{{ message }}
forked from matplotlib/matplotlib
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathpath_converters.h
More file actions
1166 lines (1015 loc) · 38.7 KB
/
Copy pathpath_converters.h
File metadata and controls
1166 lines (1015 loc) · 38.7 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
/* -*- mode: c++; c-basic-offset: 4 -*- */
#ifndef MPL_PATH_CONVERTERS_H
#define MPL_PATH_CONVERTERS_H
#include <pybind11/pybind11.h>
#include <cmath>
#include <cstdint>
#include <limits>
#include "agg_clip_liang_barsky.h"
#include "mplutils.h"
#include "agg_conv_segmentator.h"
/*
This file contains a number of vertex converters that modify
paths. They all work as iterators, where the output is generated
on-the-fly, and don't require a copy of the full data.
Each class represents a discrete step in a "path-cleansing" pipeline.
They are currently applied in the following order in the Agg backend:
1. Affine transformation (implemented in Agg, not here)
2. PathNanRemover: skips over segments containing non-finite numbers
by inserting MOVETO commands
3. PathClipper: Clips line segments to a given rectangle. This is
helpful for data reduction, and also to avoid a limitation in
Agg where coordinates cannot be larger than 24-bit signed
integers.
4. PathSnapper: Rounds the path to the nearest center-pixels.
This makes rectilinear curves look much better.
5. PathSimplifier: Removes line segments from highly dense paths
that would not have an impact on their appearance. Speeds up
rendering and reduces file sizes.
6. curve-to-line-segment conversion (implemented in Agg, not here)
7. stroking (implemented in Agg, not here)
*/
/************************************************************
This is a base class for vertex converters that need to queue their
output. It is designed to be as fast as possible vs. the STL's queue
which is more flexible.
*/
template <int QueueSize>
class EmbeddedQueue
{
protected:
EmbeddedQueue() : m_queue_read(0), m_queue_write(0)
{
// empty
}
struct item
{
item() = default;
inline void set(const unsigned cmd_, const double x_, const double y_)
{
cmd = cmd_;
x = x_;
y = y_;
}
unsigned cmd;
double x;
double y;
};
int m_queue_read;
int m_queue_write;
item m_queue[QueueSize];
inline void queue_push(const unsigned cmd, const double x, const double y)
{
m_queue[m_queue_write++].set(cmd, x, y);
}
inline bool queue_nonempty()
{
return m_queue_read < m_queue_write;
}
inline bool queue_pop(unsigned *cmd, double *x, double *y)
{
if (queue_nonempty()) {
const item &front = m_queue[m_queue_read++];
*cmd = front.cmd;
*x = front.x;
*y = front.y;
return true;
}
m_queue_read = 0;
m_queue_write = 0;
return false;
}
inline void queue_clear()
{
m_queue_read = 0;
m_queue_write = 0;
}
};
/* Defines when path segment types have more than one vertex */
static const size_t num_extra_points_map[] =
{0, 0, 0, 1,
2, 0, 0, 0,
0, 0, 0, 0,
0, 0, 0, 0
};
/* An implementation of a simple linear congruential random number
generator. This is a "classic" and fast RNG which works fine for
our purposes of sketching lines, but should not be used for things
that matter, like crypto. We are implementing this ourselves
rather than using the C stdlib so that the seed state is not shared
with other third-party code. There are recent C++ options, but we
still require nothing later than C++98 for compatibility
reasons. */
class RandomNumberGenerator
{
private:
/* These are the same constants from MS Visual C++, which
has the nice property that the modulus is 2^32, thus
saving an explicit modulo operation
*/
static const uint32_t a = 214013;
static const uint32_t c = 2531011;
uint32_t m_seed;
public:
RandomNumberGenerator() : m_seed(0) {}
RandomNumberGenerator(int seed) : m_seed(seed) {}
void seed(int seed)
{
m_seed = seed;
}
double get_double()
{
m_seed = (a * m_seed + c);
return (double)m_seed / (double)(1LL << 32);
}
};
/*
PathNanRemover is a vertex converter that removes non-finite values
from the vertices list, and inserts MOVETO commands as necessary to
skip over them. If a curve segment contains at least one non-finite
value, the entire curve segment will be skipped.
