C++ SkOpSegment::done方法代码示例

// returns true if all edges were processed
static bool bridgeXor(SkTDArray<SkOpContour*>& contourList, SkPathWriter* simple) {
    SkOpSegment* current;
    int start, end;
    bool unsortable = false;
    bool closable = true;
    while ((current = FindUndone(contourList, &start, &end))) {
        do {
    #if DEBUG_ACTIVE_SPANS
            if (!unsortable && current->done()) {
                DebugShowActiveSpans(contourList);
            }
    #endif
            SkASSERT(unsortable || !current->done());
            int nextStart = start;
            int nextEnd = end;
            SkOpSegment* next = current->findNextXor(&nextStart, &nextEnd, &unsortable);
            if (!next) {
                if (!unsortable && simple->hasMove()
                        && current->verb() != SkPath::kLine_Verb
                        && !simple->isClosed()) {
                    current->addCurveTo(start, end, simple, true);
                    SkASSERT(simple->isClosed());
                }
                break;
            }
        #if DEBUG_FLOW
            SkDebugf("%s current id=%d from=(%1.9g,%1.9g) to=(%1.9g,%1.9g)\n", __FUNCTION__,
                    current->debugID(), current->xyAtT(start).fX, current->xyAtT(start).fY,
                    current->xyAtT(end).fX, current->xyAtT(end).fY);
        #endif
            current->addCurveTo(start, end, simple, true);
            current = next;
            start = nextStart;
            end = nextEnd;
        } while (!simple->isClosed() && (!unsortable || !current->done(SkMin32(start, end))));
        if (!simple->isClosed()) {
            SkASSERT(unsortable);
            int min = SkMin32(start, end);
            if (!current->done(min)) {
                current->addCurveTo(start, end, simple, true);
                current->markDone(min, 1);
            }
            closable = false;
        }
        simple->close();
    #if DEBUG_ACTIVE_SPANS
        DebugShowActiveSpans(contourList);
    #endif
    }
    return closable;
}

void SkOpContour::topSortableSegment(const SkPoint& topLeft, SkPoint* bestXY,
        SkOpSegment** topStart) {
    int segmentCount = fSortedSegments.count();
    SkASSERT(segmentCount > 0);
    int sortedIndex = fFirstSorted;
    fDone = true;  // may be cleared below
    for ( ; sortedIndex < segmentCount; ++sortedIndex) {
        SkOpSegment* testSegment = fSortedSegments[sortedIndex];
        if (testSegment->done()) {
            if (sortedIndex == fFirstSorted) {
                ++fFirstSorted;
            }
            continue;
        }
        fDone = false;
        SkPoint testXY = testSegment->activeLeftTop(true, NULL);
        if (*topStart) {
            if (testXY.fY < topLeft.fY) {
                continue;
            }
            if (testXY.fY == topLeft.fY && testXY.fX < topLeft.fX) {
                continue;
            }
            if (bestXY->fY < testXY.fY) {
                continue;
            }
            if (bestXY->fY == testXY.fY && bestXY->fX < testXY.fX) {
                continue;
            }
        }
        *topStart = testSegment;
        *bestXY = testXY;
    }
}

