Bug 881634 - Only use a single snapshot with DrawTargetSkia. r=Bas

gfx/2d/DrawTargetSkia.cpp

@@ -76,6 +76,7 @@ public:
 };
 
 DrawTargetSkia::DrawTargetSkia()
+  : mSnapshot(nullptr)
 {
 #ifdef ANDROID
   mSoftClipping = false;
@@ -86,19 +87,20 @@ DrawTargetSkia::DrawTargetSkia()
 
 DrawTargetSkia::~DrawTargetSkia()
 {
-  MOZ_ASSERT(mSnapshots.size() == 0);
 }
 
 TemporaryRef<SourceSurface>
 DrawTargetSkia::Snapshot()
 {
-  RefPtr<SourceSurfaceSkia> source = new SourceSurfaceSkia();
+  RefPtr<SourceSurfaceSkia> snapshot = mSnapshot;
+  if (!snapshot) {
+    snapshot = new SourceSurfaceSkia();
+    mSnapshot = snapshot;
+    if (!snapshot->InitFromCanvas(mCanvas.get(), mFormat, this))
+      return nullptr;
+  }
 
-  if (!source->InitFromCanvas(mCanvas.get(), mFormat, this))
-    return nullptr;
-
-  AppendSnapshot(source);
-  return source;
+  return snapshot;
 }
 
 void SetPaintPattern(SkPaint& aPaint, const Pattern& aPattern, Float aAlpha = 1.0)
@@ -772,33 +774,20 @@ DrawTargetSkia::CreateGradientStops(GradientStop *aStops, uint32_t aNumStops, Ex
   return new GradientStopsSkia(stops, aNumStops, aExtendMode);
 }
 
-void
-DrawTargetSkia::AppendSnapshot(SourceSurfaceSkia* aSnapshot)
-{
-  mSnapshots.push_back(aSnapshot);
-}
-
-void
-DrawTargetSkia::RemoveSnapshot(SourceSurfaceSkia* aSnapshot)
-{
-  std::vector<SourceSurfaceSkia*>::iterator iter = std::find(mSnapshots.begin(), mSnapshots.end(), aSnapshot);
-  if (iter != mSnapshots.end()) {
-    mSnapshots.erase(iter);
-  }
-}
-
 void
 DrawTargetSkia::MarkChanged()
 {
-  if (mSnapshots.size()) {
-    for (std::vector<SourceSurfaceSkia*>::iterator iter = mSnapshots.begin();
-         iter != mSnapshots.end(); iter++) {
-      (*iter)->DrawTargetWillChange();
-    }
-    // All snapshots will now have copied data.
-    mSnapshots.clear();
+  if (mSnapshot) {
+    mSnapshot->DrawTargetWillChange();
+    mSnapshot = nullptr;
   }
 }
 
+void
+DrawTargetSkia::SnapshotDestroyed()
+{
+  mSnapshot = nullptr;
+}
+
 }
 }

gfx/2d/DrawTargetSkia.h

@@ -114,8 +114,7 @@ public:
 
 private:
   friend class SourceSurfaceSkia;
-  void AppendSnapshot(SourceSurfaceSkia* aSnapshot);
-  void RemoveSnapshot(SourceSurfaceSkia* aSnapshot);
+  void SnapshotDestroyed();
 
   void MarkChanged();
 
@@ -133,7 +132,7 @@ private:
 
   IntSize mSize;
   SkRefPtr<SkCanvas> mCanvas;
-  std::vector<SourceSurfaceSkia*> mSnapshots;
+  SourceSurfaceSkia* mSnapshot;
   bool mSoftClipping;
 };
 

gfx/2d/SourceSurfaceSkia.cpp

@@ -22,7 +22,10 @@ SourceSurfaceSkia::SourceSurfaceSkia()
 SourceSurfaceSkia::~SourceSurfaceSkia()
 {
   MaybeUnlock();
-  MarkIndependent();
+  if (mDrawTarget) {
+    mDrawTarget->SnapshotDestroyed();
+    mDrawTarget = nullptr;
+  }
 }
 
 IntSize
@@ -108,15 +111,6 @@ SourceSurfaceSkia::DrawTargetWillChange()
   }
 }
 
-void
-SourceSurfaceSkia::MarkIndependent()
-{
-  if (mDrawTarget) {
-    mDrawTarget->RemoveSnapshot(this);
-    mDrawTarget = nullptr;
-  }
-}
-
 void
 SourceSurfaceSkia::MaybeUnlock()
 {

gfx/2d/SourceSurfaceSkia.h

@@ -45,8 +45,6 @@ private:
   friend class DrawTargetSkia;
 
   void DrawTargetWillChange();
-  void DrawTargetDestroyed();
-  void MarkIndependent();
   void MaybeUnlock();
 
   SkBitmap mBitmap;