1 /*
2 * Copyright 2012 Google Inc.
3 *
4 * Use of this source code is governed by a BSD-style license that can be
5 * found in the LICENSE file.
6 */
7 #include "src/core/SkTSort.h"
8 #include "src/pathops/SkOpSegment.h"
9 #include "src/pathops/SkOpSpan.h"
10 #include "src/pathops/SkPathOpsPoint.h"
11 #include "src/pathops/SkPathWriter.h"
12
13 // wrap path to keep track of whether the contour is initialized and non-empty
SkPathWriter(SkPath & path)14 SkPathWriter::SkPathWriter(SkPath& path)
15 : fPathPtr(&path)
16 {
17 init();
18 }
19
close()20 void SkPathWriter::close() {
21 if (fCurrent.isEmpty()) {
22 return;
23 }
24 SkASSERT(this->isClosed());
25 #if DEBUG_PATH_CONSTRUCTION
26 SkDebugf("path.close();\n");
27 #endif
28 fCurrent.close();
29 fPathPtr->addPath(fCurrent);
30 fCurrent.reset();
31 init();
32 }
33
conicTo(const SkPoint & pt1,const SkOpPtT * pt2,SkScalar weight)34 void SkPathWriter::conicTo(const SkPoint& pt1, const SkOpPtT* pt2, SkScalar weight) {
35 SkPoint pt2pt = this->update(pt2);
36 #if DEBUG_PATH_CONSTRUCTION
37 SkDebugf("path.conicTo(%1.9g,%1.9g, %1.9g,%1.9g, %1.9g);\n",
38 pt1.fX, pt1.fY, pt2pt.fX, pt2pt.fY, weight);
39 #endif
40 fCurrent.conicTo(pt1, pt2pt, weight);
41 }
42
cubicTo(const SkPoint & pt1,const SkPoint & pt2,const SkOpPtT * pt3)43 void SkPathWriter::cubicTo(const SkPoint& pt1, const SkPoint& pt2, const SkOpPtT* pt3) {
44 SkPoint pt3pt = this->update(pt3);
45 #if DEBUG_PATH_CONSTRUCTION
46 SkDebugf("path.cubicTo(%1.9g,%1.9g, %1.9g,%1.9g, %1.9g,%1.9g);\n",
47 pt1.fX, pt1.fY, pt2.fX, pt2.fY, pt3pt.fX, pt3pt.fY);
48 #endif
49 fCurrent.cubicTo(pt1, pt2, pt3pt);
50 }
51
deferredLine(const SkOpPtT * pt)52 bool SkPathWriter::deferredLine(const SkOpPtT* pt) {
53 SkASSERT(fFirstPtT);
54 SkASSERT(fDefer[0]);
55 if (fDefer[0] == pt) {
56 // FIXME: why we're adding a degenerate line? Caller should have preflighted this.
57 return true;
58 }
59 if (pt->contains(fDefer[0])) {
60 // FIXME: why we're adding a degenerate line?
61 return true;
62 }
63 if (this->matchedLast(pt)) {
64 return false;
65 }
66 if (fDefer[1] && this->changedSlopes(pt)) {
67 this->lineTo();
68 fDefer[0] = fDefer[1];
69 }
70 fDefer[1] = pt;
71 return true;
72 }
73
deferredMove(const SkOpPtT * pt)74 void SkPathWriter::deferredMove(const SkOpPtT* pt) {
75 if (!fDefer[1]) {
76 fFirstPtT = fDefer[0] = pt;
77 return;
78 }
79 SkASSERT(fDefer[0]);
80 if (!this->matchedLast(pt)) {
81 this->finishContour();
82 fFirstPtT = fDefer[0] = pt;
83 }
84 }
85
finishContour()86 void SkPathWriter::finishContour() {
87 if (!this->matchedLast(fDefer[0])) {
88 if (!fDefer[1]) {
89 return;
90 }
91 this->lineTo();
92 }
93 if (fCurrent.isEmpty()) {
94 return;
95 }
96 if (this->isClosed()) {
97 this->close();
98 } else {
99 SkASSERT(fDefer[1]);
100 fEndPtTs.push_back(fFirstPtT);
101 fEndPtTs.push_back(fDefer[1]);
102 fPartials.push_back(fCurrent);
103 this->init();
104 }
105 }
106
init()107 void SkPathWriter::init() {
108 fCurrent.reset();
109 fFirstPtT = fDefer[0] = fDefer[1] = nullptr;
110 }
111
isClosed() const112 bool SkPathWriter::isClosed() const {
113 return this->matchedLast(fFirstPtT);
114 }
115
lineTo()116 void SkPathWriter::lineTo() {
117 if (fCurrent.isEmpty()) {
118 this->moveTo();
119 }
120 #if DEBUG_PATH_CONSTRUCTION
121 SkDebugf("path.lineTo(%1.9g,%1.9g);\n", fDefer[1]->fPt.fX, fDefer[1]->fPt.fY);
