www.pudn.com > Cimage.zip > JCMASTER.C
/*
* jcmaster.c
*
* Copyright (C) 1991-1994, 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 master control logic for the JPEG compressor.
* These routines are concerned with selecting the modules to be executed
* and with determining the number of passes and the work to be done in each
* pass.
*/
#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
/* Private state */
typedef struct {
struct jpeg_comp_master pub; /* public fields */
int pass_number; /* eventually need more complex state... */
} my_comp_master;
typedef my_comp_master * my_master_ptr;
/*
* Support routines that do various essential calculations.
*/
LOCAL void
initial_setup (j_compress_ptr cinfo)
/* Do computations that are needed before master selection phase */
{
int ci;
jpeg_component_info *compptr;
long samplesperrow;
JDIMENSION jd_samplesperrow;
/* Sanity check on image dimensions */
if (cinfo->image_height <= 0 || cinfo->image_width <= 0
|| cinfo->num_components <= 0 || cinfo->input_components <= 0)
ERREXIT(cinfo, JERR_EMPTY_IMAGE);
/* Make sure image isn't bigger than I can handle */
if ((long) cinfo->image_height > (long) JPEG_MAX_DIMENSION ||
(long) cinfo->image_width > (long) JPEG_MAX_DIMENSION)
ERREXIT1(cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION);
/* Width of an input scanline must be representable as JDIMENSION. */
samplesperrow = (long) cinfo->image_width * (long) cinfo->input_components;
jd_samplesperrow = (JDIMENSION) samplesperrow;
if ((long) jd_samplesperrow != samplesperrow)
ERREXIT(cinfo, JERR_WIDTH_OVERFLOW);
/* For now, precision must match compiled-in value... */
if (cinfo->data_precision != BITS_IN_JSAMPLE)
ERREXIT1(cinfo, JERR_BAD_PRECISION, cinfo->data_precision);
/* Check that number of components won't exceed internal array sizes */
if (cinfo->num_components > MAX_COMPONENTS)
ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
MAX_COMPONENTS);
/* Compute maximum sampling factors; check factor validity */
cinfo->max_h_samp_factor = 1;
cinfo->max_v_samp_factor = 1;
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
ci++, compptr++) {
if (compptr->h_samp_factor<=0 || compptr->h_samp_factor>MAX_SAMP_FACTOR ||
compptr->v_samp_factor<=0 || compptr->v_samp_factor>MAX_SAMP_FACTOR)
ERREXIT(cinfo, JERR_BAD_SAMPLING);
cinfo->max_h_samp_factor = MAX(cinfo->max_h_samp_factor,
compptr->h_samp_factor);
cinfo->max_v_samp_factor = MAX(cinfo->max_v_samp_factor,
compptr->v_samp_factor);
}
/* Compute dimensions of components */
for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
ci++, compptr++) {
/* For compression, we never do DCT scaling. */
compptr->DCT_scaled_size = DCTSIZE;
/* Size in DCT blocks */
compptr->width_in_blocks = (JDIMENSION)
jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
(long) (cinfo->max_h_samp_factor * DCTSIZE));
compptr->height_in_blocks = (JDIMENSION)
jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
(long) (cinfo->max_v_samp_factor * DCTSIZE));
/* Size in samples */
compptr->downsampled_width = (JDIMENSION)
jdiv_round_up((long) cinfo->image_width * (long) compptr->h_samp_factor,
(long) cinfo->max_h_samp_factor);
compptr->downsampled_height = (JDIMENSION)
jdiv_round_up((long) cinfo->image_height * (long) compptr->v_samp_factor,
(long) cinfo->max_v_samp_factor);
/* Mark component needed (this flag isn't actually used for compression) */
compptr->component_needed = TRUE;
}
/* Compute number of fully interleaved MCU rows (number of times that
* main controller will call coefficient controller).
