# dlib C++ Library - webp_loader.cpp

    // 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_LOADER_CPp_
    #define DLIB_WEBP_LOADER_CPp_

    // only do anything with this file if DLIB_WEBP_SUPPORT is defined
    #ifdef DLIB_WEBP_SUPPORT

    #include "../array2d.h"
    #include "../pixel.h"
    #include "../dir_nav.h"
    #include "webp_loader.h"

    #include <webp/decode.h>
    #include <fstream>

    namespace dlib
    {

        static std::vector<unsigned char> load_contents(const std::string& filename)
        {
            std::ifstream stream(filename, std::ios::binary);
            stream.exceptions(std::ifstream::failbit | std::ifstream::badbit | std::ifstream::eofbit);
            stream.seekg(0, std::ios_base::end);
            std::vector<unsigned char> buffer(stream.tellg());
            stream.seekg(0);
            stream.read(reinterpret_cast<char*>(buffer.data()), buffer.size());
            return buffer;
        }

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

        webp_loader::
        webp_loader(const char* filename) : height_(0), width_(0)
        {
            data_ = load_contents(filename);
            get_info();
        }

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

        webp_loader::
        webp_loader(const std::string& filename) : height_(0), width_(0)
        {
            data_ = load_contents(filename);
            get_info();
        }

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

        webp_loader::
        webp_loader(const dlib::file& f) : height_(0), width_(0)
        {
            data_ = load_contents(f.full_name());
            get_info();
        }

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

        webp_loader::
        webp_loader(const unsigned char* imgbuffer, size_t imgbuffersize) : height_(0), width_(0)
        {
            data_.resize(imgbuffersize);
            memcpy(data_.data(), imgbuffer, imgbuffersize);
            get_info();
        }

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

        void webp_loader::get_info()
        {
            if (!WebPGetInfo(data_.data(), data_.size(), &width_, &height_))
            {
                throw image_load_error("webp_loader: Invalid header");
            }
        }

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

        void webp_loader::read_argb(unsigned char *out, const size_t out_size, const int out_stride) const
        {
            if (!WebPDecodeARGBInto(data_.data(), data_.size(), out, out_size, out_stride))
            {
                throw image_load_error("webp_loader: decoding failed");
            }
        }

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

        void webp_loader::read_rgba(unsigned char *out, const size_t out_size, const int out_stride) const
        {
            if (!WebPDecodeRGBAInto(data_.data(), data_.size(), out, out_size, out_stride))
            {
                throw image_load_error("webp_loader: decoding failed");
            }
        }

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

        void webp_loader::read_bgra(unsigned char *out, const size_t out_size, const int out_stride) const
        {
            if (!WebPDecodeBGRAInto(data_.data(), data_.size(), out, out_size, out_stride))
            {
                throw image_load_error("webp_loader: decoding failed");
            }
        }

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

        void webp_loader::read_rgb(unsigned char *out, const size_t out_size, const int out_stride) const
        {
            if (!WebPDecodeRGBInto(data_.data(), data_.size(), out, out_size, out_stride))
            {
                throw image_load_error("webp_loader: decoding failed");
            }
        }

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

        void webp_loader::read_bgr(unsigned char *out, const size_t out_size, const int out_stride) const
        {
            if (!WebPDecodeBGRInto(data_.data(), data_.size(), out, out_size, out_stride))
            {
                throw image_load_error("webp_loader: decoding failed");
            }
        }

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

    }

    #endif // DLIB_WEBP_SUPPORT

    #endif // DLIB_WEBP_LOADER_CPp_