chromium/third_party/libjpeg_turbo/jcmaster.c

/*
 * jcmaster.c
 *
 * This file was part of the Independent JPEG Group's software:
 * Copyright (C) 1991-1997, Thomas G. Lane.
 * Modified 2003-2010 by Guido Vollbeding.
 * libjpeg-turbo Modifications:
 * Copyright (C) 2010, 2016, 2018, D. R. Commander.
 * For conditions of distribution and use, see the accompanying README.ijg
 * file.
 *
 * This file contains master control logic for the JPEG compressor.
 * These routines are concerned with parameter validation, initial setup,
 * and inter-pass control (determining the number of passes and the work
 * to be done in each pass).
 */

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


/* Private state */

c_pass_type;

my_comp_master;

my_master_ptr;


/*
 * Support routines that do various essential calculations.
 */

#if JPEG_LIB_VERSION >= 70
/*
 * Compute JPEG image dimensions and related values.
 * NOTE: this is exported for possible use by application.
 * Hence it mustn't do anything that can't be done twice.
 */

GLOBAL(void)
jpeg_calc_jpeg_dimensions(j_compress_ptr cinfo)
/* Do computations that are needed before master selection phase */
{
  /* Hardwire it to "no scaling" */
  cinfo->jpeg_width = cinfo->image_width;
  cinfo->jpeg_height = cinfo->image_height;
  cinfo->min_DCT_h_scaled_size = DCTSIZE;
  cinfo->min_DCT_v_scaled_size = DCTSIZE;
}
#endif


LOCAL(void)
initial_setup(j_compress_ptr cinfo, boolean transcode_only)
/* Do computations that are needed before master selection phase */
{ … }


#ifdef C_MULTISCAN_FILES_SUPPORTED

LOCAL(void)
validate_script(j_compress_ptr cinfo)
/* Verify that the scan script in cinfo->scan_info[] is valid; also
 * determine whether it uses progressive JPEG, and set cinfo->progressive_mode.
 */
{ … }

#endif /* C_MULTISCAN_FILES_SUPPORTED */


LOCAL(void)
select_scan_parameters(j_compress_ptr cinfo)
/* Set up the scan parameters for the current scan */
{ … }


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 */
{ … }


/*
 * 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)
{ … }


/*
 * 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)
{ … }


/*
 * Finish up at end of pass.
 */

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


/*
 * Initialize master compression control.
 */

GLOBAL(void)
jinit_c_master_control(j_compress_ptr cinfo, boolean transcode_only)
{ … }