bool HandleCoincidence(SkOpContourHead* contourList, SkOpCoincidence* coincidence,
SkChunkAlloc* allocator) {
SkOpGlobalState* globalState = contourList->globalState();
// combine t values when multiple intersections occur on some segments but not others
moveMultiples(contourList);
findCollapsed(contourList);
// move t values and points together to eliminate small/tiny gaps
moveNearby(contourList);
align(contourList); // give all span members common values
coincidence->fixAligned(); // aligning may have marked a coincidence pt-t deleted
#if DEBUG_VALIDATE
globalState->setPhase(SkOpGlobalState::kIntersecting);
#endif
// look for intersections on line segments formed by moving end points
addAlignIntersections(contourList, allocator);
coincidence->addMissing(allocator);
#if DEBUG_VALIDATE
globalState->setPhase(SkOpGlobalState::kWalking);
#endif
// check to see if, loosely, coincident ranges may be expanded
if (coincidence->expand()) {
coincidence->addExpanded(allocator PATH_OPS_DEBUG_VALIDATE_PARAMS(globalState));
}
// the expanded ranges may not align -- add the missing spans
coincidence->mark(); // mark spans of coincident segments as coincident
// look for coincidence missed earlier
if (missingCoincidence(contourList, coincidence, allocator)) {
(void) coincidence->expand();
coincidence->addExpanded(allocator PATH_OPS_DEBUG_VALIDATE_PARAMS(globalState));
coincidence->mark();
}
SkOpCoincidence overlaps;
do {
SkOpCoincidence* pairs = overlaps.isEmpty() ? coincidence : &overlaps;
if (!pairs->apply()) { // adjust the winding value to account for coincident edges
return false;
}
// For each coincident pair that overlaps another, when the receivers (the 1st of the pair)
// are different, construct a new pair to resolve their mutual span
pairs->findOverlaps(&overlaps, allocator);
} while (!overlaps.isEmpty());
calcAngles(contourList, allocator);
sortAngles(contourList);
if (globalState->angleCoincidence()) {
(void) missingCoincidence(contourList, coincidence, allocator);
if (!coincidence->apply()) {
return false;
}
}
#if DEBUG_ACTIVE_SPANS
coincidence->debugShowCoincidence();
DebugShowActiveSpans(contourList);
#endif
return true;
}
// please keep in sync with debugCheckForCollapsedCoincidence()
void SkOpSpanBase::checkForCollapsedCoincidence() {
SkOpCoincidence* coins = this->globalState()->coincidence();
if (coins->isEmpty()) {
return;
}
// the insert above may have put both ends of a coincident run in the same span
// for each coincident ptT in loop; see if its opposite in is also in the loop
// this implementation is the motivation for marking that a ptT is referenced by a coincident span
SkOpPtT* head = this->ptT();
SkOpPtT* test = head;
do {
if (!test->coincident()) {
continue;
}
coins->markCollapsed(test);
} while ((test = test->next()) != head);
coins->releaseDeleted();
}