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

  /* Zero out pointers to permanent structures. */
  cinfo->progress = NULL;
  cinfo->src = NULL;

  for (i = 0; i < NUM_QUANT_TBLS; i++)
    cinfo->quant_tbl_ptrs[i] = NULL;

  for (i = 0; i < NUM_HUFF_TBLS; i++) {
    cinfo->dc_huff_tbl_ptrs[i] = NULL;
    cinfo->ac_huff_tbl_ptrs[i] = NULL;
  }

  /* Initialize marker processor so application can override methods
   * for COM, APPn markers before calling jpeg_read_header.
   */
  cinfo->marker_list = NULL;
  jinit_marker_reader(cinfo);

  /* And initialize the overall input controller. */
  jinit_input_controller(cinfo);

  /* OK, I'm ready */
  cinfo->global_state = DSTATE_START;
}


/*
 * Destruction of a JPEG decompression object
 */

GLOBAL(void)
jpeg_destroy_decompress (j_decompress_ptr cinfo)
{
  jpeg_destroy((j_common_ptr) cinfo); /* use common routine */
}


/*
 * Abort processing of a JPEG decompression operation,
 * but don't destroy the object itself.
 */

GLOBAL(void)
jpeg_abort_decompress (j_decompress_ptr cinfo)
{
  jpeg_abort((j_common_ptr) cinfo); /* use common routine */
}


/*
 * Set default decompression parameters.
 */

LOCAL(void)
default_decompress_parms (j_decompress_ptr cinfo)
{
  int cid0, cid1, cid2;

  /* Guess the input colorspace, and set output colorspace accordingly. */
  /* Note application may override our guesses. */
  switch (cinfo->num_components) {
  case 1:
    cinfo->jpeg_color_space = JCS_GRAYSCALE;
    cinfo->out_color_space = JCS_GRAYSCALE;
    break;
    
  case 3:
    cid0 = cinfo->comp_info[0].component_id;
    cid1 = cinfo->comp_info[1].component_id;
    cid2 = cinfo->comp_info[2].component_id;

    /* First try to guess from the component IDs */
    if      (cid0 == 0x01 && cid1 == 0x02 && cid2 == 0x03)
      cinfo->jpeg_color_space = JCS_YCbCr;
    else if (cid0 == 0x01 && cid1 == 0x22 && cid2 == 0x23)
      cinfo->jpeg_color_space = JCS_BG_YCC;
    else if (cid0 == 0x52 && cid1 == 0x47 && cid2 == 0x42)
      cinfo->jpeg_color_space = JCS_RGB;	/* ASCII 'R', 'G', 'B' */
    else if (cid0 == 0x72 && cid1 == 0x67 && cid2 == 0x62)
      cinfo->jpeg_color_space = JCS_BG_RGB;	/* ASCII 'r', 'g', 'b' */
    else if (cinfo->saw_JFIF_marker)
      cinfo->jpeg_color_space = JCS_YCbCr;	/* assume it's YCbCr */
    else if (cinfo->saw_Adobe_marker) {
      switch (cinfo->Adobe_transform) {
      case 0:
	cinfo->jpeg_color_space = JCS_RGB;
	break;
      case 1:
	cinfo->jpeg_color_space = JCS_YCbCr;
	break;
      default:
	WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
	cinfo->jpeg_color_space = JCS_YCbCr;	/* assume it's YCbCr */
	break;
      }
    } else {
      TRACEMS3(cinfo, 1, JTRC_UNKNOWN_IDS, cid0, cid1, cid2);
      cinfo->jpeg_color_space = JCS_YCbCr;	/* assume it's YCbCr */
    }
    /* Always guess RGB is proper output colorspace. */
    cinfo->out_color_space = JCS_RGB;
    break;
    
  case 4:
    if (cinfo->saw_Adobe_marker) {
      switch (cinfo->Adobe_transform) {
      case 0:
	cinfo->jpeg_color_space = JCS_CMYK;
	break;
      case 2:
	cinfo->jpeg_color_space = JCS_YCCK;
	break;
      default:
	WARNMS1(cinfo, JWRN_ADOBE_XFORM, cinfo->Adobe_transform);
	cinfo->jpeg_color_space = JCS_YCCK;	/* assume it's YCCK */
	break;
      }
    } else {
      /* No special markers, assume straight CMYK. */
      cinfo->jpeg_color_space = JCS_CMYK;
    }
    cinfo->out_color_space = JCS_CMYK;
    break;
    
  default:
    cinfo->jpeg_color_space = JCS_UNKNOWN;
    cinfo->out_color_space = JCS_UNKNOWN;
    break;
  }

  /* Set defaults for other decompression parameters. */
  cinfo->scale_num = cinfo->block_size;		/* 1:1 scaling */
  cinfo->scale_denom = cinfo->block_size;
  cinfo->output_gamma = 1.0;
  cinfo->buffered_image = FALSE;
  cinfo->raw_data_out = FALSE;
  cinfo->dct_method = JDCT_DEFAULT;
  cinfo->do_fancy_upsampling = TRUE;
  cinfo->do_block_smoothing = TRUE;
  cinfo->quantize_colors = FALSE;
  /* We set these in case application only sets quantize_colors. */
  cinfo->dither_mode = JDITHER_FS;
#ifdef QUANT_2PASS_SUPPORTED
  cinfo->two_pass_quantize = TRUE;
#else
  cinfo->two_pass_quantize = FALSE;
#endif
  cinfo->desired_number_of_colors = 256;
  cinfo->colormap = NULL;
  /* Initialize for no mode change in buffered-image mode. */
  cinfo->enable_1pass_quant = FALSE;
  cinfo->enable_external_quant = FALSE;
  cinfo->enable_2pass_quant = FALSE;
}


/*
 * Decompression startup: read start of JPEG datastream to see what's there.
 * Need only initialize JPEG object and supply a data source before calling.
 *