bit_aligned_pixel_reference.hpp Go to the documentation of this file. /* Copyright 2005-2007 Adobe Systems Incorporated Use, modification and distribution are subject to the Boost Software License, Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt). See http://opensource.adobe.com/gil for most recent version including documentation. */ /*************************************************************************************************/ #ifndef GIL_BIT_ALIGNED_PIXEL_REFERENCE_HPP #define GIL_BIT_ALIGNED_PIXEL_REFERENCE_HPP #include <functional> #include <boost/mpl/accumulate.hpp> #include <boost/mpl/at.hpp> #include <boost/mpl/bool.hpp> #include <boost/mpl/if.hpp> #include <boost/mpl/plus.hpp> #include <boost/mpl/push_back.hpp> #include <boost/mpl/vector.hpp> #include "gil_config.hpp" #include "pixel.hpp" #include "channel.hpp" namespace boost { namespace gil { // bit_range // // 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. template <int RangeSize, bool Mutable> class bit_range { public: typedef typename mpl::if_c<Mutable,unsigned char,const unsigned char>::type byte_t; typedef std::ptrdiff_t difference_type; template <int RS, bool M> friend class bit_range; private: byte_t* _current_byte; // the starting byte of the bit range int _bit_offset; // offset from the beginning of the current byte. 0<=_bit_offset<=7 public: bit_range() : _current_byte(NULL), _bit_offset(0) {} bit_range(byte_t* current_byte, int bit_offset) : _current_byte(current_byte), _bit_offset(bit_offset) { assert(bit_offset>=0 && bit_offset<8); } bit_range(const bit_range& br) : _current_byte(br._current_byte), _bit_offset(br._bit_offset) {} template <bool M> bit_range(const bit_range<RangeSize,M>& br) : _current_byte(br._current_byte), _bit_offset(br._bit_offset) {} bit_range& operator=(const bit_range& br) { _current_byte = br._current_byte; _bit_offset=br._bit_offset; return *this; } bool operator==(const bit_range& br) const { return _current_byte==br._current_byte && _bit_offset==br._bit_offset; } bit_range& operator++() { _current_byte += (_bit_offset+RangeSize) / 8; _bit_offset = (_bit_offset+RangeSize) % 8; return *this; } bit_range& operator--() { bit_advance(-RangeSize); return *this; } void bit_advance(difference_type num_bits) { int new_offset = int(_bit_offset+num_bits); _current_byte += new_offset / 8; _bit_offset = new_offset % 8; if (_bit_offset<0) { _bit_offset+=8; --_current_byte; } } difference_type bit_distance_to(const bit_range& b) const { return (b.current_byte() - current_byte())*8 + b.bit_offset()-bit_offset(); } byte_t* current_byte() const { return _current_byte; } int bit_offset() const { return _bit_offset; } }; template <typename ChannelBitSizes, // MPL integral vector defining the number of bits for each channel. For example, for 565RGB, vector_c<int,5,6,5> typename Layout, bool IsMutable> struct bit_aligned_pixel_reference { BOOST_STATIC_CONSTANT(int, bit_size = (mpl::accumulate<ChannelBitSizes, mpl::int_<0>, mpl::plus<mpl::_1, mpl::_2> >::type::value)); typedef bit_range<bit_size,IsMutable> bit_range_t; typedef typename detail::min_fast_uint<bit_size>::type bitfield_t; typedef typename mpl::if_c<IsMutable,unsigned char*,const unsigned char*>::type data_ptr_t; typedef Layout layout_t; typedef typename packed_pixel_type<bitfield_t,ChannelBitSizes,Layout>::type value_type; typedef const bit_aligned_pixel_reference reference; typedef const bit_aligned_pixel_reference<ChannelBitSizes,Layout,false> const_reference; BOOST_STATIC_CONSTANT(bool, is_mutable = IsMutable); bit_aligned_pixel_reference(){} bit_aligned_pixel_reference(data_ptr_t