RangeSize) % 8;
63 bit_range& operator--() { bit_advance(-RangeSize); return *this; }
65 void bit_advance(difference_type num_bits) {
66 int new_offset = int(_bit_offset+num_bits);
67 _current_byte += new_offset / 8;
68 _bit_offset = new_offset % 8;
74 difference_type bit_distance_to(const bit_range& b) const {
75 return (b.current_byte() - current_byte())*8 + b.bit_offset()-bit_offset();
77 byte_t* current_byte() const { return _current_byte; }
78 int bit_offset() const { return _bit_offset; }
81 /// \defgroup ColorBaseModelNonAlignedPixel bit_aligned_pixel_reference
82 /// \ingroup ColorBaseModel
83 /// \brief A heterogeneous color base representing pixel that may not be byte aligned, i.e. it may correspond to a bit range that does not start/end at a byte boundary. Models ColorBaseConcept.
85 /// \defgroup PixelModelNonAlignedPixel bit_aligned_pixel_reference
86 /// \ingroup PixelModel
87 /// \brief A heterogeneous pixel reference used to represent non-byte-aligned pixels. Models PixelConcept
91 /// unsigned char data=0;
93 /// // A mutable reference to a 6-bit BGR pixel in "123" format (1 bit for red, 2 bits for green, 3 bits for blue)
94 /// using rgb123_ref_t = bit_aligned_pixel_reference<unsigned char, mp11::mp_list_c<int,1,2,3>, rgb_layout_t, true> const;
96 /// // create the pixel reference at bit offset 2
97 /// // (i.e. red = [2], green = [3,4], blue = [5,6,7] bits)
98 /// rgb123_ref_t ref(&data, 2);
99 /// get_color(ref, red_t()) = 1;
100 /// assert(data == 0x04);
101 /// get_color(ref, green_t()) = 3;
102 /// assert(data == 0x1C);
103 /// get_color(ref, blue_t()) = 7;
104 /// assert(data == 0xFC);
107 /// \ingroup ColorBaseModelNonAlignedPixel PixelModelNonAlignedPixel PixelBasedModel
108 /// \brief Heterogeneous pixel reference corresponding to non-byte-aligned bit range. Models ColorBaseConcept, PixelConcept, PixelBasedConcept
111 /// \tparam ChannelBitSizes Boost.MP11-compatible list of integral types defining the number of bits for each channel. For example, for 565RGB, mp_list_c<int,5,6,5>
113 /// \tparam IsMutable
114 template <typename BitField, typename ChannelBitSizes, typename Layout, bool IsMutable>
115 struct bit_aligned_pixel_reference
117 static constexpr int bit_size =
121 std::integral_constant<int, 0>,
125 using bit_range_t = boost::gil::bit_range<bit_size,IsMutable>;
126 using bitfield_t = BitField;
127 using data_ptr_t = mp11::mp_if_c<IsMutable, unsigned char*, const unsigned char*>;
129 using layout_t = Layout;
131 using value_type = typename packed_pixel_type<bitfield_t,ChannelBitSizes,Layout>::type;
132 using reference = const bit_aligned_pixel_reference<BitField, ChannelBitSizes, Layout, IsMutable>;
133 using const_reference = bit_aligned_pixel_reference<BitField,ChannelBitSizes,Layout,false> const;
135 static constexpr bool is_mutable = IsMutable;
137 bit_aligned_pixel_reference(){}
138 bit_aligned_pixel_reference(data_ptr_t data_ptr, int bit_offset) : _bit_range(data_ptr, bit_offset) {}
139 explicit bit_aligned_pixel_reference(const bit_range_t& bit_range) : _bit_range(bit_range) {}
140 template <bool IsMutable2> bit_aligned_pixel_reference(const bit_aligned_pixel_reference<BitField,ChannelBitSizes,Layout,IsMutable2>& p) : _bit_range(p._bit_range) {}
142 // Grayscale references can be constructed from the channel reference
143 explicit bit_aligned_pixel_reference(typename kth_element_type<bit_aligned_pixel_reference,0>::type const channel0)
144 : _bit_range(static_cast<data_ptr_t>(&channel0), channel0.first_bit())
146 static_assert(num_channels<bit_aligned_pixel_reference>::value == 1, "");
149 // Construct from another compatible pixel type
150 bit_aligned_pixel_reference(bit_aligned_pixel_reference const& p)
151 : _bit_range(p._bit_range) {}
153 // TODO: Why p by non-const reference?
