ceph/src/boost/boost/gil/pixel.hpp

   1 //
   2 // Copyright 2005-2007 Adobe Systems Incorporated
   3 // Copyright 2019 Mateusz Loskot <mateusz at loskot dot net>
   4 //
   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
   8 //
   9 #ifndef BOOST_GIL_PIXEL_HPP
  10 #define BOOST_GIL_PIXEL_HPP
  11
  12 #include <boost/gil/channel.hpp>
  13 #include <boost/gil/color_base.hpp>
  14 #include <boost/gil/color_base_algorithm.hpp>
  15 #include <boost/gil/concepts.hpp>
  16 #include <boost/gil/metafunctions.hpp>
  17 #include <boost/gil/utilities.hpp>
  18 #include <boost/gil/detail/mp11.hpp>
  19
  20 #include <functional>
  21 #include <type_traits>
  22
  23 namespace boost { namespace gil {
  24
  25 // Forward-declare gray_t
  26 struct gray_color_t;
  27 using gray_t = mp11::mp_list<gray_color_t>;
  28 template <typename PixelBased> struct color_space_type;
  29 template <typename PixelBased> struct channel_mapping_type;
  30 template <typename PixelBased> struct channel_type;
  31 template <typename PixelBased> struct is_planar;
  32
  33 template <typename PixelBased>
  34 struct color_space_type<PixelBased const> : color_space_type<PixelBased> {};
  35
  36 template <typename PixelBased>
  37 struct channel_mapping_type<PixelBased const> : channel_mapping_type<PixelBased> {};
  38
  39 template <typename PixelBased>
  40 struct channel_type<PixelBased const> : channel_type<PixelBased> {};
  41
  42 template <typename PixelBased>
  43 struct is_planar : std::false_type {};
  44
  45 template <typename PixelBased>
  46 struct is_planar<PixelBased const> : is_planar<PixelBased> {};
  47
  48 template <typename T> struct is_pixel : std::false_type {};
  49 template <typename T> struct is_pixel<T const> : is_pixel<T> {};
  50
  51 /// \ingroup PixelBasedAlgorithm
  52 /// \brief Returns the number of channels of a pixel-based GIL construct
  53 template <typename PixelBased>
  54 struct num_channels : mp11::mp_size<typename color_space_type<PixelBased>::type>::type {};
  55
  56 /**
  57 \addtogroup PixelBasedAlgorithm
  58
  59 Example:
  60 \code
  61 static_assert(num_channels<rgb8_view_t>::value == 3, "");
  62 static_assert(num_channels<cmyk16_planar_ptr_t>::value == 4, "");
  63
  64 static_assert(is_planar<rgb16_planar_image_t>::value));
  65 static_assert(std::is_same<color_space_type<rgb8_planar_ref_t>::type, rgb_t>::value, "");
  66 static_assert(std::is_same<channel_mapping_type<cmyk8_pixel_t>::type,
  67                              channel_mapping_type<rgba8_pixel_t>::type>::value, "");
  68 static_assert(std::is_same<channel_type<bgr8_pixel_t>::type, uint8_t>::value, "");
  69 \endcode
  70 */
  71
  72 /// \defgroup ColorBaseModelPixel pixel
  73 /// \ingroup ColorBaseModel
  74 /// \brief A homogeneous color base whose element is a channel value. Models HomogeneousColorBaseValueConcept
  75
  76 /// \defgroup PixelModelPixel pixel
  77 /// \ingroup PixelModel
  78 /// \brief A homogeneous pixel value. Models HomogeneousPixelValueConcept
  79
  80 /// \ingroup PixelModelPixel ColorBaseModelPixel PixelBasedModel
  81 /// \brief Represents a pixel value (a container of channels). Models: HomogeneousColorBaseValueConcept, PixelValueConcept, HomogeneousPixelBasedConcept
  82 ///
  83 /// A pixel is a set of channels defining the color at a given point in an image. Conceptually, a pixel is little more than a color base whose elements
  84 /// model \p ChannelConcept. The class \p pixel defines a simple, homogeneous pixel value. It is used to store
  85 /// the value of a color. The built-in C++ references to \p pixel, \p pixel& and \p const \p pixel& are used to represent a reference to a pixel
  86 /// inside an interleaved image view (a view in which all channels are together in memory). Similarly, built-in pointer types \p pixel* and \p const \p pixel*
  87 /// are used as the standard iterator over a row of interleaved homogeneous pixels.
