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/* -*- Mode: c; tab-width: 8; c-basic-offset: 4; indent-tabs-mode: t; -*- */

/* cairo - a vector graphics library with display and print output

 *

 * Copyright © 2002 University of Southern California

 * Copyright © 2011 Intel Corporation

 *

 * This library is free software; you can redistribute it and/or

 * modify it either under the terms of the GNU Lesser General Public

 * License version 2.1 as published by the Free Software Foundation

 * (the "LGPL") or, at your option, under the terms of the Mozilla

 * Public License Version 1.1 (the "MPL"). If you do not alter this

 * notice, a recipient may use your version of this file under either

 * the MPL or the LGPL.

 *

 * You should have received a copy of the LGPL along with this library

 * in the file COPYING-LGPL-2.1; if not, write to the Free Software

 * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA

 * You should have received a copy of the MPL along with this library

 * in the file COPYING-MPL-1.1

 *

 * The contents of this file are subject to the Mozilla Public License

 * Version 1.1 (the "License"); you may not use this file except in

 * compliance with the License. You may obtain a copy of the License at

 * http://www.mozilla.org/MPL/

 *

 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY

 * OF ANY KIND, either express or implied. See the LGPL or the MPL for

 * the specific language governing rights and limitations.

 *

 * The Original Code is the cairo graphics library.

 *

 * The Initial Developer of the Original Code is University of Southern

 * California.

 *

 * Contributor(s):

 *	Carl D. Worth 

 *	Chris Wilson 

 */

#define _BSD_SOURCE /* for hypot() */

#include "cairoint.h"

#include "cairo-box-inline.h"

#include "cairo-boxes-private.h"

#include "cairo-error-private.h"

#include "cairo-path-fixed-private.h"

#include "cairo-slope-private.h"

#include "cairo-tristrip-private.h"

struct stroker {

    cairo_stroke_style_t style;

    cairo_tristrip_t *strip;

    const cairo_matrix_t *ctm;

    const cairo_matrix_t *ctm_inverse;

    double tolerance;

    cairo_bool_t ctm_det_positive;

    cairo_pen_t pen;

    cairo_bool_t has_sub_path;

    cairo_point_t first_point;

    cairo_bool_t has_current_face;

    cairo_stroke_face_t current_face;

    cairo_bool_t has_first_face;

    cairo_stroke_face_t first_face;

    cairo_box_t limit;

    cairo_bool_t has_limits;

};

static inline double

normalize_slope (double *dx, double *dy);

static void

compute_face (const cairo_point_t *point,

	      const cairo_slope_t *dev_slope,

	      struct stroker *stroker,

	      cairo_stroke_face_t *face);

static void

translate_point (cairo_point_t *point, const cairo_point_t *offset)

{

    point->x += offset->x;

    point->y += offset->y;

}

static int

slope_compare_sgn (double dx1, double dy1, double dx2, double dy2)

{

    double  c = (dx1 * dy2 - dx2 * dy1);

    if (c > 0) return 1;

    if (c < 0) return -1;

    return 0;

}

static inline int

range_step (int i, int step, int max)

{

    i += step;

    if (i < 0)

	i = max - 1;

    if (i >= max)

	i = 0;

    return i;

}

/*

 * Construct a fan around the midpoint using the vertices from pen between

 * inpt and outpt.

 */

static void

add_fan (struct stroker *stroker,

	 const cairo_slope_t *in_vector,

	 const cairo_slope_t *out_vector,

	 const cairo_point_t *midpt,

	 const cairo_point_t *inpt,

	 const cairo_point_t *outpt,

	 cairo_bool_t clockwise)

{

    int start, stop, step, i, npoints;

    if (clockwise) {

	step  = 1;

	start = _cairo_pen_find_active_cw_vertex_index (&stroker->pen,

							in_vector);

	if (_cairo_slope_compare (&stroker->pen.vertices[start].slope_cw,

				  in_vector) < 0)

	    start = range_step (start, 1, stroker->pen.num_vertices);

	stop  = _cairo_pen_find_active_cw_vertex_index (&stroker->pen,

							out_vector);

	if (_cairo_slope_compare (&stroker->pen.vertices[stop].slope_ccw,

				  out_vector) > 0)

	{

	    stop = range_step (stop, -1, stroker->pen.num_vertices);

	    if (_cairo_slope_compare (&stroker->pen.vertices[stop].slope_cw,

				      in_vector) < 0)

		return;

	}

	npoints = stop - start;