154 template <typename BF, typename CR>
155 bit_aligned_pixel_reference(packed_pixel<BF, CR, Layout>& p)
156 : _bit_range(static_cast<data_ptr_t>(&gil::at_c<0>(p)), gil::at_c<0>(p).first_bit())
158 check_compatible<packed_pixel<BF, CR, Layout>>();
161 auto operator=(bit_aligned_pixel_reference const& p) const
162 -> bit_aligned_pixel_reference const&
164 static_copy(p, *this);
168 template <typename P>
169 auto operator=(P const& p) const -> bit_aligned_pixel_reference const&
171 assign(p, is_pixel<P>());
175 template <typename P>
176 bool operator==(P const& p) const
178 return equal(p, is_pixel<P>());
181 template <typename P>
182 bool operator!=(P const& p) const { return !(*this==p); }
184 auto operator->() const -> bit_aligned_pixel_reference const* { return this; }
186 bit_range_t const& bit_range() const { return _bit_range; }
189 mutable bit_range_t _bit_range;
190 template <typename B, typename C, typename L, bool M> friend struct bit_aligned_pixel_reference;
192 template <typename Pixel> static void check_compatible() { gil_function_requires<PixelsCompatibleConcept<Pixel,bit_aligned_pixel_reference> >(); }
194 template <typename Pixel>
195 void assign(Pixel const& p, std::true_type) const
197 check_compatible<Pixel>();
198 static_copy(p, *this);
201 template <typename Pixel>
202 bool equal(Pixel const& p, std::true_type) const
204 check_compatible<Pixel>();
205 return static_equal(*this, p);
209 static void check_gray()
211 static_assert(std::is_same<typename Layout::color_space_t, gray_t>::value, "");
214 template <typename Channel>
215 void assign(Channel const& channel, std::false_type) const
218 gil::at_c<0>(*this) = channel;
221 template <typename Channel>
222 bool equal (Channel const& channel, std::false_type) const
225 return gil::at_c<0>(*this) == channel;
229 /////////////////////////////
231 /////////////////////////////
233 template <typename BitField, typename ChannelBitSizes, typename L, bool IsMutable, int K>
234 struct kth_element_type
236 bit_aligned_pixel_reference<BitField, ChannelBitSizes, L, IsMutable>,
240 using type = packed_dynamic_channel_reference
243 mp11::mp_at_c<ChannelBitSizes, K>::value,
248 template <typename B, typename C, typename L, bool M, int K>
249 struct kth_element_reference_type<bit_aligned_pixel_reference<B,C,L,M>, K>
250 : public kth_element_type<bit_aligned_pixel_reference<B,C,L,M>, K> {};
252 template <typename B, typename C, typename L, bool M, int K>
253 struct kth_element_const_reference_type<bit_aligned_pixel_reference<B,C,L,M>, K>
254 : public kth_element_type<bit_aligned_pixel_reference<B,C,L,M>, K> {};
258 // returns sum of IntegralVector[0] ... IntegralVector[K-1]
259 template <typename IntegralVector, int K>
263 sum_k<IntegralVector, K - 1>,
264 typename mp11::mp_at_c<IntegralVector, K - 1>::type
268 template <typename IntegralVector>
269 struct sum_k<IntegralVector, 0> : std::integral_constant<int, 0> {};
271 } // namespace detail
273 // at_c required by MutableColorBaseConcept
274 template <int K, typename BitField, typename ChannelBitSizes, typename L, bool IsMutable>
276 auto at_c(const bit_aligned_pixel_reference<BitField, ChannelBitSizes, L, IsMutable>& p)
277 -> typename kth_element_reference_type<bit_aligned_pixel_reference<BitField, ChannelBitSizes, L, IsMutable>, K>::type
279 using pixel_t = bit_aligned_pixel_reference<BitField, ChannelBitSizes, L, IsMutable>;
280 using channel_t = typename kth_element_reference_type<pixel_t, K>::type;
281 using bit_range_t = typename pixel_t::bit_range_t;
