chromium/third_party/libjpeg_turbo/jcmarker.c

/*
 * jcmarker.c
 *
 * This file was part of the Independent JPEG Group's software:
 * Copyright (C) 1991-1998, Thomas G. Lane.
 * Modified 2003-2010 by Guido Vollbeding.
 * libjpeg-turbo Modifications:
 * Copyright (C) 2010, D. R. Commander.
 * For conditions of distribution and use, see the accompanying README.ijg
 * file.
 *
 * This file contains routines to write JPEG datastream markers.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"
#include "jpegcomp.h"


JPEG_MARKER;


/* Private state */

my_marker_writer;

my_marker_ptr;


/*
 * Basic output routines.
 *
 * Note that we do not support suspension while writing a marker.
 * Therefore, an application using suspension must ensure that there is
 * enough buffer space for the initial markers (typ. 600-700 bytes) before
 * calling jpeg_start_compress, and enough space to write the trailing EOI
 * (a few bytes) before calling jpeg_finish_compress.  Multipass compression
 * modes are not supported at all with suspension, so those two are the only
 * points where markers will be written.
 */

LOCAL(void)
emit_byte(j_compress_ptr cinfo, int val)
/* Emit a byte */
{ … }


LOCAL(void)
emit_marker(j_compress_ptr cinfo, JPEG_MARKER mark)
/* Emit a marker code */
{ … }


LOCAL(void)
emit_2bytes(j_compress_ptr cinfo, int value)
/* Emit a 2-byte integer; these are always MSB first in JPEG files */
{ … }


/*
 * Routines to write specific marker types.
 */

LOCAL(int)
emit_dqt(j_compress_ptr cinfo, int index)
/* Emit a DQT marker */
/* Returns the precision used (0 = 8bits, 1 = 16bits) for baseline checking */
{ … }


LOCAL(void)
emit_dht(j_compress_ptr cinfo, int index, boolean is_ac)
/* Emit a DHT marker */
{ … }


LOCAL(void)
emit_dac(j_compress_ptr cinfo)
/* Emit a DAC marker */
/* Since the useful info is so small, we want to emit all the tables in */
/* one DAC marker.  Therefore this routine does its own scan of the table. */
{ … }


LOCAL(void)
emit_dri(j_compress_ptr cinfo)
/* Emit a DRI marker */
{ … }


LOCAL(void)
emit_sof(j_compress_ptr cinfo, JPEG_MARKER code)
/* Emit a SOF marker */
{ … }


LOCAL(void)
emit_sos(j_compress_ptr cinfo)
/* Emit a SOS marker */
{ … }


LOCAL(void)
emit_jfif_app0(j_compress_ptr cinfo)
/* Emit a JFIF-compliant APP0 marker */
{ … }


LOCAL(void)
emit_adobe_app14(j_compress_ptr cinfo)
/* Emit an Adobe APP14 marker */
{ … }


/*
 * These routines allow writing an arbitrary marker with parameters.
 * The only intended use is to emit COM or APPn markers after calling
 * write_file_header and before calling write_frame_header.
 * Other uses are not guaranteed to produce desirable results.
 * Counting the parameter bytes properly is the caller's responsibility.
 */

METHODDEF(void)
write_marker_header(j_compress_ptr cinfo, int marker, unsigned int datalen)
/* Emit an arbitrary marker header */
{ … }

METHODDEF(void)
write_marker_byte(j_compress_ptr cinfo, int val)
/* Emit one byte of marker parameters following write_marker_header */
{ … }


/*
 * Write datastream header.
 * This consists of an SOI and optional APPn markers.
 * We recommend use of the JFIF marker, but not the Adobe marker,
 * when using YCbCr or grayscale data.  The JFIF marker should NOT
 * be used for any other JPEG colorspace.  The Adobe marker is helpful
 * to distinguish RGB, CMYK, and YCCK colorspaces.
 * Note that an application can write additional header markers after
 * jpeg_start_compress returns.
 */

METHODDEF(void)
write_file_header(j_compress_ptr cinfo)
{ … }


/*
 * Write frame header.
 * This consists of DQT and SOFn markers.
 * Note that we do not emit the SOF until we have emitted the DQT(s).
 * This avoids compatibility problems with incorrect implementations that
 * try to error-check the quant table numbers as soon as they see the SOF.
 */

METHODDEF(void)
write_frame_header(j_compress_ptr cinfo)
{ … }


/*
 * Write scan header.
 * This consists of DHT or DAC markers, optional DRI, and SOS.
 * Compressed data will be written following the SOS.
 */

METHODDEF(void)
write_scan_header(j_compress_ptr cinfo)
{ … }


/*
 * Write datastream trailer.
 */

METHODDEF(void)
write_file_trailer(j_compress_ptr cinfo)
{ … }


/*
 * Write an abbreviated table-specification datastream.
 * This consists of SOI, DQT and DHT tables, and EOI.
 * Any table that is defined and not marked sent_table = TRUE will be
 * emitted.  Note that all tables will be marked sent_table = TRUE at exit.
 */

METHODDEF(void)
write_tables_only(j_compress_ptr cinfo)
{ … }


/*
 * Initialize the marker writer module.
 */

GLOBAL(void)
jinit_marker_writer(j_compress_ptr cinfo)
{ … }