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 * Copyright © 2011 Intel Corporation
6 *
7 * This library is free software; you can redistribute it and/or
8 * modify it either under the terms of the GNU Lesser General Public
9 * License version 2.1 as published by the Free Software Foundation
10 * (the "LGPL") or, at your option, under the terms of the Mozilla
11 * Public License Version 1.1 (the "MPL"). If you do not alter this
12 * notice, a recipient may use your version of this file under either
13 * the MPL or the LGPL.
14 *
15 * You should have received a copy of the LGPL along with this library
16 * in the file COPYING-LGPL-2.1; if not, write to the Free Software
17 * Foundation, Inc., 51 Franklin Street, Suite 500, Boston, MA 02110-1335, USA
18 * You should have received a copy of the MPL along with this library
19 * in the file COPYING-MPL-1.1
20 *
21 * The contents of this file are subject to the Mozilla Public License
22 * Version 1.1 (the "License"); you may not use this file except in
23 * compliance with the License. You may obtain a copy of the License at
24 * http://www.mozilla.org/MPL/
25 *
26 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY
27 * OF ANY KIND, either express or implied. See the LGPL or the MPL for
28 * the specific language governing rights and limitations.
29 *
30 * The Original Code is the cairo graphics library.
31 *
32 * The Initial Developer of the Original Code is University of Southern
33 * California.
34 *
35 * Contributor(s):
36 * Carl D. Worth <cworth@cworth.org>
37 * Chris Wilson <chris@chris-wilson.co.uk>
38 */
39
40 #define _DEFAULT_SOURCE /* for hypot() */
41 #include "cairoint.h"
42
43 #include "cairo-box-inline.h"
44 #include "cairo-boxes-private.h"
45 #include "cairo-error-private.h"
46 #include "cairo-path-fixed-private.h"
47 #include "cairo-slope-private.h"
48 #include "cairo-tristrip-private.h"
49
50 struct stroker {
51 cairo_stroke_style_t style;
52
53 cairo_tristrip_t *strip;
54
55 const cairo_matrix_t *ctm;
56 const cairo_matrix_t *ctm_inverse;
57 double tolerance;
58 cairo_bool_t ctm_det_positive;
59
60 cairo_pen_t pen;
61
62 cairo_bool_t has_sub_path;
63
64 cairo_point_t first_point;
65
66 cairo_bool_t has_current_face;
67 cairo_stroke_face_t current_face;
68
69 cairo_bool_t has_first_face;
70 cairo_stroke_face_t first_face;
71
72 cairo_box_t limit;
73 cairo_bool_t has_limits;
74 };
75
76 static inline double
77 normalize_slope (double *dx, double *dy);
78
79 static void
80 compute_face (const cairo_point_t *point,
81 const cairo_slope_t *dev_slope,
82 struct stroker *stroker,
83 cairo_stroke_face_t *face);
84
85 static void
translate_point(cairo_point_t * point,const cairo_point_t * offset)86 translate_point (cairo_point_t *point, const cairo_point_t *offset)
87 {
88 point->x += offset->x;
89 point->y += offset->y;
90 }
91
92 static int
slope_compare_sgn(double dx1,double dy1,double dx2,double dy2)93 slope_compare_sgn (double dx1, double dy1, double dx2, double dy2)
94 {
95 double c = (dx1 * dy2 - dx2 * dy1);
96
97 if (c > 0) return 1;
98 if (c < 0) return -1;
99 return 0;
100 }
101
102 static inline int
range_step(int i,int step,int max)103 range_step (int i, int step, int max)
104 {
105 i += step;
106 if (i < 0)
107 i = max - 1;
108 if (i >= max)
109 i = 0;
110 return i;
111 }
112
113 /*
114 * Construct a fan around the midpoint using the vertices from pen between
115 * inpt and outpt.
