mrpt_jpeglib.h

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2020, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */

#pragma once

/*
 * First we include the configuration files that record how this
 * installation of the JPEG library is set up.  mrpt_jconfig.h can be
 * generated automatically for many systems.  jmorecfg.h contains
 * manual configuration options that most people need not worry about.
 */

#ifndef JCONFIG_INCLUDED /* in case jinclude.h already did */
#include "mrpt_jconfig.h" /* widely used configuration options */
#endif
#include "jmorecfg.h" /* seldom changed options */

/* Version ID for the JPEG library.
 * Might be useful for tests like "#if JPEG_LIB_VERSION >= 60".
 */

#define JPEG_LIB_VERSION 62 /* Version 6b */

/* Various constants determining the sizes of things.
 * All of these are specified by the JPEG standard, so don't change them
 * if you want to be compatible.
 */

#define DCTSIZE 8 /* The basic DCT block is 8x8 samples */
#define DCTSIZE2 64 /* DCTSIZE squared; # of elements in a block */
#define NUM_QUANT_TBLS 4 /* Quantization tables are numbered 0..3 */
#define NUM_HUFF_TBLS 4 /* Huffman tables are numbered 0..3 */
#define NUM_ARITH_TBLS 16 /* Arith-coding tables are numbered 0..15 */
#define MAX_COMPS_IN_SCAN 4 /* JPEG limit on # of components in one scan */
#define MAX_SAMP_FACTOR 4 /* JPEG limit on sampling factors */
/* Unfortunately, some bozo at Adobe saw no reason to be bound by the standard;
 * the PostScript DCT filter can emit files with many more than 10 blocks/MCU.
 * If you happen to run across such a file, you can up D_MAX_BLOCKS_IN_MCU
 * to handle it.  We even let you do this from the mrpt_jconfig.h file. However,
 * we strongly discourage changing C_MAX_BLOCKS_IN_MCU; just because Adobe
 * sometimes emits noncompliant files doesn't mean you should too.
 */
#define C_MAX_BLOCKS_IN_MCU 10 /* compressor's limit on blocks per MCU */
#ifndef D_MAX_BLOCKS_IN_MCU
#define D_MAX_BLOCKS_IN_MCU 10 /* decompressor's limit on blocks per MCU */
#endif

/* Data structures for images (arrays of samples and of DCT coefficients).
 * On 80x86 machines, the image arrays are too big for near pointers,
 * but the pointer arrays can fit in near memory.
 */

typedef JSAMPLE FAR* JSAMPROW; /* ptr to one image row of pixel samples. */
typedef JSAMPROW* JSAMPARRAY; /* ptr to some rows (a 2-D sample array) */
typedef JSAMPARRAY* JSAMPIMAGE; /* a 3-D sample array: top index is color */

typedef JCOEF JBLOCK[DCTSIZE2]; /* one block of coefficients */
typedef JBLOCK FAR* JBLOCKROW; /* pointer to one row of coefficient blocks */
typedef JBLOCKROW* JBLOCKARRAY; /* a 2-D array of coefficient blocks */
typedef JBLOCKARRAY* JBLOCKIMAGE; /* a 3-D array of coefficient blocks */

typedef JCOEF FAR* JCOEFPTR; /* useful in a couple of places */

/* Types for JPEG compression parameters and working tables. */

/* DCT coefficient quantization tables. */

typedef struct
{
    /* This array gives the coefficient quantizers in natural array order
     * (not the zigzag order in which they are stored in a JPEG DQT marker).
     * CAUTION: IJG versions prior to v6a kept this array in zigzag order.
     */
    UINT16 quantval[DCTSIZE2]; /* quantization step for each coefficient */
    /* This field is used only during compression.  It's initialized FALSE when
     * the table is created, and set TRUE when it's been output to the file.
     * You could suppress output of a table by setting this to TRUE.
     * (See jpeg_suppress_tables for an example.)
     */
    boolean sent_table; /* TRUE when table has been output */
} JQUANT_TBL;

/* Huffman coding tables. */

typedef struct
{
    /* These two fields directly represent the contents of a JPEG DHT marker */
    UINT8 bits[17]; /* bits[k] = # of symbols with codes of */
    /* length k bits; bits[0] is unused */
    UINT8 huffval[256]; /* The symbols, in order of incr code length */
    /* This field is used only during compression.  It's initialized FALSE when
     * the table is created, and set TRUE when it's been output to the file.
     * You could suppress output of a table by setting this to TRUE.
     * (See jpeg_suppress_tables for an example.)
     */
    boolean sent_table; /* TRUE when table has been output */
} JHUFF_TBL;

/* Basic info about one component (color channel). */

typedef struct
{
    /* These values are fixed over the whole image. */
    /* For compression, they must be supplied by parameter setup; */
    /* for decompression, they are read from the SOF marker. */
    int component_id; /* identifier for this component (0..255) */
    int component_index; /* its index in SOF or cinfo->comp_info[] */
    int h_samp_factor; /* horizontal sampling factor (1..4) */
    int v_samp_factor; /* vertical sampling factor (1..4) */
    int quant_tbl_no; /* quantization table selector (0..3) */
    /* These values may vary between scans. */
    /* For compression, they must be supplied by parameter setup; */
    /* for decompression, they are read from the SOS marker. */
    /* The decompressor output side may not use these variables. */
    int dc_tbl_no; /* DC entropy table selector (0..3) */
    int ac_tbl_no; /* AC entropy table selector (0..3) */

    /* Remaining fields should be treated as private by applications. */

    /* These values are computed during compression or decompression startup: */
    /* Component's size in DCT blocks.
     * Any dummy blocks added to complete an MCU are not counted; therefore
     * these values do not depend on whether a scan is interleaved or not.
     */
    JDIMENSION width_in_blocks;
    JDIMENSION height_in_blocks;
    /* Size of a DCT block in samples.  Always DCTSIZE for compression.
     * For decompression this is the size of the output from one DCT block,
     * reflecting any scaling we choose to apply during the IDCT step.
     * Values of 1,2,4,8 are likely to be supported.  Note that different
     * components may receive different IDCT scalings.
     */
    int DCT_scaled_size;
    /* The downsampled dimensions are the component's actual, unpadded number
     * of samples at the main buffer (preprocessing/compression interface), thus
     * downsampled_width = ceil(image_width * Hi/Hmax)
     * and similarly for height.  For decompression, IDCT scaling is included,
     * so
     * downsampled_width = ceil(image_width * Hi/Hmax * DCT_scaled_size/DCTSIZE)
     */
    JDIMENSION downsampled_width; /* actual width in samples */
    JDIMENSION downsampled_height; /* actual height in samples */
    /* This flag is used only for decompression.  In cases where some of the
     * components will be ignored (eg grayscale output from YCbCr image),
     * we can skip most computations for the unused components.
     */
    boolean component_needed; /* do we need the value of this component? */