*/
template <class VertexSource>
class PathNanRemover : protected EmbeddedQueue<4>
{
VertexSource *m_source;
bool m_remove_nans;
bool m_has_codes;
bool valid_segment_exists;
bool m_last_segment_valid;
bool m_was_broken;
double m_initX;
double m_initY;
public:
/* has_codes should be true if the path contains bezier curve segments, or
* closed loops, as this requires a slower algorithm to remove the NaNs.
* When in doubt, set to true.
*/
PathNanRemover(VertexSource &source, bool remove_nans, bool has_codes)
: m_source(&source), m_remove_nans(remove_nans), m_has_codes(has_codes),
m_last_segment_valid(false), m_was_broken(false),
m_initX(nan("")), m_initY(nan(""))
{
// ignore all close/end_poly commands until after the first valid
// (nan-free) command is encountered
valid_segment_exists = false;
}
inline void rewind(unsigned path_id)
{
queue_clear();
m_source->rewind(path_id);
}
inline unsigned vertex(double *x, double *y)
{
unsigned code;
if (!m_remove_nans) {
return m_source->vertex(x, y);
}
if (m_has_codes) {
/* This is the slow method for when there might be curves or closed
* loops. */
if (queue_pop(&code, x, y)) {
return code;
}
bool needs_move_to = false;
while (true) {
/* The approach here is to push each full curve
segment into the queue. If any non-finite values
are found along the way, the queue is emptied, and
the next curve segment is handled. */
code = m_source->vertex(x, y);
/* The vertices attached to STOP and CLOSEPOLY are never used,
* so we leave them as-is even if NaN. */
if (code == agg::path_cmd_stop) {
return code;
} else if (code == (agg::path_cmd_end_poly |
agg::path_flags_close) &&
valid_segment_exists) {
/* However, CLOSEPOLY only makes sense if a valid MOVETO
* command has already been emitted. But if a NaN was
* removed in the path, then we cannot close it as it is no
* longer a loop. We must emulate that by inserting a
* LINETO instead. */
if (m_was_broken) {
if (m_last_segment_valid && (
std::isfinite(m_initX) &&
std::isfinite(m_initY))) {
/* Join to start if both ends are valid. */
queue_push(agg::path_cmd_line_to, m_initX, m_initY);
break;
} else {
/* Skip the close, in case there are additional
* subpaths. */
continue;
}
m_was_broken = false;
break;
} else {
return code;
}
} else if (code == agg::path_cmd_move_to) {
/* Save the initial point in order to produce the last
* segment closing a loop, *if* we broke the loop. */
m_initX = *x;
m_initY = *y;
m_was_broken = false;
}
if (needs_move_to) {
queue_push(agg::path_cmd_move_to, *x, *y);
}
size_t num_extra_points = num_extra_points_map[code & 0xF];
m_last_segment_valid = (std::isfinite(*x) && std::isfinite(*y));
queue_push(code, *x, *y);
/* Note: this test cannot be short-circuited, since we need to
advance through the entire curve no matter what */
for (size_t i = 0; i < num_extra_points; ++i) {
m_source->vertex(x, y);
m_last_segment_valid = m_last_segment_valid &&
(std::isfinite(*x) && std::isfinite(*y));
queue_push(code, *x, *y);
}
if (m_last_segment_valid) {
valid_segment_exists = true;
break;
}
m_was_broken = true;
queue_clear();
/* If the last point is finite, we use that for the
moveto, otherwise, we'll use the first vertex of
the next curve. */
if (std::isfinite(*x) && std::isfinite(*y)) {
queue_push(agg::path_cmd_move_to, *x, *y);
needs_move_to = false;
} else {
needs_move_to = true;
}
}
if (queue_pop(&code, x, y)) {
return code;
} else {
return agg::path_cmd_stop;
}
} else // !m_has_codes
{
/* This is the fast path for when we know we have no codes. */
code = m_source->vertex(x, y);
if (code == agg::path_cmd_stop ||
(code == (agg::path_cmd_end_poly | agg::path_flags_close) &&
valid_segment_exists)) {
return code;
}
if (!(std::isfinite(*x) && std::isfinite(*y))) {
do {
code = m_source->vertex(x, y);
if (code == agg::path_cmd_stop ||
(code == (agg::path_cmd_end_poly | agg::path_flags_close) &&
valid_segment_exists)) {
return code;
}
} while (!(std::isfinite(*x) && std::isfinite(*y)));
return agg::path_cmd_move_to;
}
valid_segment_exists = true;
return code;
}
}
};
/************************************************************
PathClipper uses the Liang-Barsky line clipping algorithm (as
implemented in Agg) to clip the path to a given rectangle. Lines
will never extend outside of the rectangle. Curve segments are not
clipped, but are always included in their entirety.