    } else {

	step  = -1;

	start = _cairo_pen_find_active_ccw_vertex_index (&stroker->pen,

							 in_vector);

	if (_cairo_slope_compare (&stroker->pen.vertices[start].slope_ccw,

				  in_vector) < 0)

	    start = range_step (start, -1, stroker->pen.num_vertices);

	stop  = _cairo_pen_find_active_ccw_vertex_index (&stroker->pen,

							 out_vector);

	if (_cairo_slope_compare (&stroker->pen.vertices[stop].slope_cw,

				  out_vector) > 0)

	{

	    stop = range_step (stop, 1, stroker->pen.num_vertices);

	    if (_cairo_slope_compare (&stroker->pen.vertices[stop].slope_ccw,

				      in_vector) < 0)

		return;

	}

	npoints = start - stop;

    }

    stop = range_step (stop, step, stroker->pen.num_vertices);

    if (npoints < 0)

	npoints += stroker->pen.num_vertices;

    if (npoints <= 1)

	return;

    for (i = start;

	 i != stop;

	i = range_step (i, step, stroker->pen.num_vertices))

    {

	cairo_point_t p = *midpt;

	translate_point (&p, &stroker->pen.vertices[i].point);

	//contour_add_point (stroker, c, &p);

    }

}

static int

join_is_clockwise (const cairo_stroke_face_t *in,

		   const cairo_stroke_face_t *out)

{

    return _cairo_slope_compare (&in->dev_vector, &out->dev_vector) < 0;

}

static void

inner_join (struct stroker *stroker,

	    const cairo_stroke_face_t *in,

	    const cairo_stroke_face_t *out,

	    int clockwise)

{

    const cairo_point_t *outpt;

    if (clockwise) {

	outpt = &out->ccw;

    } else {

	outpt = &out->cw;

    }

    //contour_add_point (stroker, inner, &in->point);

    //contour_add_point (stroker, inner, outpt);

}

static void

inner_close (struct stroker *stroker,

	     const cairo_stroke_face_t *in,

	     cairo_stroke_face_t *out)

{

    const cairo_point_t *inpt;

    if (join_is_clockwise (in, out)) {

	inpt = &out->ccw;

    } else {

	inpt = &out->cw;

    }

    //contour_add_point (stroker, inner, &in->point);

    //contour_add_point (stroker, inner, inpt);

    //*_cairo_contour_first_point (&inner->contour) =

	//*_cairo_contour_last_point (&inner->contour);

}

static void

outer_close (struct stroker *stroker,

	     const cairo_stroke_face_t *in,

	     const cairo_stroke_face_t *out)

{

    const cairo_point_t	*inpt, *outpt;

    int	clockwise;

    if (in->cw.x == out->cw.x && in->cw.y == out->cw.y &&

	in->ccw.x == out->ccw.x && in->ccw.y == out->ccw.y)

    {

	return;

    }

    clockwise = join_is_clockwise (in, out);

    if (clockwise) {

	inpt = &in->cw;

	outpt = &out->cw;

    } else {

	inpt = &in->ccw;

	outpt = &out->ccw;

    }

    switch (stroker->style.line_join) {

    case CAIRO_LINE_JOIN_ROUND:

	/* construct a fan around the common midpoint */

	add_fan (stroker,

		 &in->dev_vector,

		 &out->dev_vector,

		 &in->point, inpt, outpt,

		 clockwise);

	break;

    case CAIRO_LINE_JOIN_MITER:

    default: {

	/* dot product of incoming slope vector with outgoing slope vector */

	double	in_dot_out = -in->usr_vector.x * out->usr_vector.x +

			     -in->usr_vector.y * out->usr_vector.y;

	double	ml = stroker->style.miter_limit;

	/* Check the miter limit -- lines meeting at an acute angle

	 * can generate long miters, the limit converts them to bevel

	 *

	 * Consider the miter join formed when two line segments

	 * meet at an angle psi:

	 *

	 *	   /.\

	 *	  /. .\

	 *	 /./ \.\

	 *	/./psi\.\

	 *

	 * We can zoom in on the right half of that to see:

	 *

	 *	    |\

	 *	    | \ psi/2

	 *	    |  \

	 *	    |   \

	 *	    |    \

	 *	    |     \

	 *	  miter    \

	 *	 length     \

	 *	    |        \

	 *	    |        .\

	 *	    |    .     \

	 *	    |.   line   \

	 *	     \    width  \

	 *	      \           \

	 *

	 *

	 * The right triangle in that figure, (the line-width side is

	 * shown faintly with three '.' characters), gives us the

	 * following expression relating miter length, angle and line

	 * width:

