+++ /dev/null
-/*
- * jcprepct.c
- *
- * Copyright (C) 1994-1998, Thomas G. Lane.
- * This file is part of the Independent JPEG Group's software.
- * For conditions of distribution and use, see the accompanying README file.
- *
- * This file contains the compression preprocessing controller.
- * This controller manages the color conversion, downsampling,
- * and edge expansion steps.
- *
- * Most of the complexity here is associated with buffering input rows
- * as required by the downsampler. See the comments at the head of
- * jcsample.c for the downsampler's needs.
- */
-
-#define JPEG_INTERNALS
-#include "jinclude.h"
-#include "jpeglib.h"
-
-
-/* At present, jcsample.c can request context rows only for smoothing.
- * In the future, we might also need context rows for CCIR601 sampling
- * or other more-complex downsampling procedures. The code to support
- * context rows should be compiled only if needed.
- */
-#ifdef INPUT_SMOOTHING_SUPPORTED
-#define CONTEXT_ROWS_SUPPORTED
-#endif
-
-
-/*
- * For the simple (no-context-row) case, we just need to buffer one
- * row group's worth of pixels for the downsampling step. At the bottom of
- * the image, we pad to a full row group by replicating the last pixel row.
- * The downsampler's last output row is then replicated if needed to pad
- * out to a full iMCU row.
- *
- * When providing context rows, we must buffer three row groups' worth of
- * pixels. Three row groups are physically allocated, but the row pointer
- * arrays are made five row groups high, with the extra pointers above and
- * below "wrapping around" to point to the last and first real row groups.
- * This allows the downsampler to access the proper context rows.
- * At the top and bottom of the image, we create dummy context rows by
- * copying the first or last real pixel row. This copying could be avoided
- * by pointer hacking as is done in jdmainct.c, but it doesn't seem worth the
- * trouble on the compression side.
- */
-
-
-/* Private buffer controller object */
-
-typedef struct {
- struct jpeg_c_prep_controller pub; /* public fields */
-
- /* Downsampling input buffer. This buffer holds color-converted data
- * until we have enough to do a downsample step.
- */
- JSAMPARRAY color_buf[MAX_COMPONENTS];
-
- JDIMENSION rows_to_go; /* counts rows remaining in source image */
- int next_buf_row; /* index of next row to store in color_buf */
-
-#ifdef CONTEXT_ROWS_SUPPORTED /* only needed for context case */
- int this_row_group; /* starting row index of group to process */
- int next_buf_stop; /* downsample when we reach this index */
-#endif
-} my_prep_controller;
-
-typedef my_prep_controller * my_prep_ptr;
-
-
-/*
- * Initialize for a processing pass.
- */
-
-METHODDEF(void)
-start_pass_prep (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
-{
- 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
-}
-
-
-/*
- * Expand an image vertically from height input_rows to height output_rows,
- * by duplicating the bottom row.
- */
-
-LOCAL(void)
-expand_bottom_edge (JSAMPARRAY image_data, JDIMENSION num_cols,
- int input_rows, int output_rows)
-{
- 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);
- }
-}
-
-
-/*
- * Process some data in the simple no-context case.
- *
- * Preprocessor output data is counted in "row groups". A row group
- * is defined to be v_samp_factor sample rows of each component.
- * Downsampling will produce this much data from each max_v_samp_factor
- * input rows.
- */
-
-METHODDEF(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)
-{
- 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_data_units * cinfo->data_unit,
- (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 */
- }
- }
-}
-
-
-#ifdef CONTEXT_ROWS_SUPPORTED
-
-/*
- * Process some data in the context case.
- */
-
-METHODDEF(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)
-{
- 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;
- }
- }
-}
-
-
-/*
- * Create the wrapped-around downsampling input buffer needed for context mode.
- */
-
-LOCAL(void)
-create_context_buffer (j_compress_ptr cinfo)
-{
- 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_data_units * cinfo->data_unit *
- 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 */
- }
-}
-
-#endif /* CONTEXT_ROWS_SUPPORTED */
-
-
-/*
- * Initialize preprocessing controller.
- */
-
-GLOBAL(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_data_units * cinfo->data_unit *
- cinfo->max_h_samp_factor) / compptr->h_samp_factor),
- (JDIMENSION) cinfo->max_v_samp_factor);
- }
- }
-}
git://git.creatis.insa-lyon.fr / gdcm.git / blobdiff