/* Copyright (C) 1998, 1999 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.
 */

/*$Id: gxshade.c $ */
/* 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"

/* 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)) {
	cs->s = params->DataSource.data.strm;
    } 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);
    double max_value = (double)(uint) ((1 << num_bits) - 1);

    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;
	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;
}

/* Check whether 4 colors fall within the smoothness criterion. */
bool
shade_colors4_converge(const gs_client_color cc[4],
		       const shading_fill_state_t * pfs)
{
    int ci;

    for (ci = 0; ci < pfs->num_components; ++ci) {
	float
	      c0 = cc[0].paint.values[ci], c1 = cc[1].paint.values[ci],
	      c2 = cc[2].paint.values[ci], c3 = cc[3].paint.values[ci];
	float min01, max01, min23, max23;

	if (c0 < c1)
	    min01 = c0, max01 = c1;
	else
	    min01 = c1, max01 = c0;
	if (c2 < c3)
	    min23 = c2, max23 = c3;
	else
	    min23 = c3, max23 = c2;
	if (max(max01, max23) - min(min01, min23) > pfs->cc_max_error[ci])
	    return false;
    }
    return true;
}

/* 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);
}
