###

#

channel.hpp
//
// Copyright 2005-2007 Adobe Systems Incorporated
//
// Distributed under 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
//
#ifndef BOOST_GIL_CHANNEL_HPP
#define BOOST_GIL_CHANNEL_HPP
#include <boost/gil/utilities.hpp>
#include <boost/assert.hpp>
#include <boost/config.hpp>
#include <boost/config/pragma_message.hpp>
#include <boost/integer/integer_mask.hpp>
#include <cstdint>
#include <limits>
#include <type_traits>
#ifdef BOOST_GIL_DOXYGEN_ONLY
#define BOOST_GIL_CONFIG_HAS_UNALIGNED_ACCESS
#endif
#ifdef BOOST_GIL_CONFIG_HAS_UNALIGNED_ACCESS
#if defined(sun) || defined(__sun) || \ // SunOS
defined(__osf__) || defined(__osf) || \ // Tru64
defined(_hpux) || defined(hpux) || \ // HP-UX
defined(__arm__) || defined(__ARM_ARCH) || \ // ARM
defined(_AIX) // AIX
#error Unaligned access strictly disabled for some UNIX platforms or ARM architecture
#elif defined(__i386__) || defined(__x86_64__) || defined(__vax__)
// The check for little-endian architectures that tolerate unaligned memory
// accesses is just an optimization. Nothing will break if it fails to detect
// a suitable architecture.
//
// Unfortunately, this optimization may be a C/C++ strict aliasing rules violation
// if accessed data buffer has effective type that cannot be aliased
// without leading to undefined behaviour.
BOOST_PRAGMA_MESSAGE("CAUTION: Unaligned access tolerated on little-endian may cause undefined behaviour")
#else
#error Unaligned access disabled for unknown platforms and architectures
#endif
#endif // defined(BOOST_GIL_CONFIG_HAS_UNALIGNED_ACCESS)
namespace boost { namespace gil {
namespace detail {
template <typename T, bool IsClass>
struct channel_traits_impl;
// channel traits for custom class
template <typename T>
struct channel_traits_impl<T, true>
{
using value_type = typename T::value_type;
using reference = typename T::reference;
using pointer = typename T::pointer;
using const_reference = typename T::const_reference;
using const_pointer = typename T::const_pointer;
static constexpr bool is_mutable = T::is_mutable;
static value_type min_value() { return T::min_value(); }
static value_type max_value() { return T::max_value(); }
};
// channel traits implementation for built-in integral or floating point channel type
template <typename T>
struct channel_traits_impl<T, false>
{
using value_type = T;
using reference = T&;
using pointer = T*;
using const_reference = T const&;
using const_pointer = T const*;
static constexpr bool is_mutable = true;
static value_type min_value() { return (std::numeric_limits<T>::min)(); }
static value_type max_value() { return (std::numeric_limits<T>::max)(); }
};
// channel traits implementation for constant built-in scalar or floating point type
template <typename T>
struct channel_traits_impl<T const, false> : channel_traits_impl<T, false>
{
using reference = T const&;
using pointer = T const*;
static constexpr bool is_mutable = false;
};
} // namespace detail
template <typename T>
struct channel_traits : detail::channel_traits_impl<T, std::is_class<T>::value> {};
// Channel traits for C++ reference type - remove the reference
template <typename T>
struct channel_traits<T&> : channel_traits<T> {};
// Channel traits for constant C++ reference type
template <typename T>
struct channel_traits<T const&> : channel_traits<T>
{
using reference = typename channel_traits<T>::const_reference;
using pointer = typename channel_traits<T>::const_pointer;
static constexpr bool is_mutable = false;
};
template <typename BaseChannelValue, typename MinVal, typename MaxVal>
struct scoped_channel_value
{
using value_type = scoped_channel_value<BaseChannelValue, MinVal, MaxVal>;
using reference = value_type&;
using pointer = value_type*;
using const_reference = value_type const&;
using const_pointer = value_type const*;
static constexpr bool is_mutable = channel_traits<BaseChannelValue>::is_mutable;
using base_channel_t = BaseChannelValue;
static value_type min_value() { return MinVal::apply(); }
static value_type max_value() { return MaxVal::apply(); }
scoped_channel_value() = default;
scoped_channel_value(scoped_channel_value const& other) : value_(other.value_) {}
scoped_channel_value& operator=(scoped_channel_value const& other) = default;
scoped_channel_value(BaseChannelValue value) : value_(value) {}
