//
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// Copyright 2005-2007 Adobe Systems Incorporated
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// Copyright 2019 Mateusz Loskot <mateusz at loskot dot net>
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//
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// Distributed under the Boost Software License, Version 1.0
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// See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt
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//
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#ifndef BOOST_GIL_BIT_ALIGNED_PIXEL_REFERENCE_HPP
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#define BOOST_GIL_BIT_ALIGNED_PIXEL_REFERENCE_HPP
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#include <boost/gil/pixel.hpp>
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#include <boost/gil/channel.hpp>
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#include <boost/gil/detail/mp11.hpp>
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#include <boost/assert.hpp>
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#include <boost/config.hpp>
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#include <functional>
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#include <type_traits>
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namespace boost { namespace gil {
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/// A model of a heterogeneous pixel that is not byte aligned.
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/// Examples are bitmap (1-bit pixels) or 6-bit RGB (222).
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/////////////////////////////
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// bit_range
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//
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// 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.
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/////////////////////////////
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template <int RangeSize, bool IsMutable>
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class bit_range {
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public:
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using byte_t = mp11::mp_if_c<IsMutable, unsigned char, unsigned char const>;
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using difference_type = std::ptrdiff_t;
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template <int RS, bool M> friend class bit_range;
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private:
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byte_t* _current_byte; // the starting byte of the bit range
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int _bit_offset; // offset from the beginning of the current byte. 0<=_bit_offset<=7
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public:
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bit_range() : _current_byte(nullptr), _bit_offset(0) {}
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bit_range(byte_t* current_byte, int bit_offset)
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: _current_byte(current_byte)
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, _bit_offset(bit_offset)
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{
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BOOST_ASSERT(bit_offset >= 0 && bit_offset < 8);
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}
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bit_range(const bit_range& br) : _current_byte(br._current_byte), _bit_offset(br._bit_offset) {}
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template <bool M> bit_range(const bit_range<RangeSize,M>& br) : _current_byte(br._current_byte), _bit_offset(br._bit_offset) {}
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bit_range& operator=(const bit_range& br) { _current_byte = br._current_byte; _bit_offset=br._bit_offset; return *this; }
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bool operator==(const bit_range& br) const { return _current_byte==br._current_byte && _bit_offset==br._bit_offset; }
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bit_range& operator++() {
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_current_byte += (_bit_offset+RangeSize) / 8;
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_bit_offset = (_bit_offset+RangeSize) % 8;
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return *this;
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}
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bit_range& operator--() { bit_advance(-RangeSize); return *this; }
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void bit_advance(difference_type num_bits) {
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int new_offset = int(_bit_offset+num_bits);
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_current_byte += new_offset / 8;
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_bit_offset = new_offset % 8;
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if (_bit_offset<0) {
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_bit_offset+=8;
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--_current_byte;
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}
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}
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difference_type bit_distance_to(const bit_range& b) const {
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return (b.current_byte() - current_byte())*8 + b.bit_offset()-bit_offset();
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}
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byte_t* current_byte() const { return _current_byte; }
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int bit_offset() const { return _bit_offset; }
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};
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/// \defgroup ColorBaseModelNonAlignedPixel bit_aligned_pixel_reference
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/// \ingroup ColorBaseModel
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/// \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.
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///
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/// \defgroup PixelModelNonAlignedPixel bit_aligned_pixel_reference
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/// \ingroup PixelModel
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/// \brief A heterogeneous pixel reference used to represent non-byte-aligned pixels. Models PixelConcept
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///
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/// Example:
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/// \code
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/// unsigned char data=0;
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///
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/// // A mutable reference to a 6-bit BGR pixel in "123" format (1 bit for red, 2 bits for green, 3 bits for blue)
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/// using rgb123_ref_t = bit_aligned_pixel_reference<unsigned char, mp11::mp_list_c<int,1,2,3>, rgb_layout_t, true> const;
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///
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/// // create the pixel reference at bit offset 2
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/// // (i.e. red = [2], green = [3,4], blue = [5,6,7] bits)
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/// rgb123_ref_t ref(&data, 2);
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/// get_color(ref, red_t()) = 1;
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/// assert(data == 0x04);
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/// get_color(ref, green_t()) = 3;
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/// assert(data == 0x1C);
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/// get_color(ref, blue_t()) = 7;
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/// assert(data == 0xFC);
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/// \endcode
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///
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/// \ingroup ColorBaseModelNonAlignedPixel PixelModelNonAlignedPixel PixelBasedModel
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/// \brief Heterogeneous pixel reference corresponding to non-byte-aligned bit range. Models ColorBaseConcept, PixelConcept, PixelBasedConcept
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///
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/// \tparam BitField
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/// \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>
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/// \tparam Layout
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/// \tparam IsMutable
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template <typename BitField, typename ChannelBitSizes, typename Layout, bool IsMutable>
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struct bit_aligned_pixel_reference
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{
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static constexpr int bit_size =
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mp11::mp_fold
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<
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ChannelBitSizes,
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std::integral_constant<int, 0>,
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mp11::mp_plus
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>::value;