283 bit_range_t bit_range(p.bit_range());
284 bit_range.bit_advance(detail::sum_k<ChannelBitSizes, K>::value);
286 return channel_t(bit_range.current_byte(), bit_range.bit_offset());
289 /////////////////////////////
291 /////////////////////////////
293 /// Metafunction predicate that flags bit_aligned_pixel_reference as a model of PixelConcept. Required by PixelConcept
294 template <typename B, typename C, typename L, bool M>
295 struct is_pixel<bit_aligned_pixel_reference<B, C, L, M> > : std::true_type {};
297 /////////////////////////////
299 /////////////////////////////
301 template <typename B, typename C, typename L, bool M>
302 struct color_space_type<bit_aligned_pixel_reference<B, C, L, M>>
304 using type = typename L::color_space_t;
307 template <typename B, typename C, typename L, bool M>
308 struct channel_mapping_type<bit_aligned_pixel_reference<B, C, L, M>>
310 using type = typename L::channel_mapping_t;
313 template <typename B, typename C, typename L, bool M>
314 struct is_planar<bit_aligned_pixel_reference<B, C, L, M>> : std::false_type {};
316 /////////////////////////////
317 // pixel_reference_type
318 /////////////////////////////
320 // Constructs a homogeneous bit_aligned_pixel_reference given a channel reference
321 template <typename BitField, int NumBits, typename Layout>
322 struct pixel_reference_type
324 packed_dynamic_channel_reference<BitField, NumBits, false> const,
329 using channel_bit_sizes_t = mp11::mp_repeat
331 mp11::mp_list<std::integral_constant<unsigned, NumBits>>,
332 mp11::mp_size<typename Layout::color_space_t>
337 bit_aligned_pixel_reference<BitField, channel_bit_sizes_t, Layout, false>;
340 // Same but for the mutable case. We cannot combine the mutable
341 // and read-only cases because this triggers ambiguity
342 template <typename BitField, int NumBits, typename Layout>
343 struct pixel_reference_type
345 packed_dynamic_channel_reference<BitField, NumBits, true> const,
350 using channel_bit_sizes_t = mp11::mp_repeat
352 mp11::mp_list<std::integral_constant<unsigned, NumBits>>,
353 mp11::mp_size<typename Layout::color_space_t>
357 using type = bit_aligned_pixel_reference<BitField, channel_bit_sizes_t, Layout, true>;
360 } } // namespace boost::gil
364 // We are forced to define swap inside std namespace because on some platforms (Visual Studio 8) STL calls swap qualified.
365 // swap with 'left bias':
366 // - swap between proxy and anything
367 // - swap between value type and proxy
368 // - swap between proxy and proxy
369 // Having three overloads allows us to swap between different (but compatible) models of PixelConcept
371 template <typename B, typename C, typename L, typename R> inline
372 void swap(const boost::gil::bit_aligned_pixel_reference<B,C,L,true> x, R& y) {
373 boost::gil::swap_proxy<typename boost::gil::bit_aligned_pixel_reference<B,C,L,true>::value_type>(x,y);
377 template <typename B, typename C, typename L> inline
378 void swap(typename boost::gil::bit_aligned_pixel_reference<B,C,L,true>::value_type& x, const boost::gil::bit_aligned_pixel_reference<B,C,L,true> y) {
379 boost::gil::swap_proxy<typename boost::gil::bit_aligned_pixel_reference<B,C,L,true>::value_type>(x,y);
383 template <typename B, typename C, typename L> inline
384 void swap(const boost::gil::bit_aligned_pixel_reference<B,C,L,true> x, const boost::gil::bit_aligned_pixel_reference<B,C,L,true> y) {
385 boost::gil::swap_proxy<typename boost::gil::bit_aligned_pixel_reference<B,C,L,true>::value_type>(x,y);