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#include <stdio.h>
#include <stdlib.h>
#ifdef ENABLED_PNG
#include <png.h>
#endif
#include <zbar.h>
#include <jpeglib.h>
#include <jerror.h>

zbar_image_scanner_t *scanner = NULL;

#ifdef ENABLED_PNG
/* to complete a runnable example, this abbreviated implementation of
 * get_data() will use libpng to read an image file. refer to libpng
 * documentation for details
 */
static void get_data (const char *name,
                      int *width, int *height,
                      void **raw)
{
    FILE *file = fopen(name, "rb");
    if(!file) exit(2);
    png_structp png =
        png_create_read_struct(PNG_LIBPNG_VER_STRING,
                               NULL, NULL, NULL);
    if(!png) exit(3);
    if(setjmp(png_jmpbuf(png))) exit(4);
    png_infop info = png_create_info_struct(png);
    if(!info) exit(5);
    png_init_io(png, file);
    png_read_info(png, info);
    /* configure for 8bpp grayscale input */
    int color = png_get_color_type(png, info);
    int bits = png_get_bit_depth(png, info);
    if(color & PNG_COLOR_TYPE_PALETTE)
        png_set_palette_to_rgb(png);
    if(color == PNG_COLOR_TYPE_GRAY && bits < 8)
        png_set_expand_gray_1_2_4_to_8(png);
    if(bits == 16)
        png_set_strip_16(png);
    if(color & PNG_COLOR_MASK_ALPHA)
        png_set_strip_alpha(png);
    if(color & PNG_COLOR_MASK_COLOR)
        png_set_rgb_to_gray_fixed(png, 1, -1, -1);
    /* allocate image */
    *width = png_get_image_width(png, info);
    *height = png_get_image_height(png, info);
    *raw = malloc(*width * *height);
    png_bytep rows[*height];
    int i;
    for(i = 0; i < *height; i++)
        rows[i] = *raw + (*width * i);
    png_read_image(png, rows);
}
#endif

void print_jpeg_info(struct jpeg_decompress_struct *cinfo)
{
    printf("JPEG File Information: \n");
    printf("Image width and height: %d pixels and %d pixels.\n", cinfo->image_width, cinfo->image_height);
    printf("Color components per pixel: %d.\n", cinfo->num_components);
    printf("Color space: %d.\n", cinfo->jpeg_color_space);
    printf("Raw flag is: %d.\n", cinfo->raw_data_out);
}

static int get_jpeg_data (const char *filename,
                      int *width, int *height,
                      void **raw)
{
    struct jpeg_decompress_struct cinfo;
        struct jpeg_error_mgr err;          //the error handler
    /* More stuff */
        int ret;
    FILE * infile;      /* source file */
    JSAMPARRAY buffer;      /* Output row buffer */
        unsigned char * rowptr[1];  // pointer to an array
    int row_stride;     /* physical row width in output buffer */
    if ((infile = fopen(filename, "rb")) == NULL) {
        fprintf(stderr, "can't open %s\n", filename);
        return 0;
    }

    /* Step 1: allocate and initialize JPEG decompression object */

    /* We set up the normal JPEG error routines, then override error_exit. */
    cinfo.err = jpeg_std_error(&err);
    /* Now we can initialize the JPEG decompression object. */

    jpeg_create_decompress(&cinfo);
        
    /* Step 2: specify data source (eg, a file) */

    jpeg_stdio_src(&cinfo, infile);

    /* Step 3: read file parameters with jpeg_read_header() */

    (void) jpeg_read_header(&cinfo, TRUE);
    /* Step 4: set parameters for decompression */
        cinfo.out_color_space = JCS_GRAYSCALE;
        //cinfo.num_components = 1;

        print_jpeg_info(&cinfo);
        
    /* Step 5: Start decompressor */

    (void) jpeg_start_decompress(&cinfo);

        *width = cinfo.image_width;
    *height = cinfo.image_height;

    row_stride = cinfo.output_width * cinfo.output_components;

        *raw = (void *)malloc(cinfo.output_width * cinfo.output_height * 3);

    long counter = 0;

        //step 6, read the image line by line
    unsigned bpl = cinfo.output_width * cinfo.output_components;
    JSAMPROW buf = (void*)*raw;
    JSAMPARRAY line = &buf;
    for(; cinfo.output_scanline < cinfo.output_height; buf += bpl) {
        jpeg_read_scanlines(&cinfo, line, 1);
        /* FIXME pad out to dst->width */
    }
        /*
    while (cinfo.output_scanline < cinfo.output_height) {
                // Enable jpeg_read_scanlines() to fill our jdata array
                rowptr[0] = (unsigned char *)(*raw) +  // secret to method
                        3* cinfo.output_width * cinfo.output_scanline; 

                jpeg_read_scanlines(&cinfo, rowptr, 1);

    }*/

        /* Step 7: Finish decompression */

    (void) jpeg_finish_decompress(&cinfo);
    /* Step 8: Release JPEG decompression object */

    /* This is an important step since it will release a good deal of memory. */
    jpeg_destroy_decompress(&cinfo);

    fclose(infile);
    /* And we're done! */
    return 1;
}

int main (int argc, char **argv)
{
    if(argc < 2) return(1);

    /* create a reader */
    scanner = zbar_image_scanner_create();

    /* configure the reader */
    zbar_image_scanner_set_config(scanner, 0, ZBAR_CFG_ENABLE, 1);

    /* obtain image data */
    int width = 0, height = 0;
    void *raw = NULL;
    //get_data(argv[1], &width, &height, &raw);
        printf("load %s\n", argv[1]);
    get_jpeg_data(argv[1], &width, &height, &raw);
        printf("load %s done\n", argv[1]);

    /* wrap image data */
    zbar_image_t *image = zbar_image_create();
    zbar_image_set_format(image, *(int*)"Y800");
    zbar_image_set_size(image, width, height);
    zbar_image_set_data(image, raw, width * height, zbar_image_free_data);

        printf("starting to scan\n");
    /* scan the image for barcodes */
    int n = zbar_scan_image(scanner, image);

    /* extract results */
    const zbar_symbol_t *symbol = zbar_image_first_symbol(image);
    for(; symbol; symbol = zbar_symbol_next(symbol)) {
        /* do something useful with results */
        zbar_symbol_type_t typ = zbar_symbol_get_type(symbol);
        const char *data = zbar_symbol_get_data(symbol);
        printf("decoded %s symbol \"%s\"\n",
               zbar_get_symbol_name(typ), data);
    }

    /* clean up */
    zbar_image_destroy(image);
    zbar_image_scanner_destroy(scanner);

    return(0);
}