/* Copyright (C) 1998, 1999 artofcode LLC.  All rights reserved.
  
  This program 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 of the License, or (at your
  option) any later version.

  This program 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 this program; if not, write to the Free Software Foundation, Inc.,
  59 Temple Place, Suite 330, Boston, MA, 02111-1307.

*/

/*$Id: gxshade.c,v 1.6.2.1.2.1 2003/01/17 00:49:04 giles Exp $ */
/* Shading rendering support */
#include "math_.h"
#include "gx.h"
#include "gserrors.h"
#include "gsrect.h"
#include "gxcspace.h"
#include "gscie.h"		/* requires gscspace.h */
#include "gxdevcli.h"
#include "gxistate.h"
#include "gxdht.h"		/* for computing # of different colors */
#include "gxpaint.h"
#include "gxshade.h"
#include "gsicc.h"

/* Define a maximum smoothness value. */
/* smoothness > 0.2 produces severely blocky output. */
#define MAX_SMOOTHNESS 0.2

/* ================ Packed coordinate streams ================ */

/* Forward references */
private int cs_next_packed_value(P3(shade_coord_stream_t *, int, uint *));
private int cs_next_array_value(P3(shade_coord_stream_t *, int, uint *));
private int cs_next_packed_decoded(P4(shade_coord_stream_t *, int,
				      const float[2], float *));
private int cs_next_array_decoded(P4(shade_coord_stream_t *, int,
				     const float[2], float *));

/* Initialize a packed value stream. */
void
shade_next_init(shade_coord_stream_t * cs,
		const gs_shading_mesh_params_t * params,
		const gs_imager_state * pis)
{
    cs->params = params;
    cs->pctm = &pis->ctm;
    if (data_source_is_stream(params->DataSource)) {
	/*
	 * Reset the data stream iff it is reusable -- either a reusable
	 * file or a reusable string.
	 */
	stream *s = cs->s = params->DataSource.data.strm;

	if ((s->file != 0 && s->file_limit != max_long) ||
	    (s->file == 0 && s->strm == 0)
	    )
	    sreset(s);
    } else {
	sread_string(&cs->ds, params->DataSource.data.str.data,
		     params->DataSource.data.str.size);
	cs->s = &cs->ds;
    }
    if (data_source_is_array(params->DataSource)) {
	cs->get_value = cs_next_array_value;
	cs->get_decoded = cs_next_array_decoded;
    } else {
	cs->get_value = cs_next_packed_value;
	cs->get_decoded = cs_next_packed_decoded;
    }
    cs->left = 0;
}

/* Get the next (integer) value from a packed value stream. */
/* 1 <= num_bits <= sizeof(uint) * 8. */
private int
cs_next_packed_value(shade_coord_stream_t * cs, int num_bits, uint * pvalue)
{
    uint bits = cs->bits;
    int left = cs->left;

    if (left >= num_bits) {
	/* We can satisfy this request with the current buffered bits. */
	cs->left = left -= num_bits;
	*pvalue = (bits >> left) & ((1 << num_bits) - 1);
    } else {
	/* We need more bits. */
	int needed = num_bits - left;
	uint value = bits & ((1 << left) - 1);	/* all the remaining bits */

	for (; needed >= 8; needed -= 8) {
	    int b = sgetc(cs->s);

	    if (b < 0)
		return_error(gs_error_rangecheck);
	    value = (value << 8) + b;
	}
	if (needed == 0) {
	    cs->left = 0;
	    *pvalue = value;
	} else {
	    int b = sgetc(cs->s);

	    if (b < 0)
		return_error(gs_error_rangecheck);
	    cs->bits = b;
	    cs->left = left = 8 - needed;
	    *pvalue = (value << needed) + (b >> left);
	}
    }
    return 0;
}

/* Get the next (integer) value from an unpacked array. */
private int
cs_next_array_value(shade_coord_stream_t * cs, int num_bits, uint * pvalue)
{
    float value;
    uint read;

    if (sgets(cs->s, (byte *)&value, sizeof(float), &read) < 0 ||
	read != sizeof(float) || value < 0 || value >= (1 << num_bits) ||
	value != (int)value
	)
	return_error(gs_error_rangecheck);
    *pvalue = (uint) value;
    return 0;
}

/* Get the next decoded floating point value. */
private int
cs_next_packed_decoded(shade_coord_stream_t * cs, int num_bits,
		       const float decode[2], float *pvalue)
{
    uint value;
    int code = cs->get_value(cs, num_bits, &value);
#if ARCH_CAN_SHIFT_FULL_LONG
    double max_value = (double)(uint) ((1 << num_bits) - 1);
#else
    double max_value = (double)(uint)
	(num_bits == sizeof(uint) * 8 ? ~0 : ((1 << num_bits) - 1));
#endif

    if (code < 0)
	return code;
    *pvalue =
	(decode == 0 ? value / max_value :
	 decode[0] + value * (decode[1] - decode[0]) / max_value);
    return 0;
}

/* Get the next floating point value from an array, without decoding. */
private int
cs_next_array_decoded(shade_coord_stream_t * cs, int num_bits,
		      const float decode[2], float *pvalue)
{
    float value;
    uint read;

    if (sgets(cs->s, (byte *)&value, sizeof(float), &read) < 0 ||
	read != sizeof(float)
    )
	return_error(gs_error_rangecheck);
    *pvalue = value;
    return 0;
}