data_ptr, int bit_offset) : _bit_range(data_ptr, bit_offset) {} explicit bit_aligned_pixel_reference(const bit_range_t& bit_range) : _bit_range(bit_range) {} template <bool IsMutable2> bit_aligned_pixel_reference(const bit_aligned_pixel_reference<ChannelBitSizes,Layout,IsMutable2>& p) : _bit_range(p._bit_range) {} // Grayscale references can be constructed from the channel reference explicit bit_aligned_pixel_reference(const typename kth_element_type<bit_aligned_pixel_reference,0>::type channel0) : _bit_range(static_cast<data_ptr_t>(&channel0), channel0.first_bit()) { BOOST_STATIC_ASSERT((num_channels<bit_aligned_pixel_reference>::value==1)); } // Construct from another compatible pixel type bit_aligned_pixel_reference(const bit_aligned_pixel_reference& p) : _bit_range(p._bit_range) {} template <typename BF, typename CR> bit_aligned_pixel_reference(packed_pixel<BF,CR,Layout>& p) : _bit_range(static_cast<data_ptr_t>(&at_c<0>(p)), at_c<0>(p).first_bit()) { check_compatible<packed_pixel<BF,CR,Layout> >(); } template <typename P> const bit_aligned_pixel_reference& operator=(const P& p) const { check_compatible<P>(); static_copy(p,*this); return *this; } const bit_aligned_pixel_reference& operator=(const bit_aligned_pixel_reference& p) const { static_copy(p,*this); return *this; } template <typename P> bool operator==(const P& p) const { check_compatible<P>(); return static_equal(*this,p); } template <typename P> bool operator!=(const P& p) const { return !(*this==p); } const bit_aligned_pixel_reference* operator->() const { return this; } const bit_range_t& bit_range() const { return _bit_range; } private: mutable bit_range_t _bit_range; template <typename C, typename L, bool M> friend struct bit_aligned_pixel_reference; template <typename Pixel> static void check_compatible() { gil_function_requires<PixelsCompatibleConcept<Pixel,bit_aligned_pixel_reference> >(); } }; // ColorBasedConcept template <typename ChannelBitSizes, typename L, bool IsMutable, int K> struct kth_element_type<bit_aligned_pixel_reference<ChannelBitSizes,L,IsMutable>, K> { private: typedef typename bit_aligned_pixel_reference<ChannelBitSizes,L,IsMutable>::bitfield_t bitfield_t; public: typedef const packed_dynamic_channel_reference<bitfield_t, mpl::at_c<ChannelBitSizes,K>::type::value, IsMutable> type; }; template <typename C, typename L, bool M, int K> struct kth_element_reference_type<bit_aligned_pixel_reference<C,L,M>, K> : public kth_element_type<bit_aligned_pixel_reference<C,L,M>, K> {}; template <typename C, typename L, bool M, int K> struct kth_element_const_reference_type<bit_aligned_pixel_reference<C,L,M>, K> : public kth_element_type<bit_aligned_pixel_reference<C,L,M>, K> {}; namespace detail { // returns sum of IntegralVector[0] ... IntegralVector[K-1] template <typename IntegralVector, int K> struct sum_k : public mpl::plus<sum_k<IntegralVector,K-1>, typename mpl::at_c<IntegralVector,K-1>::type > {}; template <typename IntegralVector> struct sum_k<IntegralVector,0> : public mpl::int_<0> {}; } // at_c required by MutableColorBaseConcept template <int K, typename ChannelBitSizes, typename L, bool Mutable> inline typename kth_element_reference_type<bit_aligned_pixel_reference<ChannelBitSizes,L,Mutable>,K>::type at_c(const bit_aligned_pixel_reference<ChannelBitSizes,L,Mutable>& p) { typedef bit_aligned_pixel_reference<ChannelBitSizes,L,Mutable> pixel_t; typedef typename kth_element_reference_type<pixel_t,K>::type channel_t; typedef typename pixel_t::bit_range_t bit_range_t; bit_range_t bit_range(p.bit_range()); bit_range.bit_advance(detail::sum_k<ChannelBitSizes,K>::value); return