	 *

	 *	1 /sin (psi/2) = miter_length / line_width

	 *

	 * The right-hand side of this relationship is the same ratio

	 * in which the miter limit (ml) is expressed. We want to know

	 * when the miter length is within the miter limit. That is

	 * when the following condition holds:

	 *

	 *	1/sin(psi/2) <= ml

	 *	1 <= ml sin(psi/2)

	 *	1 <= ml² sin²(psi/2)

	 *	2 <= ml² 2 sin²(psi/2)

	 *				2·sin²(psi/2) = 1-cos(psi)

	 *	2 <= ml² (1-cos(psi))

	 *

	 *				in · out = |in| |out| cos (psi)

	 *

	 * in and out are both unit vectors, so:

	 *

	 *				in · out = cos (psi)

	 *

	 *	2 <= ml² (1 - in · out)

	 *

	 */

	if (2 <= ml * ml * (1 - in_dot_out)) {

	    double		x1, y1, x2, y2;

	    double		mx, my;

	    double		dx1, dx2, dy1, dy2;

	    double		ix, iy;

	    double		fdx1, fdy1, fdx2, fdy2;

	    double		mdx, mdy;

	    /*

	     * we've got the points already transformed to device

	     * space, but need to do some computation with them and

	     * also need to transform the slope from user space to

	     * device space

	     */

	    /* outer point of incoming line face */

	    x1 = _cairo_fixed_to_double (inpt->x);

	    y1 = _cairo_fixed_to_double (inpt->y);

	    dx1 = in->usr_vector.x;

	    dy1 = in->usr_vector.y;

	    cairo_matrix_transform_distance (stroker->ctm, &dx1, &dy1);

	    /* outer point of outgoing line face */

	    x2 = _cairo_fixed_to_double (outpt->x);

	    y2 = _cairo_fixed_to_double (outpt->y);

	    dx2 = out->usr_vector.x;

	    dy2 = out->usr_vector.y;

	    cairo_matrix_transform_distance (stroker->ctm, &dx2, &dy2);

	    /*

	     * Compute the location of the outer corner of the miter.

	     * That's pretty easy -- just the intersection of the two

	     * outer edges.  We've got slopes and points on each

	     * of those edges.  Compute my directly, then compute

	     * mx by using the edge with the larger dy; that avoids

	     * dividing by values close to zero.

	     */

	    my = (((x2 - x1) * dy1 * dy2 - y2 * dx2 * dy1 + y1 * dx1 * dy2) /

		  (dx1 * dy2 - dx2 * dy1));

	    if (fabs (dy1) >= fabs (dy2))

		mx = (my - y1) * dx1 / dy1 + x1;

	    else

		mx = (my - y2) * dx2 / dy2 + x2;

	    /*

	     * When the two outer edges are nearly parallel, slight

	     * perturbations in the position of the outer points of the lines

	     * caused by representing them in fixed point form can cause the

	     * intersection point of the miter to move a large amount. If

	     * that moves the miter intersection from between the two faces,

	     * then draw a bevel instead.

	     */

	    ix = _cairo_fixed_to_double (in->point.x);

	    iy = _cairo_fixed_to_double (in->point.y);

	    /* slope of one face */

	    fdx1 = x1 - ix; fdy1 = y1 - iy;

	    /* slope of the other face */

	    fdx2 = x2 - ix; fdy2 = y2 - iy;

	    /* slope from the intersection to the miter point */

	    mdx = mx - ix; mdy = my - iy;

	    /*

	     * Make sure the miter point line lies between the two

	     * faces by comparing the slopes

	     */

	    if (slope_compare_sgn (fdx1, fdy1, mdx, mdy) !=

		slope_compare_sgn (fdx2, fdy2, mdx, mdy))

	    {

		cairo_point_t p;

		p.x = _cairo_fixed_from_double (mx);

		p.y = _cairo_fixed_from_double (my);

		//*_cairo_contour_last_point (&outer->contour) = p;

		//*_cairo_contour_first_point (&outer->contour) = p;

		return;

	    }

	}

	break;

    }

    case CAIRO_LINE_JOIN_BEVEL:

	break;

    }

    //contour_add_point (stroker, outer, outpt);

}

static void

outer_join (struct stroker *stroker,

	    const cairo_stroke_face_t *in,

	    const cairo_stroke_face_t *out,

	    int clockwise)