*/
template <class VertexSource>
class PathClipper : public EmbeddedQueue<3>
{
VertexSource *m_source;
bool m_do_clipping;
agg::rect_base<double> m_cliprect;
double m_lastX;
double m_lastY;
bool m_moveto;
double m_initX;
double m_initY;
bool m_has_init;
bool m_was_clipped;
public:
PathClipper(VertexSource &source, bool do_clipping, double width, double height)
: m_source(&source),
m_do_clipping(do_clipping),
m_cliprect(-1.0, -1.0, width + 1.0, height + 1.0),
m_lastX(nan("")),
m_lastY(nan("")),
m_moveto(true),
m_initX(nan("")),
m_initY(nan("")),
m_has_init(false),
m_was_clipped(false)
{
// empty
}
PathClipper(VertexSource &source, bool do_clipping, const agg::rect_base<double> &rect)
: m_source(&source),
m_do_clipping(do_clipping),
m_cliprect(rect),
m_lastX(nan("")),
m_lastY(nan("")),
m_moveto(true),
m_initX(nan("")),
m_initY(nan("")),
m_has_init(false),
m_was_clipped(false)
{
m_cliprect.x1 -= 1.0;
m_cliprect.y1 -= 1.0;
m_cliprect.x2 += 1.0;
m_cliprect.y2 += 1.0;
}
inline void rewind(unsigned path_id)
{
m_has_init = false;
m_was_clipped = false;
m_moveto = true;
m_source->rewind(path_id);
}
int draw_clipped_line(double x0, double y0, double x1, double y1,
bool closed=false)
{
unsigned moved = agg::clip_line_segment(&x0, &y0, &x1, &y1, m_cliprect);
// moved >= 4 - Fully clipped
// moved & 1 != 0 - First point has been moved
// moved & 2 != 0 - Second point has been moved
m_was_clipped = m_was_clipped || (moved != 0);
if (moved < 4) {
if (moved & 1 || m_moveto) {
queue_push(agg::path_cmd_move_to, x0, y0);
}
queue_push(agg::path_cmd_line_to, x1, y1);
if (closed && !m_was_clipped) {
// Close the path only if the end point hasn't moved.
queue_push(agg::path_cmd_end_poly | agg::path_flags_close,
x1, y1);
}
m_moveto = false;
return 1;
}
return 0;
}
unsigned vertex(double *x, double *y)
{
unsigned code;
bool emit_moveto = false;
if (!m_do_clipping) {
// If not doing any clipping, just pass along the vertices verbatim
return m_source->vertex(x, y);
}
/* This is the slow path where we actually do clipping */
if (queue_pop(&code, x, y)) {
return code;
}
while ((code = m_source->vertex(x, y)) != agg::path_cmd_stop) {
emit_moveto = false;
switch (code) {
case (agg::path_cmd_end_poly | agg::path_flags_close):
if (m_has_init) {
// Queue the line from last point to the initial point, and
// if never clipped, add a close code.
draw_clipped_line(m_lastX, m_lastY, m_initX, m_initY,
true);
} else {
// An empty path that is immediately closed.
queue_push(
agg::path_cmd_end_poly | agg::path_flags_close,
m_lastX, m_lastY);
}
// If paths were not clipped, then the above code queued
// something, and we should exit the loop. Otherwise, continue
// to the next point, as there may be a new subpath.
if (queue_nonempty()) {
goto exit_loop;
}
break;
case agg::path_cmd_move_to:
// was the last command a moveto (and we have
// seen at least one command ?
