    // Copyright (C) 2008  Davis E. King (davis@dlib.net), Nils Labugt
    // License: Boost Software License   See LICENSE.txt for the full license.
    #ifndef DLIB_PNG_IMPORT
    #define DLIB_PNG_IMPORT

    #include "png_loader_abstract.h"
    #include "../smart_pointers.h"
    #include "image_loader.h"
    #include "../pixel.h"
    #include "../dir_nav.h"

    namespace dlib
    {

        struct LibpngData;
        class png_loader : noncopyable
        {
        public:

            png_loader( const char* filename );
            png_loader( const std::string& filename );
            png_loader( const dlib::file& f );
            ~png_loader();

            bool is_gray() const;
            bool is_graya() const;
            bool is_rgb() const;
            bool is_rgba() const;

            unsigned int bit_depth () const { return bit_depth_; }

            template<typename T>
            void get_image( T& t) const
            {
    #ifndef DLIB_PNG_SUPPORT
                /* !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
                    You are getting this error because you are trying to use the png_loader
                    object but you haven't defined DLIB_PNG_SUPPORT.  You must do so to use
                    this object.   You must also make sure you set your build environment
                    to link against the libpng library.
                !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!*/
                COMPILE_TIME_ASSERT(sizeof(T) == 0);
    #endif

                typedef typename T::type pixel_type;
                t.set_size( height_, width_ );

                if (is_gray() && bit_depth_ == 8)
                {
                    for ( unsigned n = 0; n < height_;n++ )
                    {
                        const unsigned char* v = get_row( n );
                        for ( unsigned m = 0; m < width_;m++ )
                        {
                            unsigned char p = v[m];
                            assign_pixel( t[n][m], p );
                        }
                    }
                }
                else if (is_gray() && bit_depth_ == 16)
                {
                    for ( unsigned n = 0; n < height_;n++ )
                    {
                        const uint16* v = (uint16*)get_row( n );
                        for ( unsigned m = 0; m < width_;m++ )
                        {
                            dlib::uint16 p = v[m];
                            assign_pixel( t[n][m], p );
                        }
                    }
                }
                else if (is_graya() && bit_depth_ == 8)
                {
                    for ( unsigned n = 0; n < height_;n++ )
                    {
                        const unsigned char* v = get_row( n );
                        for ( unsigned m = 0; m < width_; m++ )
                        {
                            unsigned char p = v[m*2];
                            if (!pixel_traits<pixel_type>::has_alpha)
                            {
                                assign_pixel( t[n][m], p );
                            }
                            else
                            {
                                unsigned char pa = v[m*2+1];
                                rgb_alpha_pixel pix;
                                assign_pixel(pix, p);
                                assign_pixel(pix.alpha, pa);
                                assign_pixel(t[n][m], pix);
                            }
                        }
                    }
                }
                else if (is_graya() && bit_depth_ == 16)
                {
                    for ( unsigned n = 0; n < height_;n++ )
                    {
                        const uint16* v = (uint16*)get_row( n );
                        for ( unsigned m = 0; m < width_; m++ )
                        {
                            dlib::uint16 p = v[m*2];
                            if (!pixel_traits<pixel_type>::has_alpha)
                            {
                                assign_pixel( t[n][m], p );
                            }
                            else
                            {
                                dlib::uint16 pa = v[m*2+1];
                                rgb_alpha_pixel pix;
                                assign_pixel(pix, p);
                                assign_pixel(pix.alpha, pa);
                                assign_pixel(t[n][m], pix);
                            }
                        }
                    }
                }
                else if (is_rgb() && bit_depth_ == 8)
                {
                    for ( unsigned n = 0; n < height_;n++ )
                    {
                        const unsigned char* v = get_row( n );
                        for ( unsigned m = 0; m < width_;m++ )
                        {
                            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 );
                        }
                    }
                }
                else if (is_rgb() && bit_depth_ == 16)
                {
                    for ( unsigned n = 0; n < height_;n++ )
                    {
                        const uint16* v = (uint16*)get_row( n );
                        for ( unsigned m = 0; m < width_;m++ )
                        {
                            rgb_pixel p;
                            p.red   = static_cast<uint8>(v[m*3]);
                            p.green = static_cast<uint8>(v[m*3+1]);
                            p.blue  = static_cast<uint8>(v[m*3+2]);
                            assign_pixel( t[n][m], p );
                        }
                    }
                }
                else if (is_rgba() && bit_depth_ == 8)
                {
                    if (!pixel_traits<typename T::type>::has_alpha)
                        assign_all_pixels(t,0);

                    for ( unsigned n = 0; n < height_;n++ )
                    {
                        const unsigned char* v = get_row( n );
                        for ( unsigned m = 0; m < width_;m++ )
                        {
                            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_rgba() && bit_depth_ == 16)
                {
                    if (!pixel_traits<typename T::type>::has_alpha)
                        assign_all_pixels(t,0);

                    for ( unsigned n = 0; n < height_;n++ )
                    {
                        const uint16* v = (uint16*)get_row( n );
                        for ( unsigned m = 0; m < width_;m++ )
                        {
                            rgb_alpha_pixel p;
                            p.red   = static_cast<uint8>(v[m*4]);
                            p.green = static_cast<uint8>(v[m*4+1]);
                            p.blue  = static_cast<uint8>(v[m*4+2]);
                            p.alpha = static_cast<uint8>(v[m*4+3]);
                            assign_pixel( t[n][m], p );
                        }
                    }
                }
            }

        private:
            const unsigned char* get_row( unsigned i ) const;
            void read_image( const char* filename );
            unsigned height_, width_;
            unsigned bit_depth_;
            int color_type_;
            scoped_ptr<LibpngData> ld_;
        };

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

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

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

    }

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

    #endif // DLIB_PNG_IMPORT