/* Copyright (C) 2002 artofcode LLC.  All rights reserved.
  
  This file is part of GNU ghostscript

  GNU ghostscript is free software; you can redistribute it and/or modify it under
  the terms of the GNU General Public License as published by the Free Software
  Foundation; either version 2, or (at your option) any later version.

  GNU ghostscript is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

  You should have received a copy of the GNU General Public License along with
  ghostscript; see the file COPYING. If not, write to the Free Software Foundation,
  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.

  
*/
/*$Id: gxwts.c,v 1.3 2005/12/13 16:57:24 jemarch Exp $ */
/* Rendering using Well Tempered Screening. */
#include "stdpre.h"
#include "memory_.h" /* for memcmp */
#include <stdlib.h> /* for malloc */
#include "gx.h"
#include "gxstate.h"
#include "gsht.h"
#include "math_.h"
#include "gserrors.h"
#include "gxdcolor.h"
#include "gxdevcli.h"
#include "gxdht.h"
#include "gxwts.h"

#define GXWTS_USE_DOUBLE

#ifndef UNIT_TEST
/* device color type for wts. */

/* todo: trace and relocate pointers */
gs_private_st_simple(st_dc_wts, gx_device_color, "dc_wts");
private dev_color_proc_save_dc(gx_dc_wts_save_dc);
private dev_color_proc_get_dev_halftone(gx_dc_wts_get_dev_halftone);
private dev_color_proc_load(gx_dc_wts_load);
private dev_color_proc_fill_rectangle(gx_dc_wts_fill_rectangle);
private dev_color_proc_equal(gx_dc_wts_equal);
private dev_color_proc_write(gx_dc_wts_write);
private dev_color_proc_read(gx_dc_wts_read);
private dev_color_proc_get_nonzero_comps(gx_dc_wts_get_nonzero_comps);
const gx_device_color_type_t gx_dc_type_data_wts = {
    &st_dc_wts,
    gx_dc_wts_save_dc, gx_dc_wts_get_dev_halftone,
    gx_dc_ht_get_phase,
    gx_dc_wts_load, gx_dc_wts_fill_rectangle,
    gx_dc_default_fill_masked, gx_dc_wts_equal,
    gx_dc_wts_write, gx_dc_wts_read,
    gx_dc_wts_get_nonzero_comps
};
#undef gx_dc_type_wts
const gx_device_color_type_t *const gx_dc_type_wts =
&gx_dc_type_data_wts;
#endif

/* Low-level implementation follows. */

/**
 * mul_shr_16: Multiply and shift right 16.
 * @a: 32-bit signed number.
 * @b: 32-bit signed number.
 *
 * Multiply @a and @b, then shift right 16 bits. Allow intermediate value
 * to overflow 32 bits.
 *
 * Return value: result.
 **/
#ifdef GXWTS_USE_DOUBLE
private int
mul_shr_16 (int a, int b)
{
  return (int)floor(((double) a) * ((double) b) * (1.0 / (1 << 16)));
}
#else
#error todo: supply mul_shr_16 based on 64 bit integer type
#endif

/* Implementation of wts_get_samples for rational cells. */
#if 0
private int
wts_get_samples_rat(const wts_screen_t *ws, int x, int y,
		    wts_screen_sample_t **samples, int *p_nsamples)
{
    int d = y / ws->cell_height;
    int r = y % ws->cell_height;
    int x_ix = ((d * ws->cell_shift) + x) % ws->cell_width;
    *p_nsamples = ws->cell_width - x_ix;
    *samples = ws->samples + x_ix + r * ws->cell_width;
    return 0;
}
#endif

/* Implementation of wts_get_samples for Screen J. */
private int
wts_get_samples_j(const wts_screen_t *ws, int x, int y,
		  wts_screen_sample_t **samples, int *p_nsamples)
{
    const wts_screen_j_t *wsj = (const wts_screen_j_t *)ws;
    /* int d = y / ws->cell_height; */
    int y_ix = y;
    int x_ix = x;
    double pad = (wsj->pa) * (1.0 / (1 << 16));
    double pbd = (wsj->pb) * (1.0 / (1 << 16));
    double afrac = x * pad;
    double bfrac = x * pbd;
    int acount = (int)floor(afrac);
    int bcount = (int)floor(bfrac);
    int ccount = mul_shr_16(y, wsj->pc);
    int dcount = mul_shr_16(y, wsj->pd);
    int nsamples;

    x_ix += acount * wsj->XA + bcount * wsj->XB +
	ccount * wsj->XC + dcount * wsj->XD;
    y_ix += acount * wsj->YA + bcount * wsj->YB +
	ccount * wsj->YC + dcount * wsj->YD;

    x_ix += (y_ix / ws->cell_height) * ws->cell_shift;
    x_ix %= ws->cell_width;
    y_ix %= ws->cell_height;

