jdmaster.cpp File Reference

#include "jinclude.h"
#include "jpeglib.h"

Include dependency graph for jdmaster.cpp:

Classes
struct	my_decomp_master

Macros
#define	JPEG_INTERNALS

Typedefs
typedef my_decomp_master *	my_master_ptr

Functions
static boolean	use_merged_upsample (j_decompress_ptr cinfo)
void	jpeg_calc_output_dimensions (j_decompress_ptr cinfo)
static void	prepare_range_limit_table (j_decompress_ptr cinfo)
static void	master_selection (j_decompress_ptr cinfo)
static void	prepare_for_output_pass (j_decompress_ptr cinfo)
static void	finish_output_pass (j_decompress_ptr cinfo)
void	jpeg_new_colormap (j_decompress_ptr cinfo)
void	jinit_master_decompress (j_decompress_ptr cinfo)

Macro Definition Documentation

#define JPEG_INTERNALS

Typedef Documentation

typedef my_decomp_master* my_master_ptr

Function Documentation

static boolean use_merged_upsample ( j_decompress_ptr  cinfo )

static

{
#ifdef UPSAMPLE_MERGING_SUPPORTED
  /* Merging is the equivalent of plain box-filter upsampling */
  if (cinfo->do_fancy_upsampling || cinfo->CCIR601_sampling)
    return FALSE;
  /* jdmerge.c only supports YCC=>RGB color conversion */
  if (cinfo->jpeg_color_space != JCS_YCbCr || cinfo->num_components != 3 ||
      cinfo->out_color_space != JCS_RGB ||
      cinfo->out_color_components != RGB_PIXELSIZE)
    return FALSE;
  /* and it only handles 2h1v or 2h2v sampling ratios */
  if (cinfo->comp_info[0].h_samp_factor != 2 ||
      cinfo->comp_info[1].h_samp_factor != 1 ||
      cinfo->comp_info[2].h_samp_factor != 1 ||
      cinfo->comp_info[0].v_samp_factor >  2 ||
      cinfo->comp_info[1].v_samp_factor != 1 ||
      cinfo->comp_info[2].v_samp_factor != 1)
    return FALSE;
  /* furthermore, it doesn't work if we've scaled the IDCTs differently */
  if (cinfo->comp_info[0].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
      cinfo->comp_info[1].DCT_scaled_size != cinfo->min_DCT_scaled_size ||
      cinfo->comp_info[2].DCT_scaled_size != cinfo->min_DCT_scaled_size)
    return FALSE;
  /* ??? also need to test for upsample-time rescaling, when & if supported */
  return TRUE;          /* by golly, it'll work... */
#else
  return FALSE;
#endif
}

void jpeg_calc_output_dimensions

(

j_decompress_ptr

cinfo

)

{
#ifdef IDCT_SCALING_SUPPORTED
  int ci;
  jpeg_component_info *compptr;
#endif

  /* Prevent application from calling me at wrong times */
  if (cinfo->global_state != DSTATE_READY)
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

#ifdef IDCT_SCALING_SUPPORTED

  /* Compute actual output image dimensions and DCT scaling choices. */
  if (cinfo->scale_num * 8 <= cinfo->scale_denom) {
    /* Provide 1/8 scaling */
    cinfo->output_width = (JDIMENSION)
      jdiv_round_up((long) cinfo->image_width, 8L);
    cinfo->output_height = (JDIMENSION)
      jdiv_round_up((long) cinfo->image_height, 8L);
    cinfo->min_DCT_scaled_size = 1;
  } else if (cinfo->scale_num * 4 <= cinfo->scale_denom) {
    /* Provide 1/4 scaling */
    cinfo->output_width = (JDIMENSION)
      jdiv_round_up((long) cinfo->image_width, 4L);
    cinfo->output_height = (JDIMENSION)
      jdiv_round_up((long) cinfo->image_height, 4L);
    cinfo->min_DCT_scaled_size = 2;
  } else if (cinfo->scale_num * 2 <= cinfo->scale_denom) {
    /* Provide 1/2 scaling */
    cinfo->output_width = (JDIMENSION)
      jdiv_round_up((long) cinfo->image_width, 2L);
    cinfo->output_height = (JDIMENSION)
      jdiv_round_up((long) cinfo->image_height, 2L);
    cinfo->min_DCT_scaled_size = 4;
  } else {
    /* Provide 1/1 scaling */
    cinfo->output_width = cinfo->image_width;
    cinfo->output_height = cinfo->image_height;
    cinfo->min_DCT_scaled_size = DCTSIZE;
  }
  /* In selecting the actual DCT scaling for each component, we try to
   * scale up the chroma components via IDCT scaling rather than upsampling.
   * This saves time if the upsampler gets to use 1:1 scaling.
   * Note this code assumes that the supported DCT scalings are powers of 2.
   */
  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
       ci++, compptr++) {
    int ssize = cinfo->min_DCT_scaled_size;
    while (ssize < DCTSIZE &&
       (compptr->h_samp_factor * ssize * 2 <=
        cinfo->max_h_samp_factor * cinfo->min_DCT_scaled_size) &&
       (compptr->v_samp_factor * ssize * 2 <=
        cinfo->max_v_samp_factor * cinfo->min_DCT_scaled_size)) {
      ssize = ssize * 2;
    }
    compptr->DCT_scaled_size = ssize;
  }

