jcapistd.cpp

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          http://www.mrpt.org/                          |
   |                                                                        |
   | Copyright (c) 2005-2017, Individual contributors, see AUTHORS file     |
   | See: http://www.mrpt.org/Authors - All rights reserved.                |
   | Released under BSD License. See details in http://www.mrpt.org/License |
   +------------------------------------------------------------------------+ */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "mrpt_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 != nullptr)
        {
                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 != nullptr)
        {
                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;
}