116 */
117 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)118 add_fan (struct stroker *stroker,
119 const cairo_slope_t *in_vector,
120 const cairo_slope_t *out_vector,
121 const cairo_point_t *midpt,
122 const cairo_point_t *inpt,
123 const cairo_point_t *outpt,
124 cairo_bool_t clockwise)
125 {
126 int start, stop, step, i, npoints;
127
128 if (clockwise) {
129 step = 1;
130
131 start = _cairo_pen_find_active_cw_vertex_index (&stroker->pen,
132 in_vector);
133 if (_cairo_slope_compare (&stroker->pen.vertices[start].slope_cw,
134 in_vector) < 0)
135 start = range_step (start, 1, stroker->pen.num_vertices);
136
137 stop = _cairo_pen_find_active_cw_vertex_index (&stroker->pen,
138 out_vector);
139 if (_cairo_slope_compare (&stroker->pen.vertices[stop].slope_ccw,
140 out_vector) > 0)
141 {
142 stop = range_step (stop, -1, stroker->pen.num_vertices);
143 if (_cairo_slope_compare (&stroker->pen.vertices[stop].slope_cw,
144 in_vector) < 0)
145 return;
146 }
147
148 npoints = stop - start;
149 } else {
150 step = -1;
151
152 start = _cairo_pen_find_active_ccw_vertex_index (&stroker->pen,
153 in_vector);
154 if (_cairo_slope_compare (&stroker->pen.vertices[start].slope_ccw,
155 in_vector) < 0)
156 start = range_step (start, -1, stroker->pen.num_vertices);
157
158 stop = _cairo_pen_find_active_ccw_vertex_index (&stroker->pen,
159 out_vector);
160 if (_cairo_slope_compare (&stroker->pen.vertices[stop].slope_cw,
161 out_vector) > 0)
162 {
163 stop = range_step (stop, 1, stroker->pen.num_vertices);
164 if (_cairo_slope_compare (&stroker->pen.vertices[stop].slope_ccw,
165 in_vector) < 0)
166 return;
167 }
168
169 npoints = start - stop;
170 }
171 stop = range_step (stop, step, stroker->pen.num_vertices);
172 if (npoints < 0)
173 npoints += stroker->pen.num_vertices;
174 if (npoints <= 1)
175 return;
176
177 for (i = start;
178 i != stop;
179 i = range_step (i, step, stroker->pen.num_vertices))
180 {
181 cairo_point_t p = *midpt;
182 translate_point (&p, &stroker->pen.vertices[i].point);
183 //contour_add_point (stroker, c, &p);
184 }
185 }
186
187 static int
join_is_clockwise(const cairo_stroke_face_t * in,const cairo_stroke_face_t * out)188 join_is_clockwise (const cairo_stroke_face_t *in,
189 const cairo_stroke_face_t *out)
190 {
191 return _cairo_slope_compare (&in->dev_vector, &out->dev_vector) < 0;
192 }
193
194 static void
inner_join(struct stroker * stroker,const cairo_stroke_face_t * in,const cairo_stroke_face_t * out,int clockwise)195 inner_join (struct stroker *stroker,
196 const cairo_stroke_face_t *in,
197 const cairo_stroke_face_t *out,
198 int clockwise)
199 {
200 const cairo_point_t *outpt;
201
202 if (clockwise) {
203 outpt = &out->ccw;
204 } else {
205 outpt = &out->cw;
206 }
207 //contour_add_point (stroker, inner, &in->point);
208 //contour_add_point (stroker, inner, outpt);
209 }
210
211 static void
inner_close(struct stroker * stroker,const cairo_stroke_face_t * in,cairo_stroke_face_t * out)212 inner_close (struct stroker *stroker,
213 const cairo_stroke_face_t *in,
214 cairo_stroke_face_t *out)
215 {
216 const cairo_point_t *inpt;
217
218 if (join_is_clockwise (in, out)) {
219 inpt = &out->ccw;
220 } else {
221 inpt = &out->cw;
222 }
223
224 //contour_add_point (stroker, inner, &in->point);
225 //contour_add_point (stroker, inner, inpt);
226 //*_cairo_contour_first_point (&inner->contour) =
227 //*_cairo_contour_last_point (&inner->contour);
228 }
229
230 static void
outer_close(struct stroker * stroker,const cairo_stroke_face_t * in,const cairo_stroke_face_t * out)231 outer_close (struct stroker *stroker,
232 const cairo_stroke_face_t *in,
233 const cairo_stroke_face_t *out)
234 {
235 const cairo_point_t *inpt, *outpt;
236 int clockwise;
237
238 if (in->cw.x == out->cw.x && in->cw.y == out->cw.y &&
239 in->ccw.x == out->ccw.x && in->ccw.y == out->ccw.y)
240 {
241 return;
242 }
243 clockwise = join_is_clockwise (in, out);
244 if (clockwise) {
245 inpt = &in->cw;
246 outpt = &out->cw;
247 } else {
248 inpt = &in->ccw;
249 outpt = &out->ccw;
250 }
251
252 switch (stroker->style.line_join) {
253 case CAIRO_LINE_JOIN_ROUND:
254 /* construct a fan around the common midpoint */
255 add_fan (stroker,
256 &in->dev_vector,
257 &out->dev_vector,
258 &in->point, inpt, outpt,
259 clockwise);
260 break;
261
262 case CAIRO_LINE_JOIN_MITER:
263 default: {