{

    const cairo_point_t	*inpt, *outpt;

    if (in->cw.x == out->cw.x && in->cw.y == out->cw.y &&

	in->ccw.x == out->ccw.x && in->ccw.y == out->ccw.y)

    {

	return;

    }

    if (clockwise) {

	inpt = &in->cw;

	outpt = &out->cw;

    } else {

	inpt = &in->ccw;

	outpt = &out->ccw;

    }

    switch (stroker->style.line_join) {

    case CAIRO_LINE_JOIN_ROUND:

	/* construct a fan around the common midpoint */

	add_fan (stroker,

		 &in->dev_vector,

		 &out->dev_vector,

		 &in->point, inpt, outpt,

		 clockwise);

	break;

    case CAIRO_LINE_JOIN_MITER:

    default: {

	/* dot product of incoming slope vector with outgoing slope vector */

	double	in_dot_out = -in->usr_vector.x * out->usr_vector.x +

			     -in->usr_vector.y * out->usr_vector.y;

	double	ml = stroker->style.miter_limit;

	/* Check the miter limit -- lines meeting at an acute angle

	 * can generate long miters, the limit converts them to bevel

	 *

	 * Consider the miter join formed when two line segments

	 * meet at an angle psi:

	 *

	 *	   /.\

	 *	  /. .\

	 *	 /./ \.\

	 *	/./psi\.\

	 *

	 * We can zoom in on the right half of that to see:

	 *

	 *	    |\

	 *	    | \ psi/2

	 *	    |  \

	 *	    |   \

	 *	    |    \

	 *	    |     \

	 *	  miter    \

	 *	 length     \

	 *	    |        \

	 *	    |        .\

	 *	    |    .     \

	 *	    |.   line   \

	 *	     \    width  \

	 *	      \           \

	 *

	 *

	 * The right triangle in that figure, (the line-width side is

	 * shown faintly with three '.' characters), gives us the

	 * following expression relating miter length, angle and line

	 * width:

	 *

	 *	1 /sin (psi/2) = miter_length / line_width

	 *

	 * The right-hand side of this relationship is the same ratio

	 * in which the miter limit (ml) is expressed. We want to know

	 * when the miter length is within the miter limit. That is

	 * when the following condition holds:

	 *

	 *	1/sin(psi/2) <= ml

	 *	1 <= ml sin(psi/2)

	 *	1 <= ml² sin²(psi/2)

	 *	2 <= ml² 2 sin²(psi/2)

	 *				2·sin²(psi/2) = 1-cos(psi)

	 *	2 <= ml² (1-cos(psi))

	 *

	 *				in · out = |in| |out| cos (psi)

	 *

	 * in and out are both unit vectors, so:

	 *

	 *				in · out = cos (psi)

	 *

	 *	2 <= ml² (1 - in · out)

	 *

	 */

	if (2 <= ml * ml * (1 - in_dot_out)) {

	    double		x1, y1, x2, y2;

	    double		mx, my;

	    double		dx1, dx2, dy1, dy2;

	    double		ix, iy;

	    double		fdx1, fdy1, fdx2, fdy2;

	    double		mdx, mdy;

	    /*

	     * we've got the points already transformed to device

	     * space, but need to do some computation with them and

	     * also need to transform the slope from user space to

	     * device space

	     */

	    /* outer point of incoming line face */

	    x1 = _cairo_fixed_to_double (inpt->x);

	    y1 = _cairo_fixed_to_double (inpt->y);

	    dx1 = in->usr_vector.x;

	    dy1 = in->usr_vector.y;

	    cairo_matrix_transform_distance (stroker->ctm, &dx1, &dy1);

	    /* outer point of outgoing line face */

	    x2 = _cairo_fixed_to_double (outpt->x);

	    y2 = _cairo_fixed_to_double (outpt->y);

	    dx2 = out->usr_vector.x;

	    dy2 = out->usr_vector.y;

	    cairo_matrix_transform_distance (stroker->ctm, &dx2, &dy2);

	    /*

	     * Compute the location of the outer corner of the miter.

	     * That's pretty easy -- just the intersection of the two

	     * outer edges.  We've got slopes and points on each

	     * of those edges.  Compute my directly, then compute

	     * mx by using the edge with the larger dy; that avoids

	     * dividing by values close to zero.

