SkPathOpsCommon.cpp revision 54359294a7c9dc54802d512a5d891a35c1663392 
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 "SkAddIntersections.h"
8#include "SkOpCoincidence.h"
9#include "SkOpEdgeBuilder.h"
10#include "SkPathOpsCommon.h"
11#include "SkPathWriter.h"
12#include "SkTSort.h"
13
14static int contourRangeCheckY(const SkTDArray<SkOpContour* >& contourList,
15        SkOpSegment** currentPtr, SkOpSpanBase** startPtr, SkOpSpanBase** endPtr,
16        double* bestHit, SkScalar* bestDx, bool* tryAgain, double* midPtr, bool opp) {
17    SkOpSpanBase* start = *startPtr;
18    SkOpSpanBase* end = *endPtr;
19    const double mid = *midPtr;
20    const SkOpSegment* current = *currentPtr;
21    double tAtMid = SkOpSegment::TAtMid(start, end, mid);
22    SkPoint basePt = current->ptAtT(tAtMid);
23    int contourCount = contourList.count();
24    SkScalar bestY = SK_ScalarMin;
25    SkOpSegment* bestSeg = NULL;
26    SkOpSpan* bestTSpan = NULL;
27    bool bestOpp;
28    bool hitSomething = false;
29    for (int cTest = 0; cTest < contourCount; ++cTest) {
30        SkOpContour* contour = contourList[cTest];
31        bool testOpp = contour->operand() ^ current->operand() ^ opp;
32        if (basePt.fY < contour->bounds().fTop) {
33            continue;
34        }
35        if (bestY > contour->bounds().fBottom) {
36            continue;
37        }
38        SkOpSegment* testSeg = contour->first();
39        SkASSERT(testSeg);
40        do {
41            SkScalar testY = bestY;
42            double testHit;
43            bool vertical;
44            SkOpSpan* testTSpan = testSeg->crossedSpanY(basePt, tAtMid, testOpp,
45                    testSeg == current, &testY, &testHit, &hitSomething, &vertical);
46            if (!testTSpan) {
47                if (vertical) {
48                    hitSomething = true;
49                    bestSeg = NULL;
50                    goto abortContours;  // vertical encountered, return and try different point
51                }
52                continue;
53            }
54            if (testSeg == current && SkOpSegment::BetweenTs(start, testHit, end)) {
55                double baseT = start->t();
56                double endT = end->t();
57                double newMid = (testHit - baseT) / (endT - baseT);
58#if DEBUG_WINDING
59                double midT = SkOpSegment::TAtMid(start, end, mid);
60                SkPoint midXY = current->ptAtT(midT);
61                double newMidT = SkOpSegment::TAtMid(start, end, newMid);
62                SkPoint newXY = current->ptAtT(newMidT);
63                SkDebugf("%s [%d] mid=%1.9g->%1.9g s=%1.9g (%1.9g,%1.9g) m=%1.9g (%1.9g,%1.9g)"
64                        " n=%1.9g (%1.9g,%1.9g) e=%1.9g (%1.9g,%1.9g)\n", __FUNCTION__,
65                        current->debugID(), mid, newMid,
66                        baseT, start->pt().fX, start->pt().fY,
67                        baseT + mid * (endT - baseT), midXY.fX, midXY.fY,
68                        baseT + newMid * (endT - baseT), newXY.fX, newXY.fY,
69                        endT, end->pt().fX, end->pt().fY);
70#endif
71                *midPtr = newMid * 2;  // calling loop with divide by 2 before continuing
72                return SK_MinS32;
73            }
74            bestSeg = testSeg;
75            *bestHit = testHit;
76            bestOpp = testOpp;
77            bestTSpan = testTSpan;
78            bestY = testY;
79        } while ((testSeg = testSeg->next()));
80    }
81abortContours:
82    int result;
83    if (!bestSeg) {
84        result = hitSomething ? SK_MinS32 : 0;
85    } else {