    /* These values are computed before starting a scan of the component. */
    /* The decompressor output side may not use these variables. */
    int MCU_width; /* number of blocks per MCU, horizontally */
    int MCU_height; /* number of blocks per MCU, vertically */
    int MCU_blocks; /* MCU_width * MCU_height */
    int MCU_sample_width; /* MCU width in samples, MCU_width*DCT_scaled_size */
    int last_col_width; /* # of non-dummy blocks across in last MCU */
    int last_row_height; /* # of non-dummy blocks down in last MCU */

    /* Saved quantization table for component; nullptr if none yet saved.
     * See jdinput.c comments about the need for this information.
     * This field is currently used only for decompression.
     */
    JQUANT_TBL* quant_table;

    /* Private per-component storage for DCT or IDCT subsystem. */
    void* dct_table;
} jpeg_component_info;

/* The script for encoding a multiple-scan file is an array of these: */

typedef struct
{
    int comps_in_scan; /* number of components encoded in this scan */
    int component_index[MAX_COMPS_IN_SCAN]; /* their SOF/comp_info[] indexes */
    int Ss, Se; /* progressive JPEG spectral selection parms */
    int Ah, Al; /* progressive JPEG successive approx. parms */
} jpeg_scan_info;

/* The decompressor can save APPn and COM markers in a list of these: */

typedef struct jpeg_marker_struct FAR* jpeg_saved_marker_ptr;

struct jpeg_marker_struct
{
    jpeg_saved_marker_ptr next; /* next in list, or nullptr */
    UINT8 marker; /* marker code: JPEG_COM, or JPEG_APP0+n */
    unsigned int original_length; /* # bytes of data in the file */
    unsigned int data_length; /* # bytes of data saved at data[] */
    JOCTET FAR* data; /* the data contained in the marker */
    /* the marker length word is not counted in data_length or original_length
     */
};

/* Known color spaces. */

typedef enum
{
    JCS_UNKNOWN, /* error/unspecified */
    JCS_GRAYSCALE, /* monochrome */
    JCS_RGB, /* red/green/blue */
    JCS_YCbCr, /* Y/Cb/Cr (also known as YUV) */
    JCS_CMYK, /* C/M/Y/K */
    JCS_YCCK /* Y/Cb/Cr/K */
} J_COLOR_SPACE;

/* DCT/IDCT algorithm options. */

typedef enum
{
    JDCT_ISLOW, /* slow but accurate integer algorithm */
    JDCT_IFAST, /* faster, less accurate integer method */
    JDCT_FLOAT /* floating-point: accurate, fast on fast HW */
} J_DCT_METHOD;

#ifndef JDCT_DEFAULT /* may be overridden in mrpt_jconfig.h */
#define JDCT_DEFAULT JDCT_ISLOW
#endif
#ifndef JDCT_FASTEST /* may be overridden in mrpt_jconfig.h */
#define JDCT_FASTEST JDCT_IFAST
#endif

/* Dithering options for decompression. */

typedef enum
{
    JDITHER_NONE, /* no dithering */
    JDITHER_ORDERED, /* simple ordered dither */
    JDITHER_FS /* Floyd-Steinberg error diffusion dither */
} J_DITHER_MODE;

/* Common fields between JPEG compression and decompression master structs. */

#define jpeg_common_fields                                                \
    struct jpeg_error_mgr* err; /* Error handler module */                \
    struct jpeg_memory_mgr* mem; /* Memory manager module */              \
    struct jpeg_progress_mgr*                                             \
        progress; /* Progress monitor, or nullptr if none */              \
    void* client_data; /* Available for use by application */             \
    boolean is_decompressor; /* So common code can tell which is which */ \
    int global_state /* For checking call sequence validity */

/* Routines that are to be used by both halves of the library are declared
 * to receive a pointer to this structure.  There are no actual instances of
 * jpeg_common_struct, only of jpeg_compress_struct and jpeg_decompress_struct.
 */
struct jpeg_common_struct
{
    jpeg_common_fields; /* Fields common to both master struct types */
    /* Additional fields follow in an actual jpeg_compress_struct or
     * jpeg_decompress_struct.  All three structs must agree on these
     * initial fields!  (This would be a lot cleaner in C++.)
     */
};

typedef struct jpeg_common_struct* j_common_ptr;
typedef struct jpeg_compress_struct* j_compress_ptr;
typedef struct jpeg_decompress_struct* j_decompress_ptr;

/* Master record for a compression instance */

struct jpeg_compress_struct
{
    jpeg_common_fields; /* Fields shared with jpeg_decompress_struct */

    /* Destination for compressed data */
    struct jpeg_destination_mgr* dest;

    /* Description of source image --- these fields must be filled in by
     * outer application before starting compression.  in_color_space must
     * be correct before you can even call jpeg_set_defaults().
     */

    JDIMENSION image_width; /* input image width */
    JDIMENSION image_height; /* input image height */
    int input_components; /* # of color components in input image */
    J_COLOR_SPACE in_color_space; /* colorspace of input image */

    double input_gamma; /* image gamma of input image */

    /* Compression parameters --- these fields must be set before calling
     * jpeg_start_compress().  We recommend calling jpeg_set_defaults() to
     * initialize everything to reasonable defaults, then changing anything
     * the application specifically wants to change.  That way you won't get
     * burnt when new parameters are added.  Also note that there are several
     * helper routines to simplify changing parameters.
     */

    int data_precision; /* bits of precision in image data */

    int num_components; /* # of color components in JPEG image */
    J_COLOR_SPACE jpeg_color_space; /* colorspace of JPEG image */

    jpeg_component_info* comp_info;
    /* comp_info[i] describes component that appears i'th in SOF */