// please keep in sync with debugMergeMatches()
// Look to see if pt-t linked list contains same segment more than once
// if so, and if each pt-t is directly pointed to by spans in that segment,
// merge them
// keep the points, but remove spans so that the segment doesn't have 2 or more
// spans pointing to the same pt-t loop at different loop elements
void SkOpSpanBase::mergeMatches(SkOpSpanBase* opp) {
    SkOpPtT* test = &fPtT;
    SkOpPtT* testNext;
    const SkOpPtT* stop = test;
    do {
        testNext = test->next();
        if (test->deleted()) {
            continue;
        }
        SkOpSpanBase* testBase = test->span();
        SkASSERT(testBase->ptT() == test);
        SkOpSegment* segment = test->segment();
        if (segment->done()) {
            continue;
        }
        SkOpPtT* inner = opp->ptT();
        const SkOpPtT* innerStop = inner;
        do {
            if (inner->segment() != segment) {
                continue;
            }
            if (inner->deleted()) {
                continue;
            }
            SkOpSpanBase* innerBase = inner->span();
            SkASSERT(innerBase->ptT() == inner);
            // when the intersection is first detected, the span base is marked if there are 
            // more than one point in the intersection.
            if (!zero_or_one(inner->fT)) {
                innerBase->upCast()->release(test);
            } else {
                SkOPASSERT(inner->fT != test->fT);
                if (!zero_or_one(test->fT)) {
                    testBase->upCast()->release(inner);
                } else {
                    segment->markAllDone();  // mark segment as collapsed
                    SkDEBUGCODE(testBase->debugSetDeleted());
                    test->setDeleted();
                    SkDEBUGCODE(innerBase->debugSetDeleted());
                    inner->setDeleted();
                }
            }
#ifdef SK_DEBUG   // assert if another undeleted entry points to segment
            const SkOpPtT* debugInner = inner;
            while ((debugInner = debugInner->next()) != innerStop) {
                if (debugInner->segment() != segment) {
                    continue;
                }
                if (debugInner->deleted()) {
                    continue;
                }
                SkOPASSERT(0);
            }
#endif
            break;
        } while ((inner = inner->next()) != innerStop);
    } while ((test = testNext) != stop);
    this->checkForCollapsedCoincidence();
}

SkOpSegment* SkOpContour::undoneSegment(SkOpSpanBase** startPtr, SkOpSpanBase** endPtr) {
    SkOpSegment* segment = &fHead;
    do {
        if (segment->done()) {
            continue;
        }
        segment->undoneSpan(startPtr, endPtr);
        return segment;
    } while ((segment = segment->next()));
    return nullptr;
}

SkOpSpan* SkOpContour::undoneSpan() {
    SkOpSegment* testSegment = &fHead;
    do {
        if (testSegment->done()) {
            continue;
        }
        return testSegment->undoneSpan();
    } while ((testSegment = testSegment->next()));
    fDone = true;
    return nullptr;
}

SkOpSegment* SkOpContour::undoneSegment(int* start, int* end) {
    int segmentCount = fSegments.count();
    for (int test = 0; test < segmentCount; ++test) {
        SkOpSegment* testSegment = &fSegments[test];
        if (testSegment->done()) {
            continue;
        }
        testSegment->undoneSpan(start, end);
        return testSegment;
    }
    return NULL;
}

SkOpSegment* SkOpContour::nonVerticalSegment(int* start, int* end) {
    int segmentCount = fSortedSegments.count();
    SkASSERT(segmentCount > 0);
    for (int sortedIndex = fFirstSorted; sortedIndex < segmentCount; ++sortedIndex) {
        SkOpSegment* testSegment = fSortedSegments[sortedIndex];
        if (testSegment->done()) {
            continue;
        }
        *start = *end = 0;
        while (testSegment->nextCandidate(start, end)) {
            if (!testSegment->isVertical(*start, *end)) {
                return testSegment;
            }
        }
    }
    return NULL;
}

SkOpSegment* SkOpContour::nonVerticalSegment(SkOpSpanBase** start, SkOpSpanBase** end) {
    int segmentCount = fSortedSegments.count();
    SkASSERT(segmentCount > 0);
    for (int sortedIndex = fFirstSorted; sortedIndex < segmentCount; ++sortedIndex) {
        SkOpSegment* testSegment = fSortedSegments[sortedIndex];
        if (testSegment->done()) {
            continue;
        }
        SkOpSpanBase* span = testSegment->head();
        SkOpSpanBase* testS, * testE;
        while (SkOpSegment::NextCandidate(span, &testS, &testE)) {
            if (!testSegment->isVertical(testS, testE)) {
                *start = testS;
                *end = testE;
                return testSegment;
            }
            span = span->upCast()->next();
        }
    }
    return NULL;
}