86        if (bestTSpan->windSum() == SK_MinS32) {
87            *currentPtr = bestSeg;
88            *startPtr = bestTSpan;
89            *endPtr = bestTSpan->next();
90            SkASSERT(*startPtr != *endPtr && *startPtr && *endPtr);
91            *tryAgain = true;
92            return 0;
93        }
94        result = bestSeg->windingAtT(*bestHit, bestTSpan, bestOpp, bestDx);
95        SkASSERT(result == SK_MinS32 || *bestDx);
96    }
97    double baseT = (*startPtr)->t();
98    double endT = (*endPtr)->t();
99    *bestHit = baseT + mid * (endT - baseT);
100    return result;
101}
102
103SkOpSegment* FindUndone(SkTDArray<SkOpContour* >& contourList, SkOpSpanBase** startPtr,
104         SkOpSpanBase** endPtr) {
105    int contourCount = contourList.count();
106    SkOpSegment* result;
107    for (int cIndex = 0; cIndex < contourCount; ++cIndex) {
108        SkOpContour* contour = contourList[cIndex];
109        result = contour->undoneSegment(startPtr, endPtr);
110        if (result) {
111            return result;
112        }
113    }
114    return NULL;
115}
116
117SkOpSegment* FindChase(SkTDArray<SkOpSpanBase*>* chase, SkOpSpanBase** startPtr,
118        SkOpSpanBase** endPtr) {
119    while (chase->count()) {
120        SkOpSpanBase* span;
121        chase->pop(&span);
122        SkOpSegment* segment = span->segment();
123        *startPtr = span->ptT()->next()->span();
124        bool sortable = true;
125        bool done = true;
126        *endPtr = NULL;
127        if (SkOpAngle* last = segment->activeAngle(*startPtr, startPtr, endPtr, &done,
128                &sortable)) {
129            if (last->unorderable()) {
130                continue;
131            }
132            *startPtr = last->start();
133            *endPtr = last->end();
134    #if TRY_ROTATE
135            *chase->insert(0) = span;
136    #else
137            *chase->append() = span;
138    #endif
139            return last->segment();
140        }
141        if (done) {
142            continue;
143        }
144        if (!sortable) {
145            continue;
146        }
147        // find first angle, initialize winding to computed wind sum
148        const SkOpAngle* angle = segment->spanToAngle(*startPtr, *endPtr);
149        if (!angle) {
150            continue;
151        }
152        const SkOpAngle* firstAngle = angle;
153        bool loop = false;
154        int winding = SK_MinS32;
155        do {
156            angle = angle->next();
157            if (angle == firstAngle && loop) {
158                break;    // if we get here, there's no winding, loop is unorderable
159            }
160            loop |= angle == firstAngle;
161            segment = angle->segment();
162            winding = segment->windSum(angle);
163        } while (winding == SK_MinS32);
164        if (winding == SK_MinS32) {
165            continue;
166        }
167        int sumWinding = segment->updateWindingReverse(angle);
168        SkOpSegment* first = NULL;
169        firstAngle = angle;
170        while ((angle = angle->next()) != firstAngle) {
171            segment = angle->segment();
172            SkOpSpanBase* start = angle->start();
173            SkOpSpanBase* end = angle->end();
174            int maxWinding;
175            segment->setUpWinding(start, end, &maxWinding, &sumWinding);
176            if (!segment->done(angle)) {
177                if (!first) {
178                    first = segment;
179                    *startPtr = start;
180                    *endPtr = end;
181                }
182                // OPTIMIZATION: should this also add to the chase?
