/* Copyright (C) 1993, 1994, 1997 Aladdin Enterprises.  All rights reserved.
  
  This file is part of AFPL Ghostscript.
  
  AFPL Ghostscript is distributed with NO WARRANTY OF ANY KIND.  No author or
  distributor accepts any responsibility for the consequences of using it, or
  for whether it serves any particular purpose or works at all, unless he or
  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
  to copy, modify and redistribute AFPL Ghostscript, but only under certain
  conditions described in the License.  Among other things, the License
  requires that the copyright notice and this notice be preserved on all
  copies.
*/

/*$Id$ */
/* Public interface to halftone functionality */

#ifndef gsht_INCLUDED
#  define gsht_INCLUDED

/* Client definition of (Type 1) halftones */
typedef struct gs_screen_halftone_s {
    float frequency;
    float angle;
    float (*spot_function) (P2(floatp, floatp));
    /* setscreen or sethalftone sets these: */
    /* (a Level 2 feature, but we include them in Level 1) */
    float actual_frequency;
    float actual_angle;
} gs_screen_halftone;

#define st_screen_halftone_max_ptrs 0

/* Client definition of color (Type 2) halftones */
typedef struct gs_colorscreen_halftone_s {
    union _css {
	gs_screen_halftone indexed[4];
	struct _csc {
	    gs_screen_halftone red, green, blue, gray;
	} colored;
    } screens;
} gs_colorscreen_halftone;

#define st_colorscreen_halftone_max_ptrs 0

/* Procedural interface */
int gs_setscreen(P2(gs_state *, gs_screen_halftone *));
int gs_currentscreen(P2(const gs_state *, gs_screen_halftone *));
int gs_currentscreenlevels(P1(const gs_state *));

/*
 * Enumeration-style definition of a single screen.  The client must:
 *      - probably, call gs_screen_enum_alloc;
 *      - call gs_screen_init;
 *      - in a loop,
 *              - call gs_screen_currentpoint; if it returns 1, exit;
 *              - call gs_screen_next;
 *      - if desired, call gs_screen_install to install the screen.
 */
typedef struct gs_screen_enum_s gs_screen_enum;
gs_screen_enum *gs_screen_enum_alloc(P2(gs_memory_t *, client_name_t));
int gs_screen_init(P3(gs_screen_enum *, gs_state *,
		      gs_screen_halftone *));
int gs_screen_currentpoint(P2(gs_screen_enum *, gs_point *));
int gs_screen_next(P2(gs_screen_enum *, floatp));
int gs_screen_install(P1(gs_screen_enum *));

#endif /* gsht_INCLUDED */