scoped_channel_value& operator=(BaseChannelValue value)
{
value_ = value;
return *this;
}
scoped_channel_value& operator++() { ++value_; return *this; }
scoped_channel_value& operator--() { --value_; return *this; }
scoped_channel_value operator++(int) { scoped_channel_value tmp=*this; this->operator++(); return tmp; }
scoped_channel_value operator--(int) { scoped_channel_value tmp=*this; this->operator--(); return tmp; }
template <typename Scalar2> scoped_channel_value& operator+=(Scalar2 v) { value_+=v; return *this; }
template <typename Scalar2> scoped_channel_value& operator-=(Scalar2 v) { value_-=v; return *this; }
template <typename Scalar2> scoped_channel_value& operator*=(Scalar2 v) { value_*=v; return *this; }
template <typename Scalar2> scoped_channel_value& operator/=(Scalar2 v) { value_/=v; return *this; }
operator BaseChannelValue() const { return value_; }
private:
BaseChannelValue value_{};
};
template <typename T>
struct float_point_zero
{
static constexpr T apply() { return 0.0f; }
};
template <typename T>
struct float_point_one
{
static constexpr T apply() { return 1.0f; }
};
// It is necessary for packed channels to have their own value type. They cannot simply use an integral large enough to store the data. Here is why:
// - Any operation that requires returning the result by value will otherwise return the built-in integral type, which will have incorrect range
// That means that after getting the value of the channel we cannot properly do channel_convert, channel_invert, etc.
// - Two channels are declared compatible if they have the same value type. That means that a packed channel is incorrectly declared compatible with an integral type
namespace detail {
// returns the smallest fast unsigned integral type that has at least NumBits bits
template <int NumBits>
struct min_fast_uint :
std::conditional
<
NumBits <= 8,
std::uint_least8_t,
typename std::conditional
<
NumBits <= 16,
std::uint_least16_t,
typename std::conditional
<
NumBits <= 32,
std::uint_least32_t,
std::uintmax_t
>::type
>::type
>
{};
template <int NumBits>
struct num_value_fn
: std::conditional<NumBits < 32, std::uint32_t, std::uint64_t>
{};
template <int NumBits>
struct max_value_fn
: std::conditional<NumBits <= 32, std::uint32_t, std::uint64_t>
{};
} // namespace detail
template <int NumBits>
class packed_channel_value
{
public:
using integer_t = typename detail::min_fast_uint<NumBits>::type;
using value_type = packed_channel_value<NumBits>;
using reference = value_type&;
using const_reference = value_type const&;
using pointer = value_type*;
using const_pointer = value_type const*;
static constexpr bool is_mutable = true;
static value_type min_value() { return 0; }
static value_type max_value() { return low_bits_mask_t< NumBits >::sig_bits; }
packed_channel_value() = default;
packed_channel_value(integer_t v)
{
value_ = static_cast<integer_t>(v & low_bits_mask_t<NumBits>::sig_bits_fast);
}
template <typename Scalar>
packed_channel_value(Scalar v)
{
value_ = packed_channel_value(static_cast<integer_t>(v));
}
static unsigned int num_bits() { return NumBits; }
operator integer_t() const { return value_; }
private:
integer_t value_{};
};
namespace detail {
template <std::size_t K>
struct static_copy_bytes
{
void operator()(unsigned char const* from, unsigned char* to) const
{
*to = *from;
static_copy_bytes<K - 1>()(++from, ++to);
}
};
template <>
struct static_copy_bytes<0>
{
void operator()(unsigned char const*, unsigned char*) const {}
};
template <typename Derived, typename BitField, int NumBits, bool IsMutable>
class packed_channel_reference_base
{
protected:
using data_ptr_t = typename std::conditional<IsMutable, void*, void const*>::type;
public:
data_ptr_t _data_ptr; // void* pointer to the first byte of the bit range
using value_type = packed_channel_value<NumBits>;
using reference = const Derived;
using pointer = value_type *;
using const_pointer = const value_type *;
static constexpr int num_bits = NumBits;
static constexpr bool is_mutable = IsMutable;
static value_type min_value() { return channel_traits<value_type>::min_value(); }
static value_type max_value() { return channel_traits<value_type>::max_value(); }
using bitfield_t = BitField;
using integer_t = typename value_type::integer_t;