183                (void) segment->markAngle(maxWinding, sumWinding, angle);
184            }
185        }
186        if (first) {
187       #if TRY_ROTATE
188            *chase->insert(0) = span;
189       #else
190            *chase->append() = span;
191       #endif
192            return first;
193        }
194    }
195    return NULL;
196}
197
198#if DEBUG_ACTIVE_SPANS
199void DebugShowActiveSpans(SkTDArray<SkOpContour* >& contourList) {
200    int index;
201    for (index = 0; index < contourList.count(); ++ index) {
202        contourList[index]->debugShowActiveSpans();
203    }
204}
205#endif
206
207static SkOpSegment* findTopSegment(const SkTDArray<SkOpContour* >& contourList,
208        bool firstPass, SkOpSpanBase** start, SkOpSpanBase** end, SkPoint* topLeft,
209        bool* unsortable, bool* done, SkChunkAlloc* allocator) {
210    SkOpSegment* result;
211    const SkOpSegment* lastTopStart = NULL;
212    SkOpSpanBase* lastStart = NULL, * lastEnd = NULL;
213    do {
214        SkPoint bestXY = {SK_ScalarMax, SK_ScalarMax};
215        int contourCount = contourList.count();
216        SkOpSegment* topStart = NULL;
217        *done = true;
218        for (int cIndex = 0; cIndex < contourCount; ++cIndex) {
219            SkOpContour* contour = contourList[cIndex];
220            if (contour->done()) {
221                continue;
222            }
223            const SkPathOpsBounds& bounds = contour->bounds();
224            if (bounds.fBottom < topLeft->fY) {
225                *done = false;
226                continue;
227            }
228            if (bounds.fBottom == topLeft->fY && bounds.fRight < topLeft->fX) {
229                *done = false;
230                continue;
231            }
232            contour->topSortableSegment(*topLeft, &bestXY, &topStart);
233            if (!contour->done()) {
234                *done = false;
235            }
236        }
237        if (!topStart) {
238            return NULL;
239        }
240        *topLeft = bestXY;
241        result = topStart->findTop(firstPass, start, end, unsortable, allocator);
242        if (!result) {
243            if (lastTopStart == topStart && lastStart == *start && lastEnd == *end) {
244                *done = true;
245                return NULL;
246            }
247            lastTopStart = topStart;
248            lastStart = *start;
249            lastEnd = *end;
250        }
251    } while (!result);
252    return result;
253}
254
255static int rightAngleWinding(const SkTDArray<SkOpContour* >& contourList,
256        SkOpSegment** currentPtr, SkOpSpanBase** start, SkOpSpanBase** end, double* tHit,
257        SkScalar* hitDx, bool* tryAgain, bool* onlyVertical, bool opp) {
258    double test = 0.9;
259    int contourWinding;
260    do {
261        contourWinding = contourRangeCheckY(contourList, currentPtr, start, end,
262                tHit, hitDx, tryAgain, &test, opp);
263        if (contourWinding != SK_MinS32 || *tryAgain) {
264            return contourWinding;
265        }
266        if (*currentPtr && (*currentPtr)->isVertical()) {
267            *onlyVertical = true;
268            return contourWinding;
269        }
270        test /= 2;
271    } while (!approximately_negative(test));
272    SkASSERT(0);  // FIXME: incomplete functionality
273    return contourWinding;
274}
275
276static void skipVertical(const SkTDArray<SkOpContour* >& contourList,
277        SkOpSegment** current, SkOpSpanBase** start, SkOpSpanBase** end) {
278    if (!(*current)->isVertical(*start, *end)) {
279        return;
280    }
281    int contourCount = contourList.count();
282    for (int cIndex = 0; cIndex < contourCount; ++cIndex) {
283        SkOpContour* contour = contourList[cIndex];
284        if (contour->done()) {
285            continue;
286        }
287        SkOpSegment* nonVertical = contour->nonVerticalSegment(start, end);
288        if (nonVertical) {
289            *current = nonVertical;
290            return;
291        }
292    }
293    return;
294}
295
296struct SortableTop2 {  // error if local in pre-C++11
297    SkOpSpanBase* fStart;
298    SkOpSpanBase* fEnd;
299};
300
301SkOpSegment* FindSortableTop(const SkTDArray<SkOpContour* >& contourList, bool firstPass,
