JPEGView/Independent JPEG Group/jpegint.h

/*
 * jpegint.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 provides common declarations for the various JPEG modules.
 * These declarations are considered internal to the JPEG library; most
 * applications using the library shouldn't need to include this file.
 */


/* Declarations for both compression & decompression */

typedef enum {			/* Operating modes for buffer controllers */
	JBUF_PASS_THRU,		/* Plain stripwise operation */
	JBUF_CRANK_SOURCE,	/* Run source subobject only, no output */
	/* Remaining modes require a full-image buffer to have been created */
	JBUF_SAVE_SOURCE,	/* Run source subobject only, save output */
	JBUF_CRANK_DEST,	/* Run dest subobject only, using saved data */
	JBUF_SAVE_AND_PASS	/* Run both subobjects, save output */
} J_BUF_MODE;

/* Values of global_state field */
#define CSTATE_START	100	/* after create_compress */
#define CSTATE_SCANNING	101	/* start_compress done, write_scanlines OK */
#define DSTATE_START	200	/* after create_decompress */
#define DSTATE_INHEADER	201	/* read_header initialized but not done */
#define DSTATE_READY	202	/* read_header done, found image */
#define DSTATE_SCANNING	203	/* start_decompress done, read_scanlines OK */
#define DSTATE_STOPPING	204	/* done reading data, looking for EOI */


/* Declarations for compression modules */

/* Master control module */
struct jpeg_comp_master {
  JMETHOD(void, prepare_for_pass, (j_compress_ptr cinfo));
  JMETHOD(void, pass_startup, (j_compress_ptr cinfo));
  JMETHOD(void, finish_pass, (j_compress_ptr cinfo));

  /* State variables made visible to other modules */
  boolean call_pass_startup;	/* True if pass_startup must be called */
  boolean is_last_pass;		/* True during last pass */
};

/* Main buffer control (downsampled-data buffer) */
struct jpeg_c_main_controller {
  JMETHOD(void, start_pass, (j_compress_ptr cinfo, J_BUF_MODE pass_mode));
  JMETHOD(void, process_data, (j_compress_ptr cinfo,
			       JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
			       JDIMENSION in_rows_avail));
};

/* Compression preprocessing (downsampling input buffer control) */
struct jpeg_c_prep_controller {
  JMETHOD(void, start_pass, (j_compress_ptr cinfo, J_BUF_MODE pass_mode));
  JMETHOD(void, pre_process_data, (j_compress_ptr cinfo,
				   JSAMPARRAY input_buf,
				   JDIMENSION *in_row_ctr,
				   JDIMENSION in_rows_avail,
				   JSAMPIMAGE output_buf,
				   JDIMENSION *out_row_group_ctr,
				   JDIMENSION out_row_groups_avail));
};

/* Coefficient buffer control */
struct jpeg_c_coef_controller {
  JMETHOD(void, start_pass, (j_compress_ptr cinfo, J_BUF_MODE pass_mode));
  JMETHOD(void, compress_data, (j_compress_ptr cinfo,
				JSAMPIMAGE input_buf,
				JDIMENSION *in_mcu_ctr));
};

/* Colorspace conversion */
struct jpeg_color_converter {
  JMETHOD(void, start_pass, (j_compress_ptr cinfo));
  JMETHOD(void, color_convert, (j_compress_ptr cinfo,
				JSAMPARRAY input_buf, JSAMPIMAGE output_buf,
				JDIMENSION output_row, int num_rows));
};

/* Downsampling */
struct jpeg_downsampler {
  JMETHOD(void, start_pass, (j_compress_ptr cinfo));
  JMETHOD(void, downsample, (j_compress_ptr cinfo,
			     JSAMPIMAGE input_buf, JSAMPIMAGE output_buf,
			     JDIMENSION out_row_group_index));

  boolean need_context_rows;	/* TRUE if need rows above & below */
};

/* Forward DCT (also controls coefficient quantization) */
struct jpeg_forward_dct {
  JMETHOD(void, start_pass, (j_compress_ptr cinfo));
  /* perhaps this should be an array??? */
  JMETHOD(void, forward_DCT, (j_compress_ptr cinfo,
			      jpeg_component_info * compptr,
			      JSAMPARRAY sample_data, JBLOCKROW coef_blocks,
			      JDIMENSION start_row, JDIMENSION start_col,
			      JDIMENSION num_blocks));
};

/* JCQUANT_TBL details made visible for jpeg_alloc_quant_table */

typedef struct {
  JQUANT_TBL pub;		/* public fields */

  /* Extra data for encoding */

  /* The actual pre-DCT divisors -- may differ from quantiz