    JQUANT_TBL* quant_tbl_ptrs[NUM_QUANT_TBLS];
    /* ptrs to coefficient quantization tables, or nullptr if not defined */

    JHUFF_TBL* dc_huff_tbl_ptrs[NUM_HUFF_TBLS];
    JHUFF_TBL* ac_huff_tbl_ptrs[NUM_HUFF_TBLS];
    /* ptrs to Huffman coding tables, or nullptr if not defined */

    UINT8 arith_dc_L[NUM_ARITH_TBLS]; /* L values for DC arith-coding tables */
    UINT8 arith_dc_U[NUM_ARITH_TBLS]; /* U values for DC arith-coding tables */
    UINT8 arith_ac_K[NUM_ARITH_TBLS]; /* Kx values for AC arith-coding tables */

    int num_scans; /* # of entries in scan_info array */
    const jpeg_scan_info*
        scan_info; /* script for multi-scan file, or nullptr */
    /* The default value of scan_info is nullptr, which causes a single-scan
     * sequential JPEG file to be emitted.  To create a multi-scan file,
     * set num_scans and scan_info to point to an array of scan definitions.
     */

    boolean raw_data_in; /* TRUE=caller supplies downsampled data */
    boolean arith_code; /* TRUE=arithmetic coding, FALSE=Huffman */
    boolean optimize_coding; /* TRUE=optimize entropy encoding parms */
    boolean CCIR601_sampling; /* TRUE=first samples are cosited */
    int smoothing_factor; /* 1..100, or 0 for no input smoothing */
    J_DCT_METHOD dct_method; /* DCT algorithm selector */

    /* The restart interval can be specified in absolute MCUs by setting
     * restart_interval, or in MCU rows by setting restart_in_rows
     * (in which case the correct restart_interval will be figured
     * for each scan).
     */
    unsigned int restart_interval; /* MCUs per restart, or 0 for no restart */
    int restart_in_rows; /* if > 0, MCU rows per restart interval */

    /* Parameters controlling emission of special markers. */

    boolean write_JFIF_header; /* should a JFIF marker be written? */
    UINT8 JFIF_major_version; /* What to write for the JFIF version number */
    UINT8 JFIF_minor_version;
    /* These three values are not used by the JPEG code, merely copied */
    /* into the JFIF APP0 marker.  density_unit can be 0 for unknown, */
    /* 1 for dots/inch, or 2 for dots/cm.  Note that the pixel aspect */
    /* ratio is defined by X_density/Y_density even when density_unit=0. */
    UINT8 density_unit; /* JFIF code for pixel size units */
    UINT16 X_density; /* Horizontal pixel density */
    UINT16 Y_density; /* Vertical pixel density */
    boolean write_Adobe_marker; /* should an Adobe marker be written? */

    /* State variable: index of next scanline to be written to
     * jpeg_write_scanlines().  Application may use this to control its
     * processing loop, e.g., "while (next_scanline < image_height)".
     */

    JDIMENSION next_scanline; /* 0 .. image_height-1  */

    /* Remaining fields are known throughout compressor, but generally
     * should not be touched by a surrounding application.
     */

    /*
     * These fields are computed during compression startup
     */
    boolean progressive_mode; /* TRUE if scan script uses progressive mode */
    int max_h_samp_factor; /* largest h_samp_factor */
    int max_v_samp_factor; /* largest v_samp_factor */

    JDIMENSION total_iMCU_rows; /* # of iMCU rows to be input to coef ctlr */
    /* The coefficient controller receives data in units of MCU rows as defined
     * for fully interleaved scans (whether the JPEG file is interleaved or
     * not).
     * There are v_samp_factor * DCTSIZE sample rows of each component in an
     * "iMCU" (interleaved MCU) row.
     */

    /*
     * These fields are valid during any one scan.
     * They describe the components and MCUs actually appearing in the scan.
     */
    int comps_in_scan; /* # of JPEG components in this scan */
    jpeg_component_info* cur_comp_info[MAX_COMPS_IN_SCAN];
    /* *cur_comp_info[i] describes component that appears i'th in SOS */

    JDIMENSION MCUs_per_row; /* # of MCUs across the image */
    JDIMENSION MCU_rows_in_scan; /* # of MCU rows in the image */

    int blocks_in_MCU; /* # of DCT blocks per MCU */
    int MCU_membership[C_MAX_BLOCKS_IN_MCU];
    /* MCU_membership[i] is index in cur_comp_info of component owning */
    /* i'th block in an MCU */

    int Ss, Se, Ah, Al; /* progressive JPEG parameters for scan */

    /*
     * Links to compression subobjects (methods and private variables of
     * modules)
     */
    struct jpeg_comp_master* master;
    struct jpeg_c_main_controller* main;
    struct jpeg_c_prep_controller* prep;
    struct jpeg_c_coef_controller* coef;
    struct jpeg_marker_writer* marker;
    struct jpeg_color_converter* cconvert;
    struct jpeg_downsampler* downsample;
    struct jpeg_forward_dct* fdct;
    struct jpeg_entropy_encoder* entropy;
    jpeg_scan_info* script_space; /* workspace for jpeg_simple_progression */
    int script_space_size;
};

/* Master record for a decompression instance */

struct jpeg_decompress_struct
{
    jpeg_common_fields; /* Fields shared with jpeg_compress_struct */

    /* Source of compressed data */
    struct jpeg_source_mgr* src;

    /* Basic description of image --- filled in by jpeg_read_header(). */
    /* Application may inspect these values to decide how to process image. */

    JDIMENSION image_width; /* nominal image width (from SOF marker) */
    JDIMENSION image_height; /* nominal image height */
    int num_components; /* # of color components in JPEG image */
    J_COLOR_SPACE jpeg_color_space; /* colorspace of JPEG image */

    /* Decompression processing parameters --- these fields must be set before
     * calling jpeg_start_decompress().  Note that jpeg_read_header()
     * initializes
     * them to default values.
     */