302        SkOpAngle::IncludeType angleIncludeType, bool* firstContour, SkOpSpanBase** startPtr,
303        SkOpSpanBase** endPtr, SkPoint* topLeft, bool* unsortable, bool* done, bool* onlyVertical,
304        SkChunkAlloc* allocator) {
305    SkOpSegment* current = findTopSegment(contourList, firstPass, startPtr, endPtr, topLeft,
306            unsortable, done, allocator);
307    if (!current) {
308        return NULL;
309    }
310    SkOpSpanBase* start = *startPtr;
311    SkOpSpanBase* end = *endPtr;
312    SkASSERT(current == start->segment());
313    if (*firstContour) {
314        current->initWinding(start, end, angleIncludeType);
315        *firstContour = false;
316        return current;
317    }
318    SkOpSpan* minSpan = start->starter(end);
319    int sumWinding = minSpan->windSum();
320    if (sumWinding == SK_MinS32) {
321        SkOpSpanBase* iSpan = end;
322        SkOpSpanBase* oSpan = start;
323        do {
324            bool checkFrom = oSpan->t() < iSpan->t();
325            if ((checkFrom ? iSpan->fromAngle() : iSpan->upCast()->toAngle()) == NULL) {
326                iSpan->addSimpleAngle(checkFrom, allocator);
327            }
328            sumWinding = current->computeSum(oSpan, iSpan, angleIncludeType);
329            SkTSwap(iSpan, oSpan);
330        } while (sumWinding == SK_MinS32 && iSpan == start);
331    }
332    if (sumWinding != SK_MinS32 && sumWinding != SK_NaN32) {
333        return current;
334    }
335    int contourWinding;
336    int oppContourWinding = 0;
337    // the simple upward projection of the unresolved points hit unsortable angles
338    // shoot rays at right angles to the segment to find its winding, ignoring angle cases
339    bool tryAgain;
340    double tHit;
341    SkScalar hitDx = 0;
342    SkScalar hitOppDx = 0;
343    // keep track of subsequent returns to detect infinite loops
344    SkTDArray<SortableTop2> sortableTops;
345    do {
346        // if current is vertical, find another candidate which is not
347        // if only remaining candidates are vertical, then they can be marked done
348        SkASSERT(*startPtr != *endPtr && *startPtr && *endPtr);
349        SkASSERT(current == (*startPtr)->segment());
350        skipVertical(contourList, &current, startPtr, endPtr);
351        SkASSERT(current);  // FIXME: if null, all remaining are vertical
352        SkASSERT(*startPtr != *endPtr && *startPtr && *endPtr);
353        SkASSERT(current == (*startPtr)->segment());
354        tryAgain = false;
355        contourWinding = rightAngleWinding(contourList, &current, startPtr, endPtr, &tHit,
356                &hitDx, &tryAgain, onlyVertical, false);
357        SkASSERT(current == (*startPtr)->segment());
358        if (tryAgain) {
359            bool giveUp = false;
360            int count = sortableTops.count();
361            for (int index = 0; index < count; ++index) {
362                const SortableTop2& prev = sortableTops[index];
363                if (giveUp) {
364                    prev.fStart->segment()->markDone(prev.fStart->starter(prev.fEnd));
365                } else if (prev.fStart == *startPtr || prev.fEnd == *endPtr) {
366                    // remaining edges are non-vertical and cannot have their winding computed
367                    // mark them as done and return, and hope that assembly can fill the holes
368                    giveUp = true;
369                    index = -1;
370                }
371            }
372            if (giveUp) {
373                *done = true;
374                return NULL;
375            }
376        }
377        SortableTop2* sortableTop = sortableTops.append();
378        sortableTop->fStart = *startPtr;
379        sortableTop->fEnd = *endPtr;
380#if DEBUG_SORT
381        SkDebugf("%s current=%d index=%d endIndex=%d tHit=%1.9g hitDx=%1.9g try=%d vert=%d\n",
382                __FUNCTION__, current->debugID(), (*startPtr)->debugID(), (*endPtr)->debugID(),
383                tHit, hitDx, tryAgain, *onlyVertical);
384#endif
385        if (*onlyVertical) {
386            return current;
387        }
388        if (tryAgain) {
389            continue;
390        }
391        if (angleIncludeType < SkOpAngle::kBinarySingle) {