// if so, shove it in the queue if in clip box
if (m_moveto && m_has_init &&
m_lastX >= m_cliprect.x1 &&
m_lastX <= m_cliprect.x2 &&
m_lastY >= m_cliprect.y1 &&
m_lastY <= m_cliprect.y2) {
// push the last moveto onto the queue
queue_push(agg::path_cmd_move_to, m_lastX, m_lastY);
// flag that we need to emit it
emit_moveto = true;
}
// update the internal state for this moveto
m_initX = m_lastX = *x;
m_initY = m_lastY = *y;
m_has_init = true;
m_moveto = true;
m_was_clipped = false;
// if the last command was moveto exit the loop to emit the code
if (emit_moveto) {
goto exit_loop;
}
// else, break and get the next point
break;
case agg::path_cmd_line_to:
if (draw_clipped_line(m_lastX, m_lastY, *x, *y)) {
m_lastX = *x;
m_lastY = *y;
goto exit_loop;
}
m_lastX = *x;
m_lastY = *y;
break;
default:
if (m_moveto) {
queue_push(agg::path_cmd_move_to, m_lastX, m_lastY);
m_moveto = false;
}
queue_push(code, *x, *y);
m_lastX = *x;
m_lastY = *y;
goto exit_loop;
}
}
exit_loop:
if (queue_pop(&code, x, y)) {
return code;
}
if (m_moveto && m_has_init &&
m_lastX >= m_cliprect.x1 &&
m_lastX <= m_cliprect.x2 &&
m_lastY >= m_cliprect.y1 &&
m_lastY <= m_cliprect.y2) {
*x = m_lastX;
*y = m_lastY;
m_moveto = false;
return agg::path_cmd_move_to;
}
return agg::path_cmd_stop;
}
};
/************************************************************
PathSnapper rounds vertices to their nearest center-pixels. This
makes rectilinear paths (rectangles, horizontal and vertical lines
etc.) look much cleaner.
*/
enum e_snap_mode {
SNAP_AUTO,
SNAP_FALSE,
SNAP_TRUE
};
namespace PYBIND11_NAMESPACE { namespace detail {
template <> struct type_caster<e_snap_mode> {
public:
PYBIND11_TYPE_CASTER(e_snap_mode, const_name("e_snap_mode"));
bool load(handle src, bool) {
if (src.is_none()) {
value = SNAP_AUTO;
return true;
}
value = src.cast<bool>() ? SNAP_TRUE : SNAP_FALSE;
return true;
}
};
}} // namespace PYBIND11_NAMESPACE::detail
template <class VertexSource>
class PathSnapper
{
private:
VertexSource *m_source;
bool m_snap;
double m_snap_value;
static bool should_snap(VertexSource &path, e_snap_mode snap_mode, unsigned total_vertices)
{
// If this contains only straight horizontal or vertical lines, it should be
// snapped to the nearest pixels
double x0 = 0, y0 = 0, x1 = 0, y1 = 0;
unsigned code;
switch (snap_mode) {
case SNAP_AUTO:
if (total_vertices > 1024) {
return false;
}
code = path.vertex(&x0, &y0);
if (code == agg::path_cmd_stop) {
return false;
}
while ((code = path.vertex(&x1, &y1)) != agg::path_cmd_stop) {
switch (code) {
case agg::path_cmd_curve3:
case agg::path_cmd_curve4:
return false;
case agg::path_cmd_line_to:
if (fabs(x0 - x1) >= 1e-4 && fabs(y0 - y1) >= 1e-4) {
return false;
}
}
x0 = x1;
y0 = y1;
}
return true;
case SNAP_FALSE:
return false;
case SNAP_TRUE:
return true;
}
return false;
}
public:
/*
snap_mode should be one of:
- SNAP_AUTO: Examine the path to determine if it should be snapped
- SNAP_TRUE: Force snapping
- SNAP_FALSE: No snapping
*/
PathSnapper(VertexSource &source,
e_snap_mode snap_mode,
unsigned total_vertices = 15,
double stroke_width = 0.0)
: m_source(&source)
{
m_snap = should_snap(source, snap_mode, total_vertices);
if (m_snap) {
int is_odd = mpl_round_to_int(stroke_width) % 2;
m_snap_value = (is_odd) ? 0.5 : 0.0;
}
source.rewind(0);
}
inline void rewind(unsigned path_id)
{