    J_COLOR_SPACE out_color_space; /* colorspace for output */

    unsigned int scale_num, scale_denom; /* fraction by which to scale image */

    double output_gamma; /* image gamma wanted in output */

    boolean buffered_image; /* TRUE=multiple output passes */
    boolean raw_data_out; /* TRUE=downsampled data wanted */

    J_DCT_METHOD dct_method; /* IDCT algorithm selector */
    boolean do_fancy_upsampling; /* TRUE=apply fancy upsampling */
    boolean do_block_smoothing; /* TRUE=apply interblock smoothing */

    boolean quantize_colors; /* TRUE=colormapped output wanted */
    /* the following are ignored if not quantize_colors: */
    J_DITHER_MODE dither_mode; /* type of color dithering to use */
    boolean two_pass_quantize; /* TRUE=use two-pass color quantization */
    int desired_number_of_colors; /* max # colors to use in created colormap */
    /* these are significant only in buffered-image mode: */
    boolean enable_1pass_quant; /* enable future use of 1-pass quantizer */
    boolean enable_external_quant; /* enable future use of external colormap */
    boolean enable_2pass_quant; /* enable future use of 2-pass quantizer */

    /* Description of actual output image that will be returned to application.
     * These fields are computed by jpeg_start_decompress().
     * You can also use jpeg_calc_output_dimensions() to determine these values
     * in advance of calling jpeg_start_decompress().
     */

    JDIMENSION output_width; /* scaled image width */
    JDIMENSION output_height; /* scaled image height */
    int out_color_components; /* # of color components in out_color_space */
    int output_components; /* # of color components returned */
    /* output_components is 1 (a colormap index) when quantizing colors;
     * otherwise it equals out_color_components.
     */
    int rec_outbuf_height; /* min recommended height of scanline buffer */
    /* If the buffer passed to jpeg_read_scanlines() is less than this many rows
     * high, space and time will be wasted due to unnecessary data copying.
     * Usually rec_outbuf_height will be 1 or 2, at most 4.
     */

    /* When quantizing colors, the output colormap is described by these fields.
     * The application can supply a colormap by setting colormap non-NULL before
     * calling jpeg_start_decompress; otherwise a colormap is created during
     * jpeg_start_decompress or jpeg_start_output.
     * The map has out_color_components rows and actual_number_of_colors
     * columns.
     */
    int actual_number_of_colors; /* number of entries in use */
    JSAMPARRAY colormap; /* The color map as a 2-D pixel array */

    /* State variables: these variables indicate the progress of decompression.
     * The application may examine these but must not modify them.
     */

    /* Row index of next scanline to be read from jpeg_read_scanlines().
     * Application may use this to control its processing loop, e.g.,
     * "while (output_scanline < output_height)".
     */
    JDIMENSION output_scanline; /* 0 .. output_height-1  */

    /* Current input scan number and number of iMCU rows completed in scan.
     * These indicate the progress of the decompressor input side.
     */
    int input_scan_number; /* Number of SOS markers seen so far */
    JDIMENSION input_iMCU_row; /* Number of iMCU rows completed */

    /* The "output scan number" is the notional scan being displayed by the
     * output side.  The decompressor will not allow output scan/row number
     * to get ahead of input scan/row, but it can fall arbitrarily far behind.
     */
    int output_scan_number; /* Nominal scan number being displayed */
    JDIMENSION output_iMCU_row; /* Number of iMCU rows read */

    /* Current progression status.  coef_bits[c][i] indicates the precision
     * with which component c's DCT coefficient i (in zigzag order) is known.
     * It is -1 when no data has yet been received, otherwise it is the point
     * transform (shift) value for the most recent scan of the coefficient
     * (thus, 0 at completion of the progression).
     * This pointer is nullptr when reading a non-progressive file.
     */
    int (*coef_bits)[DCTSIZE2]; /* -1 or current Al value for each coef */

    /* Internal JPEG parameters --- the application usually need not look at
     * these fields.  Note that the decompressor output side may not use
     * any parameters that can change between scans.
     */

    /* Quantization and Huffman tables are carried forward across input
     * datastreams when processing abbreviated JPEG datastreams.
     */

    JQUANT_TBL* quant_tbl_ptrs[NUM_QUANT_TBLS];
    /* ptrs to coefficient quantization tables, or nullptr if not defined */

    JHUFF_TBL* dc_huff_tbl_ptrs[NUM_HUFF_TBLS];
    JHUFF_TBL* ac_huff_tbl_ptrs[NUM_HUFF_TBLS];
    /* ptrs to Huffman coding tables, or nullptr if not defined */

    /* These parameters are never carried across datastreams, since they
     * are given in SOF/SOS markers or defined to be reset by SOI.
     */

    int data_precision; /* bits of precision in image data */

    jpeg_component_info* comp_info;
    /* comp_info[i] describes component that appears i'th in SOF */

    boolean progressive_mode; /* TRUE if SOFn specifies progressive mode */
    boolean arith_code; /* TRUE=arithmetic coding, FALSE=Huffman */

    UINT8 arith_dc_L[NUM_ARITH_TBLS]; /* L values for DC arith-coding tables */
    UINT8 arith_dc_U[NUM_ARITH_TBLS]; /* U values for DC arith-coding tables */
    UINT8 arith_ac_K[NUM_ARITH_TBLS]; /* Kx values for AC arith-coding tables */

    unsigned int
        restart_interval; /* MCUs per restart interval, or 0 for no restart */

    /* These fields record data obtained from optional markers recognized by
     * the JPEG library.
     */
    boolean saw_JFIF_marker; /* TRUE iff a JFIF APP0 marker was found */
    /* Data copied from JFIF marker; only valid if saw_JFIF_marker is TRUE: */
    UINT8 JFIF_major_version; /* JFIF version number */
    UINT8 JFIF_minor_version;
    UINT8 density_unit; /* JFIF code for pixel size units */
    UINT16 X_density; /* Horizontal pixel density */
    UINT16 Y_density; /* Vertical pixel density */
    boolean saw_Adobe_marker; /* TRUE iff an Adobe APP14 marker was found */
    UINT8 Adobe_transform; /* Color transform code from Adobe marker */

    boolean CCIR601_sampling; /* TRUE=first samples are cosited */

    /* Aside from the specific data retained from APPn markers known to the
     * library, the uninterpreted contents of any or all APPn and COM markers
     * can be saved in a list for examination by the application.
     */
    jpeg_saved_marker_ptr marker_list; /* Head of list of saved markers */