packed_channel_reference_base(data_ptr_t data_ptr) : _data_ptr(data_ptr) {}
packed_channel_reference_base(const packed_channel_reference_base& ref) : _data_ptr(ref._data_ptr) {}
const Derived& operator=(integer_t v) const { set(v); return derived(); }
const Derived& operator++() const { set(get()+1); return derived(); }
const Derived& operator--() const { set(get()-1); return derived(); }
Derived operator++(int) const { Derived tmp=derived(); this->operator++(); return tmp; }
Derived operator--(int) const { Derived tmp=derived(); this->operator--(); return tmp; }
template <typename Scalar2> const Derived& operator+=(Scalar2 v) const { set( static_cast<integer_t>( get() + v )); return derived(); }
template <typename Scalar2> const Derived& operator-=(Scalar2 v) const { set( static_cast<integer_t>( get() - v )); return derived(); }
template <typename Scalar2> const Derived& operator*=(Scalar2 v) const { set( static_cast<integer_t>( get() * v )); return derived(); }
template <typename Scalar2> const Derived& operator/=(Scalar2 v) const { set( static_cast<integer_t>( get() / v )); return derived(); }
operator integer_t() const { return get(); }
data_ptr_t operator &() const {return _data_ptr;}
protected:
using num_value_t = typename detail::num_value_fn<NumBits>::type;
using max_value_t = typename detail::max_value_fn<NumBits>::type;
static const num_value_t num_values = static_cast< num_value_t >( 1 ) << NumBits ;
static const max_value_t max_val = static_cast< max_value_t >( num_values - 1 );
#if defined(BOOST_GIL_CONFIG_HAS_UNALIGNED_ACCESS)
const bitfield_t& get_data() const { return *static_cast<const bitfield_t*>(_data_ptr); }
void set_data(const bitfield_t& val) const { *static_cast< bitfield_t*>(_data_ptr) = val; }
#else
bitfield_t get_data() const {
bitfield_t ret;
static_copy_bytes<sizeof(bitfield_t) >()(gil_reinterpret_cast_c<const unsigned char*>(_data_ptr),gil_reinterpret_cast<unsigned char*>(&ret));
return ret;
}
void set_data(const bitfield_t& val) const {
static_copy_bytes<sizeof(bitfield_t) >()(gil_reinterpret_cast_c<const unsigned char*>(&val),gil_reinterpret_cast<unsigned char*>(_data_ptr));
}
#endif
private:
void set(integer_t value) const { // can this be done faster??
this->derived().set_unsafe(((value % num_values) + num_values) % num_values);
}
integer_t get() const { return derived().get(); }
const Derived& derived() const { return static_cast<const Derived&>(*this); }
};
} // namespace detail
template <typename BitField, int FirstBit, int NumBits, bool IsMutable>
class packed_channel_reference;
template <typename BitField, int NumBits, bool IsMutable>
class packed_dynamic_channel_reference;
template <typename BitField, int FirstBit, int NumBits>
class packed_channel_reference<BitField, FirstBit, NumBits, false>
: public detail::packed_channel_reference_base
<
packed_channel_reference<BitField, FirstBit, NumBits, false>,
BitField,
NumBits,
false
>
{
using parent_t = detail::packed_channel_reference_base
<
packed_channel_reference<BitField, FirstBit, NumBits, false>,
BitField,
NumBits,
false
>;
friend class packed_channel_reference<BitField, FirstBit, NumBits, true>;
static const BitField channel_mask = static_cast<BitField>(parent_t::max_val) << FirstBit;
void operator=(packed_channel_reference const&);
public:
using const_reference = packed_channel_reference<BitField,FirstBit,NumBits,false> const;
using mutable_reference = packed_channel_reference<BitField,FirstBit,NumBits,true> const;
using integer_t = typename parent_t::integer_t;
explicit packed_channel_reference(const void* data_ptr) : parent_t(data_ptr) {}
packed_channel_reference(const packed_channel_reference& ref) : parent_t(ref._data_ptr) {}
packed_channel_reference(const mutable_reference& ref) : parent_t(ref._data_ptr) {}
unsigned first_bit() const { return FirstBit; }
integer_t get() const { return integer_t((this->get_data()&channel_mask) >> FirstBit); }
};
template <typename BitField, int FirstBit, int NumBits>
class packed_channel_reference<BitField,FirstBit,NumBits,true>
: public detail::packed_channel_reference_base<packed_channel_reference<BitField,FirstBit,NumBits,true>,BitField,NumBits,true>
{
using parent_t = detail::packed_channel_reference_base<packed_channel_reference<BitField,FirstBit,NumBits,true>,BitField,NumBits,true>;
