From a2318576d6510dc63513ce335ed0027666bd55bf Mon Sep 17 00:00:00 2001
From: Brian Osman <brianosman@google.com>
Date: Mon, 10 Jul 2017 15:09:26 -0400
Subject: Correctly stroke zero length segments in multi-contour paths

Bug: skia:
Change-Id: I959287780ef94a258a6746132f3acb9f90e6c6cc
Reviewed-on: https://skia-review.googlesource.com/21863
Reviewed-by: Cary Clark <caryclark@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
---
 src/core/SkPath.cpp   |  6 +++---
 src/core/SkStroke.cpp | 12 +++++++-----
 2 files changed, 10 insertions(+), 8 deletions(-)

(limited to 'src')

diff --git a/src/core/SkPath.cpp b/src/core/SkPath.cpp
index f4c8e8b7c4..2be3251401 100644
--- a/src/core/SkPath.cpp
+++ b/src/core/SkPath.cpp
@@ -1192,12 +1192,12 @@ bool SkPath::hasOnlyMoveTos() const {
     return true;
 }
 
-bool SkPath::isZeroLength() const {
-    int count = fPathRef->countPoints();
+bool SkPath::isZeroLengthSincePoint(int startPtIndex) const {
+    int count = fPathRef->countPoints() - startPtIndex;
     if (count < 2) {
         return true;
     }
-    const SkPoint* pts = fPathRef.get()->points();
+    const SkPoint* pts = fPathRef.get()->points() + startPtIndex;
     const SkPoint& first = *pts;
     for (int index = 1; index < count; ++index) {
         if (first != pts[index]) {
diff --git a/src/core/SkStroke.cpp b/src/core/SkStroke.cpp
index e384df1ef7..61bd730e67 100644
--- a/src/core/SkStroke.cpp
+++ b/src/core/SkStroke.cpp
@@ -136,14 +136,14 @@ public:
 
     void done(SkPath* dst, bool isLine) {
         this->finishContour(false, isLine);
-        fOuter.addPath(fExtra);
         dst->swap(fOuter);
     }
 
     SkScalar getResScale() const { return fResScale; }
 
-    bool isZeroLength() const {
-        return fInner.isZeroLength() && fOuter.isZeroLength();
+    bool isCurrentContourEmpty() const {
+        return fInner.isZeroLengthSincePoint(0) &&
+               fOuter.isZeroLengthSincePoint(fFirstOuterPtIndexInContour);
     }
 
 private:
@@ -156,6 +156,7 @@ private:
     SkVector    fFirstNormal, fPrevNormal, fFirstUnitNormal, fPrevUnitNormal;
     SkPoint     fFirstPt, fPrevPt;  // on original path
     SkPoint     fFirstOuterPt;
+    int         fFirstOuterPtIndexInContour;
     int         fSegmentCount;
     bool        fPrevIsLine;
     bool        fCanIgnoreCenter;
@@ -164,7 +165,6 @@ private:
     SkStrokerPriv::JoinProc fJoiner;
 
     SkPath  fInner, fOuter; // outer is our working answer, inner is temp
-    SkPath  fExtra;         // added as extra complete contours
 
     enum StrokeType {
         kOuter_StrokeType = 1,      // use sign-opposite values later to flip perpendicular axis
@@ -325,6 +325,7 @@ void SkPathStroker::finishContour(bool close, bool currIsLine) {
     // reallocating its internal storage.
     fInner.rewind();
     fSegmentCount = -1;
+    fFirstOuterPtIndexInContour = fOuter.countPoints();
 }
 
 ///////////////////////////////////////////////////////////////////////////////
@@ -352,6 +353,7 @@ SkPathStroker::SkPathStroker(const SkPath& src,
     fCapper = SkStrokerPriv::CapFactory(cap);
     fJoiner = SkStrokerPriv::JoinFactory(join);
     fSegmentCount = -1;
+    fFirstOuterPtIndexInContour = 0;
     fPrevIsLine = false;
 
     // Need some estimate of how large our final result (fOuter)
@@ -1431,7 +1433,7 @@ void SkStroke::strokePath(const SkPath& src, SkPath* dst) const {
                     /* If the stroke consists of a moveTo followed by one or more zero-length
                        verbs, then followed by a close, treat is as if it were followed by a
                        zero-length line. Lines without length can have square & round end caps. */
-                    if (stroker.isZeroLength()) {
+                    if (stroker.isCurrentContourEmpty()) {
                 ZERO_LENGTH:
                         lastSegment = SkPath::kLine_Verb;
                         break;
-- 
cgit v1.2.3