dlib C++ Library - jpeg_loader.h

    // Copyright (C) 2010  Davis E. King (davis@dlib.net), Nils Labugt
    // License: Boost Software License   See LICENSE.txt for the full license.
    #ifndef DLIB_JPEG_IMPORT
    #define DLIB_JPEG_IMPORT

    #include <vector>

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

    namespace dlib
    {

        class jpeg_loader : noncopyable
        {
        public:

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

            bool is_gray() const;
            bool is_rgb() const;
            bool is_rgba() const;
            long nr() const;
            long nc() const;

            template<typename T>
            void get_image( T& t_) const
            {
    #ifndef DLIB_JPEG_SUPPORT
                /* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
                    You are getting this error because you are trying to use the jpeg_loader
                    object but you haven't defined DLIB_JPEG_SUPPORT.  You must do so to use
                    this object.   You must also make sure you set your build environment
                    to link against the libjpeg library.
                !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!*/
                COMPILE_TIME_ASSERT(sizeof(T) == 0);
    #endif
                image_view<T> t(t_);
                t.set_size( height_, width_ );
                for (size_t n = 0; n < height_;n++ )
                {
                    const unsigned char* v = get_row( n );
                    for (size_t m = 0; m < width_;m++ )
                    {
                        if ( is_gray() )
                        {
                            unsigned char p = v[m];
                            assign_pixel( t[n][m], p );
                        }
                        else if ( is_rgba() ) {
                            rgb_alpha_pixel p;
                            p.red = v[m*4];
                            p.green = v[m*4+1];
                            p.blue = v[m*4+2];
                            p.alpha = v[m*4+3];
                            assign_pixel( t[n][m], p );
                        }
                        else // if ( is_rgb() )
                        {
                            rgb_pixel p;
                            p.red = v[m*3];
                            p.green = v[m*3+1];
                            p.blue = v[m*3+2];
                            assign_pixel( t[n][m], p );
                        }
                    }
                }
            }

        private:
            const unsigned char* get_row(size_t i) const
            {
                return &data[i*width_*output_components_];
            }

            FILE * check_file(const char* filename );
            void read_image( FILE *file, const unsigned char* imgbuffer, size_t imgbuffersize );
            size_t height_;
            size_t width_;
            size_t output_components_;
            std::vector<unsigned char> data;
        };

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

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

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

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

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

    }

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

    #endif // DLIB_JPEG_IMPORT