jcprepct.cpp File Reference

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

Include dependency graph for jcprepct.cpp:

Classes
struct	my_prep_controller

Macros
#define	JPEG_INTERNALS
#define	CONTEXT_ROWS_SUPPORTED

Typedefs
typedef my_prep_controller *	my_prep_ptr

Functions
static void	start_pass_prep (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
static void	expand_bottom_edge (JSAMPARRAY image_data, JDIMENSION num_cols, int input_rows, int output_rows)
static void	pre_process_data (j_compress_ptr cinfo, JSAMPARRAY input_buf, JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail, JSAMPIMAGE output_buf, JDIMENSION *out_row_group_ctr, JDIMENSION out_row_groups_avail)
static void	pre_process_context (j_compress_ptr cinfo, JSAMPARRAY input_buf, JDIMENSION *in_row_ctr, JDIMENSION in_rows_avail, JSAMPIMAGE output_buf, JDIMENSION *out_row_group_ctr, JDIMENSION out_row_groups_avail)
static void	create_context_buffer (j_compress_ptr cinfo)
void	jinit_c_prep_controller (j_compress_ptr cinfo, boolean need_full_buffer)

Macro Definition Documentation

#define JPEG_INTERNALS

#define CONTEXT_ROWS_SUPPORTED

Typedef Documentation

typedef my_prep_controller* my_prep_ptr

Function Documentation

static void start_pass_prep ( j_compress_ptr  cinfo, J_BUF_MODE  pass_mode  )

static

{
  my_prep_ptr prep = (my_prep_ptr) cinfo->prep;

  if (pass_mode != JBUF_PASS_THRU)
    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

  /* Initialize total-height counter for detecting bottom of image */
  prep->rows_to_go = cinfo->image_height;
  /* Mark the conversion buffer empty */
  prep->next_buf_row = 0;
#ifdef CONTEXT_ROWS_SUPPORTED
  /* Preset additional state variables for context mode.
   * These aren't used in non-context mode, so we needn't test which mode.
   */
  prep->this_row_group = 0;
  /* Set next_buf_stop to stop after two row groups have been read in. */
  prep->next_buf_stop = 2 * cinfo->max_v_samp_factor;
#endif
}

static void expand_bottom_edge ( JSAMPARRAY  image_data, JDIMENSION  num_cols, int  input_rows, int  output_rows  )

static

{
  register int row;

  for (row = input_rows; row < output_rows; row++) {
    jcopy_sample_rows(image_data, input_rows-1, image_data, row,
              1, num_cols);
  }
}

static void pre_process_data ( j_compress_ptr  cinfo, JSAMPARRAY  input_buf, JDIMENSION *  in_row_ctr, JDIMENSION  in_rows_avail, JSAMPIMAGE  output_buf, JDIMENSION *  out_row_group_ctr, JDIMENSION  out_row_groups_avail  )

static

{
  my_prep_ptr prep = (my_prep_ptr) cinfo->prep;
  int numrows, ci;
  JDIMENSION inrows;
  jpeg_component_info * compptr;

  while (*in_row_ctr < in_rows_avail &&
     *out_row_group_ctr < out_row_groups_avail) {
    /* Do color conversion to fill the conversion buffer. */
    inrows = in_rows_avail - *in_row_ctr;
    numrows = cinfo->max_v_samp_factor - prep->next_buf_row;
    numrows = (int) MIN((JDIMENSION) numrows, inrows);
    (*cinfo->cconvert->color_convert) (cinfo, input_buf + *in_row_ctr,
                       prep->color_buf,
                       (JDIMENSION) prep->next_buf_row,
                       numrows);
    *in_row_ctr += numrows;
    prep->next_buf_row += numrows;
    prep->rows_to_go -= numrows;
    /* If at bottom of image, pad to fill the conversion buffer. */
    if (prep->rows_to_go == 0 &&
    prep->next_buf_row < cinfo->max_v_samp_factor) {
      for (ci = 0; ci < cinfo->num_components; ci++) {
    expand_bottom_edge(prep->color_buf[ci], cinfo->image_width,
               prep->next_buf_row, cinfo->max_v_samp_factor);
      }
      prep->next_buf_row = cinfo->max_v_samp_factor;
    }
    /* If we've filled the conversion buffer, empty it. */
    if (prep->next_buf_row == cinfo->max_v_samp_factor) {
      (*cinfo->downsample->downsample) (cinfo,
                    prep->color_buf, (JDIMENSION) 0,
                    output_buf, *out_row_group_ctr);
      prep->next_buf_row = 0;
      (*out_row_group_ctr)++;
    }
    /* If at bottom of image, pad the output to a full iMCU height.
     * Note we assume the caller is providing a one-iMCU-height output buffer!
     */
    if (prep->rows_to_go == 0 &&
    *out_row_group_ctr < out_row_groups_avail) {
      for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
       ci++, compptr++) {
    expand_bottom_edge(output_buf[ci],
               compptr->width_in_blocks * DCTSIZE,
               (int) (*out_row_group_ctr * compptr->v_samp_factor),
               (int) (out_row_groups_avail * compptr->v_samp_factor));
      }
      *out_row_group_ctr = out_row_groups_avail;
      break;            /* can exit outer loop without test */
    }
  }
}

static void pre_process_context ( j_compress_ptr  cinfo, JSAMPARRAY  input_buf, JDIMENSION *  in_row_ctr, JDIMENSION  in_rows_avail, JSAMPIMAGE  output_buf, JDIMENSION *  out_row_group_ctr, JDIMENSION  out_row_groups_avail  )

static

{
  my_prep_ptr prep = (my_prep_ptr) cinfo->prep;
  int numrows, ci;
  int buf_height = cinfo->max_v_samp_factor * 3;
  JDIMENSION inrows;

