dlib C++ Library - webp_loader.h

    // Copyright (C) 2022  Davis E. King (davis@dlib.net), Martin Sandsmark, Adrià Arrufat
    // License: Boost Software License   See LICENSE.txt for the full license.
    #ifndef DLIB_WEBP_IMPORT
    #define DLIB_WEBP_IMPORT

    #include <vector>

    #include "webp_loader_abstract.h"
    #include "image_loader.h"
    #include "../pixel.h"
    #include "../dir_nav.h"
    #include "../test_for_odr_violations.h"

    namespace dlib
    {

        class webp_loader : noncopyable
        {
        public:

            webp_loader(const char* filename);
            webp_loader(const std::string& filename);
            webp_loader(const dlib::file& f);
            webp_loader(const unsigned char* imgbuffer, size_t buffersize);

            long nr() const;
            long nc() const;

            template<typename image_type>
            void get_image(image_type& image) const
            {
    #ifndef DLIB_WEBP_SUPPORT
                /* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
                    You are getting this error because you are trying to use the webp_loader
                    object but you haven't defined DLIB_WEBP_SUPPORT.  You must do so to use
                    this object.   You must also make sure you set your build environment
                    to link against the libwebp library.
                !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!*/
                static_assert(sizeof(image_type) == 0, "webp support not enabled.");
    #endif
                image_view<image_type> vimg(image);
                vimg.set_size(height_, width_);
                typedef typename image_traits<image_type>::pixel_type pixel_type;

                unsigned char* output = reinterpret_cast<unsigned char*>(image_data(vimg));
                const int stride = width_step(vimg);
                const size_t output_size = stride * height_;

                if (pixel_traits<pixel_type>::rgb_alpha)
                {
                    if (pixel_traits<pixel_type>::bgr_layout)
                        read_bgra(output, output_size, stride);
                    else
                        read_rgba(output, output_size, stride);
                    return;
                }
                if (pixel_traits<pixel_type>::rgb)
                {
                    if (pixel_traits<pixel_type>::bgr_layout)
                        read_bgr(output, output_size, stride);
                    else
                        read_rgb(output, output_size, stride);
                    return;
                }
                // If we end up here, we are out of our fast path, and have to do it manually

                array2d<rgb_alpha_pixel> decoded;
                decoded.set_size(height_, width_);
                unsigned char* output_dec = reinterpret_cast<unsigned char*>(image_data(decoded));
                const int stride_dec = width_step(decoded);
                const size_t output_dec_size = stride_dec * height_;

                read_rgba(output_dec, output_dec_size, stride_dec);

                for (int r = 0; r < height_; r++)
                {
                    for (int c = 0; c < width_; c++)
                    {
                        assign_pixel(vimg[r][c], decoded[r][c]);
                    }
                }
            }

        private:
            void get_info();
            void read_bgra(unsigned char *out, const size_t out_size, const int out_stride) const;
            void read_bgr(unsigned char *out, const size_t out_size, const int out_stride) const;
            void read_rgba(unsigned char *out, const size_t out_size, const int out_stride) const;
            void read_rgb(unsigned char *out, const size_t out_size, const int out_stride) const;
            void read_argb(unsigned char *out, const size_t out_size, const int out_stride) const;

            int height_;
            int width_;
            std::vector<unsigned char> data_;
        };

    // ----------------------------------------------------------------------------------------

        template <
            typename image_type
            >
        void load_webp (
            image_type& image,
            const std::string& file_name
       )
        {
            webp_loader(file_name).get_image(image);
        }

        template <
            typename image_type
            >
        void load_webp (
            image_type& image,
            const unsigned char* imgbuff,
            size_t imgbuffsize
       )
        {
            webp_loader(imgbuff, imgbuffsize).get_image(image);
        }

        template <
            typename image_type
            >
        void load_webp (
            image_type& image,
            const char* imgbuff,
            size_t imgbuffsize
       )
        {
            webp_loader(reinterpret_cast<const unsigned char*>(imgbuff), imgbuffsize).get_image(image);
        }

    // ----------------------------------------------------------------------------------------

    }

    #ifdef NO_MAKEFILE
    #include "webp_loader.cpp"
    #endif

    #endif // DLIB_WEBP_IMPORT