    /* Remaining fields are known throughout decompressor, but generally
     * should not be touched by a surrounding application.
     */

    /*
     * These fields are computed during decompression startup
     */
    int max_h_samp_factor; /* largest h_samp_factor */
    int max_v_samp_factor; /* largest v_samp_factor */

    int min_DCT_scaled_size; /* smallest DCT_scaled_size of any component */

    JDIMENSION total_iMCU_rows; /* # of iMCU rows in image */
    /* The coefficient controller's input and output progress is measured in
     * units of "iMCU" (interleaved MCU) rows.  These are the same as MCU rows
     * in fully interleaved JPEG scans, but are used whether the scan is
     * interleaved or not.  We define an iMCU row as v_samp_factor DCT block
     * rows of each component.  Therefore, the IDCT output contains
     * v_samp_factor*DCT_scaled_size sample rows of a component per iMCU row.
     */

    JSAMPLE* sample_range_limit; /* table for fast range-limiting */

    /*
     * These fields are valid during any one scan.
     * They describe the components and MCUs actually appearing in the scan.
     * Note that the decompressor output side must not use these fields.
     */
    int comps_in_scan; /* # of JPEG components in this scan */
    jpeg_component_info* cur_comp_info[MAX_COMPS_IN_SCAN];
    /* *cur_comp_info[i] describes component that appears i'th in SOS */

    JDIMENSION MCUs_per_row; /* # of MCUs across the image */
    JDIMENSION MCU_rows_in_scan; /* # of MCU rows in the image */

    int blocks_in_MCU; /* # of DCT blocks per MCU */
    int MCU_membership[D_MAX_BLOCKS_IN_MCU];
    /* MCU_membership[i] is index in cur_comp_info of component owning */
    /* i'th block in an MCU */

    int Ss, Se, Ah, Al; /* progressive JPEG parameters for scan */

    /* This field is shared between entropy decoder and marker parser.
     * It is either zero or the code of a JPEG marker that has been
     * read from the data source, but has not yet been processed.
     */
    int unread_marker;

    /*
     * Links to decompression subobjects (methods, private variables of modules)
     */
    struct jpeg_decomp_master* master;
    struct jpeg_d_main_controller* main;
    struct jpeg_d_coef_controller* coef;
    struct jpeg_d_post_controller* post;
    struct jpeg_input_controller* inputctl;
    struct jpeg_marker_reader* marker;
    struct jpeg_entropy_decoder* entropy;
    struct jpeg_inverse_dct* idct;
    struct jpeg_upsampler* upsample;
    struct jpeg_color_deconverter* cconvert;
    struct jpeg_color_quantizer* cquantize;
};

/* "Object" declarations for JPEG modules that may be supplied or called
 * directly by the surrounding application.
 * As with all objects in the JPEG library, these structs only define the
 * publicly visible methods and state variables of a module.  Additional
 * private fields may exist after the public ones.
 */

/* Error handler object */

struct jpeg_error_mgr
{
    /* Error exit handler: does not return to caller */
    JMETHOD(void, error_exit, (j_common_ptr cinfo));
    /* Conditionally emit a trace or warning message */
    JMETHOD(void, emit_message, (j_common_ptr cinfo, int msg_level));
    /* Routine that actually outputs a trace or error message */
    JMETHOD(void, output_message, (j_common_ptr cinfo));
    /* Format a message string for the most recent JPEG error or message */
    JMETHOD(void, format_message, (j_common_ptr cinfo, char* buffer));
#define JMSG_LENGTH_MAX 200 /* recommended size of format_message buffer */
    /* Reset error state variables at start of a new image */
    JMETHOD(void, reset_error_mgr, (j_common_ptr cinfo));

    /* The message ID code and any parameters are saved here.
     * A message can have one string parameter or up to 8 int parameters.
     */
    int msg_code;
#define JMSG_STR_PARM_MAX 80
    union {
        int i[8];
        char s[JMSG_STR_PARM_MAX];
    } msg_parm;

    /* Standard state variables for error facility */

    int trace_level; /* max msg_level that will be displayed */

    /* For recoverable corrupt-data errors, we emit a warning message,
     * but keep going unless emit_message chooses to abort.  emit_message
     * should count warnings in num_warnings.  The surrounding application
     * can check for bad data by seeing if num_warnings is nonzero at the
     * end of processing.
     */
    long num_warnings; /* number of corrupt-data warnings */

    /* These fields point to the table(s) of error message strings.
     * An application can change the table pointer to switch to a different
     * message list (typically, to change the language in which errors are
     * reported).  Some applications may wish to add additional error codes
     * that will be handled by the JPEG library error mechanism; the second
     * table pointer is used for this purpose.
     *
     * First table includes all errors generated by JPEG library itself.
     * Error code 0 is reserved for a "no such error string" message.
     */
    const char* const* jpeg_message_table; /* Library errors */
    int last_jpeg_message; /* Table contains strings 0..last_jpeg_message */
    /* Second table can be added by application (see cjpeg/djpeg for example).
     * It contains strings numbered first_addon_message..last_addon_message.
     */
    const char* const* addon_message_table; /* Non-library errors */
    int first_addon_message; /* code for first string in addon table */
    int last_addon_message; /* code for last string in addon table */
};

/* Progress monitor object */

struct jpeg_progress_mgr
{
    JMETHOD(void, progress_monitor, (j_common_ptr cinfo));

    long pass_counter; /* work units completed in this pass */
    long pass_limit; /* total number of work units in this pass */
    int completed_passes; /* passes completed so far */
    int total_passes; /* total number of passes expected */
};

/* Data destination object for compression */

struct jpeg_destination_mgr
{
    JOCTET* next_output_byte; /* => next byte to write in buffer */
    size_t free_in_buffer; /* # of byte spaces remaining in buffer */

    JMETHOD(void, init_destination, (j_compress_ptr cinfo));
    JMETHOD(boolean, empty_output_buffer, (j_compress_ptr cinfo));
    JMETHOD(void, term_destination, (j_compress_ptr cinfo));
};