122 #endif
123 fCurrent.lineTo(fDefer[1]->fPt);
124 }
125
matchedLast(const SkOpPtT * test) const126 bool SkPathWriter::matchedLast(const SkOpPtT* test) const {
127 if (test == fDefer[1]) {
128 return true;
129 }
130 if (!test) {
131 return false;
132 }
133 if (!fDefer[1]) {
134 return false;
135 }
136 return test->contains(fDefer[1]);
137 }
138
moveTo()139 void SkPathWriter::moveTo() {
140 #if DEBUG_PATH_CONSTRUCTION
141 SkDebugf("path.moveTo(%1.9g,%1.9g);\n", fFirstPtT->fPt.fX, fFirstPtT->fPt.fY);
142 #endif
143 fCurrent.moveTo(fFirstPtT->fPt);
144 }
145
quadTo(const SkPoint & pt1,const SkOpPtT * pt2)146 void SkPathWriter::quadTo(const SkPoint& pt1, const SkOpPtT* pt2) {
147 SkPoint pt2pt = this->update(pt2);
148 #if DEBUG_PATH_CONSTRUCTION
149 SkDebugf("path.quadTo(%1.9g,%1.9g, %1.9g,%1.9g);\n",
150 pt1.fX, pt1.fY, pt2pt.fX, pt2pt.fY);
151 #endif
152 fCurrent.quadTo(pt1, pt2pt);
153 }
154
155 // if last point to be written matches the current path's first point, alter the
156 // last to avoid writing a degenerate lineTo when the path is closed
update(const SkOpPtT * pt)157 SkPoint SkPathWriter::update(const SkOpPtT* pt) {
158 if (!fDefer[1]) {
159 this->moveTo();
160 } else if (!this->matchedLast(fDefer[0])) {
161 this->lineTo();
162 }
163 SkPoint result = pt->fPt;
164 if (fFirstPtT && result != fFirstPtT->fPt && fFirstPtT->contains(pt)) {
165 result = fFirstPtT->fPt;
166 }
167 fDefer[0] = fDefer[1] = pt; // set both to know that there is not a pending deferred line
168 return result;
169 }
170
someAssemblyRequired()171 bool SkPathWriter::someAssemblyRequired() {
172 this->finishContour();
173 return fEndPtTs.count() > 0;
174 }
175
changedSlopes(const SkOpPtT * ptT) const176 bool SkPathWriter::changedSlopes(const SkOpPtT* ptT) const {
177 if (matchedLast(fDefer[0])) {
178 return false;
179 }
180 SkVector deferDxdy = fDefer[1]->fPt - fDefer[0]->fPt;
181 SkVector lineDxdy = ptT->fPt - fDefer[1]->fPt;
182 return deferDxdy.fX * lineDxdy.fY != deferDxdy.fY * lineDxdy.fX;
183 }
184
185 class DistanceLessThan {
186 public:
DistanceLessThan(double * distances)187 DistanceLessThan(double* distances) : fDistances(distances) { }
188 double* fDistances;
operator ()(const int one,const int two) const189 bool operator()(const int one, const int two) const {
190 return fDistances[one] < fDistances[two];
191 }
192 };
193
194 /*
195 check start and end of each contour
196 if not the same, record them
197 match them up
198 connect closest
199 reassemble contour pieces into new path
200 */
assemble()201 void SkPathWriter::assemble() {
202 if (!this->someAssemblyRequired()) {
203 return;
204 }
205 #if DEBUG_PATH_CONSTRUCTION
206 SkDebugf("%s\n", __FUNCTION__);
207 #endif
208 SkOpPtT const* const* runs = fEndPtTs.begin(); // starts, ends of partial contours
209 int endCount = fEndPtTs.count(); // all starts and ends
210 SkASSERT(endCount > 0);
211 SkASSERT(endCount == fPartials.count() * 2);
212 #if DEBUG_ASSEMBLE
213 for (int index = 0; index < endCount; index += 2) {
214 const SkOpPtT* eStart = runs[index];
215 const SkOpPtT* eEnd = runs[index + 1];
216 SkASSERT(eStart != eEnd);
217 SkASSERT(!eStart->contains(eEnd));
218 SkDebugf("%s contour start=(%1.9g,%1.9g) end=(%1.9g,%1.9g)\n", __FUNCTION__,
219 eStart->fPt.fX, eStart->fPt.fY, eEnd->fPt.fX, eEnd->fPt.fY);