SkOpSegment* FindSortableTop(const SkTArray<SkOpContour*, true>& contourList,
        SkOpAngle::IncludeType angleIncludeType, bool* firstContour, int* indexPtr,
        int* endIndexPtr, SkPoint* topLeft, bool* unsortable, bool* done, bool* onlyVertical,
        bool firstPass) {
    SkOpSegment* current = findTopSegment(contourList, indexPtr, endIndexPtr, topLeft, unsortable,
            done, firstPass);
    if (!current) {
        return NULL;
    }
    const int startIndex = *indexPtr;
    const int endIndex = *endIndexPtr;
    if (*firstContour) {
        current->initWinding(startIndex, endIndex, angleIncludeType);
        *firstContour = false;
        return current;
    }
    int minIndex = SkMin32(startIndex, endIndex);
    int sumWinding = current->windSum(minIndex);
    if (sumWinding == SK_MinS32) {
        int index = endIndex;
        int oIndex = startIndex;
        do { 
            const SkOpSpan& span = current->span(index);
            if ((oIndex < index ? span.fFromAngle : span.fToAngle) == NULL) {
                current->addSimpleAngle(index);
            }
            sumWinding = current->computeSum(oIndex, index, angleIncludeType);
            SkTSwap(index, oIndex);
        } while (sumWinding == SK_MinS32 && index == startIndex);
    }
    if (sumWinding != SK_MinS32 && sumWinding != SK_NaN32) {
        return current;
    }
    int contourWinding;
    int oppContourWinding = 0;
    // the simple upward projection of the unresolved points hit unsortable angles
    // shoot rays at right angles to the segment to find its winding, ignoring angle cases
    bool tryAgain;
    double tHit;
    SkScalar hitDx = 0;
    SkScalar hitOppDx = 0;
    do {
        // if current is vertical, find another candidate which is not
        // if only remaining candidates are vertical, then they can be marked done
        SkASSERT(*indexPtr != *endIndexPtr && *indexPtr >= 0 && *endIndexPtr >= 0);
        skipVertical(contourList, &current, indexPtr, endIndexPtr);
        SkASSERT(current);  // FIXME: if null, all remaining are vertical
        SkASSERT(*indexPtr != *endIndexPtr && *indexPtr >= 0 && *endIndexPtr >= 0);
        tryAgain = false;
        contourWinding = rightAngleWinding(contourList, &current, indexPtr, endIndexPtr, &tHit,
                &hitDx, &tryAgain, onlyVertical, false);
        if (*onlyVertical) {
            return current;
        }
        if (tryAgain) {
            continue;
        }
        if (angleIncludeType < SkOpAngle::kBinarySingle) {
            break;
        }
        oppContourWinding = rightAngleWinding(contourList, &current, indexPtr, endIndexPtr, &tHit,
                &hitOppDx, &tryAgain, NULL, true);
    } while (tryAgain);
    current->initWinding(*indexPtr, *endIndexPtr, tHit, contourWinding, hitDx, oppContourWinding,
            hitOppDx);
    if (current->done()) {
        return NULL;
    }
    return current;
}

