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