220 }
221 #endif
222 // lengthen any partial contour adjacent to a simple segment
223 for (int pIndex = 0; pIndex < endCount; pIndex++) {
224 SkOpPtT* opPtT = const_cast<SkOpPtT*>(runs[pIndex]);
225 SkPath p;
226 SkPathWriter partWriter(p);
227 do {
228 if (!zero_or_one(opPtT->fT)) {
229 break;
230 }
231 SkOpSpanBase* opSpanBase = opPtT->span();
232 SkOpSpanBase* start = opPtT->fT ? opSpanBase->prev() : opSpanBase->upCast()->next();
233 int step = opPtT->fT ? 1 : -1;
234 const SkOpSegment* opSegment = opSpanBase->segment();
235 const SkOpSegment* nextSegment = opSegment->isSimple(&start, &step);
236 if (!nextSegment) {
237 break;
238 }
239 SkOpSpanBase* opSpanEnd = start->t() ? start->prev() : start->upCast()->next();
240 if (start->starter(opSpanEnd)->alreadyAdded()) {
241 break;
242 }
243 nextSegment->addCurveTo(start, opSpanEnd, &partWriter);
244 opPtT = opSpanEnd->ptT();
245 SkOpPtT** runsPtr = const_cast<SkOpPtT**>(&runs[pIndex]);
246 *runsPtr = opPtT;
247 } while (true);
248 partWriter.finishContour();
249 const SkTArray<SkPath>& partPartials = partWriter.partials();
250 if (!partPartials.count()) {
251 continue;
252 }
253 // if pIndex is even, reverse and prepend to fPartials; otherwise, append
254 SkPath& partial = const_cast<SkPath&>(fPartials[pIndex >> 1]);
255 const SkPath& part = partPartials[0];
256 if (pIndex & 1) {
257 partial.addPath(part, SkPath::kExtend_AddPathMode);
258 } else {
259 SkPath reverse;
260 reverse.reverseAddPath(part);
261 reverse.addPath(partial, SkPath::kExtend_AddPathMode);
262 partial = reverse;
263 }
264 }
265 SkTDArray<int> sLink, eLink;
266 int linkCount = endCount / 2; // number of partial contours
267 sLink.append(linkCount);
268 eLink.append(linkCount);
269 int rIndex, iIndex;
270 for (rIndex = 0; rIndex < linkCount; ++rIndex) {
271 sLink[rIndex] = eLink[rIndex] = SK_MaxS32;
272 }
273 const int entries = endCount * (endCount - 1) / 2; // folded triangle
274 SkSTArray<8, double, true> distances(entries);
275 SkSTArray<8, int, true> sortedDist(entries);
276 SkSTArray<8, int, true> distLookup(entries);
277 int rRow = 0;
278 int dIndex = 0;
279 for (rIndex = 0; rIndex < endCount - 1; ++rIndex) {
280 const SkOpPtT* oPtT = runs[rIndex];
281 for (iIndex = rIndex + 1; iIndex < endCount; ++iIndex) {
282 const SkOpPtT* iPtT = runs[iIndex];
283 double dx = iPtT->fPt.fX - oPtT->fPt.fX;
284 double dy = iPtT->fPt.fY - oPtT->fPt.fY;
285 double dist = dx * dx + dy * dy;
286 distLookup.push_back(rRow + iIndex);
287 distances.push_back(dist); // oStart distance from iStart
288 sortedDist.push_back(dIndex++);
289 }
290 rRow += endCount;
291 }
292 SkASSERT(dIndex == entries);
293 SkTQSort<int>(sortedDist.begin(), sortedDist.end(), DistanceLessThan(distances.begin()));
294 int remaining = linkCount; // number of start/end pairs
295 for (rIndex = 0; rIndex < entries; ++rIndex) {
296 int pair = sortedDist[rIndex];
297 pair = distLookup[pair];
298 int row = pair / endCount;
299 int col = pair - row * endCount;
300 int ndxOne = row >> 1;
301 bool endOne = row & 1;
302 int* linkOne = endOne ? eLink.begin() : sLink.begin();
303 if (linkOne[ndxOne] != SK_MaxS32) {
304 continue;
305 }
306 int ndxTwo = col >> 1;
307 bool endTwo = col & 1;
308 int* linkTwo = endTwo ? eLink.begin() : sLink.begin();
309 if (linkTwo[ndxTwo] != SK_MaxS32) {
310 continue;
311 }
312 SkASSERT(&linkOne[ndxOne] != &linkTwo[ndxTwo]);
313 bool flip = endOne == endTwo;
314 linkOne[ndxOne] = flip ? ~ndxTwo : ndxTwo;
315 linkTwo[ndxTwo] = flip ? ~ndxOne : ndxOne;
316 if (!--remaining) {
317 break;
318 }
319 }
320 SkASSERT(!remaining);
321 #if DEBUG_ASSEMBLE
322 for (rIndex = 0; rIndex < linkCount; ++rIndex) {
323 int s = sLink[rIndex];
324 int e = eLink[rIndex];
325 SkDebugf("%s %c%d <- s%d - e%d -> %c%d\n", __FUNCTION__, s < 0 ? 's' : 'e',
326 s < 0 ? ~s : s, rIndex, rIndex, e < 0 ? 'e' : 's', e < 0 ? ~e : e);
327 }
328 #endif
329 rIndex = 0;
330 do {
331 bool forward = true;
332 bool first = true;
333 int sIndex = sLink[rIndex];
334 SkASSERT(sIndex != SK_MaxS32);
335 sLink[rIndex] = SK_MaxS32;
336 int eIndex;
337 if (sIndex < 0) {
338 eIndex = sLink[~sIndex];
339 sLink[~sIndex] = SK_MaxS32;
340 } else {
341 eIndex = eLink[sIndex];
342 eLink[sIndex] = SK_MaxS32;
343 }
344 SkASSERT(eIndex != SK_MaxS32);
345 #if DEBUG_ASSEMBLE
346 SkDebugf("%s sIndex=%c%d eIndex=%c%d\n", __FUNCTION__, sIndex < 0 ? 's' : 'e',
347 sIndex < 0 ? ~sIndex : sIndex, eIndex < 0 ? 's' : 'e',
348 eIndex < 0 ? ~eIndex : eIndex);
349 #endif
350 do {
351 const SkPath& contour = fPartials[rIndex];
352 if (!first) {
353 SkPoint prior, next;
354 if (!fPathPtr->getLastPt(&prior)) {
355 return;
356 }
357 if (forward) {
358 next = contour.getPoint(0);
359 } else {
360 SkAssertResult(contour.getLastPt(&next));
361 }
362 if (prior != next) {
363 /* TODO: if there is a gap between open path written so far and path to come,
364 connect by following segments from one to the other, rather than introducing
365 a diagonal to connect the two.
366 */
367 }
368 }
369 if (forward) {
370 fPathPtr->addPath(contour,
371 first ? SkPath::kAppend_AddPathMode : SkPath::kExtend_AddPathMode);
372 } else {
373 SkASSERT(!first);
374 fPathPtr->reversePathTo(contour);
375 }
376 if (first) {
377 first = false;
378 }
379 #if DEBUG_ASSEMBLE
380 SkDebugf("%s rIndex=%d eIndex=%s%d close=%d\n", __FUNCTION__, rIndex,
381 eIndex < 0 ? "~" : "", eIndex < 0 ? ~eIndex : eIndex,
382 sIndex == ((rIndex != eIndex) ^ forward ? eIndex : ~eIndex));
383 #endif
384 if (sIndex == ((rIndex != eIndex) ^ forward ? eIndex : ~eIndex)) {
385 fPathPtr->close();
386 break;
387 }
388 if (forward) {
389 eIndex = eLink[rIndex];
390 SkASSERT(eIndex != SK_MaxS32);
391 eLink[rIndex] = SK_MaxS32;
392 if (eIndex >= 0) {
393 SkASSERT(sLink[eIndex] == rIndex);
394 sLink[eIndex] = SK_MaxS32;
395 } else {
396 SkASSERT(eLink[~eIndex] == ~rIndex);
397 eLink[~eIndex] = SK_MaxS32;
398 }
399 } else {
400 eIndex = sLink[rIndex];
401 SkASSERT(eIndex != SK_MaxS32);
402 sLink[rIndex] = SK_MaxS32;
403 if (eIndex >= 0) {
404 SkASSERT(eLink[eIndex] == rIndex);
405 eLink[eIndex] = SK_MaxS32;
406 } else {
407 SkASSERT(sLink[~eIndex] == ~rIndex);
408 sLink[~eIndex] = SK_MaxS32;
409 }
410 }
411 rIndex = eIndex;
412 if (rIndex < 0) {
413 forward ^= 1;
414 rIndex = ~rIndex;
415 }
416 } while (true);
417 for (rIndex = 0; rIndex < linkCount; ++rIndex) {
418 if (sLink[rIndex] != SK_MaxS32) {
419 break;
420 }
421 }
422 } while (rIndex < linkCount);
423 #if DEBUG_ASSEMBLE
424 for (rIndex = 0; rIndex < linkCount; ++rIndex) {
425 SkASSERT(sLink[rIndex] == SK_MaxS32);
426 SkASSERT(eLink[rIndex] == SK_MaxS32);
427 }
428 #endif
429 return;
430 }
431