channel_t(bit_range.current_byte(), bit_range.bit_offset()); } // PixelConcept template <typename C, typename L, bool M> struct is_pixel<bit_aligned_pixel_reference<C,L,M> > : public mpl::true_{}; // PixelBasedConcept template <typename C, typename L, bool M> struct color_space_type<bit_aligned_pixel_reference<C,L,M> > { typedef typename L::color_space_t type; }; template <typename C, typename L, bool M> struct channel_mapping_type<bit_aligned_pixel_reference<C,L,M> > { typedef typename L::channel_mapping_t type; }; template <typename C, typename L, bool M> struct is_planar<bit_aligned_pixel_reference<C,L,M> > : mpl::false_ {}; // pixel_reference_type namespace detail { // returns a vector containing K copies of the type T template <unsigned K, typename T> struct k_copies; template <typename T> struct k_copies<0,T> { typedef mpl::vector0<> type; }; template <unsigned K, typename T> struct k_copies : public mpl::push_back<typename k_copies<K-1,T>::type, T> {}; } // Constructs a homogeneous bit_aligned_pixel_reference given a channel reference // Note: BitField must be the same type as pixel_reference_type<...>::type::bitfield_t, but it is too complicated to ensure this template <typename BitField, int NumBits, typename Layout> struct pixel_reference_type<const packed_dynamic_channel_reference<BitField,NumBits,false>, Layout, false, false> { private: typedef typename mpl::size<typename Layout::color_space_t>::type size_t; typedef typename detail::k_copies<size_t::value,mpl::integral_c<unsigned,NumBits> >::type channel_bit_sizes_t; public: typedef bit_aligned_pixel_reference<channel_bit_sizes_t, Layout, false> type; }; // Same but for the mutable case. We cannot combine the mutable and read-only cases because this triggers ambiguity // Note: BitField must be the same type as pixel_reference_type<...>::type::bitfield_t, but it is too complicated to ensure this template <typename BitField, int NumBits, typename Layout> struct pixel_reference_type<const packed_dynamic_channel_reference<BitField,NumBits,true>, Layout, false, true> { private: typedef typename mpl::size<typename Layout::color_space_t>::type size_t; typedef typename detail::k_copies<size_t::value,mpl::integral_c<unsigned,NumBits> >::type channel_bit_sizes_t; public: typedef bit_aligned_pixel_reference<channel_bit_sizes_t, Layout, true> type; }; } } // namespace boost::gil namespace std { // We are forced to define swap inside std namespace because on some platforms (Visual Studio 8) STL calls swap qualified. // swap with 'left bias': // - swap between proxy and anything // - swap between value type and proxy // - swap between proxy and proxy // Having three overloads allows us to swap between different (but compatible) models of PixelConcept template <typename C, typename L, typename R> inline void swap(boost::gil::bit_aligned_pixel_reference<C,L,true> x, R& y) { boost::gil::swap_proxy<typename boost::gil::bit_aligned_pixel_reference<C,L,true>::value_type>(x,y); } template <typename C, typename L> inline void swap(typename boost::gil::bit_aligned_pixel_reference<C,L,true>::value_type& x, boost::gil::bit_aligned_pixel_reference<C,L,true> y) { boost::gil::swap_proxy<typename boost::gil::bit_aligned_pixel_reference<C,L,true>::value_type>(x,y); } template <typename C, typename L> inline void swap(boost::gil::bit_aligned_pixel_reference<C,L,true> x, boost::gil::bit_aligned_pixel_reference<C,L,true> y) { boost::gil::swap_proxy<typename boost::gil::bit_aligned_pixel_reference<C,L,true>::value_type>(x,y); } } // namespace std #endif