m_source->rewind(path_id);
}
inline unsigned vertex(double *x, double *y)
{
unsigned code;
code = m_source->vertex(x, y);
if (m_snap && agg::is_vertex(code)) {
*x = floor(*x + 0.5) + m_snap_value;
*y = floor(*y + 0.5) + m_snap_value;
}
return code;
}
inline bool is_snapping()
{
return m_snap;
}
};
/************************************************************
PathSimplifier reduces the number of vertices in a dense path without
changing its appearance.
*/
template <class VertexSource>
class PathSimplifier : protected EmbeddedQueue<9>
{
public:
/* Set simplify to true to perform simplification */
PathSimplifier(VertexSource &source, bool do_simplify, double simplify_threshold)
: m_source(&source),
m_simplify(do_simplify),
/* we square simplify_threshold so that we can compute
norms without doing the square root every step. */
m_simplify_threshold(simplify_threshold * simplify_threshold),
m_moveto(true),
m_after_moveto(false),
m_clipped(false),
// whether the most recent MOVETO vertex is valid
m_has_init(false),
// the most recent MOVETO vertex
m_initX(0.0),
m_initY(0.0),
// the x, y values from last iteration
m_lastx(0.0),
m_lasty(0.0),
// the dx, dy comprising the original vector, used in conjunction
// with m_currVecStart* to define the original vector.
m_origdx(0.0),
m_origdy(0.0),
// the squared norm of the original vector
m_origdNorm2(0.0),
// maximum squared norm of vector in forward (parallel) direction
m_dnorm2ForwardMax(0.0),
// maximum squared norm of vector in backward (anti-parallel) direction
m_dnorm2BackwardMax(0.0),
// was the last point the furthest from lastWritten in the
// forward (parallel) direction?
m_lastForwardMax(false),
// was the last point the furthest from lastWritten in the
// backward (anti-parallel) direction?
m_lastBackwardMax(false),
// added to queue when _push is called
m_nextX(0.0),
m_nextY(0.0),
// added to queue when _push is called if any backwards
// (anti-parallel) vectors were observed
m_nextBackwardX(0.0),
m_nextBackwardY(0.0),
// start of the current vector that is being simplified
m_currVecStartX(0.0),
m_currVecStartY(0.0)
{
// empty
}
inline void rewind(unsigned path_id)
{
queue_clear();
m_moveto = true;
m_source->rewind(path_id);
}
unsigned vertex(double *x, double *y)
{
unsigned cmd;
/* The simplification algorithm doesn't support curves or compound paths
so we just don't do it at all in that case... */
if (!m_simplify) {
return m_source->vertex(x, y);
}
/* idea: we can skip drawing many lines: we can combine
sequential parallel lines into a
single line instead of redrawing lines over the same
points. The loop below works a bit like a state machine,
where what it does depends on what it did in the last
looping. To test whether sequential lines are close to
parallel, I calculate the distance moved perpendicular to
the last line. Once it gets too big, the lines cannot be
combined. */
/* This code was originally written by Allan Haldane and I
have modified to work in-place -- meaning not creating an
entirely new path list each time. In order to do that
without too much additional code complexity, it keeps a
small queue around so that multiple points can be emitted
in a single call, and those points will be popped from the
queue in subsequent calls. The following block will empty
the queue before proceeding to the main loop below.