  88 ///
  89 /// Since \p pixel inherits the properties of color base, assigning, equality comparison and copy-construcion are allowed between compatible pixels.
  90 /// This means that an 8-bit RGB pixel may be assigned to an 8-bit BGR pixel, or to an 8-bit planar reference. The channels are properly paired semantically.
  91 ///
  92 /// The single-channel (grayscale) instantiation of the class pixel, (i.e. \p pixel<T,gray_layout_t>) is also convertible to/from a channel value.
  93 /// This allows grayscale pixels to be used in simpler expressions like *gray_pix1 = *gray_pix2  instead of more complicated at_c<0>(gray_pix1) = at_c<0>(gray_pix2)
  94 /// or get_color<gray_color_t>(gray_pix1) = get_color<gray_color_t>(gray_pix2)
  95 ///
  96 /// \tparam ChannelValue TODO
  97 /// \tparam Layout mp11::make_integer_sequence<int, ColorSpace::size>
  98 template <typename ChannelValue, typename Layout>
  99 struct pixel :
 100     detail::homogeneous_color_base
 101     <
 102         ChannelValue,
 103         Layout,
 104         mp11::mp_size<typename Layout::color_space_t>::value
 105     >
 106 {
 107 private:
 108     using channel_t = ChannelValue;
 109     using parent_t = detail::homogeneous_color_base
 110         <
 111             ChannelValue,
 112             Layout,
 113             mp11::mp_size<typename Layout::color_space_t>::value
 114         >;
 115 public:
 116     using value_type = pixel<ChannelValue, Layout>;
 117     using reference = value_type&;
 118     using const_reference = value_type const&;
 119     static constexpr bool is_mutable = channel_traits<channel_t>::is_mutable;
 120
 121     pixel() = default;
 122     explicit pixel(channel_t v) : parent_t(v) {}  // sets all channels to v
 123     pixel(channel_t v0, channel_t v1) : parent_t(v0, v1) {}
 124     pixel(channel_t v0, channel_t v1, channel_t v2) : parent_t(v0, v1, v2) {}
 125
 126     pixel(channel_t v0, channel_t v1, channel_t v2, channel_t v3)
 127         : parent_t(v0, v1, v2, v3)
 128     {}
 129
 130     pixel(channel_t v0, channel_t v1, channel_t v2, channel_t v3, channel_t v4)
 131         : parent_t(v0, v1, v2, v3, v4)
 132     {}
 133
 134     pixel(channel_t v0, channel_t v1, channel_t v2, channel_t v3, channel_t v4, channel_t v5)
 135         : parent_t(v0, v1, v2, v3, v4, v5)
 136     {}
 137
 138     pixel(const pixel& p) : parent_t(p) {}
 139
 140     pixel& operator=(pixel const& p)
 141     {
 142         static_copy(p,*this);
 143         return *this;
 144     }
 145
 146     // Construct from another compatible pixel type
 147     template <typename Pixel>
 148     pixel(Pixel const& p,
 149         typename std::enable_if<is_pixel<Pixel>::value>::type* /*dummy*/ = nullptr)
 150         : parent_t(p)
 151     {
 152         check_compatible<Pixel>();
 153     }
 154
 155     template <typename Pixel>
 156     pixel& operator=(Pixel const& p)
 157     {
 158         assign(p, is_pixel<Pixel>());
 159         return *this;
 160     }
 161
 162     template <typename Pixel>
 163     bool operator==(Pixel const& p) const { return equal(p, is_pixel<Pixel>()); }
 164
 165     template <typename Pixel>
 166     bool operator!=(Pixel const& p) const { return !(*this == p); }
 167
 168     // homogeneous pixels have operator[]
 169     auto operator[](std::size_t index)
 170         -> typename channel_traits<channel_t>::reference
 171     {
 172         return dynamic_at_c(*this, index);
 173     }
 174
 175     auto operator[](std::size_t index) const
 176         -> typename channel_traits<channel_t>::const_reference
 177     {
 178         return dynamic_at_c(*this, index);
 179     }
