src/cairo-path-stroke.c

   1 /* -*- Mode: c; tab-width: 8; c-basic-offset: 4; indent-tabs-mode: t; -*- */
   2 /* cairo - a vector graphics library with display and print output
   3  *
   4  * Copyright © 2002 University of Southern California
   5  *
   6  * This library is free software; you can redistribute it and/or
   7  * modify it either under the terms of the GNU Lesser General Public
   8  * License version 2.1 as published by the Free Software Foundation
   9  * (the "LGPL") or, at your option, under the terms of the Mozilla
  10  * Public License Version 1.1 (the "MPL"). If you do not alter this
  11  * notice, a recipient may use your version of this file under either
  12  * the MPL or the LGPL.
  13  *
  14  * You should have received a copy of the LGPL along with this library
  15  * in the file COPYING-LGPL-2.1; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA
  17  * You should have received a copy of the MPL along with this library
  18  * in the file COPYING-MPL-1.1
  19  *
  20  * The contents of this file are subject to the Mozilla Public License
  21  * Version 1.1 (the "License"); you may not use this file except in
  22  * compliance with the License. You may obtain a copy of the License at
  23  * http://www.mozilla.org/MPL/
  24  *
  25  * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
  26  * OF ANY KIND, either express or implied. See the LGPL or the MPL for
  27  * the specific language governing rights and limitations.
  28  *
  29  * The Original Code is the cairo graphics library.
  30  *
  31  * The Initial Developer of the Original Code is University of Southern
  32  * California.
  33  *
  34  * Contributor(s):
  35  *      Carl D. Worth <cworth@cworth.org>
  36  *      Chris Wilson <chris@chris-wilson.co.uk>
  37  */
  38
  39 #define _BSD_SOURCE /* for hypot() */
  40 #include "cairoint.h"
  41
  42 #include "cairo-box-inline.h"
  43 #include "cairo-boxes-private.h"
  44 #include "cairo-error-private.h"
  45 #include "cairo-path-fixed-private.h"
  46 #include "cairo-slope-private.h"
  47 #include "cairo-stroke-dash-private.h"
  48 #include "cairo-traps-private.h"
  49
  50 typedef struct cairo_stroker {
  51     cairo_stroke_style_t style;
  52
  53     const cairo_matrix_t *ctm;
  54     const cairo_matrix_t *ctm_inverse;
  55     double half_line_width;
  56     double tolerance;
  57     double ctm_determinant;
  58     cairo_bool_t ctm_det_positive;
  59
  60     void *closure;
  61     cairo_status_t (*add_external_edge) (void *closure,
  62                                          const cairo_point_t *p1,
  63                                          const cairo_point_t *p2);
  64     cairo_status_t (*add_triangle) (void *closure,
  65                                     const cairo_point_t triangle[3]);
  66     cairo_status_t (*add_triangle_fan) (void *closure,
  67                                         const cairo_point_t *midpt,
  68                                         const cairo_point_t *points,
  69                                         int npoints);
  70     cairo_status_t (*add_convex_quad) (void *closure,
  71                                        const cairo_point_t quad[4]);
  72
  73     cairo_pen_t   pen;
  74
  75     cairo_point_t current_point;
  76     cairo_point_t first_point;
  77
  78     cairo_bool_t has_initial_sub_path;
  79
  80     cairo_bool_t has_current_face;
  81     cairo_stroke_face_t current_face;
  82
  83     cairo_bool_t has_first_face;
  84     cairo_stroke_face_t first_face;
  85
  86     cairo_stroker_dash_t dash;
  87
  88     cairo_bool_t has_bounds;
  89     cairo_box_t bounds;
  90 } cairo_stroker_t;
  91
  92 static cairo_bool_t
  93 _cairo_stroke_segment_intersect (cairo_point_t *p1, cairo_point_t *p2,
  94                  cairo_point_t *p3, cairo_point_t *p4,
  95                                  cairo_point_t *p)
  96 {
  97     double x1, y1, x2, y2, x3, y3, x4, y4;
  98     double pre, post;
  99     double x, y, d;
 100
 101     x1 = _cairo_fixed_to_double (p1->x);
 102     y1 = _cairo_fixed_to_double (p1->y);
 103     x2 = _cairo_fixed_to_double (p2->x);
 104     y2 = _cairo_fixed_to_double (p2->y);
 105     x3 = _cairo_fixed_to_double (p3->x);
 106     y3 = _cairo_fixed_to_double (p3->y);
 107     x4 = _cairo_fixed_to_double (p4->x);
 108     y4 = _cairo_fixed_to_double (p4->y);
 109
 110     d = (x1 - x2) * (y3 - y4) - (y1 - y2) * (x3 - x4);
 111     if (d == 0)
 112         return FALSE;
 113
 114     pre = x1 * y2 - y1 * x2;
 115     post = x3 * y4 - y3 * x4;
 116     x = (pre * (x3 - x4) - (x1 - x2) * post) / d;
 117     y = (pre * (y3 - y4) - (y1 - y2) * post) / d;
 118
 119     /* check if x, y are within both segments */
 120     if (x < MIN (x1, x2) || x > MAX (x1, x2) ||
 121         x < MIN (x3, x4) || x > MAX (x3, x4))
 122     return FALSE;
 123     if (y < MIN (y1, y2) || y > MAX (y1, y2) ||
 124         y < MIN (y1, y2) || y > MAX (y3, y4))
 125     return FALSE;
 126
 127     p->x = _cairo_fixed_from_double (x);
 128     p->y = _cairo_fixed_from_double (y);
 129     return TRUE;
 130 }
 131
 132 static void
 133 _cairo_stroker_limit (cairo_stroker_t *stroker,
 134                       const cairo_path_fixed_t *path,
 135                       const cairo_box_t *boxes,
 136                       int num_boxes)
 137 {
 138     double dx, dy;
 139     cairo_fixed_t fdx, fdy;
 140
 141     stroker->has_bounds = TRUE;
 142     _cairo_boxes_get_extents (boxes, num_boxes, &stroker->bounds);
 143
 144     /* Extend the bounds in each direction to account for the maximum area
 145      * we might generate trapezoids, to capture line segments that are outside
 146      * of the bounds but which might generate rendering that's within bounds.
