/*
* jpeglib.h
*
* Copyright (C) 1991-1998, Thomas G. Lane.
* Modified 2002-2013 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 defines the application interface for the JPEG library.
* Most applications using the library need only include this file,
* and perhaps jerror.h if they want to know the exact error codes.
*/
#ifndef JPEGLIB_H
#define JPEGLIB_H
/*
* First we include the configuration files that record how this
* installation of the JPEG library is set up. 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 "jconfig.h" /* widely used configuration options */
#endif
#include "jmorecfg.h" /* seldom changed options */
#ifdef __cplusplus
#ifndef DONT_USE_EXTERN_C
extern "C" {
#endif
#endif
/* Version IDs for the JPEG library.
* Might be useful for tests like "#if JPEG_LIB_VERSION >= 90".
*/
#define JPEG_LIB_VERSION 90 /* Compatibility version 9.0 */
#define JPEG_LIB_VERSION_MAJOR 9
#define JPEG_LIB_VERSION_MINOR 1
/* 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 coefficients */
#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 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,
* reflecting any scaling we choose to apply during the DCT step.
* Values from 1 to 16 are supported.
* Note that different components may receive different DCT scalings.
*/
int DCT_h_scaled_size;
int DCT_v_scaled_size;
/* The downsampled dimensions are the component's actual, unpadded number
* of samples at the main buffer (preprocessing/compression interface);
* DCT scaling is included, so
* downsampled_width =
* ceil(image_width * Hi/Hmax * DCT_h_scaled_size/block_size)
* and similarly for height.
*/
JDIMENSION downsampled_width; /* actual width in samples */
JDIMENSION downsampled_height; /* actual height in samples */
/* 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.
* For compression, some of the components will need further quantization
* scale by factor of 2 after DCT (eg BG_YCC output from normal RGB input).
* The field is first set TRUE for decompression, FALSE for compression
* in initial_setup, and then adapted in color conversion setup.
*/
boolean component_needed;
/* 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_h_scaled_size */
int last_col_width; /* # of non-dummy blocks across in las
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