392            break;
393        }
394        oppContourWinding = rightAngleWinding(contourList, &current, startPtr, endPtr, &tHit,
395                &hitOppDx, &tryAgain, NULL, true);
396        SkASSERT(current == (*startPtr)->segment());
397    } while (tryAgain);
398    bool success = current->initWinding(*startPtr, *endPtr, tHit, contourWinding, hitDx,
399            oppContourWinding, hitOppDx);
400    if (current->done()) {
401        return NULL;
402    } else if (!success) {  // check if the span has a valid winding
403        SkOpSpan* minSpan = (*startPtr)->t() < (*endPtr)->t() ? (*startPtr)->upCast()
404            : (*endPtr)->upCast();
405        if (minSpan->windSum() == SK_MinS32) {
406            return NULL;
407        }
408    }
409    return current;
410}
411
412void MakeContourList(SkOpContour* contour, SkTDArray<SkOpContour* >& list,
413                     bool evenOdd, bool oppEvenOdd) {
414    do {
415        if (contour->count()) {
416            contour->setOppXor(contour->operand() ? evenOdd : oppEvenOdd);
417            *list.append() = contour;
418        }
419    } while ((contour = contour->next()));
420    if (list.count() < 2) {
421        return;
422    }
423    SkTQSort<SkOpContour>(list.begin(), list.end() - 1);
424}
425
426class DistanceLessThan {
427public:
428    DistanceLessThan(double* distances) : fDistances(distances) { }
429    double* fDistances;
430    bool operator()(const int one, const int two) {
431        return fDistances[one] < fDistances[two];
432    }
433};
434
435    /*
436        check start and end of each contour
437        if not the same, record them
438        match them up
439        connect closest
440        reassemble contour pieces into new path
441    */
442void Assemble(const SkPathWriter& path, SkPathWriter* simple) {
443    SkChunkAlloc allocator(4096);  // FIXME: constant-ize, tune
444    SkOpContour contour;
445    SkOpGlobalState globalState(NULL  PATH_OPS_DEBUG_PARAMS(&contour));
446#if DEBUG_PATH_CONSTRUCTION
447    SkDebugf("%s\n", __FUNCTION__);
448#endif
449    SkOpEdgeBuilder builder(path, &contour, &allocator, &globalState);
450    builder.finish(&allocator);
451    SkTDArray<const SkOpContour* > runs;  // indices of partial contours
452    const SkOpContour* eContour = builder.head();
453    do {
454        if (!eContour->count()) {
455            continue;
456        }
457        const SkPoint& eStart = eContour->start();
458        const SkPoint& eEnd = eContour->end();
459#if DEBUG_ASSEMBLE
460        SkDebugf("%s contour", __FUNCTION__);
461        if (!SkDPoint::ApproximatelyEqual(eStart, eEnd)) {
462            SkDebugf("[%d]", runs.count());
463        } else {
464            SkDebugf("   ");
465        }
466        SkDebugf(" start=(%1.9g,%1.9g) end=(%1.9g,%1.9g)\n",
467                eStart.fX, eStart.fY, eEnd.fX, eEnd.fY);
468#endif
469        if (SkDPoint::ApproximatelyEqual(eStart, eEnd)) {
470            eContour->toPath(simple);
471            continue;
472        }
473        *runs.append() = eContour;
474    } while ((eContour = eContour->next()));
475    int count = runs.count();
476    if (count == 0) {
477        return;
478    }
479    SkTDArray<int> sLink, eLink;
480    sLink.append(count);
481    eLink.append(count);
482    int rIndex, iIndex;
483    for (rIndex = 0; rIndex < count; ++rIndex) {
484        sLink[rIndex] = eLink[rIndex] = SK_MaxS32;
485    }
486    const int ends = count * 2;  // all starts and ends
487    const int entries = (ends - 1) * count;  // folded triangle : n * (n - 1) / 2
488    SkTDArray<double> distances;
489    distances.append(entries);
490    for (rIndex = 0; rIndex < ends - 1; ++rIndex) {
491        const SkOpContour* oContour = runs[rIndex >> 1];
492        const SkPoint& oPt = rIndex & 1 ? oContour->end() : oContour->start();
493        const int row = rIndex < count - 1 ? rIndex * ends : (ends - rIndex - 2)
494                * ends - rIndex - 1;
495        for (iIndex = rIndex + 1; iIndex < ends; ++iIndex) {
496            const SkOpContour* iContour = runs[iIndex >> 1];
497            const SkPoint& iPt = iIndex & 1 ? iContour->end() : iContour->start();
498            double dx = iPt.fX - oPt.fX;
