/*

 * 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;

}