-- Michael Droettboom */
/* This code was originally written by Allan Haldane and
updated by Michael Droettboom. I have modified it to
handle anti-parallel vectors. This is done essentially
the same way as parallel vectors, but requires a little
additional book-keeping to track whether or not we have
observed an anti-parallel vector during the current run.
-- Kevin Rose */
if (queue_pop(&cmd, x, y)) {
return cmd;
}
/* The main simplification loop. The point is to consume only
as many points as necessary until something has been added
to the outbound queue, not to run through the entire path
in one go. This eliminates the need to allocate and fill
an entire additional path array on each draw. */
while ((cmd = m_source->vertex(x, y)) != agg::path_cmd_stop) {
/* if we are starting a new path segment, move to the first point
+ init */
if (m_moveto || cmd == agg::path_cmd_move_to) {
/* m_moveto check is not generally needed because
m_source generates an initial moveto; but it is
retained for safety in case circumstances arise
where this is not true. */
if (m_origdNorm2 != 0.0 && !m_after_moveto) {
/* m_origdNorm2 is nonzero only if we have a
vector; the m_after_moveto check ensures we
push this vector to the queue only once. */
_push(x, y);
}
m_after_moveto = true;
if (std::isfinite(*x) && std::isfinite(*y)) {
m_has_init = true;
m_initX = *x;
m_initY = *y;
} else {
m_has_init = false;
}
m_lastx = *x;
m_lasty = *y;
m_moveto = false;
m_origdNorm2 = 0.0;
m_dnorm2BackwardMax = 0.0;
m_clipped = true;
if (queue_nonempty()) {
/* If we did a push, empty the queue now. */
break;
}
continue;
}
m_after_moveto = false;
if(agg::is_close(cmd)) {
if (m_has_init) {
/* If we have a valid initial vertex, then
replace the current vertex with the initial vertex */
*x = m_initX;
*y = m_initY;
} else {
/* If we don't have a valid initial vertex, then
we can't close the path, so we skip the vertex */
continue;
}
}
/* NOTE: We used to skip this very short segments, but if
you have a lot of them cumulatively, you can miss
maxima or minima in the data. */
/* Don't render line segments less than one pixel long */
/* if (fabs(*x - m_lastx) < 1.0 && fabs(*y - m_lasty) < 1.0) */
/* { */
/* continue; */
/* } */
/* if we have no orig vector, set it to this vector and
continue. this orig vector is the reference vector we
will build up the line to */
if (m_origdNorm2 == 0.0) {
if (m_clipped) {
queue_push(agg::path_cmd_move_to, m_lastx, m_lasty);
m_clipped = false;
}
m_origdx = *x - m_lastx;
m_origdy = *y - m_lasty;
m_origdNorm2 = m_origdx * m_origdx + m_origdy * m_origdy;
// set all the variables to reflect this new orig vector
m_dnorm2ForwardMax = m_origdNorm2;
m_dnorm2BackwardMax = 0.0;
m_lastForwardMax = true;
m_lastBackwardMax = false;
m_currVecStartX = m_lastx;
m_currVecStartY = m_lasty;
m_nextX = m_lastx = *x;
m_nextY = m_lasty = *y;
continue;
}
/* If got to here, then we have an orig vector and we just got
a vector in the sequence. */
/* Check that the perpendicular distance we have moved
from the last written point compared to the line we are
building is not too much. If o is the orig vector (we
are building on), and v is the vector from the last
written point to the current point, then the
perpendicular vector is p = v - (o.v)o/(o.o)
(here, a.b indicates the dot product of a and b). */
/* get the v vector */
double totdx = *x - m_currVecStartX;
double totdy = *y - m_currVecStartY;
/* get the dot product o.v */