// FIXME: this and find chase should be merge together, along with
// other code that walks winding in angles
// OPTIMIZATION: Probably, the walked winding should be rolled into the angle structure
// so it isn't duplicated by walkers like this one
static SkOpSegment* findChaseOp(SkTDArray<SkOpSpan*>& chase, int& nextStart, int& nextEnd) {
    while (chase.count()) {
        SkOpSpan* span;
        chase.pop(&span);
        const SkOpSpan& backPtr = span->fOther->span(span->fOtherIndex);
        SkOpSegment* segment = backPtr.fOther;
        nextStart = backPtr.fOtherIndex;
        SkSTArray<SkOpAngle::kStackBasedCount, SkOpAngle, true> angles;
        int done = 0;
        if (segment->activeAngle(nextStart, &done, &angles)) {
            SkOpAngle* last = angles.end() - 1;
            nextStart = last->start();
            nextEnd = last->end();
   #if TRY_ROTATE
            *chase.insert(0) = span;
   #else
            *chase.append() = span;
   #endif
            return last->segment();
        }
        if (done == angles.count()) {
            continue;
        }
        SkSTArray<SkOpAngle::kStackBasedCount, SkOpAngle*, true> sorted;
        bool sortable = SkOpSegment::SortAngles(angles, &sorted,
                SkOpSegment::kMayBeUnordered_SortAngleKind);
        int angleCount = sorted.count();
#if DEBUG_SORT
        sorted[0]->segment()->debugShowSort(__FUNCTION__, sorted, 0, sortable);
#endif
        if (!sortable) {
            continue;
        }
        // find first angle, initialize winding to computed fWindSum
        int firstIndex = -1;
        const SkOpAngle* angle;
        bool foundAngle = true;
        do {
            ++firstIndex;
            if (firstIndex >= angleCount) {
                foundAngle = false;
                break;
            }
            angle = sorted[firstIndex];
            segment = angle->segment();
        } while (segment->windSum(angle) == SK_MinS32);
        if (!foundAngle) {
            continue;
        }
    #if DEBUG_SORT
        segment->debugShowSort(__FUNCTION__, sorted, firstIndex, sortable);
    #endif
        int sumMiWinding = segment->updateWindingReverse(angle);
        int sumSuWinding = segment->updateOppWindingReverse(angle);
        if (segment->operand()) {
            SkTSwap<int>(sumMiWinding, sumSuWinding);
        }
        int nextIndex = firstIndex + 1;
        int lastIndex = firstIndex != 0 ? firstIndex : angleCount;
        SkOpSegment* first = NULL;
        do {
            SkASSERT(nextIndex != firstIndex);
            if (nextIndex == angleCount) {
                nextIndex = 0;
            }
            angle = sorted[nextIndex];
            segment = angle->segment();
            int start = angle->start();
            int end = angle->end();
            int maxWinding, sumWinding, oppMaxWinding, oppSumWinding;
            segment->setUpWindings(start, end, &sumMiWinding, &sumSuWinding,
                    &maxWinding, &sumWinding, &oppMaxWinding, &oppSumWinding);
            if (!segment->done(angle)) {
                if (!first) {
                    first = segment;
                    nextStart = start;
                    nextEnd = end;
                }
                (void) segment->markAngle(maxWinding, sumWinding, oppMaxWinding,
                    oppSumWinding, angle);
            }
        } while (++nextIndex != lastIndex);
        if (first) {
       #if TRY_ROTATE
            *chase.insert(0) = span;
       #else
            *chase.append() = span;
       #endif
            return first;
        }
    }
    return NULL;
}

