kc3-lang/libjpeg-turbo/src/jdsample.h

• Show log

  Commit

• Hash : e69dd40c
  Author :
  Date : 2024-01-23T13:26:41
  

  Reorganize source to make things easier to find
  
  - Move all libjpeg documentation, except for README.ijg, into the doc/
    subdirectory.
  
  - Move the TurboJPEG C API documentation from doc/html/ into
    doc/turbojpeg/.
  
  - Move all C source code and headers into a src/ subdirectory.
  
  - Move turbojpeg-jni.c into the java/ subdirectory.
  
  Referring to #226, there is no ideal solution to this problem.  A
  semantically ideal solution would have involved placing all source code,
  including the SIMD and Java source code, under src/ (or perhaps placing
  C library source code under lib/ and C test program source code under
  test/), all header files under include/, and all documentation under
  doc/.  However:
  
  - To me it makes more sense to have separate top-level directories for
    each language, since the SIMD extensions and the Java API are
    technically optional features.  src/ now contains only the code that
    is relevant to the core C API libraries and associated programs.
  - I didn't want to bury the java/ and simd/ directories or add a level
    of depth to them, since both directories already contain source code
    that is 3-4 levels deep.
  - I would prefer not to separate the header files from the C source
    code, because:
    1. It would be disruptive.  libjpeg and libjpeg-turbo have
       historically placed C source code and headers in the same
       directory, and people who are familiar with both projects (self
       included) are used to looking for the headers in the same directory
       as the C source code.
    2. In terms of how the headers are used internally in libjpeg-turbo,
       the distinction between public and private headers is a bit fuzzy.
  - It didn't make sense to separate the test source code from the library
    source code, since there is not a clear distinction in some cases.
    (For instance, the IJG image I/O functions are used by cjpeg and djpeg
    as well as by the TurboJPEG API.)
  
  This solution is minimally disruptive, since it keeps all C source code
  and headers together and keeps java/ and simd/ as top-level directories.
  It is a bit awkward, because java/ and simd/ technically contain source
  code, even though they are not under src/.  However, other solutions
  would have been more awkward for different reasons.
  
  Closes #226
  

Download

• src/jdsample.h

• /*
   * jdsample.h
   *
   * This file was part of the Independent JPEG Group's software:
   * Copyright (C) 1991-1996, Thomas G. Lane.
   * libjpeg-turbo Modifications:
   * Copyright (C) 2022, D. R. Commander.
   * For conditions of distribution and use, see the accompanying README.ijg
   * file.
   */
  
  #define JPEG_INTERNALS
  #include "jpeglib.h"
  #include "jsamplecomp.h"
  
  
  /* Pointer to routine to upsample a single component */
  typedef void (*upsample1_ptr) (j_decompress_ptr cinfo,
                                 jpeg_component_info *compptr,
                                 _JSAMPARRAY input_data,
                                 _JSAMPARRAY *output_data_ptr);
  
  /* Private subobject */
  
  typedef struct {
    struct jpeg_upsampler pub;    /* public fields */
  
    /* Color conversion buffer.  When using separate upsampling and color
     * conversion steps, this buffer holds one upsampled row group until it
     * has been color converted and output.
     * Note: we do not allocate any storage for component(s) which are full-size,
     * ie do not need rescaling.  The corresponding entry of color_buf[] is
     * simply set to point to the input data array, thereby avoiding copying.
     */
    _JSAMPARRAY color_buf[MAX_COMPONENTS];
  
    /* Per-component upsampling method pointers */
    upsample1_ptr methods[MAX_COMPONENTS];
  
    int next_row_out;             /* counts rows emitted from color_buf */
    JDIMENSION rows_to_go;        /* counts rows remaining in image */
  
    /* Height of an input row group for each component. */
    int rowgroup_height[MAX_COMPONENTS];
  
    /* These arrays save pixel expansion factors so that int_expand need not
     * recompute them each time.  They are unused for other upsampling methods.
     */
    UINT8 h_expand[MAX_COMPONENTS];
    UINT8 v_expand[MAX_COMPONENTS];
  } my_upsampler;
  
  typedef my_upsampler *my_upsample_ptr;
  

Download