cjpeg.c

linux下的jpeg解码库

#ifdef ENTROPY_OPT_SUPPORTED
      cinfo->optimize_coding = TRUE;
#else
      fprintf(stderr, "%s: sorry, entropy optimization was not compiled\n",
	      progname);
      exit(EXIT_FAILURE);
#endif

    } else if (keymatch(arg, "outfile", 4)) {
      /* Set output file name. */
      if (++argn >= argc)	/* advance to next argument */
	usage();
      outfilename = argv[argn];	/* save it away for later use */

    } else if (keymatch(arg, "progressive", 1)) {
      /* Select simple progressive mode. */
#ifdef C_PROGRESSIVE_SUPPORTED
      simple_progressive = TRUE;
      /* We must postpone execution until num_components is known. */
#else
      fprintf(stderr, "%s: sorry, progressive output was not compiled\n",
	      progname);
      exit(EXIT_FAILURE);
#endif

    } else if (keymatch(arg, "quality", 1)) {
      /* Quality factor (quantization table scaling factor). */
      if (++argn >= argc)	/* advance to next argument */
	usage();
      if (sscanf(argv[argn], "%d", &quality) != 1)
	usage();
      /* Change scale factor in case -qtables is present. */
      q_scale_factor = jpeg_quality_scaling(quality);

    } else if (keymatch(arg, "qslots", 2)) {
      /* Quantization table slot numbers. */
      if (++argn >= argc)	/* advance to next argument */
	usage();
      qslotsarg = argv[argn];
      /* Must delay setting qslots until after we have processed any
       * colorspace-determining switches, since jpeg_set_colorspace sets
       * default quant table numbers.
       */

    } else if (keymatch(arg, "qtables", 2)) {
      /* Quantization tables fetched from file. */
      if (++argn >= argc)	/* advance to next argument */
	usage();
      qtablefile = argv[argn];
      /* We postpone actually reading the file in case -quality comes later. */

    } else if (keymatch(arg, "restart", 1)) {
      /* Restart interval in MCU rows (or in MCUs with 'b'). */
      long lval;
      char ch = 'x';

      if (++argn >= argc)	/* advance to next argument */
	usage();
      if (sscanf(argv[argn], "%ld%c", &lval, &ch) < 1)
	usage();
      if (lval < 0 || lval > 65535L)
	usage();
      if (ch == 'b' || ch == 'B') {
	cinfo->restart_interval = (unsigned int) lval;
	cinfo->restart_in_rows = 0; /* else prior '-restart n' overrides me */
      } else {
	cinfo->restart_in_rows = (int) lval;
	/* restart_interval will be computed during startup */
      }

    } else if (keymatch(arg, "sample", 2)) {
      /* Set sampling factors. */
      if (++argn >= argc)	/* advance to next argument */
	usage();
      samplearg = argv[argn];
      /* Must delay setting sample factors until after we have processed any
       * colorspace-determining switches, since jpeg_set_colorspace sets
       * default sampling factors.
       */

    } else if (keymatch(arg, "scans", 2)) {
      /* Set scan script. */
#ifdef C_MULTISCAN_FILES_SUPPORTED
      if (++argn >= argc)	/* advance to next argument */
	usage();
      scansarg = argv[argn];
      /* We must postpone reading the file in case -progressive appears. */
#else
      fprintf(stderr, "%s: sorry, multi-scan output was not compiled\n",
	      progname);
      exit(EXIT_FAILURE);
#endif

    } else if (keymatch(arg, "smooth", 2)) {
      /* Set input smoothing factor. */
      int val;

      if (++argn >= argc)	/* advance to next argument */
	usage();
      if (sscanf(argv[argn], "%d", &val) != 1)
	usage();
      if (val < 0 || val > 100)
	usage();
      cinfo->smoothing_factor = val;

    } else if (keymatch(arg, "targa", 1)) {
      /* Input file is Targa format. */
      is_targa = TRUE;

    } else {
      usage();			/* bogus switch */
    }
  }

  /* Post-switch-scanning cleanup */

  if (for_real) {

    /* Set quantization tables for selected quality. */
    /* Some or all may be overridden if -qtables is present. */
    jpeg_set_quality(cinfo, quality, force_baseline);

    if (qtablefile != NULL)	/* process -qtables if it was present */
      if (! read_quant_tables(cinfo, qtablefile,
			      q_scale_factor, force_baseline))
	usage();

    if (qslotsarg != NULL)	/* process -qslots if it was present */
      if (! set_quant_slots(cinfo, qslotsarg))
	usage();

    if (samplearg != NULL)	/* process -sample if it was present */
      if (! set_sample_factors(cinfo, samplearg))
	usage();

#ifdef C_PROGRESSIVE_SUPPORTED
    if (simple_progressive)	/* process -progressive; -scans can override */
      jpeg_simple_progression(cinfo);
#endif

