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#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <setjmp.h>
#include <string.h>
#include "jpeglib.h"
#include "meh.h"
struct error_mgr{
struct jpeg_error_mgr pub;
jmp_buf jmp_buffer;
};
struct jpeg_t{
struct image img;
FILE *f;
struct jpeg_decompress_struct cinfo;
struct error_mgr jerr;
};
static void error_exit(j_common_ptr cinfo){
(void) cinfo;
printf("\nerror!\n");
exit(1);
}
static void error_longjmp(j_common_ptr cinfo){
struct error_mgr *myerr = (struct error_mgr *)cinfo->err;
(*cinfo->err->output_message)(cinfo);
longjmp(myerr->jmp_buffer, 1);
}
/* TODO progressive */
static struct image *jpeg_open(FILE *f){
struct jpeg_t *j;
rewind(f);
if(getc(f) != 0xff || getc(f) != 0xd8)
return NULL;
j = malloc(sizeof(struct jpeg_t));
j->f = f;
j->cinfo.err = jpeg_std_error(&j->jerr.pub);
j->jerr.pub.error_exit = error_longjmp;
if (setjmp(j->jerr.jmp_buffer)) {
return NULL;
}
j->jerr.pub.error_exit = error_exit;
j->img.fmt = &libjpeg;
return (struct image *)j;
}
void jpeg_prep(struct image *img){
struct jpeg_t *j = (struct jpeg_t *)img;
jpeg_create_decompress(&j->cinfo);
rewind(j->f);
jpeg_stdio_src(&j->cinfo, j->f);
jpeg_read_header(&j->cinfo, TRUE);
/* parameters */
j->cinfo.do_fancy_upsampling = 0;
j->cinfo.do_block_smoothing = 0;
j->cinfo.quantize_colors = 0;
j->cinfo.dct_method = JDCT_FASTEST;
j->cinfo.scale_denom = img->state < FASTLOADED ? 8 : 1; /* TODO: This should be changed done only for large jpegs */
jpeg_calc_output_dimensions(&j->cinfo);
j->img.bufwidth = j->cinfo.output_width;
j->img.bufheight = j->cinfo.output_height;
}
static int jpeg_read(struct image *img){
struct jpeg_t *j = (struct jpeg_t *)img;
unsigned int row_stride;
int a = 0, b;
unsigned int x, y;
j->jerr.pub.error_exit = error_longjmp;
if(setjmp(j->jerr.jmp_buffer)){
return 1; /* ERROR */
}
row_stride = j->cinfo.output_width * j->cinfo.output_components;
jpeg_start_decompress(&j->cinfo);
if(j->cinfo.output_components == 3){
JSAMPROW rows[2];
rows[0] = img->buf;
rows[1] = rows[0] + row_stride;
for(y = 0; y < j->cinfo.output_height;){
int n = jpeg_read_scanlines(&j->cinfo, rows, 2);
y += n;
rows[0] = rows[n-1] + row_stride;
rows[1] = rows[0] + row_stride;
}
}else if(j->cinfo.output_components == 1){
JSAMPARRAY buffer = (*j->cinfo.mem->alloc_sarray)((j_common_ptr)&j->cinfo, JPOOL_IMAGE, row_stride, 4);
for(y = 0; y < j->cinfo.output_height; ){
int n = jpeg_read_scanlines(&j->cinfo, buffer, 4);
for(b = 0; b < n; b++){
for(x = 0; x < j->cinfo.output_width; x++){
img->buf[a++] = buffer[b][x];
img->buf[a++] = buffer[b][x];
img->buf[a++] = buffer[b][x];
}
}
y += n;
}
}else if(j->cinfo.output_components == 4){
JSAMPARRAY buffer = (*j->cinfo.mem->alloc_sarray)((j_common_ptr)&j->cinfo, JPOOL_IMAGE, row_stride, 4);
for(y = 0; y < j->cinfo.output_height; ){
int n = jpeg_read_scanlines(&j->cinfo, buffer, 4);
for(b = 0; b < n; b++){
for(x = 0; x < j->cinfo.output_width; x++){
int tmp = buffer[b][x*4 + 3];
img->buf[a++] = buffer[b][x*4] * tmp / 255;
img->buf[a++] = buffer[b][x*4 + 1] * tmp / 255;
img->buf[a++] = buffer[b][x*4 + 2] * tmp / 255;
}
}
y += n;
}
}else{
fprintf(stderr, "Unsupported number of output components: %u\n", j->cinfo.output_components);
return 1;
}
jpeg_finish_decompress(&j->cinfo);
img->state = j->cinfo.scale_denom == 1 ? LOADED : FASTLOADED;
return 0;
}
void jpeg_close(struct image *img){
struct jpeg_t *j = (struct jpeg_t *)img;
jpeg_destroy_decompress(&j->cinfo);
fclose(j->f);
}
struct imageformat libjpeg = {
jpeg_open,
jpeg_prep,
jpeg_read,
jpeg_close
};
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