# dlib C++ Library - jcapimin.c

    /*
     * jcapimin.c
     *
     * Copyright (C) 1994-1998, Thomas G. Lane.
     * Modified 2003-2010 by Guido Vollbeding.
     * 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 "minimum" API routines that may be
     * needed in either the normal full-compression case or the transcoding-only
     * case.
     *
     * Most of the routines intended to be called directly by an application
     * are in this file or in jcapistd.c.  But also see jcparam.c for
     * parameter-setup helper routines, jcomapi.c for routines shared by
     * compression and decompression, and jctrans.c for the transcoding case.
     */

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

    /*
     * Initialization of a JPEG compression object.
     * The error manager must already be set up (in case memory manager fails).
     */

    GLOBAL(void)
    jpeg_CreateCompress (j_compress_ptr cinfo, int version, size_t structsize)
    {
      int i;

      /* Guard against version mismatches between library and caller. */
      cinfo->mem = NULL;		/* so jpeg_destroy knows mem mgr not called */
      if (version != JPEG_LIB_VERSION)
        ERREXIT2(cinfo, JERR_BAD_LIB_VERSION, JPEG_LIB_VERSION, version);
      if (structsize != SIZEOF(struct jpeg_compress_struct))
        ERREXIT2(cinfo, JERR_BAD_STRUCT_SIZE,
    	     (int) SIZEOF(struct jpeg_compress_struct), (int) structsize);

      /* For debugging purposes, we zero the whole master structure.
       * But the application has already set the err pointer, and may have set
       * client_data, so we have to save and restore those fields.
       * Note: if application hasn't set client_data, tools like Purify may
       * complain here.
       */
      {
        struct jpeg_error_mgr * err = cinfo->err;
        void * client_data = cinfo->client_data; /* ignore Purify complaint here */
        MEMZERO(cinfo, SIZEOF(struct jpeg_compress_struct));
        cinfo->err = err;
        cinfo->client_data = client_data;
      }
      cinfo->is_decompressor = FALSE;

      /* Initialize a memory manager instance for this object */
      jinit_memory_mgr((j_common_ptr) cinfo);

      /* Zero out pointers to permanent structures. */
      cinfo->progress = NULL;
      cinfo->dest = NULL;

      cinfo->comp_info = NULL;

      for (i = 0; i < NUM_QUANT_TBLS; i++) {
        cinfo->quant_tbl_ptrs[i] = NULL;
        cinfo->q_scale_factor[i] = 100;
      }

      for (i = 0; i < NUM_HUFF_TBLS; i++) {
        cinfo->dc_huff_tbl_ptrs[i] = NULL;
        cinfo->ac_huff_tbl_ptrs[i] = NULL;
      }

      /* Must do it here for emit_dqt in case jpeg_write_tables is used */
      cinfo->block_size = DCTSIZE;
      cinfo->natural_order = jpeg_natural_order;
      cinfo->lim_Se = DCTSIZE2-1;

      cinfo->script_space = NULL;

      cinfo->input_gamma = 1.0;	/* in case application forgets */

      /* OK, I'm ready */
      cinfo->global_state = CSTATE_START;
    }

    /*
     * Destruction of a JPEG compression object
     */

    GLOBAL(void)
    jpeg_destroy_compress (j_compress_ptr cinfo)
    {
      jpeg_destroy((j_common_ptr) cinfo); /* use common routine */
    }

    /*
     * Abort processing of a JPEG compression operation,
     * but don't destroy the object itself.
     */

    GLOBAL(void)
    jpeg_abort_compress (j_compress_ptr cinfo)
    {
      jpeg_abort((j_common_ptr) cinfo); /* use common routine */
    }

    /*
     * Forcibly suppress or un-suppress all quantization and Huffman tables.
     * Marks all currently defined tables as already written (if suppress)
     * or not written (if !suppress).  This will control whether they get emitted
     * by a subsequent jpeg_start_compress call.
     *
     * This routine is exported for use by applications that want to produce
     * abbreviated JPEG datastreams.  It logically belongs in jcparam.c, but
     * since it is called by jpeg_start_compress, we put it here --- otherwise
     * jcparam.o would be linked whether the application used it or not.
     */

    GLOBAL(void)
    jpeg_suppress_tables (j_compress_ptr cinfo, boolean suppress)
    {
      int i;
      JQUANT_TBL * qtbl;
      JHUFF_TBL * htbl;

      for (i = 0; i < NUM_QUANT_TBLS; i++) {
        if ((qtbl = cinfo->quant_tbl_ptrs[i]) != NULL)
          qtbl->sent_table = suppress;
      }

      for (i = 0; i < NUM_HUFF_TBLS; i++) {
        if ((htbl = cinfo->dc_huff_tbl_ptrs[i]) != NULL)
          htbl->sent_table = suppress;
        if ((htbl = cinfo->ac_huff_tbl_ptrs[i]) != NULL)
          htbl->sent_table = suppress;
      }
    }

    /*
     * Finish JPEG compression.
     *
     * If a multipass operating mode was selected, this may do a great deal of
     * work including most of the actual output.
     */

