dlib C++ Library - save_webp.h

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

    #include "save_webp_abstract.h"

    #include "../enable_if.h"
    #include "image_saver.h"
    #include "../matrix.h"
    #include "../array2d.h"
    #include "../pixel.h"
    #include "../image_processing/generic_image.h"
    #include <string>

    namespace dlib
    {

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

        namespace impl
        {
            enum class webp_type
            {
                rgb,
                bgr,
                rgba,
                bgra
            };

            void impl_save_webp (
                const std::string& filename,
                const uint8_t* data,
                const int width,
                const int height,
                const int stride,
                const float quality,
                const webp_type type
            );
        }

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

        template <
            typename image_type
            >
        typename disable_if<is_matrix<image_type>>::type save_webp (
            const image_type& img_,
            const std::string& filename,
            float quality = 75
        )
        {
    #ifndef DLIB_WEBP_SUPPORT
                /* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
                    You are getting this error because you are trying to use the save_webp
                    function 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
            const_image_view<image_type> img(img_);
            using pixel_type = typename image_traits<image_type>::pixel_type;

            // make sure requires clause is not broken
            DLIB_CASSERT(img.size() != 0,
                "\t save_webp()"
                << "\n\t You can't save an empty image as a WEBP."
                );
            DLIB_CASSERT(0 <= quality,
                "\t save_webp()"
                << "\n\t Invalid quality value."
                << "\n\t quality: " << quality
                );

            auto data = reinterpret_cast<const uint8_t*>(image_data(img));
            const int width = img.nc();
            const int height = img.nr();
            int stride = width_step(img);
            if (pixel_traits<pixel_type>::rgb_alpha)
            {
                if (pixel_traits<pixel_type>::bgr_layout)
                    impl::impl_save_webp(filename, data, width, height, stride, quality, impl::webp_type::bgra);
                else
                    impl::impl_save_webp(filename, data, width, height, stride, quality, impl::webp_type::rgba);
            }
            else if (pixel_traits<pixel_type>::rgb)
            {
                if (pixel_traits<pixel_type>::bgr_layout)
                    impl::impl_save_webp(filename, data, width, height, stride, quality, impl::webp_type::bgr);
                else
                    impl::impl_save_webp(filename, data, width, height, stride, quality, impl::webp_type::rgb);
            }
            else
            {
                // This is some other kind of color image so just save it as an RGB image.
                // We also need to recompute the stride in case we were given a grayscale image.
                array2d<rgb_pixel> temp;
                assign_image(temp, img);
                stride = width_step(temp);
                auto data = reinterpret_cast<const uint8_t*>(image_data(temp));
                impl::impl_save_webp(filename, data, width, height, stride, quality, impl::webp_type::rgb);
            }
        }

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

        template <
            typename EXP
            >
        void save_webp(
            const matrix_exp<EXP>& img,
            const std::string& filename,
            float quality = 75
        )
        {
            array2d<typename EXP::type> temp;
            assign_image(temp, img);
            save_webp(temp, filename, quality);
        }

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

    }

    #endif // DLIB_SAVE_WEBP_Hh_