 147      */
 148
 149     _cairo_stroke_style_max_distance_from_path (&stroker->style, path,
 150                                                 stroker->ctm, &dx, &dy);
 151
 152     fdx = _cairo_fixed_from_double (dx);
 153     fdy = _cairo_fixed_from_double (dy);
 154
 155     stroker->bounds.p1.x -= fdx;
 156     stroker->bounds.p2.x += fdx;
 157
 158     stroker->bounds.p1.y -= fdy;
 159     stroker->bounds.p2.y += fdy;
 160 }
 161
 162 static cairo_status_t
 163 _cairo_stroker_init (cairo_stroker_t            *stroker,
 164                      const cairo_path_fixed_t   *path,
 165                      const cairo_stroke_style_t *stroke_style,
 166                      const cairo_matrix_t       *ctm,
 167                      const cairo_matrix_t       *ctm_inverse,
 168                      double                      tolerance,
 169                      const cairo_box_t          *limits,
 170                      int                         num_limits)
 171 {
 172     cairo_status_t status;
 173
 174     stroker->style = *stroke_style;
 175     stroker->ctm = ctm;
 176     stroker->ctm_inverse = ctm_inverse;
 177     stroker->tolerance = tolerance;
 178     stroker->half_line_width = stroke_style->line_width / 2.0;
 179
 180     stroker->ctm_determinant = _cairo_matrix_compute_determinant (stroker->ctm);
 181     stroker->ctm_det_positive = stroker->ctm_determinant >= 0.0;
 182
 183     status = _cairo_pen_init (&stroker->pen,
 184                               stroker->half_line_width, tolerance, ctm);
 185     if (unlikely (status))
 186         return status;
 187
 188     stroker->has_current_face = FALSE;
 189     stroker->has_first_face = FALSE;
 190     stroker->has_initial_sub_path = FALSE;
 191
 192     _cairo_stroker_dash_init (&stroker->dash, stroke_style);
 193
 194     stroker->add_external_edge = NULL;
 195
 196     stroker->has_bounds = FALSE;
 197     if (num_limits)
 198         _cairo_stroker_limit (stroker, path, limits, num_limits);
 199
 200     return CAIRO_STATUS_SUCCESS;
 201 }
 202
 203 static void
 204 _cairo_stroker_fini (cairo_stroker_t *stroker)
 205 {
 206     _cairo_pen_fini (&stroker->pen);
 207 }
 208
 209 static void
 210 _translate_point (cairo_point_t *point, const cairo_point_t *offset)
 211 {
 212     point->x += offset->x;
 213     point->y += offset->y;
 214 }
 215
 216 static int
 217 _cairo_stroker_join_is_clockwise (const cairo_stroke_face_t *in,
 218                                   const cairo_stroke_face_t *out)
 219 {
 220     cairo_slope_t in_slope, out_slope;
 221
 222     _cairo_slope_init (&in_slope, &in->point, &in->cw);
 223     _cairo_slope_init (&out_slope, &out->point, &out->cw);
 224
 225     return _cairo_slope_compare (&in_slope, &out_slope) < 0;
 226 }
 227
 228 /**
 229  * _cairo_slope_compare_sgn:
 230  *
 231  * Return -1, 0 or 1 depending on the relative slopes of
 232  * two lines.
 233  **/
 234 static int
 235 _cairo_slope_compare_sgn (double dx1, double dy1, double dx2, double dy2)
 236 {
 237     double  c = (dx1 * dy2 - dx2 * dy1);
 238
 239     if (c > 0) return 1;
 240     if (c < 0) return -1;
 241     return 0;
 242 }
 243
 244 static inline int
 245 _range_step (int i, int step, int max)
 246 {
 247     i += step;
 248     if (i < 0)
 249         i = max - 1;
 250     if (i >= max)
 251         i = 0;
 252     return i;
 253 }
 254
 255 /*
 256  * Construct a fan around the midpoint using the vertices from pen between
 257  * inpt and outpt.
 258  */
 259 static cairo_status_t
 260 _tessellate_fan (cairo_stroker_t *stroker,
 261                  const cairo_slope_t *in_vector,
 262                  const cairo_slope_t *out_vector,
 263                  const cairo_point_t *midpt,
 264                  const cairo_point_t *inpt,
 265                  const cairo_point_t *outpt,
 266                  cairo_bool_t clockwise)
 267 {
 268     cairo_point_t stack_points[64], *points = stack_points;
 269     cairo_pen_t *pen = &stroker->pen;
 270     int start, stop, num_points = 0;
 271     cairo_status_t status;
 272
 273     if (stroker->has_bounds &&
 274         ! _cairo_box_contains_point (&stroker->bounds, midpt))
 275         goto BEVEL;
 276
 277     assert (stroker->pen.num_vertices);
 278
 279     if (clockwise) {
 280         _cairo_pen_find_active_ccw_vertices (pen,
 281                                              in_vector, out_vector,
 282                                              &start, &stop);
 283         if (stroker->add_external_edge) {
 284             cairo_point_t last;
 285             last = *inpt;
 286             while (start != stop) {
 287                 cairo_point_t p = *midpt;
 288                 _translate_point (&p, &pen->vertices[start].point);
 289
 290                 status = stroker->add_external_edge (stroker->closure,
 291                                                      &last, &p);
 292                 if (unlikely (status))
 293                     return status;
 294                 last = p;
 295
 296                 if (start-- == 0)
 297                     start += pen->num_vertices;
 298             }
 299             status = stroker->add_external_edge (stroker->closure,
 300                                                  &last, outpt);
 301         } else {
 302             if (start == stop)
 303                 goto BEVEL;
 304
 305             num_points = stop - start;
 306             if (num_points < 0)
 307                 num_points += pen->num_vertices;
 308             num_points += 2;
 309             if (num_points > ARRAY_LENGTH(stack_points)) {
 310                 points = _cairo_malloc_ab (num_points, sizeof (cairo_point_t));
 311                 if (unlikely (points == NULL))
 312                     return _cairo_error (CAIRO_STATUS_NO_MEMORY);
 313             }
 314
 315             points[0] = *inpt;
 316             num_points = 1;
 317             while (start != stop) {
 318                 points[num_points] = *midpt;
 319                 _translate_point (&points[num_points], &pen->vertices[start].point);
 320                 num_points++;
 321
 322                 if (start-- == 0)
 323                     start += pen->num_vertices;
 324             }
 325             points[num_points++] = *outpt;
 326         }
 327     } else {
 328         _cairo_pen_find_active_cw_vertices (pen,
 329                                             in_vector, out_vector,
 330                                             &start, &stop);
 331         if (stroker->add_external_edge) {
 332             cairo_point_t last;
 333             last = *inpt;
 334             while (start != stop) {
 335                 cairo_point_t p = *midpt;
 336                 _translate_point (&p, &pen->vertices[start].point);
 337
 338                 status = stroker->add_external_edge (stroker->closure,
 339                                                      &p, &last);
 340                 if (unlikely (status))
 341                     return status;
 342                 last = p;
 343
 344                 if (++start == pen->num_vertices)
 345                     start = 0;
 346             }
 347             status = stroker->add_external_edge (stroker->closure,
 348                                                  outpt, &last);
 349         } else {
 350             if (start == stop)
 351                 goto BEVEL;
 352
 353             num_points = stop - start;
 354             if (num_points < 0)
 355                 num_points += pen->num_vertices;
 356             num_points += 2;
 357             if (num_points > ARRAY_LENGTH(stack_points)) {
 358                 points = _cairo_malloc_ab (num_points, sizeof (cairo_point_t));
 359                 if (unlikely (points == NULL))
 360                     return _cairo_error (CAIRO_STATUS_NO_MEMORY);
 361             }
 362
 363             points[0] = *inpt;