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using bit_range_t = boost::gil::bit_range<bit_size,IsMutable>;
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using bitfield_t = BitField;
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using data_ptr_t = mp11::mp_if_c<IsMutable, unsigned char*, const unsigned char*>;
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using layout_t = Layout;
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using value_type = typename packed_pixel_type<bitfield_t,ChannelBitSizes,Layout>::type;
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using reference = const bit_aligned_pixel_reference<BitField, ChannelBitSizes, Layout, IsMutable>;
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using const_reference = bit_aligned_pixel_reference<BitField,ChannelBitSizes,Layout,false> const;
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static constexpr bool is_mutable = IsMutable;
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bit_aligned_pixel_reference(){}
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bit_aligned_pixel_reference(data_ptr_t data_ptr, int bit_offset) : _bit_range(data_ptr, bit_offset) {}
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explicit bit_aligned_pixel_reference(const bit_range_t& bit_range) : _bit_range(bit_range) {}
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template <bool IsMutable2> bit_aligned_pixel_reference(const bit_aligned_pixel_reference<BitField,ChannelBitSizes,Layout,IsMutable2>& p) : _bit_range(p._bit_range) {}
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// Grayscale references can be constructed from the channel reference
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explicit bit_aligned_pixel_reference(typename kth_element_type<bit_aligned_pixel_reference,0>::type const channel0)
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: _bit_range(static_cast<data_ptr_t>(&channel0), channel0.first_bit())
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{
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static_assert(num_channels<bit_aligned_pixel_reference>::value == 1, "");
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}
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// Construct from another compatible pixel type
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bit_aligned_pixel_reference(bit_aligned_pixel_reference const& p)
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: _bit_range(p._bit_range) {}
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// TODO: Why p by non-const reference?
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template <typename BF, typename CR>
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bit_aligned_pixel_reference(packed_pixel<BF, CR, Layout>& p)
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: _bit_range(static_cast<data_ptr_t>(&gil::at_c<0>(p)), gil::at_c<0>(p).first_bit())
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{
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check_compatible<packed_pixel<BF, CR, Layout>>();
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}
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auto operator=(bit_aligned_pixel_reference const& p) const
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-> bit_aligned_pixel_reference const&
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{
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static_copy(p, *this);
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return *this;
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}
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template <typename P>
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auto operator=(P const& p) const -> bit_aligned_pixel_reference const&
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{
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assign(p, is_pixel<P>());
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return *this;
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}
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template <typename P>
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bool operator==(P const& p) const
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{
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return equal(p, is_pixel<P>());
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}
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template <typename P>
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bool operator!=(P const& p) const { return !(*this==p); }
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auto operator->() const -> bit_aligned_pixel_reference const* { return this; }
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bit_range_t const& bit_range() const { return _bit_range; }
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private:
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mutable bit_range_t _bit_range;
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template <typename B, typename C, typename L, bool M> friend struct bit_aligned_pixel_reference;
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template <typename Pixel> static void check_compatible() { gil_function_requires<PixelsCompatibleConcept<Pixel,bit_aligned_pixel_reference> >(); }
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template <typename Pixel>
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void assign(Pixel const& p, std::true_type) const
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{
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check_compatible<Pixel>();
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static_copy(p, *this);
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}
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template <typename Pixel>
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bool equal(Pixel const& p, std::true_type) const
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{
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check_compatible<Pixel>();
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return static_equal(*this, p);
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}
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private:
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static void check_gray()
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{
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static_assert(std::is_same<typename Layout::color_space_t, gray_t>::value, "");
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}
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template <typename Channel>
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void assign(Channel const& channel, std::false_type) const
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{
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check_gray();
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gil::at_c<0>(*this) = channel;
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}
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template <typename Channel>
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bool equal (Channel const& channel, std::false_type) const
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{
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check_gray();
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return gil::at_c<0>(*this) == channel;
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}
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};
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/////////////////////////////
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// ColorBasedConcept
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/////////////////////////////
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template <typename BitField, typename ChannelBitSizes, typename L, bool IsMutable, int K>
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struct kth_element_type
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<
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bit_aligned_pixel_reference<BitField, ChannelBitSizes, L, IsMutable>,
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K
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>
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{
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using type = packed_dynamic_channel_reference
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<
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BitField,
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mp11::mp_at_c<ChannelBitSizes, K>::value,
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IsMutable
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> const;
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};
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template <typename B, typename C, typename L, bool M, int K>
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struct kth_element_reference_type<bit_aligned_pixel_reference<B,C,L,M>, K>
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: public kth_element_type<bit_aligned_pixel_reference<B,C,L,M>, K> {};
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template <typename B, typename C, typename L, bool M, int K>
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struct kth_element_const_reference_type<bit_aligned_pixel_reference<B,C,L,M>, K>
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: public kth_element_type<bit_aligned_pixel_reference<B,C,L,M>, K> {};
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namespace detail {
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// returns sum of IntegralVector[0] ... IntegralVector[K-1]
