share/png/contrib/examples/iccfrompng.c

   1 /*- iccfrompng
   2  *
   3  * COPYRIGHT: Written by John Cunningham Bowler, 2011.
   4  * To the extent possible under law, the author has waived all copyright and
   5  * related or neighboring rights to this work.  This work is published from:
   6  * United States.
   7  *
   8  * Extract any icc profiles found in the given PNG files.  This is a simple
   9  * example of a program which extracts information from the header of a PNG file
  10  * without processing the image.  Notice that some header information may occur
  11  * after the image data, textual data and comments are an example; the approach
  12  * in this file won't work reliably for such data because it only looks for the
  13  * information in the section of the file that preceeds the image data.
  14  *
  15  * Compile and link against libpng and zlib, plus anything else required on the
  16  * system you use.
  17  *
  18  * To use supply a list of PNG files containing iCCP chunks, the chunks will be
  19  * extracted to a similarly named file with the extension replaced by 'icc',
  20  * which will be overwritten without warning.
  21  */
  22 #include <stdlib.h>
  23 #include <setjmp.h>
  24 #include <string.h>
  25 #include <stdio.h>
  26
  27 #include <png.h>
  28
  29 static int verbose = 1;
  30 static png_byte no_profile[] = "no profile";
  31
  32 static png_bytep
  33 extract(FILE *fp, png_uint_32 *proflen)
  34 {
  35    png_structp png_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING,0,0,0);
  36    png_infop info_ptr = NULL;
  37    png_bytep result = NULL;
  38
  39    /* Initialize for error or no profile: */
  40    *proflen = 0;
  41
  42    if (png_ptr == NULL)
  43    {
  44       fprintf(stderr, "iccfrompng: version library mismatch?\n");
  45       return 0;
  46    }
  47
  48    if (setjmp(png_jmpbuf(png_ptr)))
  49    {
  50       png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
  51       return 0;
  52    }
  53
  54    png_init_io(png_ptr, fp);
  55
  56    info_ptr = png_create_info_struct(png_ptr);
  57    if (info_ptr == NULL)
  58       png_error(png_ptr, "OOM allocating info structure");
  59
  60    png_read_info(png_ptr, info_ptr);
  61
  62    {
  63       png_charp name;
  64       int compression_type;
  65       png_bytep profile;
  66
  67       if (png_get_iCCP(png_ptr, info_ptr, &name, &compression_type, &profile,
  68          proflen) & PNG_INFO_iCCP)
  69       {
  70          result = malloc(*proflen);
  71          if (result != NULL)
  72             memcpy(result, profile, *proflen);
  73
  74          else
  75             png_error(png_ptr, "OOM allocating profile buffer");
  76       }
  77
  78       else
  79         result = no_profile;
  80    }
  81
  82    png_destroy_read_struct(&png_ptr, &info_ptr, NULL);
  83    return result;
  84 }
  85
  86 static int
  87 extract_one_file(const char *filename)
  88 {
  89    int result = 0;
  90    FILE *fp = fopen(filename, "rb");
  91
  92    if (fp != NULL)
  93    {
  94       png_uint_32 proflen = 0;
  95       png_bytep profile = extract(fp, &proflen);
  96
  97       if (profile != NULL && profile != no_profile)
  98       {
  99          size_t len;
 100          char *output;
 101
 102          {
 103             const char *ep = strrchr(filename, '.');
 104
 105             if (ep != NULL)
 106                len = ep-filename;
 107
 108             else
 109                len = strlen(filename);
 110          }
 111
 112          output = malloc(len + 5);
 113          if (output != NULL)
 114          {
 115             FILE *of;
 116
 117             memcpy(output, filename, len);
 118             strcpy(output+len, ".icc");
 119
 120             of = fopen(output, "wb");
 121             if (of != NULL)
 122             {
 123                if (fwrite(profile, proflen, 1, of) == 1 &&
 124                   fflush(of) == 0 &&
 125                   fclose(of) == 0)
 126                {
 127                   if (verbose)
 128                      printf("%s -> %s\n", filename, output);
 129                   /* Success return */
 130                   result = 1;
 131                }
 132
 133                else
 134                {
 135                   fprintf(stderr, "%s: error writing profile\n", output);
 136                   if (remove(output))
 137                      fprintf(stderr, "%s: could not remove file\n", output);
 138                }
 139             }
 140
 141             else
 142                fprintf(stderr, "%s: failed to open output file\n", output);
 143
 144             free(output);
 145          }
 146
 147          else
 148             fprintf(stderr, "%s: OOM allocating string!\n", filename);
 149
 150          free(profile);
 151       }
 152
 153       else if (verbose && profile == no_profile)
 154         printf("%s has no profile\n", filename);
 155    }
 156
 157    else
 158       fprintf(stderr, "%s: could not open file\n", filename);
 159
 160    return result;
 161 }
 162
 163 int
 164 main(int argc, char **argv)
 165 {
 166    int i;
 167    int extracted = 0;
 168
 169    for (i=1; i<argc; ++i)
 170    {
 171       if (strcmp(argv[i], "-q") == 0)
 172          verbose = 0;
 173
 174       else if (extract_one_file(argv[i]))
 175          extracted = 1;
 176    }
 177
 178    /* Exit code is true if any extract succeeds */
 179    return extracted == 0;
 180 }