Bug 1447839 - Avoid creating internal path for PathRecording unless necessary. r=jrmuizel

Differential Revision: https://phabricator.services.mozilla.com/D172869

gfx/2d/PathRecording.cpp

@@ -150,52 +150,63 @@ size_t PathOps::NumberOfOps() const {
 
 void PathBuilderRecording::MoveTo(const Point& aPoint) {
   mPathOps.MoveTo(aPoint);
-  mPathBuilder->MoveTo(aPoint);
+  mBeginPoint = aPoint;
+  mCurrentPoint = aPoint;
 }
 
 void PathBuilderRecording::LineTo(const Point& aPoint) {
   mPathOps.LineTo(aPoint);
-  mPathBuilder->LineTo(aPoint);
+  mCurrentPoint = aPoint;
 }
 
 void PathBuilderRecording::BezierTo(const Point& aCP1, const Point& aCP2,
                                     const Point& aCP3) {
   mPathOps.BezierTo(aCP1, aCP2, aCP3);
-  mPathBuilder->BezierTo(aCP1, aCP2, aCP3);
+  mCurrentPoint = aCP3;
 }
 
 void PathBuilderRecording::QuadraticBezierTo(const Point& aCP1,
                                              const Point& aCP2) {
   mPathOps.QuadraticBezierTo(aCP1, aCP2);
-  mPathBuilder->QuadraticBezierTo(aCP1, aCP2);
+  mCurrentPoint = aCP2;
 }
 
 void PathBuilderRecording::Close() {
   mPathOps.Close();
-  mPathBuilder->Close();
+  mCurrentPoint = mBeginPoint;
 }
 
 void PathBuilderRecording::Arc(const Point& aOrigin, float aRadius,
                                float aStartAngle, float aEndAngle,
                                bool aAntiClockwise) {
   mPathOps.Arc(aOrigin, aRadius, aStartAngle, aEndAngle, aAntiClockwise);
-  mPathBuilder->Arc(aOrigin, aRadius, aStartAngle, aEndAngle, aAntiClockwise);
+
+  // This just lets ArcToBezier override the current point without modifying
+  // path ops or having to instantiate a path.
+  struct CurrentPointTracker {
+    PathBuilderRecording* mPathBuilder;
+
+    void LineTo(const Point& aPoint) { mPathBuilder->SetCurrentPoint(aPoint); }
+
+    void BezierTo(const Point& aCP1, const Point& aCP2, const Point& aCP3) {
+      mPathBuilder->SetCurrentPoint(aCP3);
+    }
+  } tracker = {this};
+
+  ArcToBezier(&tracker, aOrigin, Size(aRadius, aRadius), aStartAngle, aEndAngle,
+              aAntiClockwise);
 }
 
 already_AddRefed<Path> PathBuilderRecording::Finish() {
-  // We rely on mPathBuilder to track begin and current point, but that stops
-  // when we call Finish, so we need to store them first.
-  Point beginPoint = BeginPoint();
-  Point currentPoint = CurrentPoint();
-  RefPtr<Path> path = mPathBuilder->Finish();
-  return MakeAndAddRef<PathRecording>(path, std::move(mPathOps), mFillRule,
-                                      currentPoint, beginPoint);
+  return MakeAndAddRef<PathRecording>(std::move(mPathBuilder),
+                                      std::move(mPathOps), mFillRule,
+                                      mBeginPoint, mCurrentPoint);
 }
 
-PathRecording::PathRecording(Path* aPath, PathOps&& aOps, FillRule aFillRule,
-                             const Point& aCurrentPoint,
+PathRecording::PathRecording(RefPtr<PathBuilder>&& aPathBuilder, PathOps&& aOps,
+                             FillRule aFillRule, const Point& aCurrentPoint,
                              const Point& aBeginPoint)
-    : mPath(aPath),
+    : mPathBuilder(std::move(aPathBuilder)),
       mPathOps(std::move(aOps)),
       mFillRule(aFillRule),
       mCurrentPoint(aCurrentPoint),
@@ -208,8 +219,23 @@ PathRecording::~PathRecording() {
   }
 }
 