 180
 181 private:
 182     template <typename Pixel>
 183     void assign(Pixel const& p, std::true_type)
 184     {
 185         check_compatible<Pixel>();
 186         static_copy(p, *this);
 187     }
 188
 189     template <typename Pixel>
 190     bool equal(Pixel const& p, std::true_type) const
 191     {
 192         check_compatible<Pixel>();
 193         return static_equal(*this, p);
 194     }
 195
 196     template <typename Pixel>
 197     void check_compatible() const
 198     {
 199         gil_function_requires<PixelsCompatibleConcept<Pixel, pixel>>();
 200     }
 201
 202 // Support for assignment/equality comparison of a channel with a grayscale pixel
 203
 204 private:
 205     static void check_gray()
 206     {
 207         static_assert(std::is_same<typename Layout::color_space_t, gray_t>::value, "");
 208     }
 209
 210     template <typename Channel>
 211     void assign(Channel const& channel, std::false_type)
 212     {
 213         check_gray();
 214         gil::at_c<0>(*this) = channel;
 215     }
 216
 217     template <typename Channel>
 218     bool equal (Channel const& channel, std::false_type) const
 219     {
 220         check_gray();
 221         return gil::at_c<0>(*this) == channel;
 222     }
 223
 224 public:
 225     pixel& operator= (channel_t channel)
 226     {
 227         check_gray();
 228         gil::at_c<0>(*this) = channel;
 229         return *this;
 230     }
 231
 232     bool operator==(channel_t channel) const
 233     {
 234         check_gray();
 235         return gil::at_c<0>(*this) == channel;
 236     }
 237 };
 238
 239 /////////////////////////////
 240 //  ColorBasedConcept
 241 /////////////////////////////
 242
 243 template <typename ChannelValue, typename Layout, int K>
 244 struct kth_element_type<pixel<ChannelValue,Layout>, K>
 245 {
 246     using type = ChannelValue;
 247 };
 248
 249 template <typename ChannelValue, typename Layout, int K>
 250 struct kth_element_reference_type<pixel<ChannelValue,Layout>, K>
 251 {
 252     using type = typename channel_traits<ChannelValue>::reference;
 253 };
 254
 255 template <typename ChannelValue, typename Layout, int K>
 256 struct kth_element_reference_type<const pixel<ChannelValue,Layout>, K>
 257 {
 258     using type = typename channel_traits<ChannelValue>::const_reference;
 259 };
 260
 261 template <typename ChannelValue, typename Layout, int K>
 262 struct kth_element_const_reference_type<pixel<ChannelValue,Layout>, K>
 263 {
 264     using type = typename channel_traits<ChannelValue>::const_reference;
 265 };
 266
 267 /////////////////////////////
 268 //  PixelConcept
 269 /////////////////////////////
 270
 271 template <typename ChannelValue, typename Layout>
 272 struct is_pixel<pixel<ChannelValue,Layout>> : std::true_type {};
 273
 274 /////////////////////////////
 275 //  HomogeneousPixelBasedConcept
 276 /////////////////////////////
 277
 278 template <typename ChannelValue, typename Layout>
 279 struct color_space_type<pixel<ChannelValue, Layout>>
 280 {
 281     using type = typename Layout::color_space_t;
 282 };
 283
 284 template <typename ChannelValue, typename Layout>
 285 struct channel_mapping_type<pixel<ChannelValue, Layout>>
 286 {
 287     using type = typename Layout::channel_mapping_t;
 288 };
 289
 290 template <typename ChannelValue, typename Layout>
 291 struct is_planar<pixel<ChannelValue, Layout>> : std::false_type {};
 292
 293 template <typename ChannelValue, typename Layout>
 294 struct channel_type<pixel<ChannelValue, Layout>>
 295 {
 296     using type = ChannelValue;
 297 };
 298
 299 }}  // namespace boost::gil
 300
 301 #endif