/* Get the next flag value. */
/* Note that this always starts a new data byte. */
int
shade_next_flag(shade_coord_stream_t * cs, int BitsPerFlag)
{
    uint flag;
    int code;

    cs->left = 0;		/* start a new byte if packed */
    code = cs->get_value(cs, BitsPerFlag, &flag);
    return (code < 0 ? code : flag);
}

/* Get one or more coordinate pairs. */
int
shade_next_coords(shade_coord_stream_t * cs, gs_fixed_point * ppt,
		  int num_points)
{
    int num_bits = cs->params->BitsPerCoordinate;
    const float *decode = cs->params->Decode;
    int code = 0;
    int i;

    for (i = 0; i < num_points; ++i) {
	float x, y;

	if ((code = cs->get_decoded(cs, num_bits, decode, &x)) < 0 ||
	    (code = cs->get_decoded(cs, num_bits, decode + 2, &y)) < 0 ||
	    (code = gs_point_transform2fixed(cs->pctm, x, y, &ppt[i])) < 0
	    )
	    break;
    }
    return code;
}

/* Get a color.  Currently all this does is look up Indexed colors. */
int
shade_next_color(shade_coord_stream_t * cs, float *pc)
{
    const float *decode = cs->params->Decode + 4;	/* skip coord decode */
    const gs_color_space *pcs = cs->params->ColorSpace;
    gs_color_space_index index = gs_color_space_get_index(pcs);
    int num_bits = cs->params->BitsPerComponent;

    if (index == gs_color_space_index_Indexed) {
	uint i;
	int code = cs->get_value(cs, num_bits, &i);

	if (code < 0)
	    return code;
	/****** DO INDEXED LOOKUP TO pc[] ******/
    } else {
	int i, code;
	int ncomp = gs_color_space_num_components(pcs);

	for (i = 0; i < ncomp; ++i)
	    if ((code = cs->get_decoded(cs, num_bits, decode + i * 2, &pc[i])) < 0)
		return code;
    }
    return 0;
}

/* Get the next vertex for a mesh element. */
int
shade_next_vertex(shade_coord_stream_t * cs, mesh_vertex_t * vertex)
{
    int code = shade_next_coords(cs, &vertex->p, 1);

    if (code >= 0)
	code = shade_next_color(cs, vertex->cc);
    return code;
}

/* ================ Shading rendering ================ */

/* Initialize the common parts of the recursion state. */
void
shade_init_fill_state(shading_fill_state_t * pfs, const gs_shading_t * psh,
		      gx_device * dev, gs_imager_state * pis)
{
    const gs_color_space *pcs = psh->params.ColorSpace;
    float max_error = min(pis->smoothness, MAX_SMOOTHNESS);
    /*
     * There's no point in trying to achieve smoothness beyond what
     * the device can implement, i.e., the number of representable
     * colors times the number of halftone levels.
     */
    long num_colors =
	max(dev->color_info.max_gray, dev->color_info.max_color) + 1;
    const gs_range *ranges = 0;
    int ci;

    pfs->dev = dev;
    pfs->pis = pis;
    pfs->num_components = gs_color_space_num_components(pcs);
top:
    switch ( gs_color_space_get_index(pcs) )
	{
	case gs_color_space_index_Indexed:
	    pcs = gs_cspace_base_space(pcs);
	    goto top;
	case gs_color_space_index_CIEDEFG:
	    ranges = pcs->params.defg->RangeDEFG.ranges;
	    break;
	case gs_color_space_index_CIEDEF:
	    ranges = pcs->params.def->RangeDEF.ranges;
	    break;
	case gs_color_space_index_CIEABC:
	    ranges = pcs->params.abc->RangeABC.ranges;
	    break;
	case gs_color_space_index_CIEA:
	    ranges = &pcs->params.a->RangeA;
	    break;
        case gs_color_space_index_CIEICC:
            ranges = pcs->params.icc.picc_info->Range.ranges;
	default:
	    break;
	}
    if (num_colors <= 32) {
	/****** WRONG FOR MULTI-PLANE HALFTONES ******/
	num_colors *= pis->dev_ht->order.num_levels;
    }
    if (max_error < 1.0 / num_colors)
	max_error = 1.0 / num_colors;
    for (ci = 0; ci < pfs->num_components; ++ci)
	pfs->cc_max_error[ci] =
	    (ranges == 0 ? max_error :
	     max_error * (ranges[ci].rmax - ranges[ci].rmin));
}

/* Transform a bounding box into device space. */
int
shade_bbox_transform2fixed(const gs_rect * rect, const gs_imager_state * pis,
			   gs_fixed_rect * rfixed)
{
    gs_rect dev_rect;
    int code = gs_bbox_transform(rect, &ctm_only(pis), &dev_rect);

    if (code >= 0) {
	rfixed->p.x = float2fixed(dev_rect.p.x);
	rfixed->p.y = float2fixed(dev_rect.p.y);
	rfixed->q.x = float2fixed(dev_rect.q.x);
	rfixed->q.y = float2fixed(dev_rect.q.y);
    }
    return code;
}

/* Fill one piece of a shading. */
int
shade_fill_path(const shading_fill_state_t * pfs, gx_path * ppath,
		gx_device_color * pdevc)
{
    gx_fill_params params;

    params.rule = -1;		/* irrelevant */
    params.adjust = pfs->pis->fill_adjust;
    params.flatness = 0;	/* irrelevant */
    params.fill_zero_width = false;
    return (*dev_proc(pfs->dev, fill_path)) (pfs->dev, pfs->pis, ppath,
					     &params, pdevc, NULL);
}