 364             num_points = 1;
 365             while (start != stop) {
 366                 points[num_points] = *midpt;
 367                 _translate_point (&points[num_points], &pen->vertices[start].point);
 368                 num_points++;
 369
 370                 if (++start == pen->num_vertices)
 371                     start = 0;
 372             }
 373             points[num_points++] = *outpt;
 374         }
 375     }
 376
 377     if (num_points) {
 378         status = stroker->add_triangle_fan (stroker->closure,
 379                                             midpt, points, num_points);
 380     }
 381
 382     if (points != stack_points)
 383         free (points);
 384
 385     return status;
 386
 387 BEVEL:
 388     /* Ensure a leak free connection... */
 389     if (stroker->add_external_edge != NULL) {
 390         if (clockwise)
 391             return stroker->add_external_edge (stroker->closure, inpt, outpt);
 392         else
 393             return stroker->add_external_edge (stroker->closure, outpt, inpt);
 394     } else {
 395         stack_points[0] = *midpt;
 396         stack_points[1] = *inpt;
 397         stack_points[2] = *outpt;
 398         return stroker->add_triangle (stroker->closure, stack_points);
 399     }
 400 }
 401
 402 static cairo_status_t
 403 _cairo_stroker_join (cairo_stroker_t *stroker,
 404                      const cairo_stroke_face_t *in,
 405                      const cairo_stroke_face_t *out)
 406 {
 407     int  clockwise = _cairo_stroker_join_is_clockwise (out, in);
 408     const cairo_point_t *inpt, *outpt;
 409     cairo_point_t points[4];
 410     cairo_status_t status;
 411
 412     if (in->cw.x  == out->cw.x  && in->cw.y  == out->cw.y &&
 413         in->ccw.x == out->ccw.x && in->ccw.y == out->ccw.y)
 414     {
 415         return CAIRO_STATUS_SUCCESS;
 416     }
 417
 418     if (clockwise) {
 419         if (stroker->add_external_edge != NULL) {
 420             status = stroker->add_external_edge (stroker->closure,
 421                                                  &out->cw, &in->point);
 422             if (unlikely (status))
 423                 return status;
 424
 425             status = stroker->add_external_edge (stroker->closure,
 426                                                  &in->point, &in->cw);
 427             if (unlikely (status))
 428                 return status;
 429         }
 430
 431         inpt = &in->ccw;
 432         outpt = &out->ccw;
 433     } else {
 434         if (stroker->add_external_edge != NULL) {
 435             status = stroker->add_external_edge (stroker->closure,
 436                                                  &in->ccw, &in->point);
 437             if (unlikely (status))
 438                 return status;
 439
 440             status = stroker->add_external_edge (stroker->closure,
 441                                                  &in->point, &out->ccw);
 442             if (unlikely (status))
 443                 return status;
 444         }
 445
 446         inpt = &in->cw;
 447         outpt = &out->cw;
 448     }
 449
 450     switch (stroker->style.line_join) {
 451     case CAIRO_LINE_JOIN_ROUND:
 452         /* construct a fan around the common midpoint */
 453         return _tessellate_fan (stroker,
 454                                 &in->dev_vector,
 455                                 &out->dev_vector,
 456                                 &in->point, inpt, outpt,
 457                                 clockwise);
 458
 459     case CAIRO_LINE_JOIN_MITER:
 460     default: {
 461         /* dot product of incoming slope vector with outgoing slope vector */
 462         double  in_dot_out = -in->usr_vector.x * out->usr_vector.x +
 463                              -in->usr_vector.y * out->usr_vector.y;
 464         double  ml = stroker->style.miter_limit;
 465
 466         /* Check the miter limit -- lines meeting at an acute angle
 467          * can generate long miters, the limit converts them to bevel
 468          *
 469          * Consider the miter join formed when two line segments
 470          * meet at an angle psi:
 471          *
 472          *         /.\
 473          *        /. .\
 474          *       /./ \.\
 475          *      /./psi\.\
 476          *
 477          * We can zoom in on the right half of that to see:
 478          *
 479          *          |\
 480          *          | \ psi/2
 481          *          |  \
 482          *          |   \
 483          *          |    \
 484          *          |     \
 485          *        miter    \
 486          *       length     \
 487          *          |        \
 488          *          |        .\
 489          *          |    .     \
 490          *          |.   line   \
 491          *           \    width  \
 492          *            \           \
 493          *
 494          *
 495          * The right triangle in that figure, (the line-width side is
 496          * shown faintly with three '.' characters), gives us the
 497          * following expression relating miter length, angle and line
 498          * width:
 499          *
 500          *      1 /sin (psi/2) = miter_length / line_width
 501          *
 502          * The right-hand side of this relationship is the same ratio
 503          * in which the miter limit (ml) is expressed. We want to know
 504          * when the miter length is within the miter limit. That is
 505          * when the following condition holds:
 506          *
 507          *      1/sin(psi/2) <= ml
 508          *      1 <= ml sin(psi/2)
 509          *      1 <= ml² sin²(psi/2)
 510          *      2 <= ml² 2 sin²(psi/2)
 511          *                              2·sin²(psi/2) = 1-cos(psi)
 512          *      2 <= ml² (1-cos(psi))
 513          *
 514          *                              in · out = |in| |out| cos (psi)
 515          *
 516          * in and out are both unit vectors, so:
 517          *
 518          *                              in · out = cos (psi)
 519          *
 520          *      2 <= ml² (1 - in · out)
 521          *
 522          */
 523         if (2 <= ml * ml * (1 - in_dot_out)) {
 524             double              x1, y1, x2, y2;
 525             double              mx, my;
 526             double              dx1, dx2, dy1, dy2;
 527             double              ix, iy;
 528             double              fdx1, fdy1, fdx2, fdy2;
 529             double              mdx, mdy;
 530
 531             /*
 532              * we've got the points already transformed to device
 533              * space, but need to do some computation with them and
 534              * also need to transform the slope from user space to
 535              * device space
 536              */
 537             /* outer point of incoming line face */
 538             x1 = _cairo_fixed_to_double (inpt->x);
 539             y1 = _cairo_fixed_to_double (inpt->y);
 540             dx1 = in->usr_vector.x;
 541             dy1 = in->usr_vector.y;
 542             cairo_matrix_transform_distance (stroker->ctm, &dx1, &dy1);
 543
 544             /* outer point of outgoing line face */
 545             x2 = _cairo_fixed_to_double (outpt->x);
 546             y2 = _cairo_fixed_to_double (outpt->y);
 547             dx2 = out->usr_vector.x;
 548             dy2 = out->usr_vector.y;
 549             cairo_matrix_transform_distance (stroker->ctm, &dx2, &dy2);
 550
 551             /*
 552              * Compute the location of the outer corner of the miter.
 553              * That's pretty easy -- just the intersection of the two
 554              * outer edges.  We've got slopes and points on each
 555              * of those edges.  Compute my directly, then compute
 556              * mx by using the edge with the larger dy; that avoids
 557              * dividing by values close to zero.
