rework xor to be more like winding

Pathops is very well exercised with winding paths,
but less so with xor (even odd) paths.

Rewrite the xor main loop to look like the winding
one to take advantage of the latter's bug fixes.

TBR=reed@google.com
BUG=skia:6041

Change-Id: Ied8d522254a327b1817b54f0abbf4414f5fab7da
Reviewed-on: https://skia-review.googlesource.com/6228
Reviewed-by: Cary Clark <caryclark@google.com>
Commit-Queue: Cary Clark <caryclark@google.com>

1 files changed, 10 insertions, 6 deletions

diff --git a/src/pathops/SkOpContour.cpp b/src/pathops/SkOpContour.cpp
index 98467c558c..62380ab4fa 100644
--- a/src/pathops/SkOpContour.cpp
+++ b/src/pathops/SkOpContour.cpp
@@ -31,15 +31,19 @@ void SkOpContour::toReversePath(SkPathWriter* path) const {
     path->assemble();
 }
 
-SkOpSegment* SkOpContour::undoneSegment(SkOpSpanBase** startPtr, SkOpSpanBase** endPtr) {
-    SkOpSegment* segment = &fHead;
+SkOpSpan* SkOpContour::undoneSpan() {
+    SkOpSegment* testSegment = &fHead;
+    bool allDone = true;
     do {
-        if (segment->done()) {
+        if (testSegment->done()) {
             continue;
         }
-        segment->undoneSpan(startPtr, endPtr);
-        return segment;
-    } while ((segment = segment->next()));
+        allDone = false;
+        return testSegment->undoneSpan();
+    } while ((testSegment = testSegment->next()));
+    if (allDone) {
+      fDone = true;
+    }
     return nullptr;
 }