    nsamples = ws->cell_width - x_ix;
    if (floor (afrac + (nsamples - 1) * pad) > acount)
	nsamples = (int)ceil((acount + 1 - afrac) / pad);

    if (floor (bfrac + (nsamples - 1) * pbd) > bcount)
	nsamples = (int)ceil((bcount + 1 - bfrac) / pbd);
#if 0
    printf("get_samples: (%d, %d) -> (%d, %d) %d (cc=%d)\n",
	   x, y, x_ix, y_ix, nsamples, ccount);
#endif
    *p_nsamples = nsamples;
    *samples = ws->samples + x_ix + y_ix * ws->cell_width;
    return 0;
}

private int
wts_screen_h_offset(int x, double p1, int m1, int m2)
{
    /* todo: this is a linear search; constant time should be feasible */
    double running_p = 0;
    int width_so_far;
    int this_width;

    for (width_so_far = 0;; width_so_far += this_width) {
	running_p += p1;
	if (running_p >= 0.5) {
	    this_width = m1;
	    running_p -= 1;
	} else {
	    this_width = m2;
	}
	if (width_so_far + this_width > x)
	    break;
    }
    return x - width_so_far + (this_width == m1 ? 0 : m1);
}

/* Implementation of wts_get_samples for Screen H. */
private int
wts_get_samples_h(const wts_screen_t *ws, int x, int y,
		  wts_screen_sample_t **samples, int *p_nsamples)
{
    const wts_screen_h_t *wsh = (const wts_screen_h_t *)ws;
    int x_ix = wts_screen_h_offset(x, wsh->px,
				   wsh->x1, ws->cell_width - wsh->x1);
    int y_ix = wts_screen_h_offset(y, wsh->py,
				   wsh->y1, ws->cell_height - wsh->y1);
    *p_nsamples = (x_ix >= wsh->x1 ? ws->cell_width : wsh->x1) - x_ix;
    *samples = ws->samples + x_ix + y_ix * ws->cell_width;
    return 0;
}

/**
 * wts_get_samples: Get samples from Well Tempered Screening cell.
 * @ws: Well Tempered Screening cell.
 * @x: X coordinate of starting point.
 * @y: Y coordinate of starting point.
 * @samples: Where to store pointer to samples.
 * @p_nsamples: Where to store number of valid samples.
 *
 * Finds samples from the cell for use in halftoning. On success,
 * @p_nsamples is set to the number of valid samples, ie for 0 <= i <
 * nsamples, samples[i] is a valid sample for coordinate (x + i, y).
 * p_nsamples is guaranteed to at least 1. The samples in @samples
 * are valid for the lifetime of the cell, or until the next garbage
 * collection, whichever comes first.
 *
 * Todo: describe meaning of wts_screen_sample_t (particularly edge
 * cases).
 *
 * Note: may want to add a "cursor" to the api as an optimization. It
 * can wait, though.
 *
 * Return value: 0 on success.
 **/
int
wts_get_samples(const wts_screen_t *ws, int x, int y,
		wts_screen_sample_t **samples, int *p_nsamples)
{
    if (ws->type == WTS_SCREEN_J)
	return wts_get_samples_j(ws, x, y, samples, p_nsamples);
    if (ws->type == WTS_SCREEN_H)
	return wts_get_samples_h(ws, x, y, samples, p_nsamples);
    else
	return -1;
}

/* Device color methods follow. */

private void
gx_dc_wts_save_dc(const gx_device_color * pdevc, gx_device_color_saved * psdc)
{
    psdc->type = pdevc->type;
    memcpy( psdc->colors.wts.levels,
            pdevc->colors.wts.levels,
            sizeof(psdc->colors.wts.levels) );
    psdc->phase = pdevc->phase;
}

private const gx_device_halftone *
gx_dc_wts_get_dev_halftone(const gx_device_color * pdevc)
{
    return pdevc->colors.wts.w_ht;
}

private int
gx_dc_wts_load(gx_device_color *pdevc, const gs_imager_state * pis,
	       gx_device *ignore_dev, gs_color_select_t select)
{
    return 0;
}