friend class packed_channel_reference<BitField,FirstBit,NumBits,false>;
static const BitField channel_mask = static_cast< BitField >( parent_t::max_val ) << FirstBit;
public:
using const_reference = packed_channel_reference<BitField,FirstBit,NumBits,false> const;
using mutable_reference = packed_channel_reference<BitField,FirstBit,NumBits,true> const;
using integer_t = typename parent_t::integer_t;
explicit packed_channel_reference(void* data_ptr) : parent_t(data_ptr) {}
packed_channel_reference(const packed_channel_reference& ref) : parent_t(ref._data_ptr) {}
packed_channel_reference const& operator=(integer_t value) const
{
BOOST_ASSERT(value <= parent_t::max_val);
set_unsafe(value);
return *this;
}
const packed_channel_reference& operator=(const mutable_reference& ref) const { set_from_reference(ref.get_data()); return *this; }
const packed_channel_reference& operator=(const const_reference& ref) const { set_from_reference(ref.get_data()); return *this; }
template <bool Mutable1>
const packed_channel_reference& operator=(const packed_dynamic_channel_reference<BitField,NumBits,Mutable1>& ref) const { set_unsafe(ref.get()); return *this; }
unsigned first_bit() const { return FirstBit; }
integer_t get() const { return integer_t((this->get_data()&channel_mask) >> FirstBit); }
void set_unsafe(integer_t value) const { this->set_data((this->get_data() & ~channel_mask) | (( static_cast< BitField >( value )<<FirstBit))); }
private:
void set_from_reference(const BitField& other_bits) const { this->set_data((this->get_data() & ~channel_mask) | (other_bits & channel_mask)); }
};
}} // 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
template <typename BF, int FB, int NB, bool M, typename R>
inline
void swap(boost::gil::packed_channel_reference<BF, FB, NB, M> const x, R& y)
{
boost::gil::swap_proxy
<
typename boost::gil::packed_channel_reference<BF, FB, NB, M>::value_type
>(x, y);
}
template <typename BF, int FB, int NB, bool M>
inline
void swap(
typename boost::gil::packed_channel_reference<BF, FB, NB, M>::value_type& x,
boost::gil::packed_channel_reference<BF, FB, NB, M> const y)
{
boost::gil::swap_proxy
<
typename boost::gil::packed_channel_reference<BF, FB, NB, M>::value_type
>(x,y);
}
template <typename BF, int FB, int NB, bool M> inline
void swap(
boost::gil::packed_channel_reference<BF, FB, NB, M> const x,
boost::gil::packed_channel_reference<BF, FB, NB, M> const y)
{
boost::gil::swap_proxy
<
typename boost::gil::packed_channel_reference<BF, FB, NB, M>::value_type
>(x,y);
}
} // namespace std
namespace boost { namespace gil {
template <typename BitField, int NumBits>
class packed_dynamic_channel_reference<BitField,NumBits,false>
: public detail::packed_channel_reference_base<packed_dynamic_channel_reference<BitField,NumBits,false>,BitField,NumBits,false>
{
using parent_t = detail::packed_channel_reference_base<packed_dynamic_channel_reference<BitField,NumBits,false>,BitField,NumBits,false>;
friend class packed_dynamic_channel_reference<BitField,NumBits,true>;
unsigned _first_bit; // 0..7
void operator=(const packed_dynamic_channel_reference&);
public:
using const_reference = packed_dynamic_channel_reference<BitField,NumBits,false> const;
using mutable_reference = packed_dynamic_channel_reference<BitField,NumBits,true> const;
using integer_t = typename parent_t::integer_t;
packed_dynamic_channel_reference(const void* data_ptr, unsigned first_bit) : parent_t(data_ptr), _first_bit(first_bit) {}
packed_dynamic_channel_reference(const const_reference& ref) : parent_t(ref._data_ptr), _first_bit(ref._first_bit) {}
packed_dynamic_channel_reference(const mutable_reference& ref) : parent_t(ref._data_ptr), _first_bit(ref._first_bit) {}
unsigned first_bit() const { return _first_bit; }
integer_t get() const {
const BitField channel_mask = static_cast< integer_t >( parent_t::max_val ) <<_first_bit;
return static_cast< integer_t >(( this->get_data()&channel_mask ) >> _first_bit );
}
};
template <typename BitField, int NumBits>
class packed_dynamic_channel_reference<BitField,NumBits,true>
: public detail::packed_channel_reference_base<packed_dynamic_channel_reference<BitField,NumBits,true>,BitField,NumBits,true>
{
using parent_t = detail::packed_channel_reference_base<packed_dynamic_channel_reference<BitField,NumBits,true>,BitField,NumBits,true>;
