add cairo

1 files changed, 1088 insertions, 0 deletions

diff --git a/libs/cairo-1.16.0/src/cairo-path-stroke-tristrip.c b/libs/cairo-1.16.0/src/cairo-path-stroke-tristrip.c
new file mode 100644
index 0000000..3178765
--- /dev/null
+++ b/libs/cairo-1.16.0/src/cairo-path-stroke-tristrip.c
@@ -0,0 +1,1088 @@
+/* -*- 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 <cworth@cworth.org>
+ *	Chris Wilson <chris@chris-wilson.co.uk>
+ */
+
+#define _DEFAULT_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;
+}