    /*
     * 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, int 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;
    }