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/*
* jpeg.c:
* JPEG file support. Based on example.c in the IJG jpeg-6b distribution.
*
* Copyright (c) 2001 Chris Lightfoot. All rights reserved.
* Email: chris@ex-parrot.com; WWW: http://www.ex-parrot.com/~chris/
*
*/
static const char rcsid[] = "$Id: jpeg.c,v 1.1 2001/07/15 11:07:33 chris Exp $";
#include <stdio.h>
#include <stdlib.h>
#include <setjmp.h>
#include <jpeglib.h>
#include "img.h"
/* struct my_error_mgr:
* Error handling struct for JPEG library interaction.
*/
struct my_error_mgr {
struct jpeg_error_mgr pub;
jmp_buf jb;
};
/* my_error_exit:
* Error handler method for JPEG library.
*/
static void my_error_exit(j_common_ptr cinfo) {
struct my_error_mgr *e = (struct my_error_mgr*)cinfo->err;
(*cinfo->err->output_message)(cinfo);
longjmp(e->jb, 1);
}
/* jpeg_load_hdr:
* Load the header of a JPEG file.
*/
int jpeg_load_hdr(img I) {
struct jpeg_decompress_struct *cinfo;
struct my_error_mgr *jerr;
cinfo = (struct jpeg_decompress_struct*)calloc(sizeof(struct jpeg_decompress_struct), 1);
I->us = cinfo;
jerr = (struct my_error_mgr*)calloc(sizeof(struct my_error_mgr), 1);
cinfo->err = jpeg_std_error(&jerr->pub);
jerr->pub.error_exit = my_error_exit;
if (setjmp(jerr->jb)) {
/* Oops, something went wrong. */
I->err = IE_HDRFORMAT;
jpeg_destroy_decompress(cinfo);
return 0;
}
jpeg_create_decompress(cinfo);
jpeg_stdio_src(cinfo, I->fp);
/* Read the header of the image. */
jpeg_read_header(cinfo, TRUE);
jpeg_start_decompress(cinfo);
I->width = cinfo->output_width;
I->height = cinfo->output_height;
return 1;
}
/* jpeg_abort_load:
* Abort loading a JPEG after the header is done.
*/
int jpeg_abort_load(img I) {
jpeg_finish_decompress((struct jpeg_decompress_struct*)I->us);
jpeg_destroy_decompress((struct jpeg_decompress_struct*)I->us);
return 1;
}
/* jpeg_load_img:
* Read a JPEG file into an image.
*/
int jpeg_load_img(img I) {
struct jpeg_decompress_struct *cinfo = I->us;
struct my_error_mgr *jerr;
JSAMPARRAY buffer;
img_alloc(I);
jerr = (struct my_error_mgr*)cinfo->err;
if (setjmp(jerr->jb)) {
/* Oops, something went wrong. */
I->err = IE_IMGFORMAT;
jpeg_destroy_decompress(cinfo);
return 0;
}
cinfo->out_color_space = JCS_RGB;
cinfo->out_color_components = cinfo->output_components = 3;
/* Start decompression. */
buffer = cinfo->mem->alloc_sarray((j_common_ptr)cinfo, JPOOL_IMAGE, cinfo->output_width * cinfo->output_components, 1);
while (cinfo->output_scanline < cinfo->output_height) {
pel *p, *end;
unsigned char *q;
jpeg_read_scanlines(cinfo, buffer, 1);
/* Now we have a buffer in RGB format. */
for (p = I->data[cinfo->output_scanline - 1], end = p + I->width, q = (unsigned char*)buffer[0]; p < end; ++p, q += 3)
*p = PEL(*q, *(q + 1), *(q + 2));
}
jpeg_finish_decompress(cinfo);
jpeg_destroy_decompress(cinfo);
return 1;
}
/* jpeg_save_img:
* Write an image out into a JPEG file.
*/
int jpeg_save_img(const img I, FILE *fp) {
struct jpeg_compress_struct cinfo;
struct my_error_mgr jerr;
JSAMPROW *buffer;
cinfo.err = jpeg_std_error(&jerr.pub);
jerr.pub.error_exit = my_error_exit;
if (setjmp(jerr.jb)) {
/* Oops, something went wrong. */
I->err = IE_SYSERROR;
jpeg_destroy_compress(&cinfo);
return 0;
}
jpeg_create_compress(&cinfo);
/* Compressor will write to fp. */
jpeg_stdio_dest(&cinfo, fp);
/* Image parameters. */
cinfo.image_width = I->width;
cinfo.image_height = I->height;
cinfo.input_components = 3;
cinfo.in_color_space = JCS_RGB;
/* Default parameters. */
jpeg_set_defaults(&cinfo);
/* XXX compression quality? */
jpeg_start_compress(&cinfo, TRUE);
buffer = cinfo.mem->alloc_sarray((j_common_ptr)&cinfo, JPOOL_IMAGE, I->width * 3, 1);
while (cinfo.next_scanline < cinfo.image_height) {
pel *p, *end;
unsigned char *q;
/* Copy image data into correct format. */
for (p = I->data[cinfo.next_scanline], end = p + I->width, q = (unsigned char*)buffer[0]; p < end; ++p) {
*q++ = (unsigned char)GETR(*p);
*q++ = (unsigned char)GETG(*p);
*q++ = (unsigned char)GETB(*p);
}
/* Write scanline. */
jpeg_write_scanlines(&cinfo, buffer, 1);
}
jpeg_finish_compress(&cinfo);
jpeg_destroy_compress(&cinfo);
return 1;
}
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