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src/Source/LibJPEG/jcmarker.c  view on Meta::CPAN

  emit_byte(cinfo, 0);
  emit_byte(cinfo, cinfo->JFIF_major_version); /* Version fields */
  emit_byte(cinfo, cinfo->JFIF_minor_version);
  emit_byte(cinfo, cinfo->density_unit); /* Pixel size information */
  emit_2bytes(cinfo, (int) cinfo->X_density);
  emit_2bytes(cinfo, (int) cinfo->Y_density);
  emit_byte(cinfo, 0);		/* No thumbnail image */
  emit_byte(cinfo, 0);
}


LOCAL(void)
emit_adobe_app14 (j_compress_ptr cinfo)
/* Emit an Adobe APP14 marker */
{
  /*
   * Length of APP14 block	(2 bytes)
   * Block ID			(5 bytes - ASCII "Adobe")
   * Version Number		(2 bytes - currently 100)
   * Flags0			(2 bytes - currently 0)
   * Flags1			(2 bytes - currently 0)
   * Color transform		(1 byte)
   *
   * Although Adobe TN 5116 mentions Version = 101, all the Adobe files
   * now in circulation seem to use Version = 100, so that's what we write.
   *
   * We write the color transform byte as 1 if the JPEG color space is
   * YCbCr, 2 if it's YCCK, 0 otherwise.  Adobe's definition has to do with
   * whether the encoder performed a transformation, which is pretty useless.
   */
  
  emit_marker(cinfo, M_APP14);
  
  emit_2bytes(cinfo, 2 + 5 + 2 + 2 + 2 + 1); /* length */

  emit_byte(cinfo, 0x41);	/* Identifier: ASCII "Adobe" */
  emit_byte(cinfo, 0x64);
  emit_byte(cinfo, 0x6F);
  emit_byte(cinfo, 0x62);
  emit_byte(cinfo, 0x65);
  emit_2bytes(cinfo, 100);	/* Version */
  emit_2bytes(cinfo, 0);	/* Flags0 */
  emit_2bytes(cinfo, 0);	/* Flags1 */
  switch (cinfo->jpeg_color_space) {
  case JCS_YCbCr:
    emit_byte(cinfo, 1);	/* Color transform = 1 */
    break;
  case JCS_YCCK:
    emit_byte(cinfo, 2);	/* Color transform = 2 */
    break;
  default:
    emit_byte(cinfo, 0);	/* Color transform = 0 */
    break;
  }
}


/*
 * These routines allow writing an arbitrary marker with parameters.
 * The only intended use is to emit COM or APPn markers after calling
 * write_file_header and before calling write_frame_header.
 * Other uses are not guaranteed to produce desirable results.
 * Counting the parameter bytes properly is the caller's responsibility.
 */

METHODDEF(void)
write_marker_header (j_compress_ptr cinfo, int marker, unsigned int datalen)
/* Emit an arbitrary marker header */
{
  if (datalen > (unsigned int) 65533)		/* safety check */
    ERREXIT(cinfo, JERR_BAD_LENGTH);

  emit_marker(cinfo, (JPEG_MARKER) marker);

  emit_2bytes(cinfo, (int) (datalen + 2));	/* total length */
}

METHODDEF(void)
write_marker_byte (j_compress_ptr cinfo, int val)
/* Emit one byte of marker parameters following write_marker_header */
{
  emit_byte(cinfo, val);
}


/*
 * Write datastream header.
 * This consists of an SOI and optional APPn markers.
 * We recommend use of the JFIF marker, but not the Adobe marker,
 * when using YCbCr or grayscale data.  The JFIF marker is also used
 * for other standard JPEG colorspaces.  The Adobe marker is helpful
 * to distinguish RGB, CMYK, and YCCK colorspaces.
 * Note that an application can write additional header markers after
 * jpeg_start_compress returns.
 */

METHODDEF(void)
write_file_header (j_compress_ptr cinfo)
{
  my_marker_ptr marker = (my_marker_ptr) cinfo->marker;

  emit_marker(cinfo, M_SOI);	/* first the SOI */

  /* SOI is defined to reset restart interval to 0 */
  marker->last_restart_interval = 0;

  if (cinfo->write_JFIF_header)	/* next an optional JFIF APP0 */
    emit_jfif_app0(cinfo);
  if (cinfo->write_Adobe_marker) /* next an optional Adobe APP14 */
    emit_adobe_app14(cinfo);
}