/* Data source object for decompression */

struct jpeg_source_mgr
{
    const JOCTET* next_input_byte; /* => next byte to read from buffer */
    size_t bytes_in_buffer; /* # of bytes remaining in buffer */

    JMETHOD(void, init_source, (j_decompress_ptr cinfo));
    JMETHOD(boolean, fill_input_buffer, (j_decompress_ptr cinfo));
    JMETHOD(void, skip_input_data, (j_decompress_ptr cinfo, long num_bytes));
    JMETHOD(boolean, resync_to_restart, (j_decompress_ptr cinfo, int desired));
    JMETHOD(void, term_source, (j_decompress_ptr cinfo));
};

/* Memory manager object.
 * Allocates "small" objects (a few K total), "large" objects (tens of K),
 * and "really big" objects (virtual arrays with backing store if needed).
 * The memory manager does not allow individual objects to be freed; rather,
 * each created object is assigned to a pool, and whole pools can be freed
 * at once.  This is faster and more convenient than remembering exactly what
 * to free, especially where malloc()/free() are not too speedy.
 * NB: alloc routines never return NULL.  They exit to error_exit if not
 * successful.
 */

#define JPOOL_PERMANENT 0 /* lasts until master record is destroyed */
#define JPOOL_IMAGE 1 /* lasts until done with image/datastream */
#define JPOOL_NUMPOOLS 2

typedef struct jvirt_sarray_control* jvirt_sarray_ptr;
typedef struct jvirt_barray_control* jvirt_barray_ptr;

struct jpeg_memory_mgr
{
    /* Method pointers */
    JMETHOD(
        void*, alloc_small,
        (j_common_ptr cinfo, int pool_id, size_t sizeofobject));
    JMETHOD(
        void FAR*, alloc_large,
        (j_common_ptr cinfo, int pool_id, size_t sizeofobject));
    JMETHOD(
        JSAMPARRAY, alloc_sarray,
        (j_common_ptr cinfo, int pool_id, JDIMENSION samplesperrow,
         JDIMENSION numrows));
    JMETHOD(
        JBLOCKARRAY, alloc_barray,
        (j_common_ptr cinfo, int pool_id, JDIMENSION blocksperrow,
         JDIMENSION numrows));
    JMETHOD(
        jvirt_sarray_ptr, request_virt_sarray,
        (j_common_ptr cinfo, int pool_id, boolean pre_zero,
         JDIMENSION samplesperrow, JDIMENSION numrows, JDIMENSION maxaccess));
    JMETHOD(
        jvirt_barray_ptr, request_virt_barray,
        (j_common_ptr cinfo, int pool_id, boolean pre_zero,
         JDIMENSION blocksperrow, JDIMENSION numrows, JDIMENSION maxaccess));
    JMETHOD(void, realize_virt_arrays, (j_common_ptr cinfo));
    JMETHOD(
        JSAMPARRAY, access_virt_sarray,
        (j_common_ptr cinfo, jvirt_sarray_ptr ptr, JDIMENSION start_row,
         JDIMENSION num_rows, boolean writable));
    JMETHOD(
        JBLOCKARRAY, access_virt_barray,
        (j_common_ptr cinfo, jvirt_barray_ptr ptr, JDIMENSION start_row,
         JDIMENSION num_rows, boolean writable));
    JMETHOD(void, free_pool, (j_common_ptr cinfo, int pool_id));
    JMETHOD(void, self_destruct, (j_common_ptr cinfo));

    /* Limit on memory allocation for this JPEG object.  (Note that this is
     * merely advisory, not a guaranteed maximum; it only affects the space
     * used for virtual-array buffers.)  May be changed by outer application
     * after creating the JPEG object.
     */
    long max_memory_to_use;

    /* Maximum allocation request accepted by alloc_large. */
    long max_alloc_chunk;
};

/* Routine signature for application-supplied marker processing methods.
 * Need not pass marker code since it is stored in cinfo->unread_marker.
 */
typedef JMETHOD(boolean, jpeg_marker_parser_method, (j_decompress_ptr cinfo));

/* Declarations for routines called by application.
 * The JPP macro hides prototype parameters from compilers that can't cope.
 * Note JPP requires double parentheses.
 */

#ifdef HAVE_PROTOTYPES
#define JPP(arglist) arglist
#else
#define JPP(arglist) ()
#endif

/* Short forms of external names for systems with brain-damaged linkers.
 * We shorten external names to be unique in the first six letters, which
 * is good enough for all known systems.
 * (If your compiler itself needs names to be unique in less than 15
 * characters, you are out of luck.  Get a better compiler.)
 */

#ifdef NEED_SHORT_EXTERNAL_NAMES
#define jpeg_std_error jStdError
#define jpeg_CreateCompress jCreaCompress
#define jpeg_CreateDecompress jCreaDecompress
#define jpeg_destroy_compress jDestCompress
#define jpeg_destroy_decompress jDestDecompress
#define jpeg_stdio_dest jStdDest
#define jpeg_stdio_src jStdSrc
#define jpeg_set_defaults jSetDefaults
#define jpeg_set_colorspace jSetColorspace
#define jpeg_default_colorspace jDefColorspace
#define jpeg_set_quality jSetQuality
#define jpeg_set_linear_quality jSetLQuality
#define jpeg_add_quant_table jAddQuantTable
#define jpeg_quality_scaling jQualityScaling
#define jpeg_simple_progression jSimProgress
#define jpeg_suppress_tables jSuppressTables
#define jpeg_alloc_quant_table jAlcQTable
#define jpeg_alloc_huff_table jAlcHTable
#define jpeg_start_compress jStrtCompress
#define jpeg_write_scanlines jWrtScanlines
#define jpeg_finish_compress jFinCompress
#define jpeg_write_raw_data jWrtRawData
#define jpeg_write_marker jWrtMarker
#define jpeg_write_m_header jWrtMHeader
#define jpeg_write_m_byte jWrtMByte
#define jpeg_write_tables jWrtTables
#define jpeg_read_header jReadHeader
#define jpeg_start_decompress jStrtDecompress
#define jpeg_read_scanlines jReadScanlines
#define jpeg_finish_decompress jFinDecompress
#define jpeg_read_raw_data jReadRawData
#define jpeg_has_multiple_scans jHasMultScn
#define jpeg_start_output jStrtOutput
#define jpeg_finish_output jFinOutput
#define jpeg_input_complete jInComplete
#define jpeg_new_colormap jNewCMap
#define jpeg_consume_input jConsumeInput
#define jpeg_calc_output_dimensions jCalcDimensions
#define jpeg_save_markers jSaveMarkers
#define jpeg_set_marker_processor jSetMarker
#define jpeg_read_coefficients jReadCoefs
#define jpeg_write_coefficients jWrtCoefs
#define jpeg_copy_critical_parameters jCopyCrit
#define jpeg_abort_compress jAbrtCompress
#define jpeg_abort_decompress jAbrtDecompress
#define jpeg_abort jAbort
#define jpeg_destroy jDestroy
#define jpeg_resync_to_restart jResyncRestart
#endif /* NEED_SHORT_EXTERNAL_NAMES */

