#include "mxpng.h"



namespace mx
{


static SDL_Surface *CreateBuffer(size_t w = 640, size_t h = 480)
{

        SDL_Surface *surface;

        static int rmask, gmask, bmask, amask;
#if SDL_BYTEORDER == SDL_BIG_ENDIAN
    rmask = 0xff000000;
    gmask = 0x00ff0000;
    bmask = 0x0000ff00;
    amask = 0x000000ff;
#else
    rmask = 0x000000ff;
    gmask = 0x0000ff00;
    bmask = 0x00ff0000;
    amask = 0xff000000;
#endif
         surface =  SDL_CreateRGBSurface(SDL_SWSURFACE , w, h, 32, rmask, gmask,bmask, amask);


        return surface;
}





	mxPng::mxPng() {}


	mxPng::mxPng(std::string fname)
	{
		pngOpen(fname);

	}


	int mxPng::pngOpen(std::string fname)
	{

		png_byte header[8];	

	
	FILE *fp = fopen(fname.c_str(), "rb");
	if (!fp)
		return 0;
	fread(header, 1, 8, fp);
	if (png_sig_cmp(header, 0, 8))
		return 0;


	
	png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, NULL, NULL, NULL);
	
	if (!png_ptr)
		return 0;

	info_ptr = png_create_info_struct(png_ptr);
	if (!info_ptr)
		return 0;

	if (setjmp(png_jmpbuf(png_ptr)))
		return 0;

	png_init_io(png_ptr, fp);
	png_set_sig_bytes(png_ptr, 8);

	png_read_info(png_ptr, info_ptr);

	width = info_ptr->width;
	height = info_ptr->height;
	color_type = info_ptr->color_type;
	bit_depth = info_ptr->bit_depth;

	number_of_passes = png_set_interlace_handling(png_ptr);
	png_read_update_info(png_ptr, info_ptr);


	if (setjmp(png_jmpbuf(png_ptr)))
		return 0;

		row_pointers = (png_bytep*) malloc(sizeof(png_bytep) * height);
		for (y=0; y<height; y++)
		row_pointers[y] = (png_byte*) malloc(info_ptr->rowbytes);

		png_read_image(png_ptr, row_pointers);

	        fclose(fp);

		return 1;
	}



	int mxPng::pngClose()
	{

		for (y=0; y<height; y++)
			free(row_pointers[y]);
			
		free(row_pointers);

        
		return 1;
	}



SDL_Surface *mxPng::LoadPNG()
{

	SDL_Surface *surf;
	int pixel_space = 3;

        if(color_type == PNG_COLOR_TYPE_RGB)
        {

		pixel_space = 3;

	}

	if(color_type == PNG_COLOR_TYPE_RGBA)
		pixel_space = 4;
               



	surf = CreateBuffer(width,height);

	SDL_FillRect(surf, 0, SDL_MapRGB(surf->format, 255,255,255));


		int x,y;

		if (SDL_MUSTLOCK(surf))
		{

			if(SDL_LockSurface(surf) < 0)
				return 0;

		}

		Uint32 *buffer = (Uint32*) surf->pixels;


		for(y=0;y<height;y++)
		{

				png_byte *row = row_pointers[y];
			
				for(x=0; x<width;x++)
				{

					png_byte *ptr = &(row[x*pixel_space]);
					Uint32 *uptr = &buffer[x+y*width];
					Uint32 value = SDL_MapRGB(surf->format, ptr[0], ptr[1], ptr[2]);
					*uptr = value;
				}


		}

		if(SDL_MUSTLOCK(surf))
			SDL_UnlockSurface(surf);

		return surf;
	}

}