499            double dy = iPt.fY - oPt.fY;
500            double dist = dx * dx + dy * dy;
501            distances[row + iIndex] = dist;  // oStart distance from iStart
502        }
503    }
504    SkTDArray<int> sortedDist;
505    sortedDist.append(entries);
506    for (rIndex = 0; rIndex < entries; ++rIndex) {
507        sortedDist[rIndex] = rIndex;
508    }
509    SkTQSort<int>(sortedDist.begin(), sortedDist.end() - 1, DistanceLessThan(distances.begin()));
510    int remaining = count;  // number of start/end pairs
511    for (rIndex = 0; rIndex < entries; ++rIndex) {
512        int pair = sortedDist[rIndex];
513        int row = pair / ends;
514        int col = pair - row * ends;
515        int thingOne = row < col ? row : ends - row - 2;
516        int ndxOne = thingOne >> 1;
517        bool endOne = thingOne & 1;
518        int* linkOne = endOne ? eLink.begin() : sLink.begin();
519        if (linkOne[ndxOne] != SK_MaxS32) {
520            continue;
521        }
522        int thingTwo = row < col ? col : ends - row + col - 1;
523        int ndxTwo = thingTwo >> 1;
524        bool endTwo = thingTwo & 1;
525        int* linkTwo = endTwo ? eLink.begin() : sLink.begin();
526        if (linkTwo[ndxTwo] != SK_MaxS32) {
527            continue;
528        }
529        SkASSERT(&linkOne[ndxOne] != &linkTwo[ndxTwo]);
530        bool flip = endOne == endTwo;
531        linkOne[ndxOne] = flip ? ~ndxTwo : ndxTwo;
532        linkTwo[ndxTwo] = flip ? ~ndxOne : ndxOne;
533        if (!--remaining) {
534            break;
535        }
536    }
537    SkASSERT(!remaining);
538#if DEBUG_ASSEMBLE
539    for (rIndex = 0; rIndex < count; ++rIndex) {
540        int s = sLink[rIndex];
541        int e = eLink[rIndex];
542        SkDebugf("%s %c%d <- s%d - e%d -> %c%d\n", __FUNCTION__, s < 0 ? 's' : 'e',
543                s < 0 ? ~s : s, rIndex, rIndex, e < 0 ? 'e' : 's', e < 0 ? ~e : e);
544    }
545#endif
546    rIndex = 0;
547    do {
548        bool forward = true;
549        bool first = true;
550        int sIndex = sLink[rIndex];
551        SkASSERT(sIndex != SK_MaxS32);
552        sLink[rIndex] = SK_MaxS32;
553        int eIndex;
554        if (sIndex < 0) {
555            eIndex = sLink[~sIndex];
556            sLink[~sIndex] = SK_MaxS32;
557        } else {
558            eIndex = eLink[sIndex];
559            eLink[sIndex] = SK_MaxS32;
560        }
561        SkASSERT(eIndex != SK_MaxS32);
562#if DEBUG_ASSEMBLE
563        SkDebugf("%s sIndex=%c%d eIndex=%c%d\n", __FUNCTION__, sIndex < 0 ? 's' : 'e',
564                    sIndex < 0 ? ~sIndex : sIndex, eIndex < 0 ? 's' : 'e',
565                    eIndex < 0 ? ~eIndex : eIndex);
566#endif
567        do {
568            const SkOpContour* contour = runs[rIndex];
569            if (first) {
570                first = false;
571                const SkPoint* startPtr = &contour->start();
572                simple->deferredMove(startPtr[0]);
573            }
574            if (forward) {
575                contour->toPartialForward(simple);
576            } else {
577                contour->toPartialBackward(simple);
578            }
579#if DEBUG_ASSEMBLE
580            SkDebugf("%s rIndex=%d eIndex=%s%d close=%d\n", __FUNCTION__, rIndex,
581                eIndex < 0 ? "~" : "", eIndex < 0 ? ~eIndex : eIndex,
582                sIndex == ((rIndex != eIndex) ^ forward ? eIndex : ~eIndex));
583#endif
584            if (sIndex == ((rIndex != eIndex) ^ forward ? eIndex : ~eIndex)) {
585                simple->close();
586                break;
587            }
588            if (forward) {
589                eIndex = eLink[rIndex];
590                SkASSERT(eIndex != SK_MaxS32);
591                eLink[rIndex] = SK_MaxS32;
592                if (eIndex >= 0) {
593                    SkASSERT(sLink[eIndex] == rIndex);
594                    sLink[eIndex] = SK_MaxS32;
595                } else {
596                    SkASSERT(eLink[~eIndex] == ~rIndex);
597                    eLink[~eIndex] = SK_MaxS32;
598                }
599            } else {
600                eIndex = sLink[rIndex];
601                SkASSERT(eIndex != SK_MaxS32);
602                sLink[rIndex] = SK_MaxS32;
