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/* -*- Mode: c; tab-width: 8; c-basic-offset: 4; indent-tabs-mode: t; -*- */
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/* cairo - a vector graphics library with display and print output
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 *
4
 * Copyright © 2002 University of Southern California
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 * Copyright © 2011 Intel Corporation
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 *
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 * This library is free software; you can redistribute it and/or
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 * modify it either under the terms of the GNU Lesser General Public
9
 * License version 2.1 as published by the Free Software Foundation
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 * (the "LGPL") or, at your option, under the terms of the Mozilla
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 * Public License Version 1.1 (the "MPL"). If you do not alter this
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 * notice, a recipient may use your version of this file under either
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 * the MPL or the LGPL.
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 *
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 * 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
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 * You should have received a copy of the MPL along with this library
19
 * in the file COPYING-MPL-1.1
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 *
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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
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);
    }
    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;
}