Revert of use reversePathTo in place of addPathReverse (patchset #1 id:1 of https://codereview.chromium.org/2481463002/ )

Reason for revert:
breqking some bots

Original issue's description:
> use reversePathTo in place of addPathReverse
>
> Path ops was using addPathReverse, instead of reversePathTo.
> The former adds a moveTo always, and the latter requires
> that the caller add the moveTo if needed.
>
> Simplify the reversePathTo implementation.
>
> R=reed@google.com
> GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2481463002
>
> Committed: https://skia.googlesource.com/skia/+/d8db392be9dd1887df04b10b5670991d6b098c17

TBR=reed@google.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review-Url: https://codereview.chromium.org/2478763003

3 files changed, 36 insertions, 31 deletions

diff --git a/src/core/SkPath.cpp b/src/core/SkPath.cpp
index 6dbcda2233..c1b6327193 100644
--- a/src/core/SkPath.cpp
+++ b/src/core/SkPath.cpp
@@ -1567,38 +1567,49 @@ static int pts_in_verb(unsigned verb) {
 
 // ignore the last point of the 1st contour
 void SkPath::reversePathTo(const SkPath& path) {
-    const uint8_t* verbs = path.fPathRef->verbsMemBegin(); // points at the last verb
-    if (!verbs) {  // empty path returns nullptr
+    int i, vcount = path.fPathRef->countVerbs();
+    // exit early if the path is empty, or just has a moveTo.
+    if (vcount < 2) {
         return;
     }
-    const uint8_t* verbsEnd = path.fPathRef->verbs() - 1; // points just past the first verb
-    SkASSERT(verbsEnd[0] == kMove_Verb);
-    const SkPoint*  pts = path.fPathRef->pointsEnd() - 1;
-    const SkScalar* conicWeights = path.fPathRef->conicWeightsEnd();
 
-    while (verbs < verbsEnd) {
-        uint8_t v = *verbs++;
-        pts -= pts_in_verb(v);
-        switch (v) {
+    SkPathRef::Editor(&fPathRef, vcount, path.countPoints());
+
+    const uint8_t*  verbs = path.fPathRef->verbs();
+    const SkPoint*  pts = path.fPathRef->points();
+    const SkScalar* conicWeights = path.fPathRef->conicWeights();
+
+    SkASSERT(verbs[~0] == kMove_Verb);
+    for (i = 1; i < vcount; ++i) {
+        unsigned v = verbs[~i];
+        int n = pts_in_verb(v);
+        if (n == 0) {
+            break;
+        }
+        pts += n;
+        conicWeights += (SkPath::kConic_Verb == v);
+    }
+
+    while (--i > 0) {
+        switch (verbs[~i]) {
             case kLine_Verb:
-                this->lineTo(pts[0]);
+                this->lineTo(pts[-1].fX, pts[-1].fY);
                 break;
             case kQuad_Verb:
-                this->quadTo(pts[1], pts[0]);
+                this->quadTo(pts[-1].fX, pts[-1].fY, pts[-2].fX, pts[-2].fY);
                 break;
             case kConic_Verb:
-                this->conicTo(pts[1], pts[0], *--conicWeights);
+                this->conicTo(pts[-1], pts[-2], *--conicWeights);
                 break;
             case kCubic_Verb:
-                this->cubicTo(pts[2], pts[1], pts[0]);
-                break;
-            case kClose_Verb:
-                SkASSERT(verbs - path.fPathRef->verbsMemBegin() == 1);
+                this->cubicTo(pts[-1].fX, pts[-1].fY, pts[-2].fX, pts[-2].fY,
+                              pts[-3].fX, pts[-3].fY);
                 break;
             default:
                 SkDEBUGFAIL("bad verb");
                 break;
         }
+        pts -= pts_in_verb(verbs[~i]);
     }
 }
 
diff --git a/src/pathops/SkOpBuilder.cpp b/src/pathops/SkOpBuilder.cpp
index 075520d2c1..011d6a6aba 100644
--- a/src/pathops/SkOpBuilder.cpp
+++ b/src/pathops/SkOpBuilder.cpp
@@ -25,17 +25,7 @@ static bool one_contour(const SkPath& path) {
     return true;
 }
 
-void SkOpBuilder::ReversePath(SkPath* path) {
-    SkPath temp;
-    SkPoint lastPt;
-    SkAssertResult(path->getLastPt(&lastPt));
-    temp.moveTo(lastPt);
-    temp.reversePathTo(*path);
-    temp.close();
-    *path = temp;
-}
-
-bool SkOpBuilder::FixWinding(SkPath* path) {
+bool FixWinding(SkPath* path) {
     SkPath::FillType fillType = path->getFillType();
     if (fillType == SkPath::kInverseEvenOdd_FillType) {
         fillType = SkPath::kInverseWinding_FillType;
@@ -45,7 +35,9 @@ bool SkOpBuilder::FixWinding(SkPath* path) {
     SkPathPriv::FirstDirection dir;
     if (one_contour(*path) && SkPathPriv::CheapComputeFirstDirection(*path, &dir)) {
         if (dir != SkPathPriv::kCCW_FirstDirection) {
-            ReversePath(path);
+            SkPath temp;
+            temp.reverseAddPath(*path);
+            *path = temp;
         }
         path->setFillType(fillType);
         return true;
@@ -141,7 +133,9 @@ bool SkOpBuilder::resolve(SkPath* result) {
             if (firstDir == SkPathPriv::kUnknown_FirstDirection) {
                 firstDir = dir;
             } else if (firstDir != dir) {
-                ReversePath(test);
+                SkPath temp;
+                temp.reverseAddPath(*test);
+                *test = temp;
             }
             continue;
         }
diff --git a/src/pathops/SkPathWriter.cpp b/src/pathops/SkPathWriter.cpp
index 9893a502ca..c94809e8ec 100644
--- a/src/pathops/SkPathWriter.cpp
+++ b/src/pathops/SkPathWriter.cpp
@@ -306,7 +306,7 @@ void SkPathWriter::assemble() {
                         first ? SkPath::kAppend_AddPathMode : SkPath::kExtend_AddPathMode);
             } else {
                 SkASSERT(!first);
-                fPathPtr->reversePathTo(contour);
+                fPathPtr->reverseAddPath(contour);
             }
             if (first) {
                 first = false;