 558              */
 559             my = (((x2 - x1) * dy1 * dy2 - y2 * dx2 * dy1 + y1 * dx1 * dy2) /
 560                   (dx1 * dy2 - dx2 * dy1));
 561             if (fabs (dy1) >= fabs (dy2))
 562                 mx = (my - y1) * dx1 / dy1 + x1;
 563             else
 564                 mx = (my - y2) * dx2 / dy2 + x2;
 565
 566             /*
 567              * When the two outer edges are nearly parallel, slight
 568              * perturbations in the position of the outer points of the lines
 569              * caused by representing them in fixed point form can cause the
 570              * intersection point of the miter to move a large amount. If
 571              * that moves the miter intersection from between the two faces,
 572              * then draw a bevel instead.
 573              */
 574
 575             ix = _cairo_fixed_to_double (in->point.x);
 576             iy = _cairo_fixed_to_double (in->point.y);
 577
 578             /* slope of one face */
 579             fdx1 = x1 - ix; fdy1 = y1 - iy;
 580
 581             /* slope of the other face */
 582             fdx2 = x2 - ix; fdy2 = y2 - iy;
 583
 584             /* slope from the intersection to the miter point */
 585             mdx = mx - ix; mdy = my - iy;
 586
 587             /*
 588              * Make sure the miter point line lies between the two
 589              * faces by comparing the slopes
 590              */
 591             if (_cairo_slope_compare_sgn (fdx1, fdy1, mdx, mdy) !=
 592                 _cairo_slope_compare_sgn (fdx2, fdy2, mdx, mdy))
 593             {
 594                 if (stroker->add_external_edge != NULL) {
 595                     points[0].x = _cairo_fixed_from_double (mx);
 596                     points[0].y = _cairo_fixed_from_double (my);
 597
 598                     if (clockwise) {
 599                         status = stroker->add_external_edge (stroker->closure,
 600                                                              inpt, &points[0]);
 601                         if (unlikely (status))
 602                             return status;
 603
 604                         status = stroker->add_external_edge (stroker->closure,
 605                                                              &points[0], outpt);
 606                         if (unlikely (status))
 607                             return status;
 608                     } else {
 609                         status = stroker->add_external_edge (stroker->closure,
 610                                                              outpt, &points[0]);
 611                         if (unlikely (status))
 612                             return status;
 613
 614                         status = stroker->add_external_edge (stroker->closure,
 615                                                              &points[0], inpt);
 616                         if (unlikely (status))
 617                             return status;
 618                     }
 619
 620                     return CAIRO_STATUS_SUCCESS;
 621                 } else {
 622                     points[0] = in->point;
 623                     points[1] = *inpt;
 624                     points[2].x = _cairo_fixed_from_double (mx);
 625                     points[2].y = _cairo_fixed_from_double (my);
 626                     points[3] = *outpt;
 627
 628                     return stroker->add_convex_quad (stroker->closure, points);
 629                 }
 630             }
 631         }
 632     }
 633
 634     /* fall through ... */
 635
 636     case CAIRO_LINE_JOIN_BEVEL:
 637         if (stroker->add_external_edge != NULL) {
 638             if (clockwise) {
 639                 return stroker->add_external_edge (stroker->closure,
 640                                                    inpt, outpt);
 641             } else {
 642                 return stroker->add_external_edge (stroker->closure,
 643                                                    outpt, inpt);
 644             }
 645         } else {
 646             points[0] = in->point;
 647             points[1] = *inpt;
 648             points[2] = *outpt;
 649
 650             return stroker->add_triangle (stroker->closure, points);
 651         }
 652     }
 653 }
 654
 655 static cairo_status_t
 656 _cairo_stroker_add_cap (cairo_stroker_t *stroker,
 657                         const cairo_stroke_face_t *f)
 658 {
 659     switch (stroker->style.line_cap) {
 660     case CAIRO_LINE_CAP_ROUND: {
 661         cairo_slope_t slope;
 662
 663         slope.dx = -f->dev_vector.dx;
 664         slope.dy = -f->dev_vector.dy;
 665
 666         return _tessellate_fan (stroker,
 667                                 &f->dev_vector,
 668                                 &slope,
 669                                 &f->point, &f->cw, &f->ccw,
 670                                 FALSE);
 671
 672     }
 673
 674     case CAIRO_LINE_CAP_SQUARE: {
 675         double dx, dy;
 676         cairo_slope_t   fvector;
 677         cairo_point_t   quad[4];
 678
 679         dx = f->usr_vector.x;
 680         dy = f->usr_vector.y;
 681         dx *= stroker->half_line_width;
 682         dy *= stroker->half_line_width;
 683         cairo_matrix_transform_distance (stroker->ctm, &dx, &dy);
 684         fvector.dx = _cairo_fixed_from_double (dx);
 685         fvector.dy = _cairo_fixed_from_double (dy);
 686
 687         quad[0] = f->ccw;
 688         quad[1].x = f->ccw.x + fvector.dx;
 689         quad[1].y = f->ccw.y + fvector.dy;
 690         quad[2].x = f->cw.x + fvector.dx;
 691         quad[2].y = f->cw.y + fvector.dy;
 692         quad[3] = f->cw;
 693
 694         if (stroker->add_external_edge != NULL) {
 695             cairo_status_t status;
 696
 697             status = stroker->add_external_edge (stroker->closure,
 698                                                  &quad[0], &quad[1]);
 699             if (unlikely (status))
 700                 return status;
 701
 702             status = stroker->add_external_edge (stroker->closure,
 703                                                  &quad[1], &quad[2]);
 704             if (unlikely (status))
 705                 return status;
 706
 707             status = stroker->add_external_edge (stroker->closure,
 708                                                  &quad[2], &quad[3]);
 709             if (unlikely (status))
 710                 return status;
 711
 712             return CAIRO_STATUS_SUCCESS;
 713         } else {
 714             return stroker->add_convex_quad (stroker->closure, quad);
 715         }
 716     }
 717
 718     case CAIRO_LINE_CAP_BUTT:
 719     default:
 720         if (stroker->add_external_edge != NULL) {
 721             return stroker->add_external_edge (stroker->closure,
 722                                                &f->ccw, &f->cw);
 723         } else {
 724             return CAIRO_STATUS_SUCCESS;
 725         }
 726     }
 727 }
 728
 729 static cairo_status_t
 730 _cairo_stroker_add_leading_cap (cairo_stroker_t     *stroker,
 731                                 const cairo_stroke_face_t *face)
 732 {
 733     cairo_stroke_face_t reversed;
 734     cairo_point_t t;
 735
 736     reversed = *face;
 737
 738     /* The initial cap needs an outward facing vector. Reverse everything */
 739     reversed.usr_vector.x = -reversed.usr_vector.x;