	     */

	    my = (((x2 - x1) * dy1 * dy2 - y2 * dx2 * dy1 + y1 * dx1 * dy2) /

		  (dx1 * dy2 - dx2 * dy1));

	    if (fabs (dy1) >= fabs (dy2))

		mx = (my - y1) * dx1 / dy1 + x1;

	    else

		mx = (my - y2) * dx2 / dy2 + x2;

	    /*

	     * When the two outer edges are nearly parallel, slight

	     * perturbations in the position of the outer points of the lines

	     * caused by representing them in fixed point form can cause the

	     * intersection point of the miter to move a large amount. If

	     * that moves the miter intersection from between the two faces,

	     * then draw a bevel instead.

	     */

	    ix = _cairo_fixed_to_double (in->point.x);

	    iy = _cairo_fixed_to_double (in->point.y);

	    /* slope of one face */

	    fdx1 = x1 - ix; fdy1 = y1 - iy;

	    /* slope of the other face */

	    fdx2 = x2 - ix; fdy2 = y2 - iy;

	    /* slope from the intersection to the miter point */

	    mdx = mx - ix; mdy = my - iy;

	    /*

	     * Make sure the miter point line lies between the two

	     * faces by comparing the slopes

	     */

	    if (slope_compare_sgn (fdx1, fdy1, mdx, mdy) !=

		slope_compare_sgn (fdx2, fdy2, mdx, mdy))

	    {

		cairo_point_t p;

		p.x = _cairo_fixed_from_double (mx);

		p.y = _cairo_fixed_from_double (my);

		//*_cairo_contour_last_point (&outer->contour) = p;

		return;

	    }

	}

	break;

    }

    case CAIRO_LINE_JOIN_BEVEL:

	break;

    }

    //contour_add_point (stroker,outer, outpt);

}

static void

add_cap (struct stroker *stroker,

	 const cairo_stroke_face_t *f)

{

    switch (stroker->style.line_cap) {

    case CAIRO_LINE_CAP_ROUND: {

	cairo_slope_t slope;

	slope.dx = -f->dev_vector.dx;

	slope.dy = -f->dev_vector.dy;

	add_fan (stroker, &f->dev_vector, &slope,

		 &f->point, &f->ccw, &f->cw,

		 FALSE);

	break;

    }

    case CAIRO_LINE_CAP_SQUARE: {

	double dx, dy;

	cairo_slope_t	fvector;

	cairo_point_t	quad[4];

	dx = f->usr_vector.x;

	dy = f->usr_vector.y;

	dx *= stroker->style.line_width / 2.0;

	dy *= stroker->style.line_width / 2.0;

	cairo_matrix_transform_distance (stroker->ctm, &dx, &dy);

	fvector.dx = _cairo_fixed_from_double (dx);

	fvector.dy = _cairo_fixed_from_double (dy);

	quad[0] = f->ccw;

	quad[1].x = f->ccw.x + fvector.dx;

	quad[1].y = f->ccw.y + fvector.dy;

	quad[2].x = f->cw.x + fvector.dx;

	quad[2].y = f->cw.y + fvector.dy;

	quad[3] = f->cw;

	//contour_add_point (stroker, c, &quad[1]);

	//contour_add_point (stroker, c, &quad[2]);

    }

    case CAIRO_LINE_CAP_BUTT:

    default:

	break;

    }

    //contour_add_point (stroker, c, &f->cw);

}

static void

add_leading_cap (struct stroker *stroker,

		 const cairo_stroke_face_t *face)

{

    cairo_stroke_face_t reversed;

    cairo_point_t t;

    reversed = *face;

    /* The initial cap needs an outward facing vector. Reverse everything */

    reversed.usr_vector.x = -reversed.usr_vector.x;

    reversed.usr_vector.y = -reversed.usr_vector.y;

    reversed.dev_vector.dx = -reversed.dev_vector.dx;

    reversed.dev_vector.dy = -reversed.dev_vector.dy;

    t = reversed.cw;

    reversed.cw = reversed.ccw;

    reversed.ccw = t;

    add_cap (stroker, &reversed);

}

static void

add_trailing_cap (struct stroker *stroker,

		  const cairo_stroke_face_t *face)

{

    add_cap (stroker, face);

}

static inline double

normalize_slope (double *dx, double *dy)

{

    double dx0 = *dx, dy0 = *dy;

    double mag;

    assert (dx0 != 0.0 || dy0 != 0.0);

    if (dx0 == 0.0) {

	*dx = 0.0;

	if (dy0 > 0.0) {

	    mag = dy0;

	    *dy = 1.0;

	} else {

	    mag = -dy0;

	    *dy = -1.0;

