Bug 1546894 - Fix PathBuilderCapture::CurrentPoint when closing a path. r=lsalzman

Differential Revision: https://phabricator.services.mozilla.com/D32459

--HG--
extra : moz-landing-system : lando

gfx/2d/PathCapture.cpp

@@ -17,6 +17,7 @@ void PathBuilderCapture::MoveTo(const Point& aPoint) {
   op.mP1 = aPoint;
   mPathOps.push_back(op);
   mCurrentPoint = aPoint;
+  mFirstPoint = aPoint;
 }
 
 void PathBuilderCapture::LineTo(const Point& aPoint) {
@@ -48,28 +49,33 @@ void PathBuilderCapture::QuadraticBezierTo(const Point& aCP1,
   mCurrentPoint = aCP2;
 }
 
-void PathBuilderCapture::Arc(const Point& aOrigin, float aRadius,
+void PathBuilderCapture::Arc(const Point& aCenter, float aRadius,
                              float aStartAngle, float aEndAngle,
                              bool aAntiClockwise) {
   PathOp op;
   op.mType = PathOp::OP_ARC;
-  op.mP1 = aOrigin;
+  op.mP1 = aCenter;
   op.mRadius = aRadius;
   op.mStartAngle = aStartAngle;
   op.mEndAngle = aEndAngle;
   op.mAntiClockwise = aAntiClockwise;
   mPathOps.push_back(op);
+  mCurrentPoint = Point(aCenter.x + aRadius * cosf(aEndAngle),
+                        aCenter.y + aRadius * sinf(aEndAngle));
 }
 
 void PathBuilderCapture::Close() {
   PathOp op;
   op.mType = PathOp::OP_CLOSE;
   mPathOps.push_back(op);
+  mCurrentPoint = mFirstPoint;
 }
 
 Point PathBuilderCapture::CurrentPoint() const { return mCurrentPoint; }
 
 already_AddRefed<Path> PathBuilderCapture::Finish() {
+  mCurrentPoint = Point(0.0, 0.0);
+  mFirstPoint = Point(0.0, 0.0);
   return MakeAndAddRef<PathCapture>(std::move(mPathOps), mFillRule, mDT,
                                     mCurrentPoint);
 }

gfx/2d/PathCapture.h

@@ -62,6 +62,7 @@ class PathBuilderCapture : public PathBuilder {
   FillRule mFillRule;
   std::vector<PathOp> mPathOps;
   Point mCurrentPoint;
+  Point mFirstPoint;
   RefPtr<DrawTarget> mDT;
 };