static bool bridgeOp(SkTArray<SkOpContour*, true>& contourList, const SkPathOp op,
        const int xorMask, const int xorOpMask, SkPathWriter* simple) {
    bool firstContour = true;
    bool unsortable = false;
    bool topUnsortable = false;
    SkPoint topLeft = {SK_ScalarMin, SK_ScalarMin};
    do {
        int index, endIndex;
        bool done;
        SkOpSegment* current = FindSortableTop(contourList, SkOpAngle::kBinarySingle, &firstContour,
                &index, &endIndex, &topLeft, &topUnsortable, &done);
        if (!current) {
            if (topUnsortable || !done) {
                topUnsortable = false;
                SkASSERT(topLeft.fX != SK_ScalarMin && topLeft.fY != SK_ScalarMin);
                topLeft.fX = topLeft.fY = SK_ScalarMin;
                continue;
            }
            break;
        }
        SkTDArray<SkOpSpan*> chaseArray;
        do {
            if (current->activeOp(index, endIndex, xorMask, xorOpMask, op)) {
                do {
                    if (!unsortable && current->done()) {
            #if DEBUG_ACTIVE_SPANS
                        DebugShowActiveSpans(contourList);
            #endif
                        if (simple->isEmpty()) {
                            simple->init();
                        }
                        break;
                    }
                    SkASSERT(unsortable || !current->done());
                    int nextStart = index;
                    int nextEnd = endIndex;
                    SkOpSegment* next = current->findNextOp(&chaseArray, &nextStart, &nextEnd,
                            &unsortable, op, xorMask, xorOpMask);
                    if (!next) {
                        if (!unsortable && simple->hasMove()
                                && current->verb() != SkPath::kLine_Verb
                                && !simple->isClosed()) {
                            current->addCurveTo(index, endIndex, simple, true);
                            SkASSERT(simple->isClosed());
                        }
                        break;
                    }
        #if DEBUG_FLOW
            SkDebugf("%s current id=%d from=(%1.9g,%1.9g) to=(%1.9g,%1.9g)\n", __FUNCTION__,
                    current->debugID(), current->xyAtT(index).fX, current->xyAtT(index).fY,
                    current->xyAtT(endIndex).fX, current->xyAtT(endIndex).fY);
        #endif
                    current->addCurveTo(index, endIndex, simple, true);
                    current = next;
                    index = nextStart;
                    endIndex = nextEnd;
                } while (!simple->isClosed() && (!unsortable
                        || !current->done(SkMin32(index, endIndex))));
                if (current->activeWinding(index, endIndex) && !simple->isClosed()) {
                    // FIXME : add to simplify, xor cpaths
                    int min = SkMin32(index, endIndex);
                    if (!unsortable && !simple->isEmpty()) {
                        unsortable = current->checkSmall(min);
                    }
                    SkASSERT(unsortable || simple->isEmpty());
                    if (!current->done(min)) {
                        current->addCurveTo(index, endIndex, simple, true);
                        current->markDoneBinary(min);
                    }
                }
                simple->close();
            } else {
                SkOpSpan* last = current->markAndChaseDoneBinary(index, endIndex);
                if (last && !last->fLoop) {
                    *chaseArray.append() = last;
                }
            }
            current = findChaseOp(chaseArray, index, endIndex);
        #if DEBUG_ACTIVE_SPANS
            DebugShowActiveSpans(contourList);
        #endif
            if (!current) {
                break;
            }
        } while (true);
    } while (true);
    return simple->someAssemblyRequired();
}