 740     reversed.usr_vector.y = -reversed.usr_vector.y;
 741     reversed.dev_vector.dx = -reversed.dev_vector.dx;
 742     reversed.dev_vector.dy = -reversed.dev_vector.dy;
 743     t = reversed.cw;
 744     reversed.cw = reversed.ccw;
 745     reversed.ccw = t;
 746
 747     return _cairo_stroker_add_cap (stroker, &reversed);
 748 }
 749
 750 static cairo_status_t
 751 _cairo_stroker_add_trailing_cap (cairo_stroker_t     *stroker,
 752                                  const cairo_stroke_face_t *face)
 753 {
 754     return _cairo_stroker_add_cap (stroker, face);
 755 }
 756
 757 static inline cairo_bool_t
 758 _compute_normalized_device_slope (double *dx, double *dy,
 759                                   const cairo_matrix_t *ctm_inverse,
 760                                   double *mag_out)
 761 {
 762     double dx0 = *dx, dy0 = *dy;
 763     double mag;
 764
 765     cairo_matrix_transform_distance (ctm_inverse, &dx0, &dy0);
 766
 767     if (dx0 == 0.0 && dy0 == 0.0) {
 768         if (mag_out)
 769             *mag_out = 0.0;
 770         return FALSE;
 771     }
 772
 773     if (dx0 == 0.0) {
 774         *dx = 0.0;
 775         if (dy0 > 0.0) {
 776             mag = dy0;
 777             *dy = 1.0;
 778         } else {
 779             mag = -dy0;
 780             *dy = -1.0;
 781         }
 782     } else if (dy0 == 0.0) {
 783         *dy = 0.0;
 784         if (dx0 > 0.0) {
 785             mag = dx0;
 786             *dx = 1.0;
 787         } else {
 788             mag = -dx0;
 789             *dx = -1.0;
 790         }
 791     } else {
 792         mag = hypot (dx0, dy0);
 793         *dx = dx0 / mag;
 794         *dy = dy0 / mag;
 795     }
 796
 797     if (mag_out)
 798         *mag_out = mag;
 799
 800     return TRUE;
 801 }
 802
 803 static void
 804 _compute_face (const cairo_point_t *point,
 805                const cairo_slope_t *dev_slope,
 806                double slope_dx,
 807                double slope_dy,
 808                cairo_stroker_t *stroker,
 809                cairo_stroke_face_t *face)
 810 {
 811     double face_dx, face_dy;
 812     cairo_point_t offset_ccw, offset_cw;
 813
 814     /*
 815      * rotate to get a line_width/2 vector along the face, note that
 816      * the vector must be rotated the right direction in device space,
 817      * but by 90° in user space. So, the rotation depends on
 818      * whether the ctm reflects or not, and that can be determined
 819      * by looking at the determinant of the matrix.
 820      */
 821     if (stroker->ctm_det_positive)
 822     {
 823         face_dx = - slope_dy * stroker->half_line_width;
 824         face_dy = slope_dx * stroker->half_line_width;
 825     }
 826     else
 827     {
 828         face_dx = slope_dy * stroker->half_line_width;
 829         face_dy = - slope_dx * stroker->half_line_width;
 830     }
 831
 832     /* back to device space */
 833     cairo_matrix_transform_distance (stroker->ctm, &face_dx, &face_dy);
 834
 835     offset_ccw.x = _cairo_fixed_from_double (face_dx);
 836     offset_ccw.y = _cairo_fixed_from_double (face_dy);
 837     offset_cw.x = -offset_ccw.x;
 838     offset_cw.y = -offset_ccw.y;
 839
 840     face->ccw = *point;
 841     _translate_point (&face->ccw, &offset_ccw);
 842
 843     face->point = *point;
 844
 845     face->cw = *point;
 846     _translate_point (&face->cw, &offset_cw);
 847
 848     face->usr_vector.x = slope_dx;
 849     face->usr_vector.y = slope_dy;
 850
 851     face->dev_vector = *dev_slope;
 852 }
 853
 854 static cairo_status_t
 855 _cairo_stroker_add_caps (cairo_stroker_t *stroker)
 856 {
 857     cairo_status_t status;
 858
 859     /* check for a degenerative sub_path */
 860     if (stroker->has_initial_sub_path
 861         && ! stroker->has_first_face
 862         && ! stroker->has_current_face
 863         && stroker->style.line_cap == CAIRO_LINE_CAP_ROUND)
 864     {
 865         /* pick an arbitrary slope to use */
 866         double dx = 1.0, dy = 0.0;
 867         cairo_slope_t slope = { CAIRO_FIXED_ONE, 0 };
 868         cairo_stroke_face_t face;
 869
 870         _compute_normalized_device_slope (&dx, &dy,
 871                                           stroker->ctm_inverse, NULL);
 872
 873         /* arbitrarily choose first_point
 874          * first_point and current_point should be the same */
 875         _compute_face (&stroker->first_point, &slope, dx, dy, stroker, &face);
 876
 877         status = _cairo_stroker_add_leading_cap (stroker, &face);
 878         if (unlikely (status))
 879             return status;
 880
 881         status = _cairo_stroker_add_trailing_cap (stroker, &face);
 882         if (unlikely (status))
 883             return status;
 884     }
 885
 886     if (stroker->has_first_face) {
 887         status = _cairo_stroker_add_leading_cap (stroker,
 888                                                  &stroker->first_face);
 889         if (unlikely (status))
 890             return status;
 891     }
 892
 893     if (stroker->has_current_face) {
 894         status = _cairo_stroker_add_trailing_cap (stroker,
 895                                                   &stroker->current_face);
 896         if (unlikely (status))
 897             return status;
 898     }
 899
 900     return CAIRO_STATUS_SUCCESS;
 901 }
 902
 903 static cairo_status_t
 904 _cairo_stroker_add_sub_edge (cairo_stroker_t *stroker,
 905                              const cairo_point_t *p1,
 906                              const cairo_point_t *p2,
 907                              cairo_slope_t *dev_slope,
 908                              double slope_dx, double slope_dy,
 909                              cairo_stroke_face_t *start,
 910                              cairo_stroke_face_t *end)
 911 {
 912     _compute_face (p1, dev_slope, slope_dx, slope_dy, stroker, start);
 913     *end = *start;
 914
 915     if (p1->x == p2->x && p1->y == p2->y)
 916         return CAIRO_STATUS_SUCCESS;
 917
 918     end->point = *p2;
 919     end->ccw.x += p2->x - p1->x;
 920     end->ccw.y += p2->y - p1->y;
 921     end->cw.x += p2->x - p1->x;
 922     end->cw.y += p2->y - p1->y;
 923
 924     if (stroker->add_external_edge != NULL) {
 925         cairo_status_t status;
 926
 927         status = stroker->add_external_edge (stroker->closure,
 928                                              &end->cw, &start->cw);
 929         if (unlikely (status))
 930             return status;
 931
 932         status = stroker->add_external_edge (stroker->closure,
 933                                              &start->ccw, &end->ccw);
 934         if (unlikely (status))
 935             return status;
 936
 937         return CAIRO_STATUS_SUCCESS;
 938     } else {
 939         cairo_point_t quad[4];
 940
 941         quad[0] = start->cw;
 942         quad[1] = end->cw;
 943         quad[2] = end->ccw;
 944         quad[3] = start->ccw;
 945
 946         return stroker->add_convex_quad (stroker->closure, quad);
 947     }
 948 }
 949
 950 static cairo_status_t
 951 _cairo_stroker_move_to (void *closure,
 952                         const cairo_point_t *point)
 953 {
 954     cairo_stroker_t *stroker = closure;
 955     cairo_status_t status;
 956
 957     /* reset the dash pattern for new sub paths */
 958     _cairo_stroker_dash_start (&stroker->dash);