  /* Recompute downsampled dimensions of components;
   * application needs to know these if using raw downsampled data.
   */
  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
       ci++, compptr++) {
    /* Size in samples, after IDCT scaling */
    compptr->downsampled_width = (JDIMENSION)
      jdiv_round_up((long) cinfo->image_width *
            (long) (compptr->h_samp_factor * compptr->DCT_scaled_size),
            (long) (cinfo->max_h_samp_factor * DCTSIZE));
    compptr->downsampled_height = (JDIMENSION)
      jdiv_round_up((long) cinfo->image_height *
            (long) (compptr->v_samp_factor * compptr->DCT_scaled_size),
            (long) (cinfo->max_v_samp_factor * DCTSIZE));
  }

#else /* !IDCT_SCALING_SUPPORTED */

  /* Hardwire it to "no scaling" */
  cinfo->output_width = cinfo->image_width;
  cinfo->output_height = cinfo->image_height;
  /* jdinput.c has already initialized DCT_scaled_size to DCTSIZE,
   * and has computed unscaled downsampled_width and downsampled_height.
   */

#endif /* IDCT_SCALING_SUPPORTED */

  /* Report number of components in selected colorspace. */
  /* Probably this should be in the color conversion module... */
  switch (cinfo->out_color_space) {
  case JCS_GRAYSCALE:
    cinfo->out_color_components = 1;
    break;
  case JCS_RGB:
#if RGB_PIXELSIZE != 3
    cinfo->out_color_components = RGB_PIXELSIZE;
    break;
#endif /* else share code with YCbCr */
  case JCS_YCbCr:
    cinfo->out_color_components = 3;
    break;
  case JCS_CMYK:
  case JCS_YCCK:
    cinfo->out_color_components = 4;
    break;
  default:          /* else must be same colorspace as in file */
    cinfo->out_color_components = cinfo->num_components;
    break;
  }
  cinfo->output_components = (cinfo->quantize_colors ? 1 :
                  cinfo->out_color_components);

  /* See if upsampler will want to emit more than one row at a time */
  if (use_merged_upsample(cinfo))
    cinfo->rec_outbuf_height = cinfo->max_v_samp_factor;
  else
    cinfo->rec_outbuf_height = 1;
}

static void prepare_range_limit_table ( j_decompress_ptr  cinfo )

static

{
  JSAMPLE * table;
  int i;

  table = (JSAMPLE *)
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
        (5 * (MAXJSAMPLE+1) + CENTERJSAMPLE) * SIZEOF(JSAMPLE));
  table += (MAXJSAMPLE+1);  /* allow negative subscripts of simple table */
  cinfo->sample_range_limit = table;
  /* First segment of "simple" table: limit[x] = 0 for x < 0 */
  MEMZERO(table - (MAXJSAMPLE+1), (MAXJSAMPLE+1) * SIZEOF(JSAMPLE));
  /* Main part of "simple" table: limit[x] = x */
  for (i = 0; i <= MAXJSAMPLE; i++)
    table[i] = (JSAMPLE) i;
  table += CENTERJSAMPLE;   /* Point to where post-IDCT table starts */
  /* End of simple table, rest of first half of post-IDCT table */
  for (i = CENTERJSAMPLE; i < 2*(MAXJSAMPLE+1); i++)
    table[i] = MAXJSAMPLE;
  /* Second half of post-IDCT table */
  MEMZERO(table + (2 * (MAXJSAMPLE+1)),
      (2 * (MAXJSAMPLE+1) - CENTERJSAMPLE) * SIZEOF(JSAMPLE));
  MEMCOPY(table + (4 * (MAXJSAMPLE+1) - CENTERJSAMPLE),
      cinfo->sample_range_limit, CENTERJSAMPLE * SIZEOF(JSAMPLE));
}

static void master_selection ( j_decompress_ptr  cinfo )

static

{
  my_master_ptr master = (my_master_ptr) cinfo->master;
  boolean use_c_buffer;
  long samplesperrow;
  JDIMENSION jd_samplesperrow;