603                if (eIndex >= 0) {
604                    SkASSERT(eLink[eIndex] == rIndex);
605                    eLink[eIndex] = SK_MaxS32;
606                } else {
607                    SkASSERT(sLink[~eIndex] == ~rIndex);
608                    sLink[~eIndex] = SK_MaxS32;
609                }
610            }
611            rIndex = eIndex;
612            if (rIndex < 0) {
613                forward ^= 1;
614                rIndex = ~rIndex;
615            }
616        } while (true);
617        for (rIndex = 0; rIndex < count; ++rIndex) {
618            if (sLink[rIndex] != SK_MaxS32) {
619                break;
620            }
621        }
622    } while (rIndex < count);
623#if DEBUG_ASSEMBLE
624    for (rIndex = 0; rIndex < count; ++rIndex) {
625       SkASSERT(sLink[rIndex] == SK_MaxS32);
626       SkASSERT(eLink[rIndex] == SK_MaxS32);
627    }
628#endif
629}
630
631static void align(SkTDArray<SkOpContour* >* contourList) {
632    int contourCount = (*contourList).count();
633    for (int cTest = 0; cTest < contourCount; ++cTest) {
634        SkOpContour* contour = (*contourList)[cTest];
635        contour->align();
636    }
637}
638
639static void calcAngles(SkTDArray<SkOpContour* >* contourList, SkChunkAlloc* allocator) {
640    int contourCount = (*contourList).count();
641    for (int cTest = 0; cTest < contourCount; ++cTest) {
642        SkOpContour* contour = (*contourList)[cTest];
643        contour->calcAngles(allocator);
644    }
645}
646
647static void missingCoincidence(SkTDArray<SkOpContour* >* contourList,
648        SkOpCoincidence* coincidence, SkChunkAlloc* allocator) {
649    int contourCount = (*contourList).count();
650    for (int cTest = 0; cTest < contourCount; ++cTest) {
651        SkOpContour* contour = (*contourList)[cTest];
652        contour->missingCoincidence(coincidence, allocator);
653    }
654}
655
656static bool moveNearby(SkTDArray<SkOpContour* >* contourList) {
657    int contourCount = (*contourList).count();
658    for (int cTest = 0; cTest < contourCount; ++cTest) {
659        SkOpContour* contour = (*contourList)[cTest];
660        if (!contour->moveNearby()) {
661            return false;
662        }
663    }
664    return true;
665}
666
667static void sortAngles(SkTDArray<SkOpContour* >* contourList) {
668    int contourCount = (*contourList).count();
669    for (int cTest = 0; cTest < contourCount; ++cTest) {
670        SkOpContour* contour = (*contourList)[cTest];
671        contour->sortAngles();
672    }
673}
674
675static void sortSegments(SkTDArray<SkOpContour* >* contourList) {
676    int contourCount = (*contourList).count();
677    for (int cTest = 0; cTest < contourCount; ++cTest) {
678        SkOpContour* contour = (*contourList)[cTest];
679        contour->sortSegments();
680    }
681}
682
683bool HandleCoincidence(SkTDArray<SkOpContour* >* contourList, SkOpCoincidence* coincidence,
684        SkChunkAlloc* allocator, SkOpGlobalState* globalState) {
685    // move t values and points together to eliminate small/tiny gaps
686    if (!moveNearby(contourList)) {
687        return false;
688    }
689    align(contourList);  // give all span members common values
690#if DEBUG_VALIDATE
691    globalState->setPhase(SkOpGlobalState::kIntersecting);
692#endif
693    coincidence->addMissing(allocator);
694#if DEBUG_VALIDATE
695    globalState->setPhase(SkOpGlobalState::kWalking);
696#endif
697    coincidence->expand();  // check to see if, loosely, coincident ranges may be expanded
698    coincidence->mark();  // mark spans of coincident segments as coincident
699    missingCoincidence(contourList, coincidence, allocator);  // look for coincidence missed earlier
700    if (!coincidence->apply()) {  // adjust the winding value to account for coincident edges
701        return false;
702    }
703    sortSegments(contourList);
704    calcAngles(contourList, allocator);
705    sortAngles(contourList);
706    if (globalState->angleCoincidence()) {
707        missingCoincidence(contourList, coincidence, allocator);
708        if (!coincidence->apply()) {
709            return false;
710        }
711    }
712#if DEBUG_ACTIVE_SPANS
713    DebugShowActiveSpans(*contourList);
714#endif
715    return true;
716}
717