kc3-lang/libjpeg-turbo/jcinit.c

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• Hash : b5a9ef64
  Author :
  Date : 2022-11-13T13:00:26
  

  Don't allow 12-bit JPEG support to be disabled
  
  In libjpeg-turbo 2.1.x and prior, the WITH_12BIT CMake variable was used
  to enable 12-bit JPEG support at compile time, because the libjpeg API
  library could not handle multiple JPEG data precisions at run time.  The
  initial approach to handling multiple JPEG data precisions at run time
  (7fec5074f962b20ed00b4f5da4533e1e8d4ed8ac) created a whole new API,
  library, and applications for 12-bit data precision, so it made sense to
  repurpose WITH_12BIT to allow 12-bit data precision to be disabled.
  e8b40f3c2ba187ba95c13c3e8ce21c8534256df7 made it so that the libjpeg API
  library can handle multiple JPEG data precisions at run time via a
  handful of straightforward API extensions.  Referring to
  6c2bc901e27b047440ed46920c4d3f0480b48268, it hasn't been possible to
  build libjpeg-turbo with both forward and backward libjpeg API/ABI
  compatibility since libjpeg-turbo 1.4.x.  Thus, whereas we retain full
  backward API/ABI compatibility with libjpeg v6b-v8, forward libjpeg
  API/ABI compatibility ceased being realistic years ago, so it no longer
  makes sense to provide compile-time options that give a false sense of
  forward API/ABI compatibility by allowing some (but not all) of our
  libjpeg API extensions to be disabled.  Such options are difficult to
  maintain and clutter the code with #ifdefs.
  

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• jcinit.c

• /*
   * jcinit.c
   *
   * This file was part of the Independent JPEG Group's software:
   * Copyright (C) 1991-1997, Thomas G. Lane.
   * libjpeg-turbo Modifications:
   * Copyright (C) 2020, 2022, D. R. Commander.
   * For conditions of distribution and use, see the accompanying README.ijg
   * file.
   *
   * This file contains initialization logic for the JPEG compressor.
   * This routine is in charge of selecting the modules to be executed and
   * making an initialization call to each one.
   *
   * Logically, this code belongs in jcmaster.c.  It's split out because
   * linking this routine implies linking the entire compression library.
   * For a transcoding-only application, we want to be able to use jcmaster.c
   * without linking in the whole library.
   */
  
  #define JPEG_INTERNALS
  #include "jinclude.h"
  #include "jpeglib.h"
  #include "jpegapicomp.h"
  
  
  /*
   * Master selection of compression modules.
   * This is done once at the start of processing an image.  We determine
   * which modules will be used and give them appropriate initialization calls.
   */
  
  GLOBAL(void)
  jinit_compress_master(j_compress_ptr cinfo)
  {
    /* Initialize master control (includes parameter checking/processing) */
    jinit_c_master_control(cinfo, FALSE /* full compression */);
  
    /* Preprocessing */
    if (!cinfo->raw_data_in) {
      if (cinfo->data_precision == 12) {
        j12init_color_converter(cinfo);
        j12init_downsampler(cinfo);
        j12init_c_prep_controller(cinfo,
                                  FALSE /* never need full buffer here */);
      } else {
        jinit_color_converter(cinfo);
        jinit_downsampler(cinfo);
        jinit_c_prep_controller(cinfo, FALSE /* never need full buffer here */);
      }
    }
    /* Forward DCT */
    if (cinfo->data_precision == 12)
      j12init_forward_dct(cinfo);
    else
      jinit_forward_dct(cinfo);
    /* Entropy encoding: either Huffman or arithmetic coding. */
    if (cinfo->arith_code) {
  #ifdef C_ARITH_CODING_SUPPORTED
      jinit_arith_encoder(cinfo);
  #else
      ERREXIT(cinfo, JERR_ARITH_NOTIMPL);
  #endif
    } else {
      if (cinfo->progressive_mode) {
  #ifdef C_PROGRESSIVE_SUPPORTED
        jinit_phuff_encoder(cinfo);
  #else
        ERREXIT(cinfo, JERR_NOT_COMPILED);
  #endif
      } else
        jinit_huff_encoder(cinfo);
    }
  
    /* Need a full-image coefficient buffer in any multi-pass mode. */
    if (cinfo->data_precision == 12) {
      j12init_c_coef_controller(cinfo, (boolean)(cinfo->num_scans > 1 ||
                                                 cinfo->optimize_coding));
      j12init_c_main_controller(cinfo, FALSE /* never need full buffer here */);
    } else {
      jinit_c_coef_controller(cinfo, (boolean)(cinfo->num_scans > 1 ||
                                               cinfo->optimize_coding));
      jinit_c_main_controller(cinfo, FALSE /* never need full buffer here */);
    }
  
    jinit_marker_writer(cinfo);
  
    /* We can now tell the memory manager to allocate virtual arrays. */
    (*cinfo->mem->realize_virt_arrays) ((j_common_ptr)cinfo);
  
    /* Write the datastream header (SOI) immediately.
     * Frame and scan headers are postponed till later.
     * This lets application insert special markers after the SOI.
     */
    (*cinfo->marker->write_file_header) (cinfo);
  }
  

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