  /* Initialize dimensions and other stuff */
  jpeg_calc_output_dimensions(cinfo);
  prepare_range_limit_table(cinfo);

  /* Width of an output scanline must be representable as JDIMENSION. */
  samplesperrow = (long) cinfo->output_width * (long) cinfo->out_color_components;
  jd_samplesperrow = (JDIMENSION) samplesperrow;
  if ((long) jd_samplesperrow != samplesperrow)
    ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);

  /* Initialize my private state */
  master->pass_number = 0;
  master->using_merged_upsample = use_merged_upsample(cinfo);

  /* Color quantizer selection */
  master->quantizer_1pass = NULL;
  master->quantizer_2pass = NULL;
  /* No mode changes if not using buffered-image mode. */
  if (! cinfo->quantize_colors || ! cinfo->buffered_image) {
    cinfo->enable_1pass_quant = FALSE;
    cinfo->enable_external_quant = FALSE;
    cinfo->enable_2pass_quant = FALSE;
  }
  if (cinfo->quantize_colors) {
    if (cinfo->raw_data_out)
      ERREXIT(cinfo, JERR_NOTIMPL);
    /* 2-pass quantizer only works in 3-component color space. */
    if (cinfo->out_color_components != 3) {
      cinfo->enable_1pass_quant = TRUE;
      cinfo->enable_external_quant = FALSE;
      cinfo->enable_2pass_quant = FALSE;
      cinfo->colormap = NULL;
    } else if (cinfo->colormap != NULL) {
      cinfo->enable_external_quant = TRUE;
    } else if (cinfo->two_pass_quantize) {
      cinfo->enable_2pass_quant = TRUE;
    } else {
      cinfo->enable_1pass_quant = TRUE;
    }

    if (cinfo->enable_1pass_quant) {
#ifdef QUANT_1PASS_SUPPORTED
      jinit_1pass_quantizer(cinfo);
      master->quantizer_1pass = cinfo->cquantize;
#else
      ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif
    }

    /* We use the 2-pass code to map to external colormaps. */
    if (cinfo->enable_2pass_quant || cinfo->enable_external_quant) {
#ifdef QUANT_2PASS_SUPPORTED
      jinit_2pass_quantizer(cinfo);
      master->quantizer_2pass = cinfo->cquantize;
#else
      ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif
    }
    /* If both quantizers are initialized, the 2-pass one is left active;
     * this is necessary for starting with quantization to an external map.
     */
  }

  /* Post-processing: in particular, color conversion first */
  if (! cinfo->raw_data_out) {
    if (master->using_merged_upsample) {
#ifdef UPSAMPLE_MERGING_SUPPORTED
      jinit_merged_upsampler(cinfo); /* does color conversion too */
#else
      ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif
    } else {
      jinit_color_deconverter(cinfo);
      jinit_upsampler(cinfo);
    }
    jinit_d_post_controller(cinfo, cinfo->enable_2pass_quant);
  }
  /* Inverse DCT */
  jinit_inverse_dct(cinfo);
  /* Entropy decoding: either Huffman or arithmetic coding. */
  if (cinfo->arith_code) {
    ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
  } else {
    if (cinfo->progressive_mode) {
#ifdef D_PROGRESSIVE_SUPPORTED
      jinit_phuff_decoder(cinfo);
#else
      ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif
    } else
      jinit_huff_decoder(cinfo);
  }

  /* Initialize principal buffer controllers. */
  use_c_buffer = cinfo->inputctl->has_multiple_scans || cinfo->buffered_image;
  jinit_d_coef_controller(cinfo, use_c_buffer);

  if (! cinfo->raw_data_out)
    jinit_d_main_controller(cinfo, FALSE /* never need full buffer here */);

  /* We can now tell the memory manager to allocate virtual arrays. */
  (*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);

  /* Initialize input side of decompressor to consume first scan. */
  (*cinfo->inputctl->start_input_pass) (cinfo);

