gtk2/gdk-pixbuf/io-jpeg.c

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/* GdkPixbuf library - JPEG image loader
*
* Copyright (C) 1999 Michael Zucchi
* Copyright (C) 1999 The Free Software Foundation
*
* Authors: Michael Zucchi <zucchi@zedzone.mmc.com.au>
* Federico Mena-Quintero <federico@gimp.org>
*
* 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., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include <config.h>
#include <stdio.h>
#include <setjmp.h>
#include <jpeglib.h>
#include "gdk-pixbuf.h"
/* error handler data */
struct error_handler_data {
struct jpeg_error_mgr pub;
sigjmp_buf setjmp_buffer;
};
static void
fatal_error_handler (j_common_ptr cinfo)
{
/* FIXME:
* We should somehow signal what error occurred to the caller so the
* caller can handle the error message */
struct error_handler_data *errmgr;
errmgr = (struct error_handler_data *) cinfo->err;
cinfo->err->output_message (cinfo);
siglongjmp (errmgr->setjmp_buffer, 1);
return;
}
/* Destroy notification function for the libart pixbuf */
static void
free_buffer (gpointer user_data, gpointer data)
{
free (data);
}
/* Shared library entry point */
GdkPixbuf *
image_load (FILE *f)
{
int w, h, i, j;
guchar *pixels = NULL, *dptr;
guchar *lines[4]; /* Used to expand rows, via rec_outbuf_height, from the header file:
* "* Usually rec_outbuf_height will be 1 or 2, at most 4."
*/
guchar **lptr;
struct jpeg_decompress_struct cinfo;
struct error_handler_data jerr;
GdkPixbuf *pixbuf;
/* setup error handler */
cinfo.err = jpeg_std_error (&jerr.pub);
jerr.pub.error_exit = fatal_error_handler;
if (sigsetjmp (jerr.setjmp_buffer, 1)) {
/* Whoops there was a jpeg error */
if (pixels)
free (pixels);
jpeg_destroy_decompress (&cinfo);
return NULL;
}
/* load header, setup */
jpeg_create_decompress (&cinfo);
jpeg_stdio_src (&cinfo, f);
jpeg_read_header (&cinfo, TRUE);
jpeg_start_decompress (&cinfo);
cinfo.do_fancy_upsampling = FALSE;
cinfo.do_block_smoothing = FALSE;
w = cinfo.output_width;
h = cinfo.output_height;
pixels = malloc (h * w * 3);
if (!pixels) {
jpeg_destroy_decompress (&cinfo);
return NULL;
}
dptr = pixels;
/* decompress all the lines, a few at a time */
while (cinfo.output_scanline < cinfo.output_height) {
lptr = lines;
for (i = 0; i < cinfo.rec_outbuf_height; i++) {
*lptr++ = dptr;
dptr += w * 3;
}
jpeg_read_scanlines (&cinfo, lines, cinfo.rec_outbuf_height);
if (cinfo.output_components == 1) {
/* Expand grey->colour. Expand from the end of the
* memory down, so we can use the same buffer.
*/
for (i = cinfo.rec_outbuf_height - 1; i >= 0; i--) {
guchar *from, *to;
from = lines[i] + w - 1;
to = lines[i] + w * 3 - 3;
for (j = w - 1; j >= 0; j--) {
to[0] = from[0];
to[1] = from[0];
to[2] = from[0];
to -= 3;
from--;
}
}
}
}
jpeg_finish_decompress (&cinfo);
jpeg_destroy_decompress (&cinfo);
return gdk_pixbuf_new_from_data (pixels, ART_PIX_RGB, FALSE,
w, h, w * 3,
free_buffer, NULL);
return pixbuf;
}