264 /* dot product of incoming slope vector with outgoing slope vector */
265 double in_dot_out = -in->usr_vector.x * out->usr_vector.x +
266 -in->usr_vector.y * out->usr_vector.y;
267 double ml = stroker->style.miter_limit;
268
269 /* Check the miter limit -- lines meeting at an acute angle
270 * can generate long miters, the limit converts them to bevel
271 *
272 * Consider the miter join formed when two line segments
273 * meet at an angle psi:
274 *
275 * /.\
276 * /. .\
277 * /./ \.\
278 * /./psi\.\
279 *
280 * We can zoom in on the right half of that to see:
281 *
282 * |\
283 * | \ psi/2
284 * | \
285 * | \
286 * | \
287 * | \
288 * miter \
289 * length \
290 * | \
291 * | .\
292 * | . \
293 * |. line \
294 * \ width \
295 * \ \
296 *
297 *
298 * The right triangle in that figure, (the line-width side is
299 * shown faintly with three '.' characters), gives us the
300 * following expression relating miter length, angle and line
301 * width:
302 *
303 * 1 /sin (psi/2) = miter_length / line_width
304 *
305 * The right-hand side of this relationship is the same ratio
306 * in which the miter limit (ml) is expressed. We want to know
307 * when the miter length is within the miter limit. That is
308 * when the following condition holds:
309 *
310 * 1/sin(psi/2) <= ml
311 * 1 <= ml sin(psi/2)
312 * 1 <= ml² sin²(psi/2)
313 * 2 <= ml² 2 sin²(psi/2)
314 * 2·sin²(psi/2) = 1-cos(psi)
315 * 2 <= ml² (1-cos(psi))
316 *
317 * in · out = |in| |out| cos (psi)
318 *
319 * in and out are both unit vectors, so:
320 *
321 * in · out = cos (psi)
322 *
323 * 2 <= ml² (1 - in · out)
324 *
325 */
326 if (2 <= ml * ml * (1 - in_dot_out)) {
327 double x1, y1, x2, y2;
328 double mx, my;
329 double dx1, dx2, dy1, dy2;
330 double ix, iy;
331 double fdx1, fdy1, fdx2, fdy2;
332 double mdx, mdy;
333
334 /*
335 * we've got the points already transformed to device
336 * space, but need to do some computation with them and
337 * also need to transform the slope from user space to
338 * device space
339 */
340 /* outer point of incoming line face */
341 x1 = _cairo_fixed_to_double (inpt->x);
342 y1 = _cairo_fixed_to_double (inpt->y);
343 dx1 = in->usr_vector.x;
344 dy1 = in->usr_vector.y;
345 cairo_matrix_transform_distance (stroker->ctm, &dx1, &dy1);
346
347 /* outer point of outgoing line face */
348 x2 = _cairo_fixed_to_double (outpt->x);
349 y2 = _cairo_fixed_to_double (outpt->y);
350 dx2 = out->usr_vector.x;
351 dy2 = out->usr_vector.y;
352 cairo_matrix_transform_distance (stroker->ctm, &dx2, &dy2);
353
354 /*
355 * Compute the location of the outer corner of the miter.
356 * That's pretty easy -- just the intersection of the two
357 * outer edges. We've got slopes and points on each
358 * of those edges. Compute my directly, then compute
359 * mx by using the edge with the larger dy; that avoids
360 * dividing by values close to zero.
361 */
362 my = (((x2 - x1) * dy1 * dy2 - y2 * dx2 * dy1 + y1 * dx1 * dy2) /
363 (dx1 * dy2 - dx2 * dy1));
364 if (fabs (dy1) >= fabs (dy2))
365 mx = (my - y1) * dx1 / dy1 + x1;
366 else
367 mx = (my - y2) * dx2 / dy2 + x2;
368
369 /*
370 * When the two outer edges are nearly parallel, slight
371 * perturbations in the position of the outer points of the lines
372 * caused by representing them in fixed point form can cause the
373 * intersection point of the miter to move a large amount. If
374 * that moves the miter intersection from between the two faces,
375 * then draw a bevel instead.
376 */
377
378 ix = _cairo_fixed_to_double (in->point.x);
379 iy = _cairo_fixed_to_double (in->point.y);
380
381 /* slope of one face */
382 fdx1 = x1 - ix; fdy1 = y1 - iy;
383
384 /* slope of the other face */
385 fdx2 = x2 - ix; fdy2 = y2 - iy;
386
387 /* slope from the intersection to the miter point */
388 mdx = mx - ix; mdy = my - iy;
389
390 /*
391 * Make sure the miter point line lies between the two
392 * faces by comparing the slopes
393 */
394 if (slope_compare_sgn (fdx1, fdy1, mdx, mdy) !=
395 slope_compare_sgn (fdx2, fdy2, mdx, mdy))
396 {
397 cairo_point_t p;
398
399 p.x = _cairo_fixed_from_double (mx);
400 p.y = _cairo_fixed_from_double (my);
401
402 //*_cairo_contour_last_point (&outer->contour) = p;
403 //*_cairo_contour_first_point (&outer->contour) = p;
404 return;
405 }
406 }
407 break;
408 }
409
410 case CAIRO_LINE_JOIN_BEVEL:
411 break;
412 }
413 //contour_add_point (stroker, outer, outpt);
