media/libjpeg/jcinit.c

   1 /*
   2  * jcinit.c
   3  *
   4  * This file was part of the Independent JPEG Group's software:
   5  * Copyright (C) 1991-1997, Thomas G. Lane.
   6  * libjpeg-turbo Modifications:
   7  * Copyright (C) 2020, D. R. Commander.
   8  * For conditions of distribution and use, see the accompanying README.ijg
   9  * file.
  10  *
  11  * This file contains initialization logic for the JPEG compressor.
  12  * This routine is in charge of selecting the modules to be executed and
  13  * making an initialization call to each one.
  14  *
  15  * Logically, this code belongs in jcmaster.c.  It's split out because
  16  * linking this routine implies linking the entire compression library.
  17  * For a transcoding-only application, we want to be able to use jcmaster.c
  18  * without linking in the whole library.
  19  */
  20
  21 #define JPEG_INTERNALS
  22 #include "jinclude.h"
  23 #include "jpeglib.h"
  24 #include "jpegcomp.h"
  25
  26
  27 /*
  28  * Master selection of compression modules.
  29  * This is done once at the start of processing an image.  We determine
  30  * which modules will be used and give them appropriate initialization calls.
  31  */
  32
  33 GLOBAL(void)
  34 jinit_compress_master(j_compress_ptr cinfo)
  35 {
  36   /* Initialize master control (includes parameter checking/processing) */
  37   jinit_c_master_control(cinfo, FALSE /* full compression */);
  38
  39   /* Preprocessing */
  40   if (!cinfo->raw_data_in) {
  41     jinit_color_converter(cinfo);
  42     jinit_downsampler(cinfo);
  43     jinit_c_prep_controller(cinfo, FALSE /* never need full buffer here */);
  44   }
  45   /* Forward DCT */
  46   jinit_forward_dct(cinfo);
  47   /* Entropy encoding: either Huffman or arithmetic coding. */
  48   if (cinfo->arith_code) {
  49 #ifdef C_ARITH_CODING_SUPPORTED
  50     jinit_arith_encoder(cinfo);
  51 #else
  52     ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
  53 #endif
  54   } else {
  55     if (cinfo->progressive_mode) {
  56 #ifdef C_PROGRESSIVE_SUPPORTED
  57       jinit_phuff_encoder(cinfo);
  58 #else
  59       ERREXIT(cinfo, JERR_NOT_COMPILED);
  60 #endif
  61     } else
  62       jinit_huff_encoder(cinfo);
  63   }
  64
  65   /* Need a full-image coefficient buffer in any multi-pass mode. */
  66   jinit_c_coef_controller(cinfo, (boolean)(cinfo->num_scans > 1 ||
  67                                            cinfo->optimize_coding));
  68   jinit_c_main_controller(cinfo, FALSE /* never need full buffer here */);
  69
  70   jinit_marker_writer(cinfo);
  71
  72   /* We can now tell the memory manager to allocate virtual arrays. */
  73   (*cinfo->mem->realize_virt_arrays) ((j_common_ptr)cinfo);
  74
  75   /* Write the datastream header (SOI) immediately.
  76    * Frame and scan headers are postponed till later.
  77    * This lets application insert special markers after the SOI.
  78    */
  79   (*cinfo->marker->write_file_header) (cinfo);
  80 }