/**
 * wts_draw: Draw a halftoned shade into a 1 bit deep buffer.
 * @ws: WTS screen.
 * @shade: Gray shade to draw.
 * @data: Destination buffer.
 * @data_raster: Rowstride for destination buffer.
 * @x, @y, @w, @h: coordinates of rectangle to draw.
 *
 * This is close to an implementation of the "draw" method for the
 * gx_ht_order class. Currently, only WTS screens implement this
 * method, and only WTS device colors invoke it. However, implementing
 * this for legacy order objects is probably a good idea, to improve
 * halftoning performance as the cell size scales up.
 *
 * However, it's not exactly an implementation of the "draw" method
 * for the gx_ht_order class because the "self" type would need to be
 * gx_ht_order. Currently, however, device colors don't hold a pointer
 * to the order object. Some amount of refactoring seems to be in
 * order.
 *
 * Return value: 0 on success.
 **/
private int
wts_draw(wts_screen_t *ws, wts_screen_sample_t shade,
	 byte *data, int data_raster,
	 int x, int y, int w, int h)
{
    int xo, yo;
    unsigned char *line_start = data;

    for (yo = 0; yo < h; yo++) {
	unsigned char *line_ptr = line_start;
	int mask = 0x80;
	unsigned char b = 0;
	int imax;

	for (xo = 0; xo < w; xo += imax) {
	    wts_screen_sample_t *samples;
	    int n_samples, i;

	    wts_get_samples(ws, x + xo, y + yo, &samples, &n_samples);
	    imax = min(w - xo, n_samples);
	    for (i = 0; i < imax; i++) {
		if (shade > samples[i])
		    b |= mask;
		mask >>= 1;
		if (mask == 0) {
		    *line_ptr++ = b;
		    b = 0;
		    mask = 0x80;
		}
	    }
	}
	if (mask != 0x80)
	    *line_ptr = b;
	line_start += data_raster;
    }
    return 0;
}

/**
 * Special case implementation for one component. When we do plane_mask,
 * we'll want to generalize this to handle any single-bit plane_mask.
 **/
private int
gx_dc_wts_fill_rectangle_1(const gx_device_color *pdevc,
			   int x, int y, int w, int h,
			   gx_device *dev, gs_logical_operation_t lop,
			   const gx_rop_source_t *source)
{
    /* gx_rop_source_t no_source; */
    int tile_raster = ((w + 31) & -32) >> 3;
    int tile_size = tile_raster * h;
    unsigned char *tile_data;
    int code = 0;
    gx_ht_order_component *components = pdevc->colors.wts.w_ht->components;
    wts_screen_t *ws = components[0].corder.wts;
    wts_screen_sample_t shade = pdevc->colors.wts.levels[0];
    gx_color_index color0, color1;

    color0 = dev->color_info.separable_and_linear == GX_CINFO_SEP_LIN ? 0 :
	pdevc->colors.wts.plane_vector[1];
    color1 = pdevc->colors.wts.plane_vector[0];

    tile_data = malloc(tile_size);

    wts_draw(ws, shade, tile_data, tile_raster, x, y, w, h);
 
    /* See gx_dc_ht_binary_fill_rectangle() for explanation. */
    if (dev->color_info.depth > 1)
	lop &= ~lop_T_transparent;

    /* Interesting question: should data_x be (x & 7), rather than 0,
       to improve alignment? */
    if (source == NULL && lop_no_S_is_T(lop))
	code = (*dev_proc(dev, copy_mono))
	    (dev, tile_data, 0, tile_raster, gx_no_bitmap_id,
	     x, y, w, h, color0, color1);

    free(tile_data);
    return code;
}

private int
gx_dc_wts_write(
    const gx_device_color *         pdevc,
    const gx_device_color_saved *   psdc,
    const gx_device *               dev,
    byte *                          pdata,
    uint *                          psize )
{
    /* not yet implemented */
    return_error(gs_error_unknownerror);
}

private int
gx_dc_wts_read(
    gx_device_color *       pdevc,
    const gs_imager_state * pis,
    const gx_device_color * prior_devc,
    const gx_device *       dev,
    const byte *            pdata,
    uint                    size,
    gs_memory_t *           mem )
{
    /* not yet implemented */
    return_error(gs_error_unknownerror);
}


/**
 * wts_repack_tile_4: Repack four 1-bit tiles into chunky nibbles.
 * Note: argument list will change. plane_mask and base_color will
 * probably get added as an optimization.
 *
 * Note: we round w up to an even value. We're counting on the
 * subsequent copy_color to ignore any extra bits.
 **/
private void
wts_repack_tile_4(unsigned char *ctile_data, int ctile_raster,
		  const unsigned char **tile_data, int tile_raster,
		  const gx_color_index *plane_vector, bool invert,
		  int w, int h)
{
    int y;
    int tile_idx_start = 0;
    unsigned char *ctile_start = ctile_data;
    byte inv_byte = invert ? 0xff : 0;

    for (y = 0; y < h; y++) {
	int x;
	int tile_idx = tile_idx_start;

	for (x = 0; x < w; x += 2) {
	    byte b = 0;
	    byte m0 = 0x80 >> (x & 6);
	    byte m1 = m0 >> 1;
	    byte td;

	    td = tile_data[0][tile_idx] ^ inv_byte;
	    if (td & m0) b |= plane_vector[0] << 4;
	    if (td & m1) b |= plane_vector[0];

	    td = tile_data[1][tile_idx] ^ inv_byte;
	    if (td & m0) b |= plane_vector[1] << 4;
	    if (td & m1) b |= plane_vector[1];

	    td = tile_data[2][tile_idx] ^ inv_byte;
	    if (td & m0) b |= plane_vector[2] << 4;
	    if (td & m1) b |= plane_vector[2];

	    td = tile_data[3][tile_idx] ^ inv_byte;
	    if (td & m0) b |= plane_vector[3] << 4;
	    if (td & m1) b |= plane_vector[3];

	    if ((x & 6) == 6)
		tile_idx++;
	    ctile_start[x >> 1] = b;
	}
	tile_idx_start += tile_raster;
	ctile_start += ctile_raster;
    }
}

