wrlib/jpeg.c

   1 /* jpeg.c - load JPEG image from file
   2  *
   3  * Raster graphics library
   4  *
   5  * Copyright (c) 1997-2003 Alfredo K. Kojima
   6  *
   7  *  This library is free software; you can redistribute it and/or
   8  *  modify it under the terms of the GNU Library General Public
   9  *  License as published by the Free Software Foundation; either
  10  *  version 2 of the License, or (at your option) any later version.
  11  *
  12  *  This library is distributed in the hope that it will be useful,
  13  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  *  Library General Public License for more details.
  16  *
  17  *  You should have received a copy of the GNU Library General Public
  18  *  License along with this library; if not, write to the Free
  19  *  Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston,
  20  *  MA 02110-1301, USA.
  21  */
  22
  23 #include <config.h>
  24
  25 /* Avoid a compiler warning */
  26 #undef HAVE_STDLIB_H
  27
  28 #ifdef USE_JPEG
  29
  30 #include <stdlib.h>
  31 #include <stdio.h>
  32 #include <string.h>
  33
  34 #include <jpeglib.h>
  35
  36 #include "wraster.h"
  37
  38 /*
  39  * <setjmp.h> is used for the optional error recovery mechanism shown in
  40  * the second part of the example.
  41  */
  42
  43 #include <setjmp.h>
  44
  45 /*
  46  * ERROR HANDLING:
  47  *
  48  * The JPEG library's standard error handler (jerror.c) is divided into
  49  * several "methods" which you can override individually.  This lets you
  50  * adjust the behavior without duplicating a lot of code, which you might
  51  * have to update with each future release.
  52  *
  53  * Our example here shows how to override the "error_exit" method so that
  54  * control is returned to the library's caller when a fatal error occurs,
  55  * rather than calling exit() as the standard error_exit method does.
  56  *
  57  * We use C's setjmp/longjmp facility to return control.  This means that the
  58  * routine which calls the JPEG library must first execute a setjmp() call to
  59  * establish the return point.  We want the replacement error_exit to do a
  60  * longjmp().  But we need to make the setjmp buffer accessible to the
  61  * error_exit routine.  To do this, we make a private extension of the
  62  * standard JPEG error handler object.  (If we were using C++, we'd say we
  63  * were making a subclass of the regular error handler.)
  64  *
  65  * Here's the extended error handler struct:
  66  */
  67
  68 struct my_error_mgr {
  69         struct jpeg_error_mgr pub;      /* "public" fields */
  70
  71         jmp_buf setjmp_buffer;  /* for return to caller */
  72 };
  73
  74 typedef struct my_error_mgr *my_error_ptr;
  75
  76 /*
  77  * Here's the routine that will replace the standard error_exit method:
  78  */
  79
  80 static void my_error_exit(j_common_ptr cinfo)
  81 {
  82         /* cinfo->err really points to a my_error_mgr struct, so coerce pointer */
  83         my_error_ptr myerr = (my_error_ptr) cinfo->err;
  84
  85         /* Always display the message. */
  86         /* We could postpone this until after returning, if we chose. */
  87         (*cinfo->err->output_message) (cinfo);
  88
  89         /* Return control to the setjmp point */
  90         longjmp(myerr->setjmp_buffer, 1);
  91 }
  92
  93 RImage *RLoadJPEG(RContext * context, char *file_name)
  94 {
  95         RImage *image = NULL;
  96         struct jpeg_decompress_struct cinfo;
  97         int i;
  98         unsigned char *ptr;
  99         JSAMPROW buffer[1], bptr;
 100         FILE *file;
 101         /* We use our private extension JPEG error handler.
 102          * Note that this struct must live as long as the main JPEG parameter
 103          * struct, to avoid dangling-pointer problems.
