JPEGView/Headers/jpeglib.h

/*
 * jpeglib.h
 *
 * Copyright (C) 1991-1994, Thomas G. Lane.
 * 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.
 */

/*
 * 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 */


/* 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 */
#define MAX_BLOCKS_IN_MCU   10	/* JPEG limit on # of blocks in an MCU */


/* This macro is used to declare a "method", that is, a function pointer.
 * We want to supply prototype parameters if the compiler can cope.
 * Note that the arglist parameter must be parenthesized!
 */

#ifdef HAVE_PROTOTYPES
#define JMETHOD(type,methodname,arglist)  type (*methodname) arglist
#else
#define JMETHOD(type,methodname,arglist)  type (*methodname) ()
#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 field directly represents the contents of a JPEG DQT marker.
   * Note: the values are always given 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 */
  /* NB: there are additional private fields in an actual quantization data
   * structure, so don't allocate one directly.  Use jpeg_alloc_quant_table.
   */
} 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 suppre