static bool bridgeOp(SkTArray<SkOpContour*, true>& contourList, const SkPathOp op,
        const int xorMask, const int xorOpMask, SkPathWriter* simple) {
    bool firstContour = true;
    bool unsortable = false;
    bool topUnsortable = false;
    bool firstPass = true;
    SkPoint lastTopLeft;
    SkPoint topLeft = {SK_ScalarMin, SK_ScalarMin};
    do {
        int index, endIndex;
        bool topDone;
        bool onlyVertical = false;
        lastTopLeft = topLeft;
        SkOpSegment* current = FindSortableTop(contourList, SkOpAngle::kBinarySingle, &firstContour,
                &index, &endIndex, &topLeft, &topUnsortable, &topDone, &onlyVertical, firstPass);
        if (!current) {
            if ((!topUnsortable || firstPass) && !topDone) {
                SkASSERT(topLeft.fX != SK_ScalarMin && topLeft.fY != SK_ScalarMin);
                if (lastTopLeft.fX == SK_ScalarMin && lastTopLeft.fY == SK_ScalarMin) {
                    if (firstPass) {
                        firstPass = false;
                    } else {
                        break;
                    }
                }
                topLeft.fX = topLeft.fY = SK_ScalarMin;
                continue;
            }
            break;
        } else if (onlyVertical) {
            break;
        }
        firstPass = !topUnsortable || lastTopLeft != topLeft;
        SkTDArray<SkOpSpan*> chase;
        do {
            if (current->activeOp(index, endIndex, xorMask, xorOpMask, op)) {
                do {
                    if (!unsortable && current->done()) {
                        break;
                    }
                    SkASSERT(unsortable || !current->done());
                    int nextStart = index;
                    int nextEnd = endIndex;
                    SkOpSegment* next = current->findNextOp(&chase, &nextStart, &nextEnd,
                            &unsortable, op, xorMask, xorOpMask);
                    if (!next) {
                        if (!unsortable && simple->hasMove()
                                && current->verb() != SkPath::kLine_Verb
                                && !simple->isClosed()) {
                            current->addCurveTo(index, endIndex, simple, true);
                    #if DEBUG_ACTIVE_SPANS
                            if (!simple->isClosed()) {
                                DebugShowActiveSpans(contourList);
                            }
                    #endif
//                            SkASSERT(simple->isClosed());
                        }
                        break;
                    }
        #if DEBUG_FLOW
            SkDebugf("%s current id=%d from=(%1.9g,%1.9g) to=(%1.9g,%1.9g)\n", __FUNCTION__,
                    current->debugID(), current->xyAtT(index).fX, current->xyAtT(index).fY,
                    current->xyAtT(endIndex).fX, current->xyAtT(endIndex).fY);
        #endif
                    current->addCurveTo(index, endIndex, simple, true);
                    current = next;
                    index = nextStart;
                    endIndex = nextEnd;
                } while (!simple->isClosed() && (!unsortable
                        || !current->done(SkMin32(index, endIndex))));
                if (current->activeWinding(index, endIndex) && !simple->isClosed()) {
                    // FIXME : add to simplify, xor cpaths
                    int min = SkMin32(index, endIndex);
                    if (!unsortable && !simple->isEmpty()) {
                        unsortable = current->checkSmall(min);
                    }
                    if (!current->done(min)) {
                        current->addCurveTo(index, endIndex, simple, true);
                        current->markDoneBinary(min);
                    }
                }
                simple->close();
            } else {
                SkOpSpan* last = current->markAndChaseDoneBinary(index, endIndex);
                if (last && !last->fChased && !last->fLoop) {
                    last->fChased = true;
                    SkASSERT(!SkPathOpsDebug::ChaseContains(chase, last));
                    *chase.append() = last;
#if DEBUG_WINDING
                    SkDebugf("%s chase.append id=%d windSum=%d small=%d\n", __FUNCTION__,
                            last->fOther->span(last->fOtherIndex).fOther->debugID(), last->fWindSum,
                            last->fSmall);
#endif
                }
            }
            current = findChaseOp(chase, &index, &endIndex);
        #if DEBUG_ACTIVE_SPANS
            DebugShowActiveSpans(contourList);
        #endif
            if (!current) {
//.........这里部分代码省略.........

static SkOpSegment* findChaseOp(SkTDArray<SkOpSpan*>& chase, int* tIndex, int* endIndex) {
    while (chase.count()) {
        SkOpSpan* span;
        chase.pop(&span);
        const SkOpSpan& backPtr = span->fOther->span(span->fOtherIndex);
        SkOpSegment* segment = backPtr.fOther;
        *tIndex = backPtr.fOtherIndex;
        bool sortable = true;
        bool done = true;
        *endIndex = -1;
        if (const SkOpAngle* last = segment->activeAngle(*tIndex, tIndex, endIndex, &done,
                &sortable)) {
            if (last->unorderable()) {
                continue;
            }
            *tIndex = last->start();
            *endIndex = last->end();
   #if TRY_ROTATE
            *chase.insert(0) = span;
   #else
            *chase.append() = span;
   #endif
            return last->segment();
        }
        if (done) {
            continue;
        }
        if (!sortable) {
            continue;
        }
        // find first angle, initialize winding to computed fWindSum
        const SkOpAngle* angle = segment->spanToAngle(*tIndex, *endIndex);
        if (!angle) {
            continue;
        }
        const SkOpAngle* firstAngle = angle;
        SkDEBUGCODE(bool loop = false);
        int winding;
        do {
            angle = angle->next();
            SkASSERT(angle != firstAngle || !loop);
            SkDEBUGCODE(loop |= angle == firstAngle);
            segment = angle->segment();
            winding = segment->windSum(angle);
        } while (winding == SK_MinS32);
        int sumMiWinding = segment->updateWindingReverse(angle);
        int sumSuWinding = segment->updateOppWindingReverse(angle);
        if (segment->operand()) {
            SkTSwap<int>(sumMiWinding, sumSuWinding);
        }
        SkOpSegment* first = NULL;
        while ((angle = angle->next()) != firstAngle) {
            segment = angle->segment();
            int start = angle->start();
            int end = angle->end();
            int maxWinding, sumWinding, oppMaxWinding, oppSumWinding;
            segment->setUpWindings(start, end, &sumMiWinding, &sumSuWinding,
                    &maxWinding, &sumWinding, &oppMaxWinding, &oppSumWinding);
            if (!segment->done(angle)) {
                if (!first) {
                    first = segment;
                    *tIndex = start;
                    *endIndex = end;
                }
                // OPTIMIZATION: should this also add to the chase?
                (void) segment->markAngle(maxWinding, sumWinding, oppMaxWinding,
                    oppSumWinding, angle);
            }
        }
        if (first) {
       #if TRY_ROTATE
            *chase.insert(0) = span;
       #else
            *chase.append() = span;
       #endif
            return first;
        }
    }
    return NULL;
}

