/*+ −
* jcapistd.c+ −
*+ −
* Copyright (C) 1994-1996, 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. These are the "standard" API routines that are+ −
* used in the normal full-compression case. They are not used by a+ −
* transcoding-only application. Note that if an application links in+ −
* jpeg_start_compress, it will end up linking in the entire compressor.+ −
* We thus must separate this file from jcapimin.c to avoid linking the+ −
* whole compression library into a transcoder.+ −
*/+ −
+ − #define JPEG_INTERNALS+ −
#include "jinclude.h"+ −
#include "jpeglib.h"+ −
+ − + − /*+ −
* 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_compress_master(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, unless suspended.+ −
*/+ −
+ − GLOBAL(JDIMENSION)+ −
jpeg_write_raw_data (j_compress_ptr cinfo, JSAMPIMAGE data,+ −
JDIMENSION num_lines)+ −
{+ −
JDIMENSION lines_per_iMCU_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_iMCU_row = cinfo->max_v_samp_factor * DCTSIZE;+ −
if (num_lines < lines_per_iMCU_row)+ −
ERREXIT(cinfo, JERR_BUFFER_SIZE);+ −
+ − /* Directly compress the row. */+ −
if (! (*cinfo->coef->compress_data) (cinfo, data)) {+ −
/* If compressor did not consume the whole row, suspend processing. */+ −
return 0;+ −
}+ −
+ − /* OK, we processed one iMCU row. */+ −
cinfo->next_scanline += lines_per_iMCU_row;+ −
return lines_per_iMCU_row;+ −
}+ −