/* * 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;}