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#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include "jpeglib.h"
#include "jpeg.h"
unsigned char *loadjpeg(char *filename, int *width, int *height){
struct jpeg_decompress_struct cinfo;
struct jpeg_error_mgr jerr;
FILE *infile;
JSAMPARRAY buffer;
int row_stride;
int i = 0;
int x, y;
unsigned char *retbuf;
if((infile = fopen(filename, "rb")) == NULL){
fprintf(stderr, "can't open %s\n", filename);
exit(1);
}
cinfo.err = jpeg_std_error(&jerr);
jpeg_create_decompress(&cinfo);
jpeg_stdio_src(&cinfo, infile);
jpeg_read_header(&cinfo, TRUE);
jpeg_start_decompress(&cinfo);
*width = cinfo.output_width;
*height = cinfo.output_height;
retbuf = malloc(cinfo.output_components * (cinfo.output_width * cinfo.output_height));
if(cinfo.output_components != 3){
fprintf(stderr, "TODO: greyscale images are not supported\n");
exit(1);
}
row_stride = cinfo.output_width * cinfo.output_components;
buffer = (*cinfo.mem->alloc_sarray)((j_common_ptr) &cinfo, JPOOL_IMAGE, row_stride, 1);
for(y = 0; y < cinfo.output_height; y++){
jpeg_read_scanlines(&cinfo, buffer, 1);
for(x = 0; x < row_stride; x++){
retbuf[i++] = buffer[0][x];
}
assert(i % *width == 0);
}
jpeg_finish_decompress(&cinfo);
jpeg_destroy_decompress(&cinfo);
fclose(infile);
return retbuf;
}
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