	}

    } else if (dy0 == 0.0) {

	*dy = 0.0;

	if (dx0 > 0.0) {

	    mag = dx0;

	    *dx = 1.0;

	} else {

	    mag = -dx0;

	    *dx = -1.0;

	}

    } else {

	mag = hypot (dx0, dy0);

	*dx = dx0 / mag;

	*dy = dy0 / mag;

    }

    return mag;

}

static void

compute_face (const cairo_point_t *point,

	      const cairo_slope_t *dev_slope,

	      struct stroker *stroker,

	      cairo_stroke_face_t *face)

{

    double face_dx, face_dy;

    cairo_point_t offset_ccw, offset_cw;

    double slope_dx, slope_dy;

    slope_dx = _cairo_fixed_to_double (dev_slope->dx);

    slope_dy = _cairo_fixed_to_double (dev_slope->dy);

    face->length = normalize_slope (&slope_dx, &slope_dy);

    face->dev_slope.x = slope_dx;

    face->dev_slope.y = slope_dy;

    /*

     * rotate to get a line_width/2 vector along the face, note that

     * the vector must be rotated the right direction in device space,

     * but by 90° in user space. So, the rotation depends on

     * whether the ctm reflects or not, and that can be determined

     * by looking at the determinant of the matrix.

     */

    if (! _cairo_matrix_is_identity (stroker->ctm_inverse)) {

	/* Normalize the matrix! */

	cairo_matrix_transform_distance (stroker->ctm_inverse,

					 &slope_dx, &slope_dy);

	normalize_slope (&slope_dx, &slope_dy);

	if (stroker->ctm_det_positive) {

	    face_dx = - slope_dy * (stroker->style.line_width / 2.0);

	    face_dy = slope_dx * (stroker->style.line_width / 2.0);

	} else {

	    face_dx = slope_dy * (stroker->style.line_width / 2.0);

	    face_dy = - slope_dx * (stroker->style.line_width / 2.0);

	}

	/* back to device space */

	cairo_matrix_transform_distance (stroker->ctm, &face_dx, &face_dy);

    } else {

	face_dx = - slope_dy * (stroker->style.line_width / 2.0);

	face_dy = slope_dx * (stroker->style.line_width / 2.0);

    }

    offset_ccw.x = _cairo_fixed_from_double (face_dx);

    offset_ccw.y = _cairo_fixed_from_double (face_dy);

    offset_cw.x = -offset_ccw.x;

    offset_cw.y = -offset_ccw.y;

    face->ccw = *point;

    translate_point (&face->ccw, &offset_ccw);

    face->point = *point;

    face->cw = *point;

    translate_point (&face->cw, &offset_cw);

    face->usr_vector.x = slope_dx;

    face->usr_vector.y = slope_dy;

    face->dev_vector = *dev_slope;

}

static void

add_caps (struct stroker *stroker)

{

    /* check for a degenerative sub_path */

    if (stroker->has_sub_path &&

	! stroker->has_first_face &&

	! stroker->has_current_face &&

	stroker->style.line_cap == CAIRO_LINE_CAP_ROUND)

    {

	/* pick an arbitrary slope to use */

	cairo_slope_t slope = { CAIRO_FIXED_ONE, 0 };

	cairo_stroke_face_t face;

	/* arbitrarily choose first_point */

	compute_face (&stroker->first_point, &slope, stroker, &face);

	add_leading_cap (stroker, &face);

	add_trailing_cap (stroker, &face);

	/* ensure the circle is complete */

	//_cairo_contour_add_point (&stroker->ccw.contour,

				  //_cairo_contour_first_point (&stroker->ccw.contour));

    } else {

	if (stroker->has_current_face)

	    add_trailing_cap (stroker, &stroker->current_face);

	//_cairo_polygon_add_contour (stroker->polygon, &stroker->ccw.contour);

	//_cairo_contour_reset (&stroker->ccw.contour);

	if (stroker->has_first_face) {

	    //_cairo_contour_add_point (&stroker->ccw.contour,

				      //&stroker->first_face.cw);

	    add_leading_cap (stroker, &stroker->first_face);

	    //_cairo_polygon_add_contour (stroker->polygon,

					//&stroker->ccw.contour);

	    //_cairo_contour_reset (&stroker->ccw.contour);

	}

    }

}

static cairo_status_t

move_to (void *closure,

	 const cairo_point_t *point)

{

    struct stroker *stroker = closure;