414 }
415
416 static void
outer_join(struct stroker * stroker,const cairo_stroke_face_t * in,const cairo_stroke_face_t * out,int clockwise)417 outer_join (struct stroker *stroker,
418 const cairo_stroke_face_t *in,
419 const cairo_stroke_face_t *out,
420 int clockwise)
421 {
422 const cairo_point_t *inpt, *outpt;
423
424 if (in->cw.x == out->cw.x && in->cw.y == out->cw.y &&
425 in->ccw.x == out->ccw.x && in->ccw.y == out->ccw.y)
426 {
427 return;
428 }
429 if (clockwise) {
430 inpt = &in->cw;
431 outpt = &out->cw;
432 } else {
433 inpt = &in->ccw;
434 outpt = &out->ccw;
435 }
436
437 switch (stroker->style.line_join) {
438 case CAIRO_LINE_JOIN_ROUND:
439 /* construct a fan around the common midpoint */
440 add_fan (stroker,
441 &in->dev_vector,
442 &out->dev_vector,
443 &in->point, inpt, outpt,
444 clockwise);
445 break;
446
447 case CAIRO_LINE_JOIN_MITER:
448 default: {
449 /* dot product of incoming slope vector with outgoing slope vector */
450 double in_dot_out = -in->usr_vector.x * out->usr_vector.x +
451 -in->usr_vector.y * out->usr_vector.y;
452 double ml = stroker->style.miter_limit;
453
454 /* Check the miter limit -- lines meeting at an acute angle
455 * can generate long miters, the limit converts them to bevel
456 *
457 * Consider the miter join formed when two line segments
458 * meet at an angle psi:
459 *
460 * /.\
461 * /. .\
462 * /./ \.\
463 * /./psi\.\
464 *
465 * We can zoom in on the right half of that to see:
466 *
467 * |\
468 * | \ psi/2
469 * | \
470 * | \
471 * | \
472 * | \
473 * miter \
474 * length \
475 * | \
476 * | .\
477 * | . \
478 * |. line \
479 * \ width \
480 * \ \
481 *
482 *
483 * The right triangle in that figure, (the line-width side is
484 * shown faintly with three '.' characters), gives us the
485 * following expression relating miter length, angle and line
486 * width:
487 *
488 * 1 /sin (psi/2) = miter_length / line_width
489 *
490 * The right-hand side of this relationship is the same ratio
491 * in which the miter limit (ml) is expressed. We want to know
492 * when the miter length is within the miter limit. That is
493 * when the following condition holds:
494 *
495 * 1/sin(psi/2) <= ml
496 * 1 <= ml sin(psi/2)
497 * 1 <= ml² sin²(psi/2)
498 * 2 <= ml² 2 sin²(psi/2)
499 * 2·sin²(psi/2) = 1-cos(psi)
500 * 2 <= ml² (1-cos(psi))
501 *
502 * in · out = |in| |out| cos (psi)
503 *
504 * in and out are both unit vectors, so:
505 *
506 * in · out = cos (psi)
507 *
508 * 2 <= ml² (1 - in · out)
509 *
510 */
511 if (2 <= ml * ml * (1 - in_dot_out)) {
512 double x1, y1, x2, y2;
513 double mx, my;
514 double dx1, dx2, dy1, dy2;
515 double ix, iy;
516 double fdx1, fdy1, fdx2, fdy2;
517 double mdx, mdy;
518
519 /*
520 * we've got the points already transformed to device
521 * space, but need to do some computation with them and
522 * also need to transform the slope from user space to
523 * device space
524 */
525 /* outer point of incoming line face */
526 x1 = _cairo_fixed_to_double (inpt->x);
527 y1 = _cairo_fixed_to_double (inpt->y);
528 dx1 = in->usr_vector.x;
529 dy1 = in->usr_vector.y;
530 cairo_matrix_transform_distance (stroker->ctm, &dx1, &dy1);
531
532 /* outer point of outgoing line face */
533 x2 = _cairo_fixed_to_double (outpt->x);
534 y2 = _cairo_fixed_to_double (outpt->y);
535 dx2 = out->usr_vector.x;
536 dy2 = out->usr_vector.y;
537 cairo_matrix_transform_distance (stroker->ctm, &dx2, &dy2);
538
539 /*
540 * Compute the location of the outer corner of the miter.
541 * That's pretty easy -- just the intersection of the two
542 * outer edges. We've got slopes and points on each
543 * of those edges. Compute my directly, then compute
544 * mx by using the edge with the larger dy; that avoids
545 * dividing by values close to zero.
546 */
547 my = (((x2 - x1) * dy1 * dy2 - y2 * dx2 * dy1 + y1 * dx1 * dy2) /
548 (dx1 * dy2 - dx2 * dy1));
549 if (fabs (dy1) >= fabs (dy2))
550 mx = (my - y1) * dx1 / dy1 + x1;
551 else
552 mx = (my - y2) * dx2 / dy2 + x2;
553
554 /*
555 * When the two outer edges are nearly parallel, slight
556 * perturbations in the position of the outer points of the lines
557 * caused by representing them in fixed point form can cause the
558 * intersection point of the miter to move a large amount. If
559 * that moves the miter intersection from between the two faces,
560 * then draw a bevel instead.
561 */
562
563 ix = _cairo_fixed_to_double (in->point.x);
564 iy = _cairo_fixed_to_double (in->point.y);
565
566 /* slope of one face */
567 fdx1 = x1 - ix; fdy1 = y1 - iy;
568
569 /* slope of the other face */
570 fdx2 = x2 - ix; fdy2 = y2 - iy;
571
572 /* slope from the intersection to the miter point */
573 mdx = mx - ix; mdy = my - iy;
574
575 /*
576 * Make sure the miter point line lies between the two
577 * faces by comparing the slopes
578 */
579 if (slope_compare_sgn (fdx1, fdy1, mdx, mdy) !=
580 slope_compare_sgn (fdx2, fdy2, mdx, mdy))
581 {
582 cairo_point_t p;
583
584 p.x = _cairo_fixed_from_double (mx);
585 p.y = _cairo_fixed_from_double (my);
586
587 //*_cairo_contour_last_point (&outer->contour) = p;
588 return;
589 }
590 }
591 break;
592 }
593
594 case CAIRO_LINE_JOIN_BEVEL:
595 break;
596 }
597 //contour_add_point (stroker,outer, outpt);
598 }
599
600 static void
add_cap(struct stroker * stroker,const cairo_stroke_face_t * f)601 add_cap (struct stroker *stroker,
602 const cairo_stroke_face_t *f)
603 {
604 switch (stroker->style.line_cap) {
605 case CAIRO_LINE_CAP_ROUND: {
606 cairo_slope_t slope;
607
608 slope.dx = -f->dev_vector.dx;
609 slope.dy = -f->dev_vector.dy;
610
611 add_fan (stroker, &f->dev_vector, &slope,
612 &f->point, &f->ccw, &f->cw,
613 FALSE);
614 break;
615 }
616
617 case CAIRO_LINE_CAP_SQUARE: {
618 double dx, dy;
619 cairo_slope_t fvector;
620 cairo_point_t quad[4];
621
622 dx = f->usr_vector.x;
623 dy = f->usr_vector.y;
624 dx *= stroker->style.line_width / 2.0;
625 dy *= stroker->style.line_width / 2.0;
626 cairo_matrix_transform_distance (stroker->ctm, &dx, &dy);
627 fvector.dx = _cairo_fixed_from_double (dx);
628 fvector.dy = _cairo_fixed_from_double (dy);
629
630 quad[0] = f->ccw;
631 quad[1].x = f->ccw.x + fvector.dx;
632 quad[1].y = f->ccw.y + fvector.dy;
633 quad[2].x = f->cw.x + fvector.dx;
634 quad[2].y = f->cw.y + fvector.dy;
635 quad[3] = f->cw;
636
637 //contour_add_point (stroker, c, &quad[1]);
638 //contour_add_point (stroker, c, &quad[2]);
639 }
640
641 case CAIRO_LINE_CAP_BUTT:
642 default:
643 break;
644 }
645 //contour_add_point (stroker, c, &f->cw);
646 }
647
648 static void
add_leading_cap(struct stroker * stroker,const cairo_stroke_face_t * face)649 add_leading_cap (struct stroker *stroker,
650 const cairo_stroke_face_t *face)
651 {
652 cairo_stroke_face_t reversed;
653 cairo_point_t t;
654
655 reversed = *face;
656
657 /* The initial cap needs an outward facing vector. Reverse everything */
658 reversed.usr_vector.x = -reversed.usr_vector.x;
659 reversed.usr_vector.y = -reversed.usr_vector.y;
660 reversed.dev_vector.dx = -reversed.dev_vector.dx;
661 reversed.dev_vector.dy = -reversed.dev_vector.dy;
662
663 t = reversed.cw;
664 reversed.cw = reversed.ccw;
665 reversed.ccw = t;
666
667 add_cap (stroker, &reversed);
668 }
669
670 static void
add_trailing_cap(struct stroker * stroker,const cairo_stroke_face_t * face)671 add_trailing_cap (struct stroker *stroker,
672 const cairo_stroke_face_t *face)
673 {
674 add_cap (stroker, face);
675 }
676
677 static inline double
normalize_slope(double * dx,double * dy)678 normalize_slope (double *dx, double *dy)
679 {
680 double dx0 = *dx, dy0 = *dy;
681 double mag;
682
683 assert (dx0 != 0.0 || dy0 != 0.0);
684
685 if (dx0 == 0.0) {
686 *dx = 0.0;
687 if (dy0 > 0.0) {
688 mag = dy0;
689 *dy = 1.0;
690 } else {
691 mag = -dy0;
692 *dy = -1.0;
693 }
694 } else if (dy0 == 0.0) {
695 *dy = 0.0;
696 if (dx0 > 0.0) {
697 mag = dx0;
698 *dx = 1.0;
699 } else {
700 mag = -dx0;
701 *dx = -1.0;
702 }
703 } else {
704 mag = hypot (dx0, dy0);
705 *dx = dx0 / mag;
706 *dy = dy0 / mag;
707 }
708
709 return mag;
710 }
711
712 static void
compute_face(const cairo_point_t * point,const cairo_slope_t * dev_slope,struct stroker * stroker,cairo_stroke_face_t * face)713 compute_face (const cairo_point_t *point,
714 const cairo_slope_t *dev_slope,
715 struct stroker *stroker,
716 cairo_stroke_face_t *face)
717 {
718 double face_dx, face_dy;
719 cairo_point_t offset_ccw, offset_cw;
720 double slope_dx, slope_dy;
721
722 slope_dx = _cairo_fixed_to_double (dev_slope->dx);
723 slope_dy = _cairo_fixed_to_double (dev_slope->dy);
724 face->length = normalize_slope (&slope_dx, &slope_dy);
725 face->dev_slope.x = slope_dx;
726 face->dev_slope.y = slope_dy;
727
728 /*
729 * rotate to get a line_width/2 vector along the face, note that
730 * the vector must be rotated the right direction in device space,
731 * but by 90° in user space. So, the rotation depends on
732 * whether the ctm reflects or not, and that can be determined
733 * by looking at the determinant of the matrix.
734 */
735 if (! _cairo_matrix_is_identity (stroker->ctm_inverse)) {
736 /* Normalize the matrix! */
737 cairo_matrix_transform_distance (stroker->ctm_inverse,
738 &slope_dx, &slope_dy);
739 normalize_slope (&slope_dx, &slope_dy);
740
741 if (stroker->ctm_det_positive) {
742 face_dx = - slope_dy * (stroker->style.line_width / 2.0);
743 face_dy = slope_dx * (stroker->style.line_width / 2.0);
744 } else {
745 face_dx = slope_dy * (stroker->style.line_width / 2.0);
746 face_dy = - slope_dx * (stroker->style.line_width / 2.0);
747 }
748
749 /* back to device space */
750 cairo_matrix_transform_distance (stroker->ctm, &face_dx, &face_dy);
751 } else {
752 face_dx = - slope_dy * (stroker->style.line_width / 2.0);
753 face_dy = slope_dx * (stroker->style.line_width / 2.0);
754 }
755
756 offset_ccw.x = _cairo_fixed_from_double (face_dx);
757 offset_ccw.y = _cairo_fixed_from_double (face_dy);
758 offset_cw.x = -offset_ccw.x;
759 offset_cw.y = -offset_ccw.y;
760
761 face->ccw = *point;
762 translate_point (&face->ccw, &offset_ccw);
763
764 face->point = *point;
765
766 face->cw = *point;
767 translate_point (&face->cw, &offset_cw);
768
769 face->usr_vector.x = slope_dx;
770 face->usr_vector.y = slope_dy;
771
772 face->dev_vector = *dev_slope;
773 }
774
775 static void
add_caps(struct stroker * stroker)776 add_caps (struct stroker *stroker)
777 {
778 /* check for a degenerative sub_path */
779 if (stroker->has_sub_path &&
780 ! stroker->has_first_face &&
781 ! stroker->has_current_face &&
782 stroker->style.line_cap == CAIRO_LINE_CAP_ROUND)
783 {
784 /* pick an arbitrary slope to use */
785 cairo_slope_t slope = { CAIRO_FIXED_ONE, 0 };
786 cairo_stroke_face_t face;
787
788 /* arbitrarily choose first_point */
789 compute_face (&stroker->first_point, &slope, stroker, &face);
790
791 add_leading_cap (stroker, &face);
792 add_trailing_cap (stroker, &face);
793
794 /* ensure the circle is complete */
795 //_cairo_contour_add_point (&stroker->ccw.contour,
796 //_cairo_contour_first_point (&stroker->ccw.contour));
797 } else {
798 if (stroker->has_current_face)
799 add_trailing_cap (stroker, &stroker->current_face);
800
801 //_cairo_polygon_add_contour (stroker->polygon, &stroker->ccw.contour);
802 //_cairo_contour_reset (&stroker->ccw.contour);
803
804 if (stroker->has_first_face) {
805 //_cairo_contour_add_point (&stroker->ccw.contour,
806 //&stroker->first_face.cw);
807 add_leading_cap (stroker, &stroker->first_face);
808 //_cairo_polygon_add_contour (stroker->polygon,
809 //&stroker->ccw.contour);
810 //_cairo_contour_reset (&stroker->ccw.contour);
811 }
812 }
813 }
814
815 static cairo_status_t
move_to(void * closure,const cairo_point_t * point)816 move_to (void *closure,
817 const cairo_point_t *point)
818 {
819 struct stroker *stroker = closure;
820
821 /* Cap the start and end of the previous sub path as needed */
822 add_caps (stroker);
823
824 stroker->has_first_face = FALSE;
825 stroker->has_current_face = FALSE;
826 stroker->has_sub_path = FALSE;
827
828 stroker->first_point = *point;
829
830 stroker->current_face.point = *point;
831
832 return CAIRO_STATUS_SUCCESS;
833 }
834
835 static cairo_status_t
line_to(void * closure,const cairo_point_t * point)836 line_to (void *closure,
837 const cairo_point_t *point)
838 {
839 struct stroker *stroker = closure;
840 cairo_stroke_face_t start;
841 cairo_point_t *p1 = &stroker->current_face.point;
842 cairo_slope_t dev_slope;
843
844 stroker->has_sub_path = TRUE;
845
846 if (p1->x == point->x && p1->y == point->y)
847 return CAIRO_STATUS_SUCCESS;
848
849 _cairo_slope_init (&dev_slope, p1, point);
850 compute_face (p1, &dev_slope, stroker, &start);
851
852 if (stroker->has_current_face) {
853 int clockwise = join_is_clockwise (&stroker->current_face, &start);
854 /* Join with final face from previous segment */
855 outer_join (stroker, &stroker->current_face, &start, clockwise);
856 inner_join (stroker, &stroker->current_face, &start, clockwise);
857 } else {
858 if (! stroker->has_first_face) {
859 /* Save sub path's first face in case needed for closing join */
860 stroker->first_face = start;
861 _cairo_tristrip_move_to (stroker->strip, &start.cw);
862 stroker->has_first_face = TRUE;
863 }
864 stroker->has_current_face = TRUE;
865
866 _cairo_tristrip_add_point (stroker->strip, &start.cw);
867 _cairo_tristrip_add_point (stroker->strip, &start.ccw);
868 }
869
870 stroker->current_face = start;
871 stroker->current_face.point = *point;
872 stroker->current_face.ccw.x += dev_slope.dx;
873 stroker->current_face.ccw.y += dev_slope.dy;
874 stroker->current_face.cw.x += dev_slope.dx;
875 stroker->current_face.cw.y += dev_slope.dy;
876
877 _cairo_tristrip_add_point (stroker->strip, &stroker->current_face.cw);
878 _cairo_tristrip_add_point (stroker->strip, &stroker->current_face.ccw);
879
880 return CAIRO_STATUS_SUCCESS;
881 }
882
883 static cairo_status_t
spline_to(void * closure,const cairo_point_t * point,const cairo_slope_t * tangent)884 spline_to (void *closure,
885 const cairo_point_t *point,
886 const cairo_slope_t *tangent)
887 {
888 struct stroker *stroker = closure;
889 cairo_stroke_face_t face;
890
891 if (tangent->dx == 0 && tangent->dy == 0) {
892 const cairo_point_t *inpt, *outpt;
893 cairo_point_t t;
894 int clockwise;
895
896 face = stroker->current_face;
897
898 face.usr_vector.x = -face.usr_vector.x;
899 face.usr_vector.y = -face.usr_vector.y;
900 face.dev_vector.dx = -face.dev_vector.dx;
901 face.dev_vector.dy = -face.dev_vector.dy;
902
903 t = face.cw;
904 face.cw = face.ccw;
905 face.ccw = t;
906
907 clockwise = join_is_clockwise (&stroker->current_face, &face);
908 if (clockwise) {
909 inpt = &stroker->current_face.cw;
910 outpt = &face.cw;
911 } else {
912 inpt = &stroker->current_face.ccw;
913 outpt = &face.ccw;
914 }
915
916 add_fan (stroker,
917 &stroker->current_face.dev_vector,
918 &face.dev_vector,
919 &stroker->current_face.point, inpt, outpt,
920 clockwise);
921 } else {
922 compute_face (point, tangent, stroker, &face);
923
924 if (face.dev_slope.x * stroker->current_face.dev_slope.x +
925 face.dev_slope.y * stroker->current_face.dev_slope.y < 0)
926 {
927 const cairo_point_t *inpt, *outpt;
928 int clockwise = join_is_clockwise (&stroker->current_face, &face);
929
930 stroker->current_face.cw.x += face.point.x - stroker->current_face.point.x;
931 stroker->current_face.cw.y += face.point.y - stroker->current_face.point.y;
932 //contour_add_point (stroker, &stroker->cw, &stroker->current_face.cw);
933
934 stroker->current_face.ccw.x += face.point.x - stroker->current_face.point.x;
935 stroker->current_face.ccw.y += face.point.y - stroker->current_face.point.y;
936 //contour_add_point (stroker, &stroker->ccw, &stroker->current_face.ccw);
937
938 if (clockwise) {
939 inpt = &stroker->current_face.cw;
940 outpt = &face.cw;
941 } else {
942 inpt = &stroker->current_face.ccw;
943 outpt = &face.ccw;
944 }
945 add_fan (stroker,
946 &stroker->current_face.dev_vector,
947 &face.dev_vector,
948 &stroker->current_face.point, inpt, outpt,
949 clockwise);
950 }
951
952 _cairo_tristrip_add_point (stroker->strip, &face.cw);
953 _cairo_tristrip_add_point (stroker->strip, &face.ccw);
954 }
955
956 stroker->current_face = face;
957
958 return CAIRO_STATUS_SUCCESS;
959 }
960
961 static cairo_status_t
curve_to(void * closure,const cairo_point_t * b,const cairo_point_t * c,const cairo_point_t * d)962 curve_to (void *closure,
963 const cairo_point_t *b,
964 const cairo_point_t *c,
965 const cairo_point_t *d)
966 {
967 struct stroker *stroker = closure;
968 cairo_spline_t spline;
969 cairo_stroke_face_t face;
970
971 if (stroker->has_limits) {
972 if (! _cairo_spline_intersects (&stroker->current_face.point, b, c, d,
973 &stroker->limit))
974 return line_to (closure, d);
975 }
976
977 if (! _cairo_spline_init (&spline, spline_to, stroker,
978 &stroker->current_face.point, b, c, d))
979 return line_to (closure, d);
980
981 compute_face (&stroker->current_face.point, &spline.initial_slope,
982 stroker, &face);
983
984 if (stroker->has_current_face) {
985 int clockwise = join_is_clockwise (&stroker->current_face, &face);
986 /* Join with final face from previous segment */
987 outer_join (stroker, &stroker->current_face, &face, clockwise);
988 inner_join (stroker, &stroker->current_face, &face, clockwise);
989 } else {
990 if (! stroker->has_first_face) {
991 /* Save sub path's first face in case needed for closing join */
992 stroker->first_face = face;
993 _cairo_tristrip_move_to (stroker->strip, &face.cw);
994 stroker->has_first_face = TRUE;
995 }
996 stroker->has_current_face = TRUE;
997
998 _cairo_tristrip_add_point (stroker->strip, &face.cw);
999 _cairo_tristrip_add_point (stroker->strip, &face.ccw);
1000 }
1001 stroker->current_face = face;
1002
1003 return _cairo_spline_decompose (&spline, stroker->tolerance);
1004 }
1005
1006 static cairo_status_t
close_path(void * closure)1007 close_path (void *closure)
1008 {
1009 struct stroker *stroker = closure;
1010 cairo_status_t status;
1011
1012 status = line_to (stroker, &stroker->first_point);
1013 if (unlikely (status))
1014 return status;
1015
1016 if (stroker->has_first_face && stroker->has_current_face) {
1017 /* Join first and final faces of sub path */
1018 outer_close (stroker, &stroker->current_face, &stroker->first_face);
1019 inner_close (stroker, &stroker->current_face, &stroker->first_face);
1020 } else {
1021 /* Cap the start and end of the sub path as needed */
1022 add_caps (stroker);
1023 }
1024
1025 stroker->has_sub_path = FALSE;
1026 stroker->has_first_face = FALSE;
1027 stroker->has_current_face = FALSE;
1028
1029 return CAIRO_STATUS_SUCCESS;
1030 }
1031
1032 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)1033 _cairo_path_fixed_stroke_to_tristrip (const cairo_path_fixed_t *path,
1034 const cairo_stroke_style_t*style,
1035 const cairo_matrix_t *ctm,
1036 const cairo_matrix_t *ctm_inverse,
1037 double tolerance,
1038 cairo_tristrip_t *strip)
1039 {
1040 struct stroker stroker;
1041 cairo_int_status_t status;
1042 int i;
1043
1044 if (style->num_dashes)
1045 return CAIRO_INT_STATUS_UNSUPPORTED;
1046
1047 stroker.style = *style;
1048 stroker.ctm = ctm;
1049 stroker.ctm_inverse = ctm_inverse;
1050 stroker.tolerance = tolerance;
1051
1052 stroker.ctm_det_positive =
1053 _cairo_matrix_compute_determinant (ctm) >= 0.0;
1054
1055 status = _cairo_pen_init (&stroker.pen,
1056 style->line_width / 2.0,
1057 tolerance, ctm);
1058 if (unlikely (status))
1059 return status;
1060
1061 if (stroker.pen.num_vertices <= 1)
1062 return CAIRO_INT_STATUS_NOTHING_TO_DO;
1063
1064 stroker.has_current_face = FALSE;
1065 stroker.has_first_face = FALSE;
1066 stroker.has_sub_path = FALSE;
1067
1068 stroker.has_limits = strip->num_limits > 0;
1069 stroker.limit = strip->limits[0];
1070 for (i = 1; i < strip->num_limits; i++)
1071 _cairo_box_add_box (&stroker.limit, &strip->limits[i]);
1072
1073 stroker.strip = strip;
1074
1075 status = _cairo_path_fixed_interpret (path,
1076 move_to,
1077 line_to,
1078 curve_to,
1079 close_path,
1080 &stroker);
1081 /* Cap the start and end of the final sub path as needed */
1082 if (likely (status == CAIRO_INT_STATUS_SUCCESS))
1083 add_caps (&stroker);
1084
1085 _cairo_pen_fini (&stroker.pen);
1086
1087 return status;
1088 }
1089