double totdot = m_origdx * totdx + m_origdy * totdy;
/* get the para vector ( = (o.v)o/(o.o)) */
double paradx = totdot * m_origdx / m_origdNorm2;
double parady = totdot * m_origdy / m_origdNorm2;
/* get the perp vector ( = v - para) */
double perpdx = totdx - paradx;
double perpdy = totdy - parady;
/* get the squared norm of perp vector ( = p.p) */
double perpdNorm2 = perpdx * perpdx + perpdy * perpdy;
/* If the perpendicular vector is less than
m_simplify_threshold pixels in size, then merge
current x,y with the current vector */
if (perpdNorm2 < m_simplify_threshold) {
/* check if the current vector is parallel or
anti-parallel to the orig vector. In either case,
test if it is the longest of the vectors
we are merging in that direction. If it is, then
update the current vector in that direction. */
double paradNorm2 = paradx * paradx + parady * parady;
m_lastForwardMax = false;
m_lastBackwardMax = false;
if (totdot > 0.0) {
if (paradNorm2 > m_dnorm2ForwardMax) {
m_lastForwardMax = true;
m_dnorm2ForwardMax = paradNorm2;
m_nextX = *x;
m_nextY = *y;
}
} else {
if (paradNorm2 > m_dnorm2BackwardMax) {
m_lastBackwardMax = true;
m_dnorm2BackwardMax = paradNorm2;
m_nextBackwardX = *x;
m_nextBackwardY = *y;
}
}
m_lastx = *x;
m_lasty = *y;
continue;
}
/* If we get here, then this vector was not similar enough to the
line we are building, so we need to draw that line and start the
next one. */
/* If the line needs to extend in the opposite direction from the
direction we are drawing in, move back to we start drawing from
back there. */
_push(x, y);
break;
}
/* Fill the queue with the remaining vertices if we've finished the
path in the above loop. */
if (cmd == agg::path_cmd_stop) {
if (m_origdNorm2 != 0.0) {
queue_push((m_moveto || m_after_moveto) ? agg::path_cmd_move_to
: agg::path_cmd_line_to,
m_nextX,
m_nextY);
if (m_dnorm2BackwardMax > 0.0) {
queue_push((m_moveto || m_after_moveto) ? agg::path_cmd_move_to
: agg::path_cmd_line_to,
m_nextBackwardX,
m_nextBackwardY);
}
m_moveto = false;
}
queue_push((m_moveto || m_after_moveto) ? agg::path_cmd_move_to : agg::path_cmd_line_to,
m_lastx,
m_lasty);
m_moveto = false;
queue_push(agg::path_cmd_stop, 0.0, 0.0);
}
/* Return the first item in the queue, if any, otherwise
indicate that we're done. */
if (queue_pop(&cmd, x, y)) {
return cmd;
} else {
return agg::path_cmd_stop;
}
}
private:
VertexSource *m_source;
bool m_simplify;
double m_simplify_threshold;
bool m_moveto;
bool m_after_moveto;
bool m_clipped;
bool m_has_init;
double m_initX, m_initY;
double m_lastx, m_lasty;
double m_origdx;
double m_origdy;
double m_origdNorm2;
double m_dnorm2ForwardMax;
double m_dnorm2BackwardMax;
bool m_lastForwardMax;
bool m_lastBackwardMax;
double m_nextX;
double m_nextY;
double m_nextBackwardX;
double m_nextBackwardY;
double m_currVecStartX;
double m_currVecStartY;
inline void _push(double *x, double *y)
{
bool needToPushBack = (m_dnorm2BackwardMax > 0.0);
/* If we observed any backward (anti-parallel) vectors, then
we need to push both forward and backward vectors. */
if (needToPushBack) {
/* If the last vector seen was the maximum in the forward direction,
then we need to push the forward after the backward. Otherwise,
the last vector seen was the maximum in the backward direction,
or somewhere in between, either way we are safe pushing forward
before backward. */
if (m_lastForwardMax) {
You can’t perform that action at this time.