/*
 * Write frame header.
 * This consists of DQT and SOFn markers,
 * a conditional LSE marker and a conditional pseudo SOS marker.
 * Note that we do not emit the SOF until we have emitted the DQT(s).
 * This avoids compatibility problems with incorrect implementations that
 * try to error-check the quant table numbers as soon as they see the SOF.
 */

METHODDEF(void)
write_frame_header (j_compress_ptr cinfo)
{
  int ci, prec;
  boolean is_baseline;
  jpeg_component_info *compptr;
  
  /* Emit DQT for each quantization table.
   * Note that emit_dqt() suppresses any duplicate tables.
   */
  prec = 0;
  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
       ci++, compptr++) {
    prec += emit_dqt(cinfo, compptr->quant_tbl_no);
  }
  /* now prec is nonzero iff there are any 16-bit quant tables. */

  /* Check for a non-baseline specification.
   * Note we assume that Huffman table numbers won't be changed later.
   */
  if (cinfo->arith_code || cinfo->progressive_mode ||
      cinfo->data_precision != 8 || cinfo->block_size != DCTSIZE) {
    is_baseline = FALSE;
  } else {
    is_baseline = TRUE;
    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
	 ci++, compptr++) {
      if (compptr->dc_tbl_no > 1 || compptr->ac_tbl_no > 1)
	is_baseline = FALSE;
    }
    if (prec && is_baseline) {
      is_baseline = FALSE;
      /* If it's baseline except for quantizer size, warn the user */
      TRACEMS(cinfo, 0, JTRC_16BIT_TABLES);
    }
  }

  /* Emit the proper SOF marker */
  if (cinfo->arith_code) {
    if (cinfo->progressive_mode)
      emit_sof(cinfo, M_SOF10); /* SOF code for progressive arithmetic */
    else
      emit_sof(cinfo, M_SOF9);  /* SOF code for sequential arithmetic */
  } else {
    if (cinfo->progressive_mode)
      emit_sof(cinfo, M_SOF2);	/* SOF code for progressive Huffman */
    else if (is_baseline)
      emit_sof(cinfo, M_SOF0);	/* SOF code for baseline implementation */
    else
      emit_sof(cinfo, M_SOF1);	/* SOF code for non-baseline Huffman file */
  }

  /* Check to emit LSE inverse color transform specification marker */
  if (cinfo->color_transform)
    emit_lse_ict(cinfo);

  /* Check to emit pseudo SOS marker */
  if (cinfo->progressive_mode && cinfo->block_size != DCTSIZE)
    emit_pseudo_sos(cinfo);
}

src/Source/LibJPEG/jcmarker.c  view on Meta::CPAN

/*
 * Write datastream trailer.
 */

METHODDEF(void)
write_file_trailer (j_compress_ptr cinfo)
{
  emit_marker(cinfo, M_EOI);
}


/*
 * Write an abbreviated table-specification datastream.
 * This consists of SOI, DQT and DHT tables, and EOI.
 * Any table that is defined and not marked sent_table = TRUE will be
 * emitted.  Note that all tables will be marked sent_table = TRUE at exit.
 */

METHODDEF(void)
write_tables_only (j_compress_ptr cinfo)
{
  int i;

  emit_marker(cinfo, M_SOI);

  for (i = 0; i < NUM_QUANT_TBLS; i++) {
    if (cinfo->quant_tbl_ptrs[i] != NULL)
      (void) emit_dqt(cinfo, i);
  }

  if (! cinfo->arith_code) {
    for (i = 0; i < NUM_HUFF_TBLS; i++) {
      if (cinfo->dc_huff_tbl_ptrs[i] != NULL)
	emit_dht(cinfo, i, FALSE);
      if (cinfo->ac_huff_tbl_ptrs[i] != NULL)
	emit_dht(cinfo, i, TRUE);
    }
  }

  emit_marker(cinfo, M_EOI);
}


/*
 * Initialize the marker writer module.
 */

GLOBAL(void)
jinit_marker_writer (j_compress_ptr cinfo)
{
  my_marker_ptr marker;

  /* Create the subobject */
  marker = (my_marker_ptr)
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
				SIZEOF(my_marker_writer));
  cinfo->marker = &marker->pub;
  /* Initialize method pointers */
  marker->pub.write_file_header = write_file_header;
  marker->pub.write_frame_header = write_frame_header;
  marker->pub.write_scan_header = write_scan_header;
  marker->pub.write_file_trailer = write_file_trailer;
  marker->pub.write_tables_only = write_tables_only;
  marker->pub.write_marker_header = write_marker_header;
  marker->pub.write_marker_byte = write_marker_byte;
  /* Initialize private state */
  marker->last_restart_interval = 0;
}