1 files changed, 58 insertions, 0 deletions
diff --git a/dom/animation/ScrollTimelineAnimationTracker.h b/dom/animation/ScrollTimelineAnimationTracker.h
new file mode 100644
index 0000000000..fec2814cec
--- /dev/null
+++ b/dom/animation/ScrollTimelineAnimationTracker.h
@@ -0,0 +1,58 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef mozilla_ScrollTimelineAnimationTracker_h
+#define mozilla_ScrollTimelineAnimationTracker_h
+
+#include "mozilla/dom/Animation.h"
+#include "nsCycleCollectