www.pudn.com > Cimage.zip > JCAPI.C
/*
* jcapi.c
*
* Copyright (C) 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 application interface code for the compression half of
* the JPEG library. Most of the routines intended to be called directly by
* an application are in this file. But also see jcparam.c for
* parameter-setup helper routines, and jcomapi.c for routines shared by
* compression and decompression.
*/
#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
/*
* Initialization of a JPEG compression object.
* The error manager must already be set up (in case memory manager fails).
*/
GLOBAL void
jpeg_create_compress (j_compress_ptr cinfo)
{
int i;
/* For debugging purposes, zero the whole master structure.
* But error manager pointer is already there, so save and restore it.
*/
{
struct jpeg_error_mgr * err = cinfo->err;
MEMZERO(cinfo, SIZEOF(struct jpeg_compress_struct));
cinfo->err = err;
}
cinfo->is_decompressor = FALSE;
/* Initialize a memory manager instance for this object */
jinit_memory_mgr((j_common_ptr) cinfo);
/* Zero out pointers to permanent structures. */
cinfo->progress = NULL;
cinfo->dest = NULL;
cinfo->comp_info = 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;
}
cinfo->input_gamma = 1.0; /* in case application forgets */
/* OK, I'm ready */
cinfo->global_state = CSTATE_START;
}
/*
* Destruction of a JPEG compression object
*/
GLOBAL void
jpeg_destroy_compress (j_compress_ptr cinfo)
{
jpeg_destroy((j_common_ptr) cinfo); /* use common routine */
}
/*
* Forcibly suppress or un-suppress all quantization and Huffman tables.
* Marks all currently defined tables as already written (if suppress)
* or not written (if !suppress). This will control whether they get emitted
* by a subsequent jpeg_start_compress call.
*
* This routine is exported for use by applications that want to produce
* abbreviated JPEG datastreams. It logically belongs in jcparam.c, but
* since it is called by jpeg_start_compress, we put it here --- otherwise
* jcparam.o would be linked whether the application used it or not.
*/
GLOBAL void
jpeg_suppress_tables (j_compress_ptr cinfo, boolean suppress)
{
int i;
JQUANT_TBL * qtbl;
JHUFF_TBL * htbl;
for (i = 0; i < NUM_QUANT_TBLS; i++) {
if ((qtbl = cinfo->quant_tbl_ptrs[i]) != NULL)
qtbl->sent_table = suppress;
}
for (i = 0; i < NUM_HUFF_TBLS; i++) {
if ((htbl = cinfo->dc_huff_tbl_ptrs[i]) != NULL)
htbl->sent_table = suppress;
if ((htbl = cinfo->ac_huff_tbl_ptrs[i]) != NULL)
htbl->sent_table = suppress;
}
}
/*
* Compression initialization.
* Before calling this, all parameters and a data destination must be set up.
*
* We require a write_all_tables parameter as a failsafe check when writing
* multiple datastreams from the same compression object. Since prior runs
* will have left all the tables marked sent_table=TRUE, a subsequent run
* would emit an abbreviated stream (no tables) by default. This may be what
* is wanted, but for safety's sake it should not be the default behavior:
* programmers should have to make a deliberate choice to emit abbreviated
* images. Therefore the documentation and examples should encourage people
* to pass write_all_tables=TRUE; then it will take active thought to do the
* wrong thing.
*/
GLOBAL void
jpeg_start_compress (j_compress_ptr cinfo, boolean write_all_tables)
{
if (cinfo->global_state != CSTATE_START)
ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
if (write_all_tables)
jpeg_suppress_tables(cinfo, FALSE); /* mark all tables to be written */
/* (Re)initialize error mgr and destination modules */
(*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
(*cinfo->dest->init_destination) (cinfo);
/* Perform master selection of active modules */
jinit_master_compress(cinfo);
/* Set up for the first pass */
(*cinfo->master->prepare_for_pass) (cinfo);
/* Ready for application to drive first pass through jpeg_write_scanlines
* or jpeg_write_raw_data.
*/
cinfo->next_scanline = 0;
cinfo->global_state = (cinfo->raw_data_in ? CSTATE_RAW_OK : CSTATE_SCANNING);
}
/*
* Write some scanlines of data to the JPEG compressor.
*
* The return value will be the number of lines actually written.
* This should be less than the supplied num_lines only in case that
* the data destination module has requested suspension of the compressor,
* or if more than image_height scanlines are passed in.
*
* Note: we warn about excess calls to jpeg_write_scanlines() since
* this likely signals an application programmer error. However,
* excess scanlines passed in the last valid call are *silently* ignored,
* so that the application need not adjust num_lines for end-of-image
* when using a multiple-scanline buffer.
*/
GLOBAL JDIMENSION
jpeg_write_scanlines (j_compress_ptr cinfo, JSAMPARRAY scanlines,
JDIMENSION num_lines)
{
JDIMENSION row_ctr, rows_left;
if (cinfo->global_state != CSTATE_SCANNING)
ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
if (cinfo->next_scanline >= cinfo->image_height)
WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
/* Call progress monitor hook if present */
if (cinfo->progress != NULL) {
cinfo->progress->pass_counter = (long) cinfo->next_scanline;
cinfo->progress->pass_limit = (long) cinfo->image_height;
(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
}
/* Give master control module another chance if this is first call to
* jpeg_write_scanlines. This lets output of the frame/scan headers be
* delayed so that application can write COM, etc, markers between
* jpeg_start_compress and jpeg_write_scanlines.
*/
if (cinfo->master->call_pass_startup)
(*cinfo->master->pass_startup) (cinfo);
/* Ignore any extra scanlines at bottom of image. */
rows_left = cinfo->image_height - cinfo->next_scanline;
if (num_lines > rows_left)
num_lines = rows_left;
row_ctr = 0;
(*cinfo->main->process_data) (cinfo, scanlines, &row_ctr, num_lines);
cinfo->next_scanline += row_ctr;
return row_ctr;
}
/*
* Alternate entry point to write raw data.
* Processes exactly one iMCU row per call.
*/
GLOBAL JDIMENSION
jpeg_write_raw_data (j_compress_ptr cinfo, JSAMPIMAGE data,
JDIMENSION num_lines)
{
JDIMENSION mcu_ctr, lines_per_MCU_row;
if (cinfo->global_state != CSTATE_RAW_OK)
ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
if (cinfo->next_scanline >= cinfo->image_height) {
WARNMS(cinfo, JWRN_TOO_MUCH_DATA);
return 0;
}
/* Call progress monitor hook if present */
if (cinfo->progress != NULL) {
cinfo->progress->pass_counter = (long) cinfo->next_scanline;
cinfo->progress->pass_limit = (long) cinfo->image_height;
(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
}
/* Give master control module another chance if this is first call to
* jpeg_write_raw_data. This lets output of the frame/scan headers be
* delayed so that application can write COM, etc, markers between
* jpeg_start_compress and jpeg_write_raw_data.
*/
if (cinfo->master->call_pass_startup)
(*cinfo->master->pass_startup) (cinfo);
/* Verify that at least one iMCU row has been passed. */
lines_per_MCU_row = cinfo->max_v_samp_factor * DCTSIZE;
if (num_lines < lines_per_MCU_row)
ERREXIT(cinfo, JERR_BUFFER_SIZE);
/* Directly compress the row. */
mcu_ctr = 0;
(*cinfo->coef->compress_data) (cinfo, data, &mcu_ctr);
/* If compressor did not consume the whole row, then we must need to
* suspend processing; this is not currently supported.
*/
if (mcu_ctr != cinfo->MCUs_per_row)
ERREXIT(cinfo, JERR_CANT_SUSPEND);
/* OK, we processed one iMCU row. */
cinfo->next_scanline += lines_per_MCU_row;
return lines_per_MCU_row;
}
/*
* Finish JPEG compression.
*
* If a multipass operating mode was selected, this may do a great deal of
* work including most of the actual output.
*/
GLOBAL void
jpeg_finish_compress (j_compress_ptr cinfo)
{
JDIMENSION iMCU_row, mcu_ctr;
if (cinfo->global_state != CSTATE_SCANNING &&
cinfo->global_state != CSTATE_RAW_OK)
ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
if (cinfo->next_scanline < cinfo->image_height)
ERREXIT(cinfo, JERR_TOO_LITTLE_DATA);
/* Terminate first pass */
(*cinfo->master->finish_pass) (cinfo);
/* Perform any remaining passes */
while (! cinfo->master->is_last_pass) {
(*cinfo->master->prepare_for_pass) (cinfo);
for (iMCU_row = 0; iMCU_row < cinfo->total_iMCU_rows; iMCU_row++) {
if (cinfo->progress != NULL) {
cinfo->progress->pass_counter = (long) iMCU_row;
cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows;
(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
}
/* We bypass the main controller and invoke coef controller directly;
* all work is being done from the coefficient buffer.
*/
mcu_ctr = 0;
(*cinfo->coef->compress_data) (cinfo, (JSAMPIMAGE) NULL, &mcu_ctr);
if (mcu_ctr != cinfo->MCUs_per_row)
ERREXIT(cinfo, JERR_CANT_SUSPEND);
}
(*cinfo->master->finish_pass) (cinfo);
}
/* Write EOI, do final cleanup */
(*cinfo->marker->write_file_trailer) (cinfo);
(*cinfo->dest->term_destination) (cinfo);
/* We can use jpeg_abort to release memory and reset global_state */
jpeg_abort((j_common_ptr) cinfo);
}
/*
* Write a special marker.
* This is only recommended for writing COM or APPn markers.
* Must be called after jpeg_start_compress() and before
* first call to jpeg_write_scanlines() or jpeg_write_raw_data().
*/
GLOBAL void
jpeg_write_marker (j_compress_ptr cinfo, int marker,
const JOCTET *dataptr, unsigned int datalen)
{
if (cinfo->next_scanline != 0 ||
(cinfo->global_state != CSTATE_SCANNING &&
cinfo->global_state != CSTATE_RAW_OK))
ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
(*cinfo->marker->write_any_marker) (cinfo, marker, dataptr, datalen);
}
/*
* Alternate compression function: just write an abbreviated table file.
* Before calling this, all parameters and a data destination must be set up.
*
* To produce a pair of files containing abbreviated tables and abbreviated
* image data, one would proceed as follows:
*
* initialize JPEG object
* set JPEG parameters
* set destination to table file
* jpeg_write_tables(cinfo);
* set destination to image file
* jpeg_start_compress(cinfo, FALSE);
* write data...
* jpeg_finish_compress(cinfo);
*
* jpeg_write_tables has the side effect of marking all tables written
* (same as jpeg_suppress_tables(..., TRUE)). Thus a subsequent start_compress
* will not re-emit the tables unless it is passed write_all_tables=TRUE.
*/
GLOBAL void
jpeg_write_tables (j_compress_ptr cinfo)
{
if (cinfo->global_state != CSTATE_START)
ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
/* (Re)initialize error mgr and destination modules */
(*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
(*cinfo->dest->init_destination) (cinfo);
/* Initialize the marker writer ... bit of a crock to do it here. */
jinit_marker_writer(cinfo);
/* Write them tables! */
(*cinfo->marker->write_tables_only) (cinfo);
/* And clean up. */
(*cinfo->dest->term_destination) (cinfo);
/* We can use jpeg_abort to release memory ... is this necessary? */
jpeg_abort((j_common_ptr) cinfo);
}
/*
* Abort processing of a JPEG compression operation,
* but don't destroy the object itself.
*/
GLOBAL void
jpeg_abort_compress (j_compress_ptr cinfo)
{
jpeg_abort((j_common_ptr) cinfo); /* use common routine */
}