/* Default error-management setup */
EXTERN(struct jpeg_error_mgr*)
jpeg_std_error JPP((struct jpeg_error_mgr * err));

/* Initialization of JPEG compression objects.
 * jpeg_create_compress() and jpeg_create_decompress() are the exported
 * names that applications should call.  These expand to calls on
 * jpeg_CreateCompress and jpeg_CreateDecompress with additional information
 * passed for version mismatch checking.
 * NB: you must set up the error-manager BEFORE calling jpeg_create_xxx.
 */
#define jpeg_create_compress(cinfo) \
    jpeg_CreateCompress(            \
        (cinfo), JPEG_LIB_VERSION,  \
        (size_t)sizeof(struct jpeg_compress_struct))
#define jpeg_create_decompress(cinfo) \
    jpeg_CreateDecompress(            \
        (cinfo), JPEG_LIB_VERSION,    \
        (size_t)sizeof(struct jpeg_decompress_struct))
EXTERN(void)
jpeg_CreateCompress JPP((j_compress_ptr cinfo, int version, size_t structsize));
EXTERN(void)
jpeg_CreateDecompress JPP(
    (j_decompress_ptr cinfo, int version, size_t structsize));
/* Destruction of JPEG compression objects */
EXTERN(void) jpeg_destroy_compress JPP((j_compress_ptr cinfo));
EXTERN(void) jpeg_destroy_decompress JPP((j_decompress_ptr cinfo));

/* Standard data source and destination managers: stdio streams. */
/* Caller is responsible for opening the file before and closing after. */
EXTERN(void) jpeg_stdio_dest JPP((j_compress_ptr cinfo, FILE* outfile));
EXTERN(void) jpeg_stdio_src JPP((j_decompress_ptr cinfo, FILE* infile));

/* Default parameter setup for compression */
EXTERN(void) jpeg_set_defaults JPP((j_compress_ptr cinfo));
/* Compression parameter setup aids */
EXTERN(void)
jpeg_set_colorspace JPP((j_compress_ptr cinfo, J_COLOR_SPACE colorspace));
EXTERN(void) jpeg_default_colorspace JPP((j_compress_ptr cinfo));
EXTERN(void)
jpeg_set_quality JPP(
    (j_compress_ptr cinfo, int quality, boolean force_baseline));
EXTERN(void)
jpeg_set_linear_quality JPP(
    (j_compress_ptr cinfo, int scale_factor, boolean force_baseline));
EXTERN(void)
jpeg_add_quant_table JPP(
    (j_compress_ptr cinfo, int which_tbl, const unsigned int* basic_table,
     int scale_factor, boolean force_baseline));
EXTERN(int) jpeg_quality_scaling JPP((int quality));
EXTERN(void) jpeg_simple_progression JPP((j_compress_ptr cinfo));
EXTERN(void) jpeg_suppress_tables JPP((j_compress_ptr cinfo, boolean suppress));
EXTERN(JQUANT_TBL*) jpeg_alloc_quant_table JPP((j_common_ptr cinfo));
EXTERN(JHUFF_TBL*) jpeg_alloc_huff_table JPP((j_common_ptr cinfo));

/* Main entry points for compression */
EXTERN(void)
jpeg_start_compress JPP((j_compress_ptr cinfo, boolean write_all_tables));
EXTERN(JDIMENSION)
jpeg_write_scanlines JPP(
    (j_compress_ptr cinfo, JSAMPARRAY scanlines, JDIMENSION num_lines));
EXTERN(void) jpeg_finish_compress JPP((j_compress_ptr cinfo));

/* Replaces jpeg_write_scanlines when writing raw downsampled data. */
EXTERN(JDIMENSION)
jpeg_write_raw_data JPP(
    (j_compress_ptr cinfo, JSAMPIMAGE data, JDIMENSION num_lines));

/* Write a special marker.  See libjpeg.doc concerning safe usage. */
EXTERN(void)
jpeg_write_marker JPP(
    (j_compress_ptr cinfo, int marker, const JOCTET* dataptr,
     unsigned int datalen));
/* Same, but piecemeal. */
EXTERN(void)
jpeg_write_m_header JPP(
    (j_compress_ptr cinfo, int marker, unsigned int datalen));
EXTERN(void) jpeg_write_m_byte JPP((j_compress_ptr cinfo, int val));

/* Alternate compression function: just write an abbreviated table file */
EXTERN(void) jpeg_write_tables JPP((j_compress_ptr cinfo));

/* Decompression startup: read start of JPEG datastream to see what's there */
EXTERN(int)
jpeg_read_header JPP((j_decompress_ptr cinfo, boolean require_image));
/* Return value is one of: */
#define JPEG_SUSPENDED 0 /* Suspended due to lack of input data */
#define JPEG_HEADER_OK 1 /* Found valid image datastream */
#define JPEG_HEADER_TABLES_ONLY                  \
    2 /* Found valid table-specs-only datastream \
       */
/* If you pass require_image = TRUE (normal case), you need not check for
 * a TABLES_ONLY return code; an abbreviated file will cause an error exit.
 * JPEG_SUSPENDED is only possible if you use a data source module that can
 * give a suspension return (the stdio source module doesn't).
 */

