fix pathops skp-derived bugs; add more failing tests

TBR=

Author: caryclark@google.com

Review URL: https://codereview.chromium.org/463883002

4 files changed, 36 insertions, 2 deletions

diff --git a/src/pathops/SkOpAngle.h b/src/pathops/SkOpAngle.h
index 63d378d73c..098c470128 100644
--- a/src/pathops/SkOpAngle.h
+++ b/src/pathops/SkOpAngle.h
@@ -160,10 +160,10 @@ public:
     void reset();
 private:
     void dump() const;  // utility to be called by user from debugger
+    SkChunkAlloc* fAngles;
 #if DEBUG_ANGLE
     int fCount;
 #endif
-    SkChunkAlloc* fAngles;
 };
 
 #endif
diff --git a/src/pathops/SkOpContour.cpp b/src/pathops/SkOpContour.cpp
index 5ef702d4c1..e4dd62a653 100644
--- a/src/pathops/SkOpContour.cpp
+++ b/src/pathops/SkOpContour.cpp
@@ -452,8 +452,14 @@ void SkOpContour::checkCoincidentPair(const SkCoincidence& oneCoin, int oneIdx,
     }
     if (cancelers) {
         if (missingT1 >= 0) {
+            if (addTo1->reversePoints(missingPt1, missingPt2)) {
+                SkTSwap(missingPt1, missingPt2);
+            }
             addTo1->addTCancel(missingPt1, missingPt2, addOther1);
         } else {
+            if (addTo2->reversePoints(missingPt1, missingPt2)) {
+                SkTSwap(missingPt1, missingPt2);
+            }
             addTo2->addTCancel(missingPt1, missingPt2, addOther2);
         }
     } else if (missingT1 >= 0) {
diff --git a/src/pathops/SkOpSegment.cpp b/src/pathops/SkOpSegment.cpp
index f6d989b18a..747cd9d497 100644
--- a/src/pathops/SkOpSegment.cpp
+++ b/src/pathops/SkOpSegment.cpp
@@ -2294,9 +2294,10 @@ void SkOpSegment::checkSmall() {
         }
         const SkOpSpan& firstSpan = this->firstSpan(*thisSpan);
         const SkOpSpan& lastSpan = this->lastSpan(*thisSpan);
+        const SkOpSpan* nextSpan = &firstSpan + 1;
         ptrdiff_t smallCount = &lastSpan - &firstSpan + 1;
         SkASSERT(1 <= smallCount && smallCount < count());
-        if (smallCount <= 1) {
+        if (smallCount <= 1 && !nextSpan->fSmall) {
             SkASSERT(1 == smallCount);
             checkSmallCoincidence(firstSpan, NULL);
             continue;
@@ -3067,6 +3068,13 @@ int SkOpSegment::findOtherT(double t, const SkOpSegment* match) const {
 
 int SkOpSegment::findT(double t, const SkPoint& pt, const SkOpSegment* match) const {
     int count = this->count();
+    // prefer exact matches over approximate matches
+    for (int index = 0; index < count; ++index) {
+        const SkOpSpan& span = fTs[index];
+        if (span.fT == t && span.fOther == match) {
+            return index;
+        }
+    }
     for (int index = 0; index < count; ++index) {
         const SkOpSpan& span = fTs[index];
         if (approximately_equal_orderable(span.fT, t) && span.fOther == match) {
@@ -3986,6 +3994,24 @@ void SkOpSegment::pinT(const SkPoint& pt, double* t) {
     }
 }
 
+bool SkOpSegment::reversePoints(const SkPoint& p1, const SkPoint& p2) const {
+    SkASSERT(p1 != p2);
+    int spanCount = count();
+    int p1IndexMin = -1;
+    int p2IndexMax = spanCount;
+    for (int index = 0; index < spanCount; ++index) {
+        const SkOpSpan& span = fTs[index];
+        if (span.fPt == p1) {
+            if (p1IndexMin < 0) {
+                p1IndexMin = index;
+            }
+        } else if (span.fPt == p2) {
+            p2IndexMax = index;
+        }
+    }
+    return p1IndexMin > p2IndexMax;
+}
+
 void SkOpSegment::setCoincidentRange(const SkPoint& startPt, const SkPoint& endPt, 
         SkOpSegment* other) {
     int count = this->count();
diff --git a/src/pathops/SkOpSegment.h b/src/pathops/SkOpSegment.h
index d191e88af2..df87d058b6 100644
--- a/src/pathops/SkOpSegment.h
+++ b/src/pathops/SkOpSegment.h
@@ -177,6 +177,8 @@ public:
         fTs.reset();
     }
 
+    bool reversePoints(const SkPoint& p1, const SkPoint& p2) const;
+
     void setOppXor(bool isOppXor) {
         fOppXor = isOppXor;
     }