harvey/sys/src/cmd/gs/src/gxht.h

/* Copyright (C) 1993, 1995, 1996, 1997, 1998 Aladdin Enterprises.  All rights reserved.
  
  This file is part of AFPL Ghostscript.
  
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  she says so in writing.  Refer to the Aladdin Free Public License (the
  "License") for full details.
  
  Every copy of AFPL Ghostscript must include a copy of the License, normally
  in a plain ASCII text file named PUBLIC.  The License grants you the right
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  requires that the copyright notice and this notice be preserved on all
  copies.
*/

/*$Id: gxht.h,v 1.2 2000/09/19 19:00:37 lpd Exp $ */
/* Rest of (client) halftone definitions */

#ifndef gxht_INCLUDED
#  define gxht_INCLUDED

#include "gscsepnm.h"
#include "gsht1.h"
#include "gsrefct.h"
#include "gxhttype.h"
#include "gxtmap.h"

/*
 * Halftone types. Note that for this implementation there are only
 * spot functions, thresholds, and multi-component halftones; the peculiar
 * colored halftones supported by PostScript (HalftoneType's 2 and 4) are
 * not supported.
 *
 * NB1: While this code supports relocation of the client data, it will not
 *      free that data when the halftone is released. The client must handle
 *      that task directly.
 *
 * NB2: The garbage collection code will deal with the user provided data as
 *      a structure pointer allocated on the heap. The client must make
 *      certain this is the case.
 *
 * There is, somewhat unfortunately, no identifier applied to these
 * halftones. This reflects the origin of this graphics library as a set
 * of routines for use by a PostScript interpreter.
 *
 * In PostScript, halftone objects do not exist in an identified form outside
 * of the graphic state. Though Level 2 and PostScript 3 support halftone
 * dictionaries, these are neither read-only structures nor tagged
 * by a unique identifier. Hence, they are not suitable for use as cache keys.
 * Caching of halftones for PostScript is confined to the graphic state,
 * and this holds true for the graphic library as well.
 *
 * Note also that implementing a generalized halftone cache is not trivial,
 * as the device-specific representation of spot halftones depends on the 
 * default transformation for the device, and more generally the device
 * specific representation of halftones may depend on the sense of the device
 * (additive or subtract). Hence, a halftone cache would need to be keyed
 * by device. (This is not an issue when caching halftones in the graphic
 * state as the device is also a component of the graphic state).
 */

/*
 * Note that the transfer_closure members will replace transfer sometime
 * in the future.  For the moment, transfer_closure is only used if
 * transfer = 0.
 */

/* Type 1 halftone.  This is just a Level 1 halftone with */
/* a few extra members. */
typedef struct gs_spot_halftone_s {
    gs_screen_halftone screen;
    bool accurate_screens;
    gs_mapping_proc transfer;	/* OBSOLETE */
    gs_mapping_closure_t transfer_closure;
} gs_spot_halftone;

#define st_spot_halftone_max_ptrs st_screen_halftone_max_ptrs + 1

/* Define common elements for Type 3 and extended Type 3 halftones. */
#define GS_THRESHOLD_HALFTONE_COMMON\
    int width;\
    int height;\
    gs_mapping_closure_t transfer_closure
typedef struct gs_threshold_halftone_common_s {
    GS_THRESHOLD_HALFTONE_COMMON;
} gs_threshold_halftone_common;

/* Type 3 halftone. */
typedef struct gs_threshold_halftone_s {
    GS_THRESHOLD_HALFTONE_COMMON; /* must be first */
    gs_const_string thresholds;
    gs_mapping_proc transfer;	/* OBSOLETE */
} gs_threshold_halftone;

#define st_threshold_halftone_max_ptrs 2

/* Extended Type 3 halftone. */
typedef struct gs_threshold2_halftone_s {
    GS_THRESHOLD_HALFTONE_COMMON; /* must be first */
    int width2;
    int height2;
    int bytes_per_sample;	/* 1 or 2 */
    gs_const_bytestring thresholds; /* nota bene */
} gs_threshold2_halftone;

/* Client-defined halftone that generates a halftone order. */
typedef struct gs_client_order_halftone_s gs_client_order_halftone;

#ifndef gx_ht_order_DEFINED
#  define gx_ht_order_DEFINED
typedef struct gx_ht_order_s gx_ht_order;
#endif
typedef struct gs_client_order_ht_procs_s {

    /*
     * Allocate and fill in the order.  gx_ht_alloc_client_order
     * (see gzht.h) does everything but fill in the actual data.
     */

    int (*create_order) (P4(gx_ht_order * porder,
			    gs_state * pgs,
			    const gs_client_order_halftone * phcop,
			    gs_memory_t * mem));

} gs_client_order_ht_procs_t;
struct gs_client_order_halftone_s {
    int width;
    int height;
    int num_levels;
    const gs_client_order_ht_procs_t *procs;
    const void *client_data;
    gs_mapping_closure_t transfer_closure;
};

#define st_client_order_halftone_max_ptrs 2

/* Define the elements of a Type 5 halftone. */
typedef struct gs_halftone_component_s {
    gs_ht_separation_name cname;
    gs_halftone_type type;
    union {
	gs_spot_halftone spot;	/* Type 1 */
	gs_threshold_halftone threshold;	/* Type 3 */
	gs_threshold2_halftone threshold2;	/* Extended Type 3 */
	gs_client_order_halftone client_order;	/* client order */
    } params;
} gs_halftone_component;

extern_st(st_halftone_component);
#define public_st_halftone_component()	/* in gsht1.c */\
  gs_public_st_composite(st_halftone_component, gs_halftone_component,\
    "gs_halftone_component", halftone_component_enum_ptrs,\
    halftone_component_reloc_ptrs)
extern_st(st_ht_component_element);
#define public_st_ht_component_element() /* in gsht1.c */\
  gs_public_st_element(st_ht_component_element, gs_halftone_component,\
    "gs_halftone_component[]", ht_comp_elt_enum_ptrs, ht_comp_elt_reloc_ptrs,\
    st_halftone_component)
#define st_halftone_component_max_ptrs\
  max(max(st_spot_halftone_max_ptrs, st_threshold_halftone_max_ptrs),\
      st_client_order_halftone_max_ptrs)

/* Define the Type 5 halftone itself. */
typedef struct gs_multiple_halftone_s {
    gs_halftone_component *components;
    uint num_comp;
} gs_multiple_halftone;

#define st_multiple_halftone_max_ptrs 1

/*
 * The halftone stored in the graphics state is the union of
 * setscreen, setcolorscreen, Type 1, Type 3, and Type 5.
 *
 * NOTE: it is assumed that all subsidiary structures of halftones (the
 * threshold array(s) for Type 3 halftones or halftone components, and the
 * components array for Type 5 halftones) are allocated with the same
 * allocator as the halftone structure itself.
 */
struct gs_halftone_s {
    gs_halftone_type type;
    rc_header rc;
    union {
	gs_screen_halftone screen;	/* setscreen */
	gs_colorscreen_halftone colorscreen;	/* setcolorscreen */
	gs_spot_halftone spot;	/* Type 1 */
	gs_threshold_halftone threshold;	/* Type 3 */
	gs_threshold2_halftone threshold2;	/* Extended Type 3 */
	gs_client_order_halftone client_order;	/* client order */
	gs_multiple_halftone multiple;	/* Type 5 */
    } params;
};

extern_st(st_halftone);
#define public_st_halftone()	/* in gsht.c */\
  gs_public_st_composite(st_halftone, gs_halftone, "gs_halftone",\
    halftone_enum_ptrs, halftone_reloc_ptrs)
#define st_halftone_max_ptrs\
  max(max(st_screen_halftone_max_ptrs, st_colorscreen_halftone_max_ptrs),\
      max(max(st_spot_halftone_max_ptrs, st_threshold_halftone_max_ptrs),\
	  max(st_client_order_halftone_max_ptrs,\
	      st_multiple_halftone_max_ptrs)))

/* Procedural interface for AccurateScreens */

/*
 * Set/get the default AccurateScreens value (for set[color]screen).
 * Note that this value is stored in a static variable.
 */
void gs_setaccuratescreens(P1(bool));
bool gs_currentaccuratescreens(P0());

/* Initiate screen sampling with optional AccurateScreens. */
int gs_screen_init_memory(P5(gs_screen_enum *, gs_state *,
			     gs_screen_halftone *, bool, gs_memory_t *));

#define gs_screen_init_accurate(penum, pgs, phsp, accurate)\
  gs_screen_init_memory(penum, pgs, phsp, accurate, pgs->memory)

/* Procedural interface for MinScreenLevels (a Ghostscript extension) */

/*
 * Set/get the MinScreenLevels value.
 *
 * Note that this value is stored in a static variable.
 */
void gs_setminscreenlevels(P1(uint));
uint gs_currentminscreenlevels(P0());

#endif /* gxht_INCLUDED */