PNG_BYTES_TO_CHECK  247 example.c         char buf[PNG_BYTES_TO_CHECK];
PNG_BYTES_TO_CHECK  254 example.c         if (fread(buf, 1, PNG_BYTES_TO_CHECK, *fp) != PNG_BYTES_TO_CHECK)
PNG_BYTES_TO_CHECK  260 example.c         return(!png_sig_cmp(buf, (png_size_t)0, PNG_BYTES_TO_CHECK));