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., 675 Mass Ave, Cambridge, MA 02139, USA.
  20  */
  21
  22 #include <config.h>
  23
  24 /* Avoid a compiler warning */
  25 #undef HAVE_STDLIB_H
  26
  27 #ifdef USE_JPEG
  28
  29 #include <stdlib.h>
  30 #include <stdio.h>
  31 #include <string.h>
  32
  33 #include <jpeglib.h>
  34
  35 #include "wraster.h"
  36
  37 /*
  38  * <setjmp.h> is used for the optional error recovery mechanism shown in
  39  * the second part of the example.
  40  */
  41
  42 #include <setjmp.h>
  43
  44 /*
  45  * ERROR HANDLING:
  46  *
  47  * The JPEG library's standard error handler (jerror.c) is divided into
  48  * several "methods" which you can override individually.  This lets you
  49  * adjust the behavior without duplicating a lot of code, which you might
  50  * have to update with each future release.
  51  *
  52  * Our example here shows how to override the "error_exit" method so that
  53  * control is returned to the library's caller when a fatal error occurs,
  54  * rather than calling exit() as the standard error_exit method does.
  55  *
  56  * We use C's setjmp/longjmp facility to return control.  This means that the
  57  * routine which calls the JPEG library must first execute a setjmp() call to
  58  * establish the return point.  We want the replacement error_exit to do a
  59  * longjmp().  But we need to make the setjmp buffer accessible to the
  60  * error_exit routine.  To do this, we make a private extension of the
  61  * standard JPEG error handler object.  (If we were using C++, we'd say we
  62  * were making a subclass of the regular error handler.)
  63  *
  64  * Here's the extended error handler struct:
  65  */
  66
  67 struct my_error_mgr {
  68         struct jpeg_error_mgr pub;      /* "public" fields */
  69
  70         jmp_buf setjmp_buffer;  /* for return to caller */
  71 };
  72
  73 typedef struct my_error_mgr *my_error_ptr;
  74
  75 /*
  76  * Here's the routine that will replace the standard error_exit method:
  77  */
  78
  79 static void my_error_exit(j_common_ptr cinfo)
  80 {
  81         /* cinfo->err really points to a my_error_mgr struct, so coerce pointer */
  82         my_error_ptr myerr = (my_error_ptr) cinfo->err;
  83
  84         /* Always display the message. */
  85         /* We could postpone this until after returning, if we chose. */
  86         (*cinfo->err->output_message) (cinfo);
  87
  88         /* Return control to the setjmp point */
  89         longjmp(myerr->setjmp_buffer, 1);
  90 }
  91
  92 RImage *RLoadJPEG(RContext * context, char *file_name)
  93 {
  94         RImage *image = NULL;
  95         struct jpeg_decompress_struct cinfo;
  96         int i;
  97         unsigned char *ptr;
  98         JSAMPROW buffer[1], bptr;
  99         FILE *file;
 100         /* We use our private extension JPEG error handler.
 101          * Note that this struct must live as long as the main JPEG parameter
 102          * struct, to avoid dangling-pointer problems.
 103          */
 104         struct my_error_mgr jerr;
 105
 106         file = fopen(file_name, "rb");
 107         if (!file) {
 108                 RErrorCode = RERR_OPEN;
 109                 return NULL;
 110         }
 111
 112         cinfo.err = jpeg_std_error(&jerr.pub);
 113         jerr.pub.error_exit = my_error_exit;
 114         /* Establish the setjmp return context for my_error_exit to use. */
 115         if (setjmp(jerr.setjmp_buffer)) {
 116                 /* If we get here, the JPEG code has signaled an error.
 117                  * We need to clean up the JPEG object, close the input file, and return.
 118                  */
 119                 jpeg_destroy_decompress(&cinfo);
 120                 fclose(file);
 121                 return NULL;
 122         }
 123
 124         jpeg_create_decompress(&cinfo);
 125
 126         jpeg_stdio_src(&cinfo, file);
 127
 128         jpeg_read_header(&cinfo, TRUE);
 129
 130         if (cinfo.image_width < 1 || cinfo.image_height < 1) {
 131                 RErrorCode = RERR_BADIMAGEFILE;
 132                 goto bye;
 133         }
 134
 135         bptr = buffer[0] = (JSAMPROW) malloc(cinfo.image_width * cinfo.num_components);
 136         if (!buffer[0]) {
 137                 RErrorCode = RERR_NOMEMORY;
 138                 goto bye;
 139         }
 140
 141         if (cinfo.jpeg_color_space == JCS_GRAYSCALE) {
 142                 cinfo.out_color_space = JCS_GRAYSCALE;
 143         } else
 144                 cinfo.out_color_space = JCS_RGB;
 145         cinfo.quantize_colors = FALSE;
 146         cinfo.do_fancy_upsampling = FALSE;
 147         cinfo.do_block_smoothing = FALSE;
 148         jpeg_calc_output_dimensions(&cinfo);
 149
 150         if (context->flags.optimize_for_speed)
 151                 image = RCreateImage(cinfo.image_width, cinfo.image_height, True);
 152         else
 153                 image = RCreateImage(cinfo.image_width, cinfo.image_height, False);
 154
 155         if (!image) {
 156                 RErrorCode = RERR_NOMEMORY;
 157                 goto bye;
 158         }
 159         jpeg_start_decompress(&cinfo);
 160
 161         ptr = image->data;
 162
 163         if (cinfo.out_color_space == JCS_RGB) {
 164                 if (context->flags.optimize_for_speed) {
 165                         while (cinfo.output_scanline < cinfo.output_height) {
 166                                 jpeg_read_scanlines(&cinfo, buffer, (JDIMENSION) 1);
 167                                 bptr = buffer[0];
 168                                 for (i = 0; i < cinfo.image_width; i++) {
 169                                         *ptr++ = *bptr++;
 170                                         *ptr++ = *bptr++;
 171                                         *ptr++ = *bptr++;
 172                                         ptr++;  /* skip alpha channel */
 173                                 }
 174                         }
 175                 } else {
 176                         while (cinfo.output_scanline < cinfo.output_height) {
 177                                 jpeg_read_scanlines(&cinfo, buffer, (JDIMENSION) 1);
 178                                 bptr = buffer[0];
 179                                 memcpy(ptr, bptr, cinfo.image_width * 3);
 180                                 ptr += cinfo.image_width * 3;
 181                         }
 182                 }
 183         } else {
 184                 while (cinfo.output_scanline < cinfo.output_height) {
 185                         jpeg_read_scanlines(&cinfo, buffer, (JDIMENSION) 1);
 186                         bptr = buffer[0];
 187                         for (i = 0; i < cinfo.image_width; i++) {
 188                                 *ptr++ = *bptr;
 189                                 *ptr++ = *bptr;
 190                                 *ptr++ = *bptr++;
 191                         }
 192                 }
 193         }
 194
 195         jpeg_finish_decompress(&cinfo);
 196
 197  bye:
 198         jpeg_destroy_decompress(&cinfo);
 199
 200         fclose(file);
 201
 202         if (buffer[0])
 203                 free(buffer[0]);
 204
 205         return image;
 206 }
 207
 208 #endif                          /* USE_JPEG */