/* Special case implementation for four components. Intermediate color
 * to the order objecttile (for copy_color) is packed 2 to a byte.
 *
 * Looking at this code, it should generalize to more than four
 * components. Probably the repack code should get factored out.
 */
private int
gx_dc_wts_fill_rectangle_4(const gx_device_color *pdevc,
			   int x, int y, int w, int h,
			   gx_device *dev, gs_logical_operation_t lop,
			   const gx_rop_source_t *source)
{
    int num_comp = pdevc->colors.wts.num_components;
    /* gx_rop_source_t no_source; */

    int tile_raster = ((w + 31) & -32) >> 3;
    int tile_size = tile_raster * h;
    unsigned char *tile_data[4];

    int ctile_raster = ((w + 7) & -8) >> 1;
    int ctile_size = ctile_raster * h;
    unsigned char *ctile_data;

    int code = 0;
    bool invert = 0 && dev->color_info.polarity == GX_CINFO_POLARITY_SUBTRACTIVE;
    int i;

    for (i = 0; i < num_comp; i++) {
	wts_screen_sample_t shade = pdevc->colors.wts.levels[i];
	gx_ht_order_component *components = pdevc->colors.wts.w_ht->components;
	wts_screen_t *ws = components[i].corder.wts;

	tile_data[i] = malloc(tile_size);
	wts_draw(ws, shade, tile_data[i], tile_raster, x, y, w, h);
    }

    ctile_data = malloc(ctile_size);
    wts_repack_tile_4(ctile_data, ctile_raster, 
    		  (const unsigned char **)tile_data, tile_raster,
		      pdevc->colors.wts.plane_vector, invert, w, h);
 
    /* See gx_dc_ht_binary_fill_rectangle() for explanation. */
    if (dev->color_info.depth > 1)
	lop &= ~lop_T_transparent;

    if (source == NULL && lop_no_S_is_T(lop))
	code = (*dev_proc(dev, copy_color))
	    (dev, ctile_data, 0, ctile_raster, gx_no_bitmap_id,
	     x, y, w, h);

    free(ctile_data);
    for (i = 0; i < num_comp; i++) {
	free(tile_data[i]);
    }

    return code;
}

private int
gx_dc_wts_fill_rectangle(const gx_device_color *pdevc,
			 int x, int y, int w, int h,
			 gx_device *dev, gs_logical_operation_t lop,
			 const gx_rop_source_t *source)
{
    int num_comp = pdevc->colors.wts.num_components;

    if (num_comp == 1)
	return gx_dc_wts_fill_rectangle_1(pdevc, x, y, w, h, dev, lop, source);
    else if (num_comp <= 4)
	return gx_dc_wts_fill_rectangle_4(pdevc, x, y, w, h, dev, lop, source);
    else
	return -1;
}

/* Compare two wts colors for equality. */
private int
gx_dc_wts_equal(const gx_device_color *pdevc1,
		const gx_device_color *pdevc2)
{
    uint num_comp = pdevc1->colors.wts.num_components;

    if (pdevc2->type != pdevc1->type ||
	pdevc1->phase.x != pdevc2->phase.x ||
	pdevc1->phase.y != pdevc2->phase.y ||
	num_comp != pdevc2->colors.wts.num_components
	)
	return false;
    return
	!memcmp(pdevc1->colors.wts.levels,
		pdevc2->colors.wts.levels,
		num_comp * sizeof(pdevc1->colors.wts.levels[0]));
}

/*
 * Get the nonzero components of a wts halftone. This is used to
 * distinguish components that are given zero intensity due to halftoning
 * from those for which the original color intensity was in fact zero.
 */
int
gx_dc_wts_get_nonzero_comps(
    const gx_device_color * pdevc,
    const gx_device *       dev_ignored,
    gx_color_index *        pcomp_bits )
{
    int                     i, ncomps =  pdevc->colors.wts.num_components;
    gx_color_index comp_bits = 0; /* todo: plane_mask */

    for (i = 0; i < ncomps; i++) {
        if (pdevc->colors.wts.levels[i] != 0)
            comp_bits |= ((gx_color_index)1) << i;
    }
    *pcomp_bits = comp_bits;

    return 0;
}