friend class packed_dynamic_channel_reference<BitField,NumBits,false>;
unsigned _first_bit;
public:
using const_reference = packed_dynamic_channel_reference<BitField,NumBits,false> const;
using mutable_reference = packed_dynamic_channel_reference<BitField,NumBits,true> const;
using integer_t = typename parent_t::integer_t;
packed_dynamic_channel_reference(void* data_ptr, unsigned first_bit) : parent_t(data_ptr), _first_bit(first_bit) {}
packed_dynamic_channel_reference(const packed_dynamic_channel_reference& ref) : parent_t(ref._data_ptr), _first_bit(ref._first_bit) {}
packed_dynamic_channel_reference const& operator=(integer_t value) const
{
BOOST_ASSERT(value <= parent_t::max_val);
set_unsafe(value);
return *this;
}
const packed_dynamic_channel_reference& operator=(const mutable_reference& ref) const { set_unsafe(ref.get()); return *this; }
const packed_dynamic_channel_reference& operator=(const const_reference& ref) const { set_unsafe(ref.get()); return *this; }
template <typename BitField1, int FirstBit1, bool Mutable1>
const packed_dynamic_channel_reference& operator=(const packed_channel_reference<BitField1, FirstBit1, NumBits, Mutable1>& ref) const
{ set_unsafe(ref.get()); return *this; }
unsigned first_bit() const { return _first_bit; }
integer_t get() const {
const BitField channel_mask = static_cast< integer_t >( parent_t::max_val ) << _first_bit;
return static_cast< integer_t >(( this->get_data()&channel_mask ) >> _first_bit );
}
void set_unsafe(integer_t value) const {
const BitField channel_mask = static_cast< integer_t >( parent_t::max_val ) << _first_bit;
this->set_data((this->get_data() & ~channel_mask) | value<<_first_bit);
}
};
} } // 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
template <typename BF, int NB, bool M, typename R> inline
void swap(const boost::gil::packed_dynamic_channel_reference<BF,NB,M> x, R& y) {
boost::gil::swap_proxy<typename boost::gil::packed_dynamic_channel_reference<BF,NB,M>::value_type>(x,y);
}
template <typename BF, int NB, bool M> inline
void swap(typename boost::gil::packed_dynamic_channel_reference<BF,NB,M>::value_type& x, const boost::gil::packed_dynamic_channel_reference<BF,NB,M> y) {
boost::gil::swap_proxy<typename boost::gil::packed_dynamic_channel_reference<BF,NB,M>::value_type>(x,y);
}
template <typename BF, int NB, bool M> inline
void swap(const boost::gil::packed_dynamic_channel_reference<BF,NB,M> x, const boost::gil::packed_dynamic_channel_reference<BF,NB,M> y) {
boost::gil::swap_proxy<typename boost::gil::packed_dynamic_channel_reference<BF,NB,M>::value_type>(x,y);
}
} // namespace std
// \brief Determines the fundamental type which may be used, e.g., to cast from larger to smaller channel types.
namespace boost { namespace gil {
template <typename T>
struct base_channel_type_impl { using type = T; };
template <int N>
struct base_channel_type_impl<packed_channel_value<N> >
{ using type = typename packed_channel_value<N>::integer_t; };
template <typename B, int F, int N, bool M>
struct base_channel_type_impl<packed_channel_reference<B, F, N, M> >
{
using type = typename packed_channel_reference<B,F,N,M>::integer_t;
};
template <typename B, int N, bool M>
struct base_channel_type_impl<packed_dynamic_channel_reference<B, N, M> >
{
using type = typename packed_dynamic_channel_reference<B,N,M>::integer_t;
};
template <typename ChannelValue, typename MinV, typename MaxV>
struct base_channel_type_impl<scoped_channel_value<ChannelValue, MinV, MaxV> >
{ using type = ChannelValue; };
template <typename T>
struct base_channel_type : base_channel_type_impl<typename std::remove_cv<T>::type> {};
}} //namespace boost::gil
#endif
std::swap
void swap(const boost::gil::packed_dynamic_channel_reference< BF, NB, M > x, const boost::gil::packed_dynamic_channel_reference< BF, NB, M > y)
swap for packed_dynamic_channel_reference
Definition: channel.hpp:688
boost::gil::packed_dynamic_channel_reference< BitField, NumBits, false >
Models a constant subbyte channel reference whose bit offset is a runtime parameter....
Definition: channel.hpp:588
boost::gil::packed_dynamic_channel_reference< BitField, NumBits, true >
Models a mutable subbyte channel reference whose bit offset is a runtime parameter....
Definition: channel.hpp:618