#ifdef D_MULTISCAN_FILES_SUPPORTED
  /* If jpeg_start_decompress will read the whole file, initialize
   * progress monitoring appropriately.  The input step is counted
   * as one pass.
   */
  if (cinfo->progress != NULL && ! cinfo->buffered_image &&
      cinfo->inputctl->has_multiple_scans) {
    int nscans;
    /* Estimate number of scans to set pass_limit. */
    if (cinfo->progressive_mode) {
      /* Arbitrarily estimate 2 interleaved DC scans + 3 AC scans/component. */
      nscans = 2 + 3 * cinfo->num_components;
    } else {
      /* For a nonprogressive multiscan file, estimate 1 scan per component. */
      nscans = cinfo->num_components;
    }
    cinfo->progress->pass_counter = 0L;
    cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows * nscans;
    cinfo->progress->completed_passes = 0;
    cinfo->progress->total_passes = (cinfo->enable_2pass_quant ? 3 : 2);
    /* Count the input pass as done */
    master->pass_number++;
  }
#endif /* D_MULTISCAN_FILES_SUPPORTED */
}

static void prepare_for_output_pass ( j_decompress_ptr  cinfo )

static

{
  my_master_ptr master = (my_master_ptr) cinfo->master;

  if (master->pub.is_dummy_pass) {
#ifdef QUANT_2PASS_SUPPORTED
    /* Final pass of 2-pass quantization */
    master->pub.is_dummy_pass = FALSE;
    (*cinfo->cquantize->start_pass) (cinfo, FALSE);
    (*cinfo->post->start_pass) (cinfo, JBUF_CRANK_DEST);
    (*cinfo->main->start_pass) (cinfo, JBUF_CRANK_DEST);
#else
    ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif /* QUANT_2PASS_SUPPORTED */
  } else {
    if (cinfo->quantize_colors && cinfo->colormap == NULL) {
      /* Select new quantization method */
      if (cinfo->two_pass_quantize && cinfo->enable_2pass_quant) {
    cinfo->cquantize = master->quantizer_2pass;
    master->pub.is_dummy_pass = TRUE;
      } else if (cinfo->enable_1pass_quant) {
    cinfo->cquantize = master->quantizer_1pass;
      } else {
    ERREXIT(cinfo, JERR_MODE_CHANGE);
      }
    }
    (*cinfo->idct->start_pass) (cinfo);
    (*cinfo->coef->start_output_pass) (cinfo);
    if (! cinfo->raw_data_out) {
      if (! master->using_merged_upsample)
    (*cinfo->cconvert->start_pass) (cinfo);
      (*cinfo->upsample->start_pass) (cinfo);
      if (cinfo->quantize_colors)
    (*cinfo->cquantize->start_pass) (cinfo, master->pub.is_dummy_pass);
      (*cinfo->post->start_pass) (cinfo,
        (master->pub.is_dummy_pass ? JBUF_SAVE_AND_PASS : JBUF_PASS_THRU));
      (*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
    }
  }

  /* Set up progress monitor's pass info if present */
  if (cinfo->progress != NULL) {
    cinfo->progress->completed_passes = master->pass_number;
    cinfo->progress->total_passes = master->pass_number +
                    (master->pub.is_dummy_pass ? 2 : 1);
    /* In buffered-image mode, we assume one more output pass if EOI not
     * yet reached, but no more passes if EOI has been reached.
     */
    if (cinfo->buffered_image && ! cinfo->inputctl->eoi_reached) {
      cinfo->progress->total_passes += (cinfo->enable_2pass_quant ? 2 : 1);
    }
  }
}

static void finish_output_pass ( j_decompress_ptr  cinfo )

static

{
  my_master_ptr master = (my_master_ptr) cinfo->master;

  if (cinfo->quantize_colors)
    (*cinfo->cquantize->finish_pass) (cinfo);
  master->pass_number++;
}

void jpeg_new_colormap

(

j_decompress_ptr

cinfo

)

{
  my_master_ptr master = (my_master_ptr) cinfo->master;

  /* Prevent application from calling me at wrong times */
  if (cinfo->global_state != DSTATE_BUFIMAGE)
    ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

  if (cinfo->quantize_colors && cinfo->enable_external_quant &&
      cinfo->colormap != NULL) {
    /* Select 2-pass quantizer for external colormap use */
    cinfo->cquantize = master->quantizer_2pass;
    /* Notify quantizer of colormap change */
    (*cinfo->cquantize->new_color_map) (cinfo);
    master->pub.is_dummy_pass = FALSE; /* just in case */
  } else
    ERREXIT(cinfo, JERR_MODE_CHANGE);
}

void jinit_master_decompress

(

j_decompress_ptr

cinfo

)

{
  my_master_ptr master;

  master = (my_master_ptr)
      (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
                  SIZEOF(my_decomp_master));
  cinfo->master = (struct jpeg_decomp_master *) master;
  master->pub.prepare_for_output_pass = prepare_for_output_pass;
  master->pub.finish_output_pass = finish_output_pass;

  master->pub.is_dummy_pass = FALSE;

  master_selection(cinfo);
}