 104          */
 105         struct my_error_mgr jerr;
 106
 107         file = fopen(file_name, "rb");
 108         if (!file) {
 109                 RErrorCode = RERR_OPEN;
 110                 return NULL;
 111         }
 112
 113         cinfo.err = jpeg_std_error(&jerr.pub);
 114         jerr.pub.error_exit = my_error_exit;
 115         /* Establish the setjmp return context for my_error_exit to use. */
 116         if (setjmp(jerr.setjmp_buffer)) {
 117                 /* If we get here, the JPEG code has signaled an error.
 118                  * We need to clean up the JPEG object, close the input file, and return.
 119                  */
 120                 jpeg_destroy_decompress(&cinfo);
 121                 fclose(file);
 122                 return NULL;
 123         }
 124
 125         jpeg_create_decompress(&cinfo);
 126
 127         jpeg_stdio_src(&cinfo, file);
 128
 129         jpeg_read_header(&cinfo, TRUE);
 130
 131         if (cinfo.image_width < 1 || cinfo.image_height < 1) {
 132                 RErrorCode = RERR_BADIMAGEFILE;
 133                 goto bye;
 134         }
 135
 136         bptr = buffer[0] = (JSAMPROW) malloc(cinfo.image_width * cinfo.num_components);
 137         if (!buffer[0]) {
 138                 RErrorCode = RERR_NOMEMORY;
 139                 goto bye;
 140         }
 141
 142         if (cinfo.jpeg_color_space == JCS_GRAYSCALE) {
 143                 cinfo.out_color_space = JCS_GRAYSCALE;
 144         } else
 145                 cinfo.out_color_space = JCS_RGB;
 146         cinfo.quantize_colors = FALSE;
 147         cinfo.do_fancy_upsampling = FALSE;
 148         cinfo.do_block_smoothing = FALSE;
 149         jpeg_calc_output_dimensions(&cinfo);
 150
 151         if (context->flags.optimize_for_speed)
 152                 image = RCreateImage(cinfo.image_width, cinfo.image_height, True);
 153         else
 154                 image = RCreateImage(cinfo.image_width, cinfo.image_height, False);
 155
 156         if (!image) {
 157                 RErrorCode = RERR_NOMEMORY;
 158                 goto bye;
 159         }
 160         jpeg_start_decompress(&cinfo);
 161
 162         ptr = image->data;
 163
 164         if (cinfo.out_color_space == JCS_RGB) {
 165                 if (context->flags.optimize_for_speed) {
 166                         while (cinfo.output_scanline < cinfo.output_height) {
 167                                 jpeg_read_scanlines(&cinfo, buffer, (JDIMENSION) 1);
 168                                 bptr = buffer[0];
 169                                 for (i = 0; i < cinfo.image_width; i++) {
 170                                         *ptr++ = *bptr++;
 171                                         *ptr++ = *bptr++;
 172                                         *ptr++ = *bptr++;
 173                                         ptr++;  /* skip alpha channel */
 174                                 }
 175                         }
 176                 } else {
 177                         while (cinfo.output_scanline < cinfo.output_height) {
 178                                 jpeg_read_scanlines(&cinfo, buffer, (JDIMENSION) 1);
 179                                 bptr = buffer[0];
 180                                 memcpy(ptr, bptr, cinfo.image_width * 3);
 181                                 ptr += cinfo.image_width * 3;
 182                         }
 183                 }
 184         } else {
 185                 while (cinfo.output_scanline < cinfo.output_height) {
 186                         jpeg_read_scanlines(&cinfo, buffer, (JDIMENSION) 1);
 187                         bptr = buffer[0];
 188                         for (i = 0; i < cinfo.image_width; i++) {
 189                                 *ptr++ = *bptr;
 190                                 *ptr++ = *bptr;
 191                                 *ptr++ = *bptr++;
 192                         }
 193                 }
 194         }
 195
 196         jpeg_finish_decompress(&cinfo);
 197
 198  bye:
 199         jpeg_destroy_decompress(&cinfo);
 200
 201         fclose(file);
 202
 203         if (buffer[0])
 204                 free(buffer[0]);
 205
 206         return image;
 207 }
 208
 209 #endif                          /* USE_JPEG */