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template <typename IntegralVector, int K>
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struct sum_k
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: mp11::mp_plus
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<
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sum_k<IntegralVector, K - 1>,
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typename mp11::mp_at_c<IntegralVector, K - 1>::type
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>
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{};
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template <typename IntegralVector>
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struct sum_k<IntegralVector, 0> : std::integral_constant<int, 0> {};
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} // namespace detail
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// at_c required by MutableColorBaseConcept
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template <int K, typename BitField, typename ChannelBitSizes, typename L, bool IsMutable>
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inline
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auto at_c(const bit_aligned_pixel_reference<BitField, ChannelBitSizes, L, IsMutable>& p)
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-> typename kth_element_reference_type<bit_aligned_pixel_reference<BitField, ChannelBitSizes, L, IsMutable>, K>::type
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{
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using pixel_t = bit_aligned_pixel_reference<BitField, ChannelBitSizes, L, IsMutable>;
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using channel_t = typename kth_element_reference_type<pixel_t, K>::type;
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using bit_range_t = typename pixel_t::bit_range_t;
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bit_range_t bit_range(p.bit_range());
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bit_range.bit_advance(detail::sum_k<ChannelBitSizes, K>::value);
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return channel_t(bit_range.current_byte(), bit_range.bit_offset());
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}
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/////////////////////////////
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// PixelConcept
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/////////////////////////////
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/// Metafunction predicate that flags bit_aligned_pixel_reference as a model of PixelConcept. Required by PixelConcept
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template <typename B, typename C, typename L, bool M>
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struct is_pixel<bit_aligned_pixel_reference<B, C, L, M> > : std::true_type {};
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/////////////////////////////
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// PixelBasedConcept
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/////////////////////////////
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template <typename B, typename C, typename L, bool M>
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struct color_space_type<bit_aligned_pixel_reference<B, C, L, M>>
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{
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using type = typename L::color_space_t;
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};
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template <typename B, typename C, typename L, bool M>
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struct channel_mapping_type<bit_aligned_pixel_reference<B, C, L, M>>
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{
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using type = typename L::channel_mapping_t;
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};
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template <typename B, typename C, typename L, bool M>
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struct is_planar<bit_aligned_pixel_reference<B, C, L, M>> : std::false_type {};
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/////////////////////////////
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// pixel_reference_type
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/////////////////////////////
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// Constructs a homogeneous bit_aligned_pixel_reference given a channel reference
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template <typename BitField, int NumBits, typename Layout>
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struct pixel_reference_type
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<
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packed_dynamic_channel_reference<BitField, NumBits, false> const,
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Layout, false, false
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>
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{
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private:
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using channel_bit_sizes_t = mp11::mp_repeat
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<
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mp11::mp_list<std::integral_constant<unsigned, NumBits>>,
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mp11::mp_size<typename Layout::color_space_t>
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>;
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public:
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using type =
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bit_aligned_pixel_reference<BitField, channel_bit_sizes_t, Layout, false>;
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};
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// Same but for the mutable case. We cannot combine the mutable
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// and read-only cases because this triggers ambiguity
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template <typename BitField, int NumBits, typename Layout>
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struct pixel_reference_type
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<
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packed_dynamic_channel_reference<BitField, NumBits, true> const,
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Layout, false, true
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>
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{
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private:
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using channel_bit_sizes_t = mp11::mp_repeat
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<
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mp11::mp_list<std::integral_constant<unsigned, NumBits>>,
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mp11::mp_size<typename Layout::color_space_t>
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>;
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public:
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using type = bit_aligned_pixel_reference<BitField, channel_bit_sizes_t, Layout, true>;
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};
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} } // namespace boost::gil
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namespace std {
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// We are forced to define swap inside std namespace because on some platforms (Visual Studio 8) STL calls swap qualified.
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// swap with 'left bias':
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// - swap between proxy and anything
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// - swap between value type and proxy
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// - swap between proxy and proxy
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// Having three overloads allows us to swap between different (but compatible) models of PixelConcept
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template <typename B, typename C, typename L, typename R> inline
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void swap(const boost::gil::bit_aligned_pixel_reference<B,C,L,true> x, R& y) {
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boost::gil::swap_proxy<typename boost::gil::bit_aligned_pixel_reference<B,C,L,true>::value_type>(x,y);
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}
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template <typename B, typename C, typename L> inline
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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) {
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boost::gil::swap_proxy<typename boost::gil::bit_aligned_pixel_reference<B,C,L,true>::value_type>(x,y);
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}
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template <typename B, typename C, typename L> inline
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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) {
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boost::gil::swap_proxy<typename boost::gil::bit_aligned_pixel_reference<B,C,L,true>::value_type>(x,y);
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}
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} // namespace std
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#endif
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