    /* Cap the start and end of the previous sub path as needed */

    add_caps (stroker);

    stroker->has_first_face = FALSE;

    stroker->has_current_face = FALSE;

    stroker->has_sub_path = FALSE;

    stroker->first_point = *point;

    stroker->current_face.point = *point;

    return CAIRO_STATUS_SUCCESS;

}

static cairo_status_t

line_to (void *closure,

	 const cairo_point_t *point)

{

    struct stroker *stroker = closure;

    cairo_stroke_face_t start;

    cairo_point_t *p1 = &stroker->current_face.point;

    cairo_slope_t dev_slope;

    stroker->has_sub_path = TRUE;

    if (p1->x == point->x && p1->y == point->y)

	return CAIRO_STATUS_SUCCESS;

    _cairo_slope_init (&dev_slope, p1, point);

    compute_face (p1, &dev_slope, stroker, &start);

    if (stroker->has_current_face) {

	int clockwise = join_is_clockwise (&stroker->current_face, &start);

	/* Join with final face from previous segment */

	outer_join (stroker, &stroker->current_face, &start, clockwise);

	inner_join (stroker, &stroker->current_face, &start, clockwise);

    } else {

	if (! stroker->has_first_face) {

	    /* Save sub path's first face in case needed for closing join */

	    stroker->first_face = start;

	    _cairo_tristrip_move_to (stroker->strip, &start.cw);

	    stroker->has_first_face = TRUE;

	}

	stroker->has_current_face = TRUE;

	_cairo_tristrip_add_point (stroker->strip, &start.cw);

	_cairo_tristrip_add_point (stroker->strip, &start.ccw);

    }

    stroker->current_face = start;

    stroker->current_face.point = *point;

    stroker->current_face.ccw.x += dev_slope.dx;

    stroker->current_face.ccw.y += dev_slope.dy;

    stroker->current_face.cw.x += dev_slope.dx;

    stroker->current_face.cw.y += dev_slope.dy;

    _cairo_tristrip_add_point (stroker->strip, &stroker->current_face.cw);

    _cairo_tristrip_add_point (stroker->strip, &stroker->current_face.ccw);

    return CAIRO_STATUS_SUCCESS;

}

static cairo_status_t

spline_to (void *closure,

	   const cairo_point_t *point,

	   const cairo_slope_t *tangent)

{

    struct stroker *stroker = closure;

    cairo_stroke_face_t face;

    if (tangent->dx == 0 && tangent->dy == 0) {

	const cairo_point_t *inpt, *outpt;

	cairo_point_t t;

	int clockwise;

	face = stroker->current_face;

	face.usr_vector.x = -face.usr_vector.x;

	face.usr_vector.y = -face.usr_vector.y;

	face.dev_vector.dx = -face.dev_vector.dx;

	face.dev_vector.dy = -face.dev_vector.dy;

	t = face.cw;

	face.cw = face.ccw;

	face.ccw = t;

	clockwise = join_is_clockwise (&stroker->current_face, &face);

	if (clockwise) {

	    inpt = &stroker->current_face.cw;

	    outpt = &face.cw;

	} else {

	    inpt = &stroker->current_face.ccw;

	    outpt = &face.ccw;

	}

	add_fan (stroker,

		 &stroker->current_face.dev_vector,

		 &face.dev_vector,

		 &stroker->current_face.point, inpt, outpt,

		 clockwise);

    } else {

	compute_face (point, tangent, stroker, &face);

	if (face.dev_slope.x * stroker->current_face.dev_slope.x +

	    face.dev_slope.y * stroker->current_face.dev_slope.y < 0)

	{

	    const cairo_point_t *inpt, *outpt;

	    int clockwise = join_is_clockwise (&stroker->current_face, &face);

	    stroker->current_face.cw.x += face.point.x - stroker->current_face.point.x;

	    stroker->current_face.cw.y += face.point.y - stroker->current_face.point.y;

	    //contour_add_point (stroker, &stroker->cw, &stroker->current_face.cw);

	    stroker->current_face.ccw.x += face.point.x - stroker->current_face.point.x;

	    stroker->current_face.ccw.y += face.point.y - stroker->current_face.point.y;

	    //contour_add_point (stroker, &stroker->ccw, &stroker->current_face.ccw);

	    if (clockwise) {

		inpt = &stroker->current_face.cw;

		outpt = &face.cw;

	    } else {

		inpt = &stroker->current_face.ccw;

		outpt = &face.ccw;

	    }

	    add_fan (stroker,

		     &stroker->current_face.dev_vector,

		     &face.dev_vector,

		     &stroker->current_face.point, inpt, outpt,

		     clockwise);