+void PathRecording::EnsurePath() const {
+  if (mPath) {
+    return;
+  }
+  MOZ_ASSERT(!!mPathBuilder);
+  if (!mPathOps.StreamToSink(*mPathBuilder)) {
+    MOZ_ASSERT(false, "Failed to stream PathOps to PathBuilder");
+  } else {
+    mPath = mPathBuilder->Finish();
+    MOZ_ASSERT(!!mPath, "Failed finishing Path from PathBuilder");
+  }
+  mPathBuilder = nullptr;
+}
+
 already_AddRefed<PathBuilder> PathRecording::CopyToBuilder(
     FillRule aFillRule) const {
+  EnsurePath();
   RefPtr<PathBuilder> pathBuilder = mPath->CopyToBuilder(aFillRule);
   RefPtr<PathBuilderRecording> recording =
       new PathBuilderRecording(pathBuilder, mPathOps, aFillRule);
@@ -220,6 +246,7 @@ already_AddRefed<PathBuilder> PathRecording::CopyToBuilder(
 
 already_AddRefed<PathBuilder> PathRecording::TransformedCopyToBuilder(
     const Matrix& aTransform, FillRule aFillRule) const {
+  EnsurePath();
   RefPtr<PathBuilder> pathBuilder =
       mPath->TransformedCopyToBuilder(aTransform, aFillRule);
   RefPtr<PathBuilderRecording> recording = new PathBuilderRecording(

gfx/2d/PathRecording.h

@@ -153,21 +153,6 @@ class PathBuilderRecording final : public PathBuilder {
   void Arc(const Point& aOrigin, float aRadius, float aStartAngle,
            float aEndAngle, bool aAntiClockwise) final;
 
-  /* Point the current subpath is at - or where the next subpath will start
-   * if there is no active subpath.
-   */
-  Point CurrentPoint() const final { return mPathBuilder->CurrentPoint(); }
-
-  Point BeginPoint() const final { return mPathBuilder->BeginPoint(); }
-
-  void SetCurrentPoint(const Point& aPoint) final {
-    mPathBuilder->SetCurrentPoint(aPoint);
-  }
-
-  void SetBeginPoint(const Point& aPoint) final {
-    mPathBuilder->SetBeginPoint(aPoint);
-  }
-
   already_AddRefed<Path> Finish() final;
 
   BackendType GetBackendType() const final { return BackendType::RECORDING; }
@@ -182,7 +167,7 @@ class PathRecording final : public Path {
  public:
   MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(PathRecording, override)
 
-  PathRecording(Path* aPath, PathOps&& aOps, FillRule aFillRule,
+  PathRecording(RefPtr<PathBuilder>&& aPath, PathOps&& aOps, FillRule aFillRule,
                 const Point& aCurrentPoint, const Point& aBeginPoint);
 
   ~PathRecording();
@@ -193,26 +178,35 @@ class PathRecording final : public Path {
       const Matrix& aTransform, FillRule aFillRule) const final;
   bool ContainsPoint(const Point& aPoint,
                      const Matrix& aTransform) const final {
+    EnsurePath();
     return mPath->ContainsPoint(aPoint, aTransform);
   }
   bool StrokeContainsPoint(const StrokeOptions& aStrokeOptions,
                            const Point& aPoint,
                            const Matrix& aTransform) const final {
+    EnsurePath();
     return mPath->StrokeContainsPoint(aStrokeOptions, aPoint, aTransform);
   }
 
   Rect GetBounds(const Matrix& aTransform = Matrix()) const final {
+    EnsurePath();
     return mPath->GetBounds(aTransform);
   }
 
   Rect GetStrokedBounds(const StrokeOptions& aStrokeOptions,
                         const Matrix& aTransform = Matrix()) const final {
+    EnsurePath();
     return mPath->GetStrokedBounds(aStrokeOptions, aTransform);
   }
 
-  Maybe<Rect> AsRect() const final { return mPath->AsRect(); }
+  Maybe<Rect> AsRect() const final {
+    EnsurePath();
+    return mPath->AsRect();
+  }
 
-  void StreamToSink(PathSink* aSink) const final { mPath->StreamToSink(aSink); }
+  void StreamToSink(PathSink* aSink) const final {
+    mPathOps.StreamToSink(*aSink);
+  }
 
   FillRule GetFillRule() const final { return mFillRule; }
 
@@ -221,7 +215,10 @@ class PathRecording final : public Path {
   friend class DrawTargetRecording;
   friend class RecordedPathCreation;
 
-  RefPtr<Path> mPath;
+  void EnsurePath() const;
+
+  mutable RefPtr<PathBuilder> mPathBuilder;
+  mutable RefPtr<Path> mPath;
   PathOps mPathOps;
   FillRule mFillRule;
   Point mCurrentPoint;