    GLOBAL(void)
    jpeg_finish_compress (j_compress_ptr cinfo)
    {
      JDIMENSION iMCU_row;

      if (cinfo->global_state == CSTATE_SCANNING ||
          cinfo->global_state == CSTATE_RAW_OK) {
        /* Terminate first pass */
        if (cinfo->next_scanline < cinfo->image_height)
          ERREXIT(cinfo, JERR_TOO_LITTLE_DATA);
        (*cinfo->master->finish_pass) (cinfo);
      } else if (cinfo->global_state != CSTATE_WRCOEFS)
        ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);
      /* Perform any remaining passes */
      while (! cinfo->master->is_last_pass) {
        (*cinfo->master->prepare_for_pass) (cinfo);
        for (iMCU_row = 0; iMCU_row < cinfo->total_iMCU_rows; iMCU_row++) {
          if (cinfo->progress != NULL) {
    	cinfo->progress->pass_counter = (long) iMCU_row;
    	cinfo->progress->pass_limit = (long) cinfo->total_iMCU_rows;
    	(*cinfo->progress->progress_monitor) ((j_common_ptr) cinfo);
          }
          /* We bypass the main controller and invoke coef controller directly;
           * all work is being done from the coefficient buffer.
           */
          if (! (*cinfo->coef->compress_data) (cinfo, (JSAMPIMAGE) NULL))
    	ERREXIT(cinfo, JERR_CANT_SUSPEND);
        }
        (*cinfo->master->finish_pass) (cinfo);
      }
      /* Write EOI, do final cleanup */
      (*cinfo->marker->write_file_trailer) (cinfo);
      (*cinfo->dest->term_destination) (cinfo);
      /* We can use jpeg_abort to release memory and reset global_state */
      jpeg_abort((j_common_ptr) cinfo);
    }

    /*
     * Write a special marker.
     * This is only recommended for writing COM or APPn markers.
     * Must be called after jpeg_start_compress() and before
     * first call to jpeg_write_scanlines() or jpeg_write_raw_data().
     */

    GLOBAL(void)
    jpeg_write_marker (j_compress_ptr cinfo, int marker,
    		   const JOCTET *dataptr, unsigned int datalen)
    {
      JMETHOD(void, write_marker_byte, (j_compress_ptr info, int val));

      if (cinfo->next_scanline != 0 ||
          (cinfo->global_state != CSTATE_SCANNING &&
           cinfo->global_state != CSTATE_RAW_OK &&
           cinfo->global_state != CSTATE_WRCOEFS))
        ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

      (*cinfo->marker->write_marker_header) (cinfo, marker, datalen);
      write_marker_byte = cinfo->marker->write_marker_byte;	/* copy for speed */
      while (datalen--) {
        (*write_marker_byte) (cinfo, *dataptr);
        dataptr++;
      }
    }

    /* Same, but piecemeal. */

    GLOBAL(void)
    jpeg_write_m_header (j_compress_ptr cinfo, int marker, unsigned int datalen)
    {
      if (cinfo->next_scanline != 0 ||
          (cinfo->global_state != CSTATE_SCANNING &&
           cinfo->global_state != CSTATE_RAW_OK &&
           cinfo->global_state != CSTATE_WRCOEFS))
        ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

      (*cinfo->marker->write_marker_header) (cinfo, marker, datalen);
    }

    GLOBAL(void)
    jpeg_write_m_byte (j_compress_ptr cinfo, int val)
    {
      (*cinfo->marker->write_marker_byte) (cinfo, val);
    }

    /*
     * Alternate compression function: just write an abbreviated table file.
     * Before calling this, all parameters and a data destination must be set up.
     *
     * To produce a pair of files containing abbreviated tables and abbreviated
     * image data, one would proceed as follows:
     *
     *		initialize JPEG object
     *		set JPEG parameters
     *		set destination to table file
     *		jpeg_write_tables(cinfo);
     *		set destination to image file
     *		jpeg_start_compress(cinfo, FALSE);
     *		write data...
     *		jpeg_finish_compress(cinfo);
     *
     * jpeg_write_tables has the side effect of marking all tables written
     * (same as jpeg_suppress_tables(..., TRUE)).  Thus a subsequent start_compress
     * will not re-emit the tables unless it is passed write_all_tables=TRUE.
     */

    GLOBAL(void)
    jpeg_write_tables (j_compress_ptr cinfo)
    {
      if (cinfo->global_state != CSTATE_START)
        ERREXIT1(cinfo, JERR_BAD_STATE, cinfo->global_state);

      /* (Re)initialize error mgr and destination modules */
      (*cinfo->err->reset_error_mgr) ((j_common_ptr) cinfo);
      (*cinfo->dest->init_destination) (cinfo);
      /* Initialize the marker writer ... bit of a crock to do it here. */
      jinit_marker_writer(cinfo);
      /* Write them tables! */
      (*cinfo->marker->write_tables_only) (cinfo);
      /* And clean up. */
      (*cinfo->dest->term_destination) (cinfo);
      /*
       * In library releases up through v6a, we called jpeg_abort() here to free
       * any working memory allocated by the destination manager and marker
       * writer.  Some applications had a problem with that: they allocated space
       * of their own from the library memory manager, and didn't want it to go
       * away during write_tables.  So now we do nothing.  This will cause a
       * memory leak if an app calls write_tables repeatedly without doing a full
       * compression cycle or otherwise resetting the JPEG object.  However, that
       * seems less bad than unexpectedly freeing memory in the normal case.
       * An app that prefers the old behavior can call jpeg_abort for itself after
       * each call to jpeg_write_tables().
       */
    }