*/
cinfo->total_iMCU_rows = (JDIMENSION)
jdiv_round_up((long) cinfo->image_height,
(long) (cinfo->max_v_samp_factor*DCTSIZE));
}
LOCAL void
per_scan_setup (j_compress_ptr cinfo)
/* Do computations that are needed before processing a JPEG scan */
/* cinfo->comps_in_scan and cinfo->cur_comp_info[] are already set */
{
int ci, mcublks, tmp;
jpeg_component_info *compptr;
if (cinfo->comps_in_scan == 1) {
/* Noninterleaved (single-component) scan */
compptr = cinfo->cur_comp_info[0];
/* Overall image size in MCUs */
cinfo->MCUs_per_row = compptr->width_in_blocks;
cinfo->MCU_rows_in_scan = compptr->height_in_blocks;
/* For noninterleaved scan, always one block per MCU */
compptr->MCU_width = 1;
compptr->MCU_height = 1;
compptr->MCU_blocks = 1;
compptr->MCU_sample_width = DCTSIZE;
compptr->last_col_width = 1;
compptr->last_row_height = 1;
/* Prepare array describing MCU composition */
cinfo->blocks_in_MCU = 1;
cinfo->MCU_membership[0] = 0;
} else {
/* Interleaved (multi-component) scan */
if (cinfo->comps_in_scan <= 0 || cinfo->comps_in_scan > MAX_COMPS_IN_SCAN)
ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
MAX_COMPS_IN_SCAN);
/* Overall image size in MCUs */
cinfo->MCUs_per_row = (JDIMENSION)
jdiv_round_up((long) cinfo->image_width,
(long) (cinfo->max_h_samp_factor*DCTSIZE));
cinfo->MCU_rows_in_scan = (JDIMENSION)
jdiv_round_up((long) cinfo->image_height,
(long) (cinfo->max_v_samp_factor*DCTSIZE));
cinfo->blocks_in_MCU = 0;
for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
compptr = cinfo->cur_comp_info[ci];
/* Sampling factors give # of blocks of component in each MCU */
compptr->MCU_width = compptr->h_samp_factor;
compptr->MCU_height = compptr->v_samp_factor;
compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
compptr->MCU_sample_width = compptr->MCU_width * DCTSIZE;
/* Figure number of non-dummy blocks in last MCU column & row */
tmp = (int) (compptr->width_in_blocks % compptr->MCU_width);
if (tmp == 0) tmp = compptr->MCU_width;
compptr->last_col_width = tmp;
tmp = (int) (compptr->height_in_blocks % compptr->MCU_height);
if (tmp == 0) tmp = compptr->MCU_height;
compptr->last_row_height = tmp;
/* Prepare array describing MCU composition */
mcublks = compptr->MCU_blocks;
if (cinfo->blocks_in_MCU + mcublks > MAX_BLOCKS_IN_MCU)
ERREXIT(cinfo, JERR_BAD_MCU_SIZE);
while (mcublks-- > 0) {
cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
}
}
}
/* Convert restart specified in rows to actual MCU count. */
/* Note that count must fit in 16 bits, so we provide limiting. */
if (cinfo->restart_in_rows > 0) {
long nominal = (long) cinfo->restart_in_rows * (long) cinfo->MCUs_per_row;
cinfo->restart_interval = (unsigned int) MIN(nominal, 65535L);
}
}
/*
* Master selection of compression modules.
* This is done once at the start of processing an image. We determine
* which modules will be used and give them appropriate initialization calls.
*/
LOCAL void
master_selection (j_compress_ptr cinfo)
{
my_master_ptr master = (my_master_ptr) cinfo->master;
initial_setup(cinfo);
master->pass_number = 0;
/* There's not a lot of smarts here right now, but it'll get more
* complicated when we have multiple implementations available...
*/
/* Preprocessing */
if (! cinfo->raw_data_in) {
jinit_color_converter(cinfo);
jinit_downsampler(cinfo);
jinit_c_prep_controller(cinfo, FALSE /* never need full buffer here */);
}
/* Forward DCT */
jinit_forward_dct(cinfo);
/* Entropy encoding: either Huffman or arithmetic coding. */
if (cinfo->arith_code) {
#ifdef C_ARITH_CODING_SUPPORTED
jinit_arith_encoder(cinfo);
#else
ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
#endif
} else
jinit_huff_encoder(cinfo);
/* For now, a full buffer is needed only for Huffman optimization. */
jinit_c_coef_controller(cinfo, cinfo->optimize_coding);
jinit_c_main_controller(cinfo, FALSE /* never need full buffer here */);
jinit_marker_writer(cinfo);
/* We can now tell the memory manager to allocate virtual arrays. */
(*cinfo->mem->realize_virt_arrays) ((j_common_ptr) cinfo);
/* Write the datastream header (SOI) immediately.
* Frame and scan headers are postponed till later.
* This lets application insert special markers after the SOI.
*/
(*cinfo->marker->write_file_header) (cinfo);
}
/*
* Per-pass setup.
* This is called at the beginning of each pass. We determine which modules
* will be active during this pass and give them appropriate start_pass calls.
* We also set is_last_pass to indicate whether any more passes will be
* required.
