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/* jpeg.c - load JPEG image from file
*
* Raster graphics library
*
* Copyright (c) 1997-2003 Alfredo K. Kojima
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library; if not, write to the Free
* Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
* MA 02110-1301, USA.
*/
#include <config.h>
/* Avoid a compiler warning */
#undef HAVE_STDLIB_H
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <jpeglib.h>
#ifdef HAVE_STDNORETURN
#include <stdnoreturn.h>
#endif
#include "wraster.h"
#include "imgformat.h"
#include "wr_i18n.h"
/*
* <setjmp.h> is used for the optional error recovery mechanism shown in
* the second part of the example.
*/
#include <setjmp.h>
/*
* ERROR HANDLING:
*
* The JPEG library's standard error handler (jerror.c) is divided into
* several "methods" which you can override individually. This lets you
* adjust the behavior without duplicating a lot of code, which you might
* have to update with each future release.
*
* Our example here shows how to override the "error_exit" method so that
* control is returned to the library's caller when a fatal error occurs,
* rather than calling exit() as the standard error_exit method does.
*
* We use C's setjmp/longjmp facility to return control. This means that the
* routine which calls the JPEG library must first execute a setjmp() call to
* establish the return point. We want the replacement error_exit to do a
* longjmp(). But we need to make the setjmp buffer accessible to the
* error_exit routine. To do this, we make a private extension of the
* standard JPEG error handler object. (If we were using C++, we'd say we
* were making a subclass of the regular error handler.)
*
* Here's the extended error handler struct:
*/
struct my_error_mgr {
struct jpeg_error_mgr pub; /* "public" fields */
jmp_buf setjmp_buffer; /* for return to caller */
};
typedef struct my_error_mgr *my_error_ptr;
/*
* Here's the routine that will replace the standard error_exit method:
*/
static noreturn void my_error_exit(j_common_ptr cinfo)
{
/* cinfo->err really points to a my_error_mgr struct, so coerce pointer */
my_error_ptr myerr = (my_error_ptr) cinfo->err;
/* Always display the message. */
/* We could postpone this until after returning, if we chose. */
(*cinfo->err->output_message) (cinfo);
/* Return control to the setjmp point */
longjmp(myerr->setjmp_buffer, 1);
}
static RImage *do_read_jpeg_file(struct jpeg_decompress_struct *cinfo, const char *file_name)
{
RImage *image = NULL;
int i;
unsigned char *ptr;
JSAMPROW buffer[1], bptr;
FILE *file;
file = fopen(file_name, "rb");
if (!file) {
RErrorCode = RERR_OPEN;
return NULL;
}
jpeg_create_decompress(cinfo);
jpeg_stdio_src(cinfo, file);
jpeg_read_header(cinfo, TRUE);
if (cinfo->image_width < 1 || cinfo->image_height < 1) {
buffer[0] = NULL; /* Initialize pointer to avoid spurious free in cleanup code */
RErrorCode = RERR_BADIMAGEFILE;
goto abort_and_release_resources;
}
buffer[0] = (JSAMPROW) malloc(cinfo->image_width * cinfo->num_components);
if (!buffer[0]) {
RErrorCode = RERR_NOMEMORY;
goto abort_and_release_resources;
}
if (cinfo->jpeg_color_space == JCS_GRAYSCALE)
cinfo->out_color_space = JCS_GRAYSCALE;
else
cinfo->out_color_space = JCS_RGB;
cinfo->quantize_colors = FALSE;
cinfo->do_fancy_upsampling = FALSE;
cinfo->do_block_smoothing = FALSE;
jpeg_calc_output_dimensions(cinfo);
image = RCreateImage(cinfo->image_width, cinfo->image_height, False);
if (!image) {
RErrorCode = RERR_NOMEMORY;
goto abort_and_release_resources;
}
jpeg_start_decompress(cinfo);
ptr = image->data;
if (cinfo->out_color_space == JCS_RGB) {
while (cinfo->output_scanline < cinfo->output_height) {
jpeg_read_scanlines(cinfo, buffer, (JDIMENSION) 1);
bptr = buffer[0];
memcpy(ptr, bptr, cinfo->image_width * 3);
ptr += cinfo->image_width * 3;
}
} else {
while (cinfo->output_scanline < cinfo->output_height) {
jpeg_read_scanlines(cinfo, buffer, (JDIMENSION) 1);
bptr = buffer[0];
for (i = 0; i < cinfo->image_width; i++) {
*ptr++ = *bptr;
*ptr++ = *bptr;
*ptr++ = *bptr++;
}
}
}
jpeg_finish_decompress(cinfo);
abort_and_release_resources:
jpeg_destroy_decompress(cinfo);
fclose(file);
if (buffer[0])
free(buffer[0]);
return image;
}
RImage *RLoadJPEG(const char *file_name)
{
struct jpeg_decompress_struct cinfo;
/* We use our private extension JPEG error handler.
* Note that this struct must live as long as the main
* JPEG parameter struct, to avoid dangling-pointer problems.
*/
struct my_error_mgr jerr;
cinfo.err = jpeg_std_error(&jerr.pub);
jerr.pub.error_exit = my_error_exit;
/* Establish the setjmp return context for my_error_exit to use. */
if (setjmp(jerr.setjmp_buffer)) {
/*
* If we get here, the JPEG code has signaled an error.
* We need to clean up the JPEG object, close the input file, and return.
*/
jpeg_destroy_decompress(&cinfo);
return NULL;
}
return do_read_jpeg_file(&cinfo, file_name);
}
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