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/* |
* 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; |
} |