#ifdef C_MULTISCAN_FILES_SUPPORTED
    if (scansarg != NULL)	/* process -scans if it was present */
      if (! read_scan_script(cinfo, scansarg))
	usage();
#endif
  }

  return argn;			/* return index of next arg (file name) */
}


/*
 * The main program.
 */

int
main (int argc, char **argv)
{
  struct jpeg_compress_struct cinfo;
  struct jpeg_error_mgr jerr;
#ifdef PROGRESS_REPORT
  struct cdjpeg_progress_mgr progress;
#endif
  int file_index;
  cjpeg_source_ptr src_mgr;
  FILE * input_file;
  FILE * output_file;
  JDIMENSION num_scanlines;

  /* On Mac, fetch a command line. */
#ifdef USE_CCOMMAND
  argc = ccommand(&argv);
#endif

  progname = argv[0];
  if (progname == NULL || progname[0] == 0)
    progname = "cjpeg";		/* in case C library doesn't provide it */

  /* Initialize the JPEG compression object with default error handling. */
  cinfo.err = jpeg_std_error(&jerr);
  jpeg_create_compress(&cinfo);
  /* Add some application-specific error messages (from cderror.h) */
  jerr.addon_message_table = cdjpeg_message_table;
  jerr.first_addon_message = JMSG_FIRSTADDONCODE;
  jerr.last_addon_message = JMSG_LASTADDONCODE;

  /* Now safe to enable signal catcher. */
#ifdef NEED_SIGNAL_CATCHER
  enable_signal_catcher((j_common_ptr) &cinfo);
#endif

  /* Initialize JPEG parameters.
   * Much of this may be overridden later.
   * In particular, we don't yet know the input file's color space,
   * but we need to provide some value for jpeg_set_defaults() to work.
   */

  cinfo.in_color_space = JCS_RGB; /* arbitrary guess */
  jpeg_set_defaults(&cinfo);

  /* Scan command line to find file names.
   * It is convenient to use just one switch-parsing routine, but the switch
   * values read here are ignored; we will rescan the switches after opening
   * the input file.
   */

  file_index = parse_switches(&cinfo, argc, argv, 0, FALSE);

#ifdef TWO_FILE_COMMANDLINE
  /* Must have either -outfile switch or explicit output file name */
  if (outfilename == NULL) {
    if (file_index != argc-2) {
      fprintf(stderr, "%s: must name one input and one output file\n",
	      progname);
      usage();
    }
    outfilename = argv[file_index+1];
  } else {
    if (file_index != argc-1) {
      fprintf(stderr, "%s: must name one input and one output file\n",
	      progname);
      usage();
    }
  }
#else
  /* Unix style: expect zero or one file name */
  if (file_index < argc-1) {
    fprintf(stderr, "%s: only one input file\n", progname);
    usage();
  }
#endif /* TWO_FILE_COMMANDLINE */

  /* Open the input file. */
  if (file_index < argc) {
    if ((input_file = fopen(argv[file_index], READ_BINARY)) == NULL) {
      fprintf(stderr, "%s: can't open %s\n", progname, argv[file_index]);
      exit(EXIT_FAILURE);
    }
  } else {
    /* default input file is stdin */
    input_file = read_stdin();
  }

  /* Open the output file. */
  if (outfilename != NULL) {
    if ((output_file = fopen(outfilename, WRITE_BINARY)) == NULL) {
      fprintf(stderr, "%s: can't open %s\n", progname, outfilename);
      exit(EXIT_FAILURE);
    }
  } else {
    /* default output file is stdout */
    output_file = write_stdout();
  }

#ifdef PROGRESS_REPORT
  start_progress_monitor((j_common_ptr) &cinfo, &progress);
#endif

  /* Figure out the input file format, and set up to read it. */
  src_mgr = select_file_type(&cinfo, input_file);
  src_mgr->input_file = input_file;

  /* Read the input file header to obtain file size & colorspace. */
  (*src_mgr->start_input) (&cinfo, src_mgr);

  /* Now that we know input colorspace, fix colorspace-dependent defaults */
  jpeg_default_colorspace(&cinfo);

  /* Adjust default compression parameters by re-parsing the options */
  file_index = parse_switches(&cinfo, argc, argv, 0, TRUE);

  /* Specify data destination for compression */
  jpeg_stdio_dest(&cinfo, output_file);

  /* Start compressor */
  jpeg_start_compress(&cinfo, TRUE);

  /* Process data */
  while (cinfo.next_scanline < cinfo.image_height) {
    num_scanlines = (*src_mgr->get_pixel_rows) (&cinfo, src_mgr);
    (void) jpeg_write_scanlines(&cinfo, src_mgr->buffer, num_scanlines);
  }

  /* Finish compression and release memory */
  (*src_mgr->finish_input) (&cinfo, src_mgr);
  jpeg_finish_compress(&cinfo);
  jpeg_destroy_compress(&cinfo);

  /* Close files, if we opened them */
  if (input_file != stdin)
    fclose(input_file);
  if (output_file != stdout)
    fclose(output_file);

#ifdef PROGRESS_REPORT
  end_progress_monitor((j_common_ptr) &cinfo);
#endif

  /* All done. */
  exit(jerr.num_warnings ? EXIT_WARNING : EXIT_SUCCESS);
  return 0;			/* suppress no-return-value warnings */
}