SkOpSegment* FindSortableTop(const SkTArray<SkOpContour*, true>& contourList,
        SkOpAngle::IncludeType angleIncludeType, bool* firstContour, int* indexPtr,
        int* endIndexPtr, SkPoint* topLeft, bool* unsortable, bool* done, bool* onlyVertical,
        bool firstPass) {
    SkOpSegment* current = findTopSegment(contourList, indexPtr, endIndexPtr, topLeft, unsortable,
            done, firstPass);
    if (!current) {
        return NULL;
    }
    const int startIndex = *indexPtr;
    const int endIndex = *endIndexPtr;
    if (*firstContour) {
        current->initWinding(startIndex, endIndex, angleIncludeType);
        *firstContour = false;
        return current;
    }
    int minIndex = SkMin32(startIndex, endIndex);
    int sumWinding = current->windSum(minIndex);
    if (sumWinding == SK_MinS32) {
        int index = endIndex;
        int oIndex = startIndex;
        do { 
            const SkOpSpan& span = current->span(index);
            if ((oIndex < index ? span.fFromAngle : span.fToAngle) == NULL) {
                current->addSimpleAngle(index);
            }
            sumWinding = current->computeSum(oIndex, index, angleIncludeType);
            SkTSwap(index, oIndex);
        } while (sumWinding == SK_MinS32 && index == startIndex);
    }
    if (sumWinding != SK_MinS32 && sumWinding != SK_NaN32) {
        return current;
    }
    int contourWinding;
    int oppContourWinding = 0;
    // the simple upward projection of the unresolved points hit unsortable angles
    // shoot rays at right angles to the segment to find its winding, ignoring angle cases
    bool tryAgain;
    double tHit;
    SkScalar hitDx = 0;
    SkScalar hitOppDx = 0;
    // keep track of subsequent returns to detect infinite loops
    SkTDArray<SortableTop> sortableTops;
    do {
        // if current is vertical, find another candidate which is not
        // if only remaining candidates are vertical, then they can be marked done
        SkASSERT(*indexPtr != *endIndexPtr && *indexPtr >= 0 && *endIndexPtr >= 0);
        skipVertical(contourList, &current, indexPtr, endIndexPtr);
        SkASSERT(current);  // FIXME: if null, all remaining are vertical
        SkASSERT(*indexPtr != *endIndexPtr && *indexPtr >= 0 && *endIndexPtr >= 0);
        tryAgain = false;
        contourWinding = rightAngleWinding(contourList, &current, indexPtr, endIndexPtr, &tHit,
                &hitDx, &tryAgain, onlyVertical, false);
        if (tryAgain) {
            bool giveUp = false;
            int count = sortableTops.count();
            for (int index = 0; index < count; ++index) {
                const SortableTop& prev = sortableTops[index];
                if (giveUp) {
                    prev.fSegment->markDoneFinal(prev.fIndex);
                } else if (prev.fSegment == current
                        && (prev.fIndex == *indexPtr || prev.fEndIndex == *endIndexPtr)) {
                    // remaining edges are non-vertical and cannot have their winding computed
                    // mark them as done and return, and hope that assembly can fill the holes
                    giveUp = true;
                    index = -1;
                }
            }
            if (giveUp) {
                *done = true;
                return NULL;
            }
        }
        SortableTop* sortableTop = sortableTops.append();
        sortableTop->fSegment = current;
        sortableTop->fIndex = *indexPtr;
        sortableTop->fEndIndex = *endIndexPtr;
#if DEBUG_SORT
        SkDebugf("%s current=%d index=%d endIndex=%d tHit=%1.9g hitDx=%1.9g try=%d vert=%d\n",
                __FUNCTION__, current->debugID(), *indexPtr, *endIndexPtr, tHit, hitDx, tryAgain,
                *onlyVertical);
#endif
        if (*onlyVertical) {
            return current;
        }
        if (tryAgain) {
            continue;
        }
        if (angleIncludeType < SkOpAngle::kBinarySingle) {
            break;
        }
        oppContourWinding = rightAngleWinding(contourList, &current, indexPtr, endIndexPtr, &tHit,
                &hitOppDx, &tryAgain, NULL, true);
    } while (tryAgain);
    bool success = current->initWinding(*indexPtr, *endIndexPtr, tHit, contourWinding, hitDx,
            oppContourWinding, hitOppDx);
    if (current->done()) {
        return NULL;
    } else if (!success) {  // check if the span has a valid winding
        int min = SkTMin(*indexPtr, *endIndexPtr);
//.........这里部分代码省略.........