 959
 960     /* Cap the start and end of the previous sub path as needed */
 961     status = _cairo_stroker_add_caps (stroker);
 962     if (unlikely (status))
 963         return status;
 964
 965     stroker->first_point = *point;
 966     stroker->current_point = *point;
 967
 968     stroker->has_first_face = FALSE;
 969     stroker->has_current_face = FALSE;
 970     stroker->has_initial_sub_path = FALSE;
 971
 972     return CAIRO_STATUS_SUCCESS;
 973 }
 974
 975 static cairo_status_t
 976 _cairo_stroker_line_to (void *closure,
 977                         const cairo_point_t *point)
 978 {
 979     cairo_stroker_t *stroker = closure;
 980     cairo_stroke_face_t start, end;
 981     cairo_point_t *p1 = &stroker->current_point;
 982     cairo_slope_t dev_slope;
 983     double slope_dx, slope_dy;
 984     cairo_status_t status;
 985
 986     stroker->has_initial_sub_path = TRUE;
 987
 988     if (p1->x == point->x && p1->y == point->y)
 989         return CAIRO_STATUS_SUCCESS;
 990
 991     _cairo_slope_init (&dev_slope, p1, point);
 992     slope_dx = _cairo_fixed_to_double (point->x - p1->x);
 993     slope_dy = _cairo_fixed_to_double (point->y - p1->y);
 994     _compute_normalized_device_slope (&slope_dx, &slope_dy,
 995                                       stroker->ctm_inverse, NULL);
 996
 997     status = _cairo_stroker_add_sub_edge (stroker,
 998                                           p1, point,
 999                                           &dev_slope,
1000                                           slope_dx, slope_dy,
1001                                           &start, &end);
1002     if (unlikely (status))
1003         return status;
1004
1005     if (stroker->has_current_face) {
1006         /* Join with final face from previous segment */
1007         status = _cairo_stroker_join (stroker,
1008                                       &stroker->current_face,
1009                                       &start);
1010         if (unlikely (status))
1011             return status;
1012     } else if (! stroker->has_first_face) {
1013         /* Save sub path's first face in case needed for closing join */
1014         stroker->first_face = start;
1015         stroker->has_first_face = TRUE;
1016     }
1017     stroker->current_face = end;
1018     stroker->has_current_face = TRUE;
1019
1020     stroker->current_point = *point;
1021
1022     return CAIRO_STATUS_SUCCESS;
1023 }
1024
1025 static cairo_status_t
1026 _cairo_stroker_spline_to (void *closure,
1027                           const cairo_point_t *point,
1028                           const cairo_slope_t *tangent)
1029 {
1030     cairo_stroker_t *stroker = closure;
1031     cairo_stroke_face_t new_face;
1032     double slope_dx, slope_dy;
1033     cairo_point_t points[3];
1034     cairo_point_t intersect_point;
1035
1036     stroker->has_initial_sub_path = TRUE;
1037
1038     if (stroker->current_point.x == point->x &&
1039         stroker->current_point.y == point->y)
1040         return CAIRO_STATUS_SUCCESS;
1041
1042     slope_dx = _cairo_fixed_to_double (tangent->dx);
1043     slope_dy = _cairo_fixed_to_double (tangent->dy);
1044
1045     if (! _compute_normalized_device_slope (&slope_dx, &slope_dy,
1046                                       stroker->ctm_inverse, NULL))
1047         return CAIRO_STATUS_SUCCESS;
1048
1049     _compute_face (point, tangent,
1050                    slope_dx, slope_dy,
1051                    stroker, &new_face);
1052
1053     assert(stroker->has_current_face);
1054
1055     if (_cairo_stroke_segment_intersect (&stroker->current_face.cw,
1056                      &stroker->current_face.ccw,
1057                                          &new_face.cw,
1058                                          &new_face.ccw,
1059                                          &intersect_point)) {
1060     points[0] = stroker->current_face.ccw;
1061     points[1] = new_face.ccw;
1062     points[2] = intersect_point;
1063     stroker->add_triangle (stroker->closure, points);
1064
1065     points[0] = stroker->current_face.cw;
1066     points[1] = new_face.cw;
1067     stroker->add_triangle (stroker->closure, points);
1068     }
1069     else {
1070     points[0] = stroker->current_face.ccw;
1071     points[1] = stroker->current_face.cw;
1072     points[2] = new_face.cw;
1073     stroker->add_triangle (stroker->closure, points);
1074
1075     points[0] = stroker->current_face.ccw;
1076     points[1] = new_face.cw;
1077     points[2] = new_face.ccw;
1078     stroker->add_triangle (stroker->closure, points);
1079     }
1080
1081     stroker->current_face = new_face;
1082     stroker->has_current_face = TRUE;
1083     stroker->current_point = *point;
1084
1085     return CAIRO_STATUS_SUCCESS;
1086 }
1087
1088 /*
1089  * Dashed lines.  Cap each dash end, join around turns when on
1090  */
1091 static cairo_status_t
1092 _cairo_stroker_line_to_dashed (void *closure,
1093                                const cairo_point_t *p2)
1094 {
1095     cairo_stroker_t *stroker = closure;
1096     double mag, remain, step_length = 0;
1097     double slope_dx, slope_dy;
1098     double dx2, dy2;
1099     cairo_stroke_face_t sub_start, sub_end;
1100     cairo_point_t *p1 = &stroker->current_point;
1101     cairo_slope_t dev_slope;
1102     cairo_line_t segment;
1103     cairo_bool_t fully_in_bounds;
1104     cairo_status_t status;
1105
1106     stroker->has_initial_sub_path = stroker->dash.dash_starts_on;
1107
1108     if (p1->x == p2->x && p1->y == p2->y)
1109         return CAIRO_STATUS_SUCCESS;
1110
1111     fully_in_bounds = TRUE;
1112     if (stroker->has_bounds &&
1113         (! _cairo_box_contains_point (&stroker->bounds, p1) ||
1114          ! _cairo_box_contains_point (&stroker->bounds, p2)))
1115     {
1116         fully_in_bounds = FALSE;
1117     }
1118
1119     _cairo_slope_init (&dev_slope, p1, p2);
1120
1121     slope_dx = _cairo_fixed_to_double (p2->x - p1->x);
1122     slope_dy = _cairo_fixed_to_double (p2->y - p1->y);
1123
1124     if (! _compute_normalized_device_slope (&slope_dx, &slope_dy,
1125                                             stroker->ctm_inverse, &mag))
1126     {
1127         return CAIRO_STATUS_SUCCESS;
1128     }
1129
1130     remain = mag;
1131     segment.p1 = *p1;
1132     while (remain) {
1133         step_length = MIN (stroker->dash.dash_remain, remain);
1134         remain -= step_length;
1135         dx2 = slope_dx * (mag - remain);
1136         dy2 = slope_dy * (mag - remain);
1137         cairo_matrix_transform_distance (stroker->ctm, &dx2, &dy2);
1138         segment.p2.x = _cairo_fixed_from_double (dx2) + p1->x;
1139         segment.p2.y = _cairo_fixed_from_double (dy2) + p1->y;
1140
1141         if (stroker->dash.dash_on &&
1142             (fully_in_bounds ||
1143              (! stroker->has_first_face && stroker->dash.dash_starts_on) ||
1144              _cairo_box_intersects_line_segment (&stroker->bounds, &segment)))
1145         {
1146             status = _cairo_stroker_add_sub_edge (stroker,
1147                                                   &segment.p1, &segment.p2,
1148                                                   &dev_slope,
1149                                                   slope_dx, slope_dy,
1150                                                   &sub_start, &sub_end);
1151             if (unlikely (status))
1152                 return status;
1153
1154             if (stroker->has_current_face)
1155             {
1156                 /* Join with final face from previous segment */
1157                 status = _cairo_stroker_join (stroker,
1158                                               &stroker->current_face,
1159                                               &sub_start);
1160                 if (unlikely (status))
1161                     return status;
1162
1163                 stroker->has_current_face = FALSE;
1164             }
1165             else if (! stroker->has_first_face &&
1166                        stroker->dash.dash_starts_on)
1167             {
1168                 /* Save sub path's first face in case needed for closing join */
1169                 stroker->first_face = sub_start;
1170                 stroker->has_first_face = TRUE;
1171             }
1172             else
1173             {
1174                 /* Cap dash start if not connecting to a previous segment */
1175                 status = _cairo_stroker_add_leading_cap (stroker, &sub_start);
1176                 if (unlikely (status))
1177                     return status;
1178             }
1179
1180             if (remain) {
1181                 /* Cap dash end if not at end of segment */
1182                 status = _cairo_stroker_add_trailing_cap (stroker, &sub_end);
1183                 if (unlikely (status))
1184                     return status;
1185             } else {
1186                 stroker->current_face = sub_end;
1187                 stroker->has_current_face = TRUE;
1188             }
1189         } else {
1190             if (stroker->has_current_face) {
1191                 /* Cap final face from previous segment */
1192                 status = _cairo_stroker_add_trailing_cap (stroker,
1193                                                           &stroker->current_face);
1194                 if (unlikely (status))
1195                     return status;
1196
1197                 stroker->has_current_face = FALSE;
1198             }
1199         }
1200
1201         _cairo_stroker_dash_step (&stroker->dash, step_length);
1202         segment.p1 = segment.p2;
1203     }
1204
1205     if (stroker->dash.dash_on && ! stroker->has_current_face) {
1206         /* This segment ends on a transition to dash_on, compute a new face
1207          * and add cap for the beginning of the next dash_on step.
1208          *
1209          * Note: this will create a degenerate cap if this is not the last line
1210          * in the path. Whether this behaviour is desirable or not is debatable.
1211          * On one side these degenerate caps can not be reproduced with regular
1212          * path stroking.
1213          * On the other hand, Acroread 7 also produces the degenerate caps.
1214          */
1215         _compute_face (p2, &dev_slope,
1216                        slope_dx, slope_dy,
1217                        stroker,
1218                        &stroker->current_face);
1219
1220         status = _cairo_stroker_add_leading_cap (stroker,
1221                                                  &stroker->current_face);
1222         if (unlikely (status))
1223             return status;
1224
1225         stroker->has_current_face = TRUE;
1226     }
1227
1228     stroker->current_point = *p2;
1229
1230     return CAIRO_STATUS_SUCCESS;
1231 }
1232 static cairo_status_t
1233 _cairo_stroker_curve_to (void *closure,
1234                          const cairo_point_t *b,
1235                          const cairo_point_t *c,
1236                          const cairo_point_t *d)
1237 {
1238     cairo_stroker_t *stroker = closure;
1239     cairo_spline_t spline;
1240     cairo_line_join_t line_join_save;
1241     cairo_stroke_face_t face;
1242     double slope_dx, slope_dy;
1243     cairo_spline_add_point_func_t line_to;
1244     cairo_spline_add_point_func_t spline_to;
1245     cairo_status_t status = CAIRO_STATUS_SUCCESS;
1246
1247     line_to = stroker->dash.dashed ?
1248         (cairo_spline_add_point_func_t) _cairo_stroker_line_to_dashed :
1249         (cairo_spline_add_point_func_t) _cairo_stroker_line_to;
1250
1251     /* spline_to is only capable of rendering non-degenerate splines. */
1252     spline_to = stroker->dash.dashed ?
1253         (cairo_spline_add_point_func_t) _cairo_stroker_line_to_dashed :
1254         (cairo_spline_add_point_func_t) _cairo_stroker_spline_to;
1255
1256     if (! _cairo_spline_init (&spline,
1257                               spline_to,
1258                               stroker,
1259                               &stroker->current_point, b, c, d))
1260     {
1261         cairo_slope_t fallback_slope;
1262         _cairo_slope_init (&fallback_slope, &stroker->current_point, d);
1263         return line_to (closure, d, &fallback_slope);
1264     }
1265
1266     /* If the line width is so small that the pen is reduced to a
1267        single point, then we have nothing to do. */
1268     if (stroker->pen.num_vertices <= 1)
1269         return CAIRO_STATUS_SUCCESS;
1270
1271     /* Compute the initial face */
1272     if (! stroker->dash.dashed || stroker->dash.dash_on) {
1273         slope_dx = _cairo_fixed_to_double (spline.initial_slope.dx);
1274         slope_dy = _cairo_fixed_to_double (spline.initial_slope.dy);
1275         if (_compute_normalized_device_slope (&slope_dx, &slope_dy,
1276                                               stroker->ctm_inverse, NULL))
1277         {
1278             _compute_face (&stroker->current_point,
1279                            &spline.initial_slope,
1280                            slope_dx, slope_dy,
1281                            stroker, &face);
1282         }
1283         if (stroker->has_current_face) {
1284             status = _cairo_stroker_join (stroker,
1285                                           &stroker->current_face, &face);
1286             if (unlikely (status))
1287                 return status;
1288         } else if (! stroker->has_first_face) {
1289             stroker->first_face = face;
1290             stroker->has_first_face = TRUE;
1291         }
1292
1293         stroker->current_face = face;
1294         stroker->has_current_face = TRUE;
1295     }
1296
1297     /* Temporarily modify the stroker to use round joins to guarantee
1298      * smooth stroked curves. */
1299     line_join_save = stroker->style.line_join;
1300     stroker->style.line_join = CAIRO_LINE_JOIN_ROUND;
1301
1302     status = _cairo_spline_decompose (&spline, stroker->tolerance);
1303     if (unlikely (status))
1304         return status;
1305
1306     /* And join the final face */
1307     if (! stroker->dash.dashed || stroker->dash.dash_on) {
1308         slope_dx = _cairo_fixed_to_double (spline.final_slope.dx);
1309         slope_dy = _cairo_fixed_to_double (spline.final_slope.dy);
1310         if (_compute_normalized_device_slope (&slope_dx, &slope_dy,
1311                                               stroker->ctm_inverse, NULL))
1312         {
1313             _compute_face (&stroker->current_point,
1314                            &spline.final_slope,
1315                            slope_dx, slope_dy,
1316                            stroker, &face);
1317         }
1318
1319         status = _cairo_stroker_join (stroker, &stroker->current_face, &face);