*/
METHODDEF void
prepare_for_pass (j_compress_ptr cinfo)
{
my_master_ptr master = (my_master_ptr) cinfo->master;
int ci;
int npasses;
/* ???? JUST A QUICK CROCK FOR NOW ??? */
/* For now, handle only single interleaved output scan; */
/* we support two passes for Huffman optimization. */
/* Prepare for single scan containing all components */
if (cinfo->num_components > MAX_COMPS_IN_SCAN)
ERREXIT2(cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
MAX_COMPS_IN_SCAN);
cinfo->comps_in_scan = cinfo->num_components;
for (ci = 0; ci < cinfo->num_components; ci++) {
cinfo->cur_comp_info[ci] = &cinfo->comp_info[ci];
}
per_scan_setup(cinfo);
if (! cinfo->optimize_coding) {
/* Standard single-pass case */
npasses = 1;
master->pub.call_pass_startup = TRUE;
master->pub.is_last_pass = TRUE;
if (! cinfo->raw_data_in) {
(*cinfo->cconvert->start_pass) (cinfo);
(*cinfo->downsample->start_pass) (cinfo);
(*cinfo->prep->start_pass) (cinfo, JBUF_PASS_THRU);
}
(*cinfo->fdct->start_pass) (cinfo);
(*cinfo->entropy->start_pass) (cinfo, FALSE);
(*cinfo->coef->start_pass) (cinfo, JBUF_PASS_THRU);
(*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
} else {
npasses = 2;
switch (master->pass_number) {
case 0:
/* Huffman optimization: run all modules, gather statistics */
master->pub.call_pass_startup = FALSE;
master->pub.is_last_pass = FALSE;
if (! cinfo->raw_data_in) {
(*cinfo->cconvert->start_pass) (cinfo);
(*cinfo->downsample->start_pass) (cinfo);
(*cinfo->prep->start_pass) (cinfo, JBUF_PASS_THRU);
}
(*cinfo->fdct->start_pass) (cinfo);
(*cinfo->entropy->start_pass) (cinfo, TRUE);
(*cinfo->coef->start_pass) (cinfo, JBUF_SAVE_AND_PASS);
(*cinfo->main->start_pass) (cinfo, JBUF_PASS_THRU);
break;
case 1:
/* Second pass: reread data from coefficient buffer */
master->pub.is_last_pass = TRUE;
(*cinfo->entropy->start_pass) (cinfo, FALSE);
(*cinfo->coef->start_pass) (cinfo, JBUF_CRANK_DEST);
/* We emit frame/scan headers now */
(*cinfo->marker->write_frame_header) (cinfo);
(*cinfo->marker->write_scan_header) (cinfo);
break;
}
}
/* Set up progress monitor's pass info if present */
if (cinfo->progress != NULL) {
cinfo->progress->completed_passes = master->pass_number;
cinfo->progress->total_passes = npasses;
}
master->pass_number++;
}
/*
* Special start-of-pass hook.
* This is called by jpeg_write_scanlines if call_pass_startup is TRUE.
* In single-pass processing, we need this hook because we don't want to
* write frame/scan headers during jpeg_start_compress; we want to let the
* application write COM markers etc. between jpeg_start_compress and the
* jpeg_write_scanlines loop.
* In multi-pass processing, this routine is not used.
*/
METHODDEF void
pass_startup (j_compress_ptr cinfo)
{
cinfo->master->call_pass_startup = FALSE; /* reset flag so call only once */
(*cinfo->marker->write_frame_header) (cinfo);
(*cinfo->marker->write_scan_header) (cinfo);
}
/*
* Finish up at end of pass.
*/
METHODDEF void
finish_pass_master (j_compress_ptr cinfo)
{
/* More complex logic later ??? */
/* The entropy coder needs an end-of-pass call, either to analyze
* statistics or to flush its output buffer.
*/
(*cinfo->entropy->finish_pass) (cinfo);
}
/*
* Initialize master compression control.
* This creates my own subrecord and also performs the master selection phase,
* which causes other modules to create their subrecords.
*/
GLOBAL void
jinit_master_compress (j_compress_ptr cinfo)
{
my_master_ptr master;
master = (my_master_ptr)
(*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
SIZEOF(my_comp_master));
cinfo->master = (struct jpeg_comp_master *) master;
master->pub.prepare_for_pass = prepare_for_pass;
master->pub.pass_startup = pass_startup;
master->pub.finish_pass = finish_pass_master;
master_selection(cinfo);
}