	}

	_cairo_tristrip_add_point (stroker->strip, &face.cw);

	_cairo_tristrip_add_point (stroker->strip, &face.ccw);

    }

    stroker->current_face = face;

    return CAIRO_STATUS_SUCCESS;

}

static cairo_status_t

curve_to (void *closure,

	  const cairo_point_t *b,

	  const cairo_point_t *c,

	  const cairo_point_t *d)

{

    struct stroker *stroker = closure;

    cairo_spline_t spline;

    cairo_stroke_face_t face;

    if (stroker->has_limits) {

	if (! _cairo_spline_intersects (&stroker->current_face.point, b, c, d,

					&stroker->limit))

	    return line_to (closure, d);

    }

    if (! _cairo_spline_init (&spline, spline_to, stroker,

			      &stroker->current_face.point, b, c, d))

	return line_to (closure, d);

    compute_face (&stroker->current_face.point, &spline.initial_slope,

		  stroker, &face);

    if (stroker->has_current_face) {

	int clockwise = join_is_clockwise (&stroker->current_face, &face);

	/* Join with final face from previous segment */

	outer_join (stroker, &stroker->current_face, &face, clockwise);

	inner_join (stroker, &stroker->current_face, &face, clockwise);

    } else {

	if (! stroker->has_first_face) {

	    /* Save sub path's first face in case needed for closing join */

	    stroker->first_face = face;

	    _cairo_tristrip_move_to (stroker->strip, &face.cw);

	    stroker->has_first_face = TRUE;

	}

	stroker->has_current_face = TRUE;

	_cairo_tristrip_add_point (stroker->strip, &face.cw);

	_cairo_tristrip_add_point (stroker->strip, &face.ccw);

    }

    stroker->current_face = face;

    return _cairo_spline_decompose (&spline, stroker->tolerance);

}

static cairo_status_t

close_path (void *closure)

{

    struct stroker *stroker = closure;

    cairo_status_t status;

    status = line_to (stroker, &stroker->first_point);

    if (unlikely (status))

	return status;

    if (stroker->has_first_face && stroker->has_current_face) {

	/* Join first and final faces of sub path */

	outer_close (stroker, &stroker->current_face, &stroker->first_face);

	inner_close (stroker, &stroker->current_face, &stroker->first_face);

    } else {

	/* Cap the start and end of the sub path as needed */

	add_caps (stroker);

    }

    stroker->has_sub_path = FALSE;

    stroker->has_first_face = FALSE;

    stroker->has_current_face = FALSE;

    return CAIRO_STATUS_SUCCESS;

}

cairo_int_status_t

_cairo_path_fixed_stroke_to_tristrip (const cairo_path_fixed_t	*path,

				      const cairo_stroke_style_t*style,

				      const cairo_matrix_t	*ctm,

				      const cairo_matrix_t	*ctm_inverse,

				      double			 tolerance,

				      cairo_tristrip_t		 *strip)

{

    struct stroker stroker;

    cairo_int_status_t status;

    int i;

    if (style->num_dashes)

	return CAIRO_INT_STATUS_UNSUPPORTED;

    stroker.style = *style;

    stroker.ctm = ctm;

    stroker.ctm_inverse = ctm_inverse;

    stroker.tolerance = tolerance;

    stroker.ctm_det_positive =

	_cairo_matrix_compute_determinant (ctm) >= 0.0;

    status = _cairo_pen_init (&stroker.pen,

		              style->line_width / 2.0,

			      tolerance, ctm);

    if (unlikely (status))

	return status;

    if (stroker.pen.num_vertices <= 1)

	return CAIRO_INT_STATUS_NOTHING_TO_DO;

    stroker.has_current_face = FALSE;

    stroker.has_first_face = FALSE;

    stroker.has_sub_path = FALSE;

    stroker.has_limits = strip->num_limits > 0;

    stroker.limit = strip->limits[0];

    for (i = 1; i < strip->num_limits; i++)

	_cairo_box_add_box (&stroker.limit, &strip->limits[i]);

    stroker.strip = strip;

    status = _cairo_path_fixed_interpret (path,

					  move_to,

					  line_to,

					  curve_to,

					  close_path,

					  &stroker);

    /* Cap the start and end of the final sub path as needed */

    if (likely (status == CAIRO_INT_STATUS_SUCCESS))

	add_caps (&stroker);

    _cairo_pen_fini (&stroker.pen);

    return status;

}