/* Main entry points for decompression */
EXTERN(boolean) jpeg_start_decompress JPP((j_decompress_ptr cinfo));
EXTERN(JDIMENSION)
jpeg_read_scanlines JPP(
    (j_decompress_ptr cinfo, JSAMPARRAY scanlines, JDIMENSION max_lines));
EXTERN(boolean) jpeg_finish_decompress JPP((j_decompress_ptr cinfo));

/* Replaces jpeg_read_scanlines when reading raw downsampled data. */
EXTERN(JDIMENSION)
jpeg_read_raw_data JPP(
    (j_decompress_ptr cinfo, JSAMPIMAGE data, JDIMENSION max_lines));

/* Additional entry points for buffered-image mode. */
EXTERN(boolean) jpeg_has_multiple_scans JPP((j_decompress_ptr cinfo));
EXTERN(boolean)
jpeg_start_output JPP((j_decompress_ptr cinfo, int scan_number));
EXTERN(boolean) jpeg_finish_output JPP((j_decompress_ptr cinfo));
EXTERN(boolean) jpeg_input_complete JPP((j_decompress_ptr cinfo));
EXTERN(void) jpeg_new_colormap JPP((j_decompress_ptr cinfo));
EXTERN(int) jpeg_consume_input JPP((j_decompress_ptr cinfo));
/* Return value is one of: */
/* #define JPEG_SUSPENDED   0    Suspended due to lack of input data */
#define JPEG_REACHED_SOS 1 /* Reached start of new scan */
#define JPEG_REACHED_EOI 2 /* Reached end of image */
#define JPEG_ROW_COMPLETED 3 /* Completed one iMCU row */
#define JPEG_SCAN_COMPLETED 4 /* Completed last iMCU row of a scan */

/* Precalculate output dimensions for current decompression parameters. */
EXTERN(void) jpeg_calc_output_dimensions JPP((j_decompress_ptr cinfo));

/* Control saving of COM and APPn markers into marker_list. */
EXTERN(void)
jpeg_save_markers JPP(
    (j_decompress_ptr cinfo, int marker_code, unsigned int length_limit));

/* Install a special processing method for COM or APPn markers. */
EXTERN(void)
jpeg_set_marker_processor JPP(
    (j_decompress_ptr cinfo, int marker_code,
     jpeg_marker_parser_method routine));

/* Read or write raw DCT coefficients --- useful for lossless transcoding. */
EXTERN(jvirt_barray_ptr*) jpeg_read_coefficients JPP((j_decompress_ptr cinfo));
EXTERN(void)
jpeg_write_coefficients JPP(
    (j_compress_ptr cinfo, jvirt_barray_ptr* coef_arrays));
EXTERN(void)
jpeg_copy_critical_parameters JPP(
    (j_decompress_ptr srcinfo, j_compress_ptr dstinfo));

/* If you choose to abort compression or decompression before completing
 * jpeg_finish_(de)compress, then you need to clean up to release memory,
 * temporary files, etc.  You can just call jpeg_destroy_(de)compress
 * if you're done with the JPEG object, but if you want to clean it up and
 * reuse it, call this:
 */
EXTERN(void) jpeg_abort_compress JPP((j_compress_ptr cinfo));
EXTERN(void) jpeg_abort_decompress JPP((j_decompress_ptr cinfo));

/* Generic versions of jpeg_abort and jpeg_destroy that work on either
 * flavor of JPEG object.  These may be more convenient in some places.
 */
EXTERN(void) jpeg_abort JPP((j_common_ptr cinfo));
EXTERN(void) jpeg_destroy JPP((j_common_ptr cinfo));

/* Default restart-marker-resync procedure for use by data source modules */
EXTERN(boolean)
jpeg_resync_to_restart JPP((j_decompress_ptr cinfo, int desired));

/* These marker codes are exported since applications and data source modules
 * are likely to want to use them.
 */

#define JPEG_RST0 0xD0 /* RST0 marker code */
#define JPEG_EOI 0xD9 /* EOI marker code */
#define JPEG_APP0 0xE0 /* APP0 marker code */
#define JPEG_COM 0xFE /* COM marker code */

/* If we have a brain-damaged compiler that emits warnings (or worse, errors)
 * for structure definitions that are never filled in, keep it quiet by
 * supplying dummy definitions for the various substructures.
 */

#ifdef INCOMPLETE_TYPES_BROKEN
#ifndef JPEG_INTERNALS /* will be defined in jpegint.h */
struct jvirt_sarray_control
{
    long dummy;
};
struct jvirt_barray_control
{
    long dummy;
};
struct jpeg_comp_master
{
    long dummy;
};
struct jpeg_c_main_controller
{
    long dummy;
};
struct jpeg_c_prep_controller
{
    long dummy;
};
struct jpeg_c_coef_controller
{
    long dummy;
};
struct jpeg_marker_writer
{
    long dummy;
};
struct jpeg_color_converter
{
    long dummy;
};
struct jpeg_downsampler
{
    long dummy;
};
struct jpeg_forward_dct
{
    long dummy;
};
struct jpeg_entropy_encoder
{
    long dummy;
};
struct jpeg_decomp_master
{
    long dummy;
};
struct jpeg_d_main_controller
{
    long dummy;
};
struct jpeg_d_coef_controller
{
    long dummy;
};
struct jpeg_d_post_controller
{
    long dummy;
};
struct jpeg_input_controller
{
    long dummy;
};
struct jpeg_marker_reader
{
    long dummy;
};
struct jpeg_entropy_decoder
{
    long dummy;
};
struct jpeg_inverse_dct
{
    long dummy;
};
struct jpeg_upsampler
{
    long dummy;
};
struct jpeg_color_deconverter
{
    long dummy;
};
struct jpeg_color_quantizer
{
    long dummy;
};
#endif /* JPEG_INTERNALS */
#endif /* INCOMPLETE_TYPES_BROKEN */

/*
 * The JPEG library modules define JPEG_INTERNALS before including this file.
 * The internal structure declarations are read only when that is true.
 * Applications using the library should not include jpegint.h, but may wish
 * to include jerror.h.
 */

#ifdef JPEG_INTERNALS
#include "jerror.h" /* fetch error codes too */
#include "jpegint.h" /* fetch private declarations */
#endif