1320         if (unlikely (status))
1321             return status;
1322
1323         stroker->current_face = face;
1324     }
1325
1326     stroker->style.line_join = line_join_save;
1327
1328     return CAIRO_STATUS_SUCCESS;
1329 }
1330
1331 static cairo_status_t
1332 _cairo_stroker_close_path (void *closure)
1333 {
1334     cairo_stroker_t *stroker = closure;
1335     cairo_status_t status;
1336
1337     if (stroker->dash.dashed)
1338         status = _cairo_stroker_line_to_dashed (stroker, &stroker->first_point);
1339     else
1340         status = _cairo_stroker_line_to (stroker, &stroker->first_point);
1341     if (unlikely (status))
1342         return status;
1343
1344     if (stroker->has_first_face && stroker->has_current_face) {
1345         /* Join first and final faces of sub path */
1346         status = _cairo_stroker_join (stroker,
1347                                       &stroker->current_face,
1348                                       &stroker->first_face);
1349         if (unlikely (status))
1350             return status;
1351     } else {
1352         /* Cap the start and end of the sub path as needed */
1353         status = _cairo_stroker_add_caps (stroker);
1354         if (unlikely (status))
1355             return status;
1356     }
1357
1358     stroker->has_initial_sub_path = FALSE;
1359     stroker->has_first_face = FALSE;
1360     stroker->has_current_face = FALSE;
1361
1362     return CAIRO_STATUS_SUCCESS;
1363 }
1364
1365 cairo_status_t
1366 _cairo_path_fixed_stroke_to_shaper (cairo_path_fixed_t  *path,
1367                                     const cairo_stroke_style_t  *stroke_style,
1368                                     const cairo_matrix_t        *ctm,
1369                                     const cairo_matrix_t        *ctm_inverse,
1370                                     double               tolerance,
1371                                     cairo_status_t (*add_triangle) (void *closure,
1372                                                                     const cairo_point_t triangle[3]),
1373                                     cairo_status_t (*add_triangle_fan) (void *closure,
1374                                                                         const cairo_point_t *midpt,
1375                                                                         const cairo_point_t *points,
1376                                                                         int npoints),
1377                                     cairo_status_t (*add_convex_quad) (void *closure,
1378                                                                        const cairo_point_t quad[4]),
1379                                     void *closure)
1380 {
1381     cairo_stroker_t stroker;
1382     cairo_status_t status;
1383
1384     status = _cairo_stroker_init (&stroker, path, stroke_style,
1385                                   ctm, ctm_inverse, tolerance,
1386                                   NULL, 0);
1387     if (unlikely (status))
1388         return status;
1389
1390     stroker.add_triangle = add_triangle;
1391     stroker.add_triangle_fan = add_triangle_fan;
1392     stroker.add_convex_quad = add_convex_quad;
1393     stroker.closure = closure;
1394
1395     status = _cairo_path_fixed_interpret (path,
1396                                           _cairo_stroker_move_to,
1397                                           stroker.dash.dashed ?
1398                                           _cairo_stroker_line_to_dashed :
1399                                           _cairo_stroker_line_to,
1400                                           _cairo_stroker_curve_to,
1401                                           _cairo_stroker_close_path,
1402                                           &stroker);
1403
1404     if (unlikely (status))
1405         goto BAIL;
1406
1407     /* Cap the start and end of the final sub path as needed */
1408     status = _cairo_stroker_add_caps (&stroker);
1409
1410 BAIL:
1411     _cairo_stroker_fini (&stroker);
1412
1413     return status;
1414 }
1415
1416 cairo_status_t
1417 _cairo_path_fixed_stroke_dashed_to_polygon (const cairo_path_fixed_t    *path,
1418                                             const cairo_stroke_style_t  *stroke_style,
1419                                             const cairo_matrix_t        *ctm,
1420                                             const cairo_matrix_t        *ctm_inverse,
1421                                             double               tolerance,
1422                                             cairo_polygon_t *polygon)
1423 {
1424     cairo_stroker_t stroker;
1425     cairo_status_t status;
1426
1427     status = _cairo_stroker_init (&stroker, path, stroke_style,
1428                                   ctm, ctm_inverse, tolerance,
1429                                   polygon->limits, polygon->num_limits);
1430     if (unlikely (status))
1431         return status;
1432
1433     stroker.add_external_edge = _cairo_polygon_add_external_edge,
1434     stroker.closure = polygon;
1435
1436     status = _cairo_path_fixed_interpret (path,
1437                                           _cairo_stroker_move_to,
1438                                           stroker.dash.dashed ?
1439                                           _cairo_stroker_line_to_dashed :
1440                                           _cairo_stroker_line_to,
1441                                           _cairo_stroker_curve_to,
1442                                           _cairo_stroker_close_path,
1443                                           &stroker);
1444
1445     if (unlikely (status))
1446         goto BAIL;
1447
1448     /* Cap the start and end of the final sub path as needed */
1449     status = _cairo_stroker_add_caps (&stroker);
1450
1451 BAIL:
1452     _cairo_stroker_fini (&stroker);
1453
1454     return status;
1455 }
1456
1457 cairo_int_status_t
1458 _cairo_path_fixed_stroke_to_traps (const cairo_path_fixed_t     *path,
1459                                    const cairo_stroke_style_t   *stroke_style,
1460                                    const cairo_matrix_t *ctm,
1461                                    const cairo_matrix_t *ctm_inverse,
1462                                    double                tolerance,
1463                                    cairo_traps_t        *traps)
1464 {
1465     cairo_int_status_t status;
1466     cairo_polygon_t polygon;
1467
1468     _cairo_polygon_init (&polygon, traps->limits, traps->num_limits);
1469     status = _cairo_path_fixed_stroke_to_polygon (path,
1470                                                   stroke_style,
1471                                                   ctm,
1472                                                   ctm_inverse,
1473                                                   tolerance,
1474                                                   &polygon);
1475     if (unlikely (status))
1476         goto BAIL;
1477
1478     status = _cairo_polygon_status (&polygon);
1479     if (unlikely (status))
1480         goto BAIL;
1481
1482     status = _cairo_bentley_ottmann_tessellate_polygon (traps, &polygon,
1483                                                         CAIRO_FILL_RULE_WINDING);
1484
1485 BAIL:
1486     _cairo_polygon_fini (&polygon);
1487
1488     return status;
1489 }