  while (*out_row_group_ctr < out_row_groups_avail) {
    if (*in_row_ctr < in_rows_avail) {
      /* Do color conversion to fill the conversion buffer. */
      inrows = in_rows_avail - *in_row_ctr;
      numrows = prep->next_buf_stop - prep->next_buf_row;
      numrows = (int) MIN((JDIMENSION) numrows, inrows);
      (*cinfo->cconvert->color_convert) (cinfo, input_buf + *in_row_ctr,
                     prep->color_buf,
                     (JDIMENSION) prep->next_buf_row,
                     numrows);
      /* Pad at top of image, if first time through */
      if (prep->rows_to_go == cinfo->image_height) {
    for (ci = 0; ci < cinfo->num_components; ci++) {
      int row;
      for (row = 1; row <= cinfo->max_v_samp_factor; row++) {
        jcopy_sample_rows(prep->color_buf[ci], 0,
                  prep->color_buf[ci], -row,
                  1, cinfo->image_width);
      }
    }
      }
      *in_row_ctr += numrows;
      prep->next_buf_row += numrows;
      prep->rows_to_go -= numrows;
    } else {
      /* Return for more data, unless we are at the bottom of the image. */
      if (prep->rows_to_go != 0)
    break;
      /* When at bottom of image, pad to fill the conversion buffer. */
      if (prep->next_buf_row < prep->next_buf_stop) {
    for (ci = 0; ci < cinfo->num_components; ci++) {
      expand_bottom_edge(prep->color_buf[ci], cinfo->image_width,
                 prep->next_buf_row, prep->next_buf_stop);
    }
    prep->next_buf_row = prep->next_buf_stop;
      }
    }
    /* If we've gotten enough data, downsample a row group. */
    if (prep->next_buf_row == prep->next_buf_stop) {
      (*cinfo->downsample->downsample) (cinfo,
                    prep->color_buf,
                    (JDIMENSION) prep->this_row_group,
                    output_buf, *out_row_group_ctr);
      (*out_row_group_ctr)++;
      /* Advance pointers with wraparound as necessary. */
      prep->this_row_group += cinfo->max_v_samp_factor;
      if (prep->this_row_group >= buf_height)
    prep->this_row_group = 0;
      if (prep->next_buf_row >= buf_height)
    prep->next_buf_row = 0;
      prep->next_buf_stop = prep->next_buf_row + cinfo->max_v_samp_factor;
    }
  }
}

static void create_context_buffer ( j_compress_ptr  cinfo )

static

{
  my_prep_ptr prep = (my_prep_ptr) cinfo->prep;
  int rgroup_height = cinfo->max_v_samp_factor;
  int ci, i;
  jpeg_component_info * compptr;
  JSAMPARRAY true_buffer, fake_buffer;

  /* Grab enough space for fake row pointers for all the components;
   * we need five row groups' worth of pointers for each component.
   */
  fake_buffer = (JSAMPARRAY)
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
                (cinfo->num_components * 5 * rgroup_height) *
                SIZEOF(JSAMPROW));

  for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
       ci++, compptr++) {
    /* Allocate the actual buffer space (3 row groups) for this component.
     * We make the buffer wide enough to allow the downsampler to edge-expand
     * horizontally within the buffer, if it so chooses.
     */
    true_buffer = (*cinfo->mem->alloc_sarray)
      ((j_common_ptr) cinfo, JPOOL_IMAGE,
       (JDIMENSION) (((long) compptr->width_in_blocks * DCTSIZE *
              cinfo->max_h_samp_factor) / compptr->h_samp_factor),
       (JDIMENSION) (3 * rgroup_height));
    /* Copy true buffer row pointers into the middle of the fake row array */
    MEMCOPY(fake_buffer + rgroup_height, true_buffer,
        3 * rgroup_height * SIZEOF(JSAMPROW));
    /* Fill in the above and below wraparound pointers */
    for (i = 0; i < rgroup_height; i++) {
      fake_buffer[i] = true_buffer[2 * rgroup_height + i];
      fake_buffer[4 * rgroup_height + i] = true_buffer[i];
    }
    prep->color_buf[ci] = fake_buffer + rgroup_height;
    fake_buffer += 5 * rgroup_height; /* point to space for next component */
  }
}

void jinit_c_prep_controller	(	j_compress_ptr	cinfo,
		boolean	need_full_buffer
	)

{
  my_prep_ptr prep;
  int ci;
  jpeg_component_info * compptr;

  if (need_full_buffer)     /* safety check */
    ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);

  prep = (my_prep_ptr)
    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
                SIZEOF(my_prep_controller));
  cinfo->prep = (struct jpeg_c_prep_controller *) prep;
  prep->pub.start_pass = start_pass_prep;

  /* Allocate the color conversion buffer.
   * We make the buffer wide enough to allow the downsampler to edge-expand
   * horizontally within the buffer, if it so chooses.
   */
  if (cinfo->downsample->need_context_rows) {
    /* Set up to provide context rows */
#ifdef CONTEXT_ROWS_SUPPORTED
    prep->pub.pre_process_data = pre_process_context;
    create_context_buffer(cinfo);
#else
    ERREXIT(cinfo, JERR_NOT_COMPILED);
#endif
  } else {
    /* No context, just make it tall enough for one row group */
    prep->pub.pre_process_data = pre_process_data;
    for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
     ci++, compptr++) {
      prep->color_buf[ci] = (*cinfo->mem->alloc_sarray)
    ((j_common_ptr) cinfo, JPOOL_IMAGE,
     (JDIMENSION) (((long) compptr->width_in_blocks * DCTSIZE *
            cinfo->max_h_samp_factor) / compptr->h_samp_factor),
     (JDIMENSION) cinfo->max_v_samp_factor);
    }
  }
}