SkOpSegment* FindChase(SkTDArray<SkOpSpanBase*>* chase, SkOpSpanBase** startPtr,
        SkOpSpanBase** endPtr) {
    while (chase->count()) {
        SkOpSpanBase* span;
        chase->pop(&span);
        SkOpSegment* segment = span->segment();
        *startPtr = span->ptT()->next()->span();
        bool done = true;
        *endPtr = nullptr;
        if (SkOpAngle* last = segment->activeAngle(*startPtr, startPtr, endPtr, &done)) {
            *startPtr = last->start();
            *endPtr = last->end();
    #if TRY_ROTATE
            *chase->insert(0) = span;
    #else
            *chase->append() = span;
    #endif
            return last->segment();
        }
        if (done) {
            continue;
        }
        // find first angle, initialize winding to computed wind sum
        int winding;
        bool sortable;
        const SkOpAngle* angle = AngleWinding(*startPtr, *endPtr, &winding, &sortable);
        if (winding == SK_MinS32) {
            continue;
        }
        int sumWinding SK_INIT_TO_AVOID_WARNING;
        if (sortable) {
            segment = angle->segment();
            sumWinding = segment->updateWindingReverse(angle);
        }
        SkOpSegment* first = nullptr;
        const SkOpAngle* firstAngle = angle;
        while ((angle = angle->next()) != firstAngle) {
            segment = angle->segment();
            SkOpSpanBase* start = angle->start();
            SkOpSpanBase* end = angle->end();
            int maxWinding;
            if (sortable) {
                segment->setUpWinding(start, end, &maxWinding, &sumWinding);
            }
            if (!segment->done(angle)) {
                if (!first && (sortable || start->starter(end)->windSum() != SK_MinS32)) {
                    first = segment;
                    *startPtr = start;
                    *endPtr = end;
                }
                // OPTIMIZATION: should this also add to the chase?
                if (sortable) {
                    (void) segment->markAngle(maxWinding, sumWinding, angle);
                }
            }
        }
        if (first) {
       #if TRY_ROTATE
            *chase->insert(0) = span;
       #else
            *chase->append() = span;
       #endif
            return first;
        }
    }
    return nullptr;
}