/* Copyright (C) 1989, 1996 Aladdin Enterprises.  All rights reserved.
  
  This file is part of Aladdin Ghostscript.
  
  Aladdin 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 Ghostscript Free Public
  License (the "License") for full details.
  
  Every copy of Aladdin 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 Aladdin 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.
*/

/* gsht.c */
/* setscreen operator for Ghostscript library */
#include "memory_.h"
#include <stdlib.h>		/* for qsort */
#include "gx.h"
#include "gserrors.h"
#include "gsstruct.h"
#include "gxarith.h"		/* for igcd */
#include "gzstate.h"
#include "gxdevice.h"			/* for gzht.h */
#include "gzht.h"

/* Forward declarations */
int gx_ht_process_screen(P4(gs_screen_enum *, gs_state *,
  gs_screen_halftone *, bool));		/* exported for gsht1.c */
void gx_set_effective_transfer(P1(gs_state *));

/* Structure types */
public_st_ht_order();
public_st_halftone();
public_st_device_halftone();

/* GC procedures */

#define hptr ((gs_halftone *)vptr)

private ENUM_PTRS_BEGIN(halftone_enum_ptrs) return 0;
	case 0:
		switch ( hptr->type )
		{
		case ht_type_threshold:
		  ENUM_RETURN_CONST_STRING_PTR(gs_halftone, params.threshold.thresholds);
		case ht_type_multiple:
		case ht_type_multiple_colorscreen:
		  *pep = hptr->params.multiple.components; break;
		default:
		  return 0;
		}
		break;
ENUM_PTRS_END

private RELOC_PTRS_BEGIN(halftone_reloc_ptrs) {
	switch ( hptr->type )
	  {
	  case ht_type_threshold:
	    RELOC_CONST_STRING_PTR(gs_halftone, params.threshold.thresholds);
	    break;
	  case ht_type_multiple:
	  case ht_type_multiple_colorscreen:
	    RELOC_PTR(gs_halftone, params.multiple.components);
	    break;
	  case ht_type_none:
	  case ht_type_screen:
	  case ht_type_colorscreen:
	  case ht_type_spot:
	    break;
	  }
} RELOC_PTRS_END

#undef hptr

/* setscreen */
int
gs_setscreen(gs_state *pgs, gs_screen_halftone *phsp)
{	gs_screen_enum senum;
	int code = gx_ht_process_screen(&senum, pgs, phsp,
					gs_currentaccuratescreens());
	if ( code < 0 )
		return code;
	return gs_screen_install(&senum);
}

/* currentscreen */
int
gs_currentscreen(const gs_state *pgs, gs_screen_halftone *phsp)
{	switch ( pgs->halftone->type )
	{
	case ht_type_screen:
		*phsp = pgs->halftone->params.screen;
		return 0;
	case ht_type_colorscreen:
		*phsp = pgs->halftone->params.colorscreen.screens.colored.gray;
		return 0;
	default:
		return_error(gs_error_undefined);
	}
}

/* .currentscreenlevels */
int
gs_currentscreenlevels(const gs_state *pgs)
{	return pgs->dev_ht->order.num_levels;
}

/* sethalftonephase */
int
gs_sethalftonephase(gs_state *pgs, int x, int y)
{	pgs->ht_phase.x = x;
	pgs->ht_phase.y = y;
	gx_unset_dev_color(pgs);
	return 0;
}

/* currenthalftonephase */
int
gs_currenthalftonephase(const gs_state *pgs, gs_int_point *pphase)
{	*pphase = pgs->ht_phase;
	return 0;
}

/* currenthalftone */
int
gs_currenthalftone(gs_state *pgs, gs_halftone *pht)
{	*pht = *pgs->halftone;
	return 0;
}

/* ------ Internal routines ------ */

/* Process one screen plane. */
int
gx_ht_process_screen(gs_screen_enum *penum, gs_state *pgs,
  gs_screen_halftone *phsp, bool accurate)
{	gs_point pt;
	int code = gs_screen_init_accurate(penum, pgs, phsp, accurate);
	if ( code < 0 ) return code;
	while ( (code = gs_screen_currentpoint(penum, &pt)) == 0 )
		if ( (code = gs_screen_next(penum, (*phsp->spot_function)(pt.x, pt.y))) < 0 )
			return code;
	return 0;
}

/* Allocate and initialize the contents of a halftone order. */
int
gx_ht_alloc_order(gx_ht_order *porder, uint width, uint height,
  uint strip_shift, uint num_levels, gs_memory_t *mem)
{	uint size = width * height;
	gx_ht_order order;

	order = *porder;
	order.width = width;
	order.height = height;
	order.raster = bitmap_raster(width);
	order.shift = strip_shift;
	order.orig_height = order.height;
	order.orig_shift = order.shift;
	order.full_height = ht_order_full_height(&order);
	order.multiple = 1;
	order.num_levels = num_levels;
	order.num_bits = size;
	order.levels =
	  (uint *)gs_alloc_byte_array(mem, num_levels, sizeof(uint),
				      "ht order(levels)");
	order.bits =
	  (gx_ht_bit *)gs_alloc_byte_array(mem, size, sizeof(gx_ht_bit),
					   "ht order(bits)");
	if ( order.levels == 0 || order.bits == 0 )
	{	gs_free_object(mem, order.bits, "ht order(bits)");
		gs_free_object(mem, order.levels, "ht order(levels)");
		return_error(gs_error_VMerror);
	}
	order.cache = 0;
	order.transfer = 0;
	*porder = order;
	return 0;
}

/* Compare keys ("masks", actually sample values) for qsort. */
private int
compare_samples(const void *p1, const void *p2)
{	ht_sample_t m1 = ((const gx_ht_bit *)p1)->mask;
	ht_sample_t m2 = ((const gx_ht_bit *)p2)->mask;
	return (m1 < m2 ? -1 : m1 > m2 ? 1 : 0);
}
/* Sort the halftone order by sample value. */
void
gx_sort_ht_order(gx_ht_bit *recs, uint N)
{	int i;
	/* Tag each sample with its index, for sorting. */
	for ( i = 0; i < N; i++ )
	  recs[i].offset = i;
	qsort((void *)recs, N, sizeof(*recs), compare_samples);
#ifdef DEBUG
if ( gs_debug_c('H') )
	{	uint i;
		dprintf("[H]Sorted samples:\n");
		for ( i = 0; i < N; i++ )
			dprintf3("%5u: %5u: %u\n",
				 i, recs[i].offset, recs[i].mask);
	}
#endif
}

/*
 * Construct the halftone order from a sampled spot function.  Only width x
 * strip samples have been filled in; we must replicate the resulting sorted
 * order vertically, shifting it by shift each time.  See gxdht.h regarding
 * the invariants that must be restored.
 */
void
gx_ht_construct_spot_order(gx_ht_order *porder)
{	uint width = porder->width;
	uint height = porder->orig_height;
	uint num_levels = porder->num_levels;	/* = width x strip */
	uint strip = num_levels / width;
	gx_ht_bit *bits = porder->bits;
	uint *levels = porder->levels;
	uint shift = porder->orig_shift;
	uint full_height = porder->full_height;
	uint num_bits = porder->num_bits;
	uint copies = num_bits / (width * strip);
	gx_ht_bit *bp = bits + num_bits - 1;
	uint i;

	gx_sort_ht_order(bits, num_levels);
	if_debug5('h',
		  "[h]spot order: num_levels=%u w=%u h=%u strip=%u shift=%u\n",
		  num_levels, width, height, strip, shift);
	/* Fill in the levels array, replicating the bits vertically */
	/* if needed. */
	for ( i = num_levels; i > 0; )
	  { uint offset = bits[--i].offset;
	    uint x = offset % width;
	    uint hy = offset - x;
	    uint k;

	    levels[i] = i * copies;
	    for ( k = 0; k < copies;
		  k++, bp--, hy += num_levels, x = (x + width - shift) % width
		)
	      bp->offset = hy + x;
	  }
	/* If we have a complete halftone, restore the invariant. */
	if ( num_bits == width * full_height )
	  { porder->height = full_height;
	    porder->shift = 0;
	  }
	gx_ht_construct_bits(porder);
}

/* Construct offset/masks from the whitening order. */
/* porder->bits[i].offset contains the index of the bit position */
/* that is i'th in the whitening order. */
void
gx_ht_construct_bits(gx_ht_order *porder)
{	uint width = porder->width;
	uint size = porder->num_bits;
	gx_ht_bit *bits = porder->bits;
	uint i;
	gx_ht_bit *phb;
	byte *pb;
	uint padding = porder->raster * 8 - width;

	for ( i = 0, phb = bits; i < size; i++, phb++ )
	{	int pix = phb->offset;
		ht_mask_t mask;
		pix += pix / width * padding;
		phb->offset = (pix >> 3) & -sizeof(mask);
		mask = (ht_mask_t)1 << (~pix & (ht_mask_bits - 1));
		/* Replicate the mask bits. */
		pix = ht_mask_bits - width;
		while ( (pix -= width) >= 0 )
			mask |= mask >> width;
		/* Store the mask, reversing bytes if necessary. */
		phb->mask = 0;
		for ( pb = (byte *)&phb->mask + (sizeof(mask) - 1);
		      mask != 0;
		      mask >>= 8, pb--
		    )
			*pb = (byte)mask;
	}
#ifdef DEBUG
if ( gs_debug_c('H') )
	   {	dprintf1("[H]Halftone order bits 0x%lx:\n", (ulong)bits);
		for ( i = 0, phb = bits; i < size; i++, phb++ )
			dprintf3("%4d: %u:0x%lx\n", i, phb->offset,
				 (ulong)phb->mask);
	   }
#endif
}

/* Install a new halftone in the graphics state. */
int
gx_ht_install(gs_state *pgs, const gs_halftone *pht,
  const gx_device_halftone *pdht)
{	gx_device_halftone *pgdht = pgs->dev_ht;
	if ( (ulong)pdht->order.raster * (pdht->order.num_bits /
	       pdht->order.width) > pgs->ht_cache->bits_size
	   )
		return_error(gs_error_limitcheck);
	*pgs->halftone = *pht;
	*pgdht = *pdht;
	/* Clear the cache, to avoid confusion in case the address of */
	/* a new order vector matches that of a (deallocated) old one. */
	gx_ht_clear_cache(pgs->ht_cache);
	/* Set the color_indices according to the device color_info. */
	/* Also compute the LCM of the primary color cell sizes. */
	/* Note that for strip halftones, the "cell size" is the */
	/* theoretical fully expanded size with shift = 0. */
	if ( pdht->components != 0 )
	{	static const gs_ht_separation_name dcnames[5][4] =
		{	{ gs_ht_separation_Default },	/* not used */
			{ gs_ht_separation_Default, gs_ht_separation_Default,
			  gs_ht_separation_Default, gs_ht_separation_Gray
			},
			{ gs_ht_separation_Default },	/* not used */
			{ gs_ht_separation_Red, gs_ht_separation_Green,
			  gs_ht_separation_Blue, gs_ht_separation_Default
			},
			{ gs_ht_separation_Cyan, gs_ht_separation_Magenta,
			  gs_ht_separation_Yellow, gs_ht_separation_Black
			}
		};
		static const gs_ht_separation_name cscnames[4] =
			{ gs_ht_separation_Red, gs_ht_separation_Green,
			  gs_ht_separation_Blue, gs_ht_separation_Default
			};
		int num_comps = gs_currentdevice_inline(pgs)->color_info.
		  num_components;
		const gs_ht_separation_name _ds *cnames = dcnames[num_comps];
		int lcm_width = 1, lcm_height = 1;
		uint i;

		/* Halftones set by setcolorscreen, and (we think) */
		/* Type 2 and Type 4 halftones, are supposed to work */
		/* for both RGB and CMYK, so we need a special check here. */
		if ( num_comps == 4 &&
		     (pht->type == ht_type_colorscreen ||
		      pht->type == ht_type_multiple_colorscreen)
		   )
		  cnames = cscnames;
		if_debug4('h', "[h]dcnames=%lu,%lu,%lu,%lu\n",
			  (ulong)cnames[0], (ulong)cnames[1],
			  (ulong)cnames[2], (ulong)cnames[3]);
		memset(pgdht->color_indices, 0, sizeof(pdht->color_indices));
		for ( i = 0; i < pdht->num_comp; i++ )
		{	const gx_ht_order_component *pcomp =
			  &pdht->components[i];
			int j;
			if_debug2('h', "[h]cname[%d]=%lu\n",
				  i, (ulong)pcomp->cname);
			for ( j = 0; j < 4; j++ )
			{	if ( pcomp->cname == cnames[j] )
				  { if_debug2('h', "[h]color_indices[%d]=%d\n",
					      j, i);
				    pgdht->color_indices[j] = i;
				  }
			}
		}
		/* Now do a second pass to compute the LCM. */
		/* We have to do it this way in case some entry in */
		/* color_indices is still 0. */
		for ( i = 0; i < 4; ++i )
		  {	const gx_ht_order_component *pcomp =
			  &pdht->components[pgdht->color_indices[i]];
			uint cw = pcomp->corder.width;
			uint ch = pcomp->corder.full_height;
			int dw = lcm_width / igcd(lcm_width, cw);
			int dh = lcm_height / igcd(lcm_height, ch);
			lcm_width = (cw > max_int / dw ? max_int : cw * dw);
			lcm_height = (ch > max_int / dh ? max_int : ch * dh);
		  }
		pgdht->lcm_width = lcm_width;
		pgdht->lcm_height = lcm_height;
	}
	else
	  {	/* Only one component. */
		pgdht->lcm_width = pgdht->order.width;
		pgdht->lcm_height = pgdht->order.full_height;
	  }
	if_debug2('h', "[h]LCM=(%d,%d)\n",
		  pgdht->lcm_width, pgdht->lcm_height);
	gx_set_effective_transfer(pgs);
	gx_unset_dev_color(pgs);
	return 0;
}

/* Reestablish the effective transfer functions, taking into account */
/* any overrides from halftone dictionaries. */
void
gx_set_effective_transfer(gs_state *pgs)
{	const gx_device_halftone *pdht = pgs->dev_ht;
	pgs->effective_transfer = pgs->set_transfer;		/* default */
	if ( pdht->components == 0 )
	{	/* Check for transfer function override in single halftone */
		gx_transfer_map *pmap = pdht->order.transfer;
		if ( pmap != 0 )
		  pgs->effective_transfer.indexed[0] =
		    pgs->effective_transfer.indexed[1] =
		    pgs->effective_transfer.indexed[2] =
		    pgs->effective_transfer.indexed[3] = pmap;
	}
	else
	{	/* Check in all 4 standard separations */
		int i;
		for ( i = 0; i < 4; ++i )
		{	gx_transfer_map *pmap =
			  pdht->components[pdht->color_indices[i]].corder.
			    transfer;
			if ( pmap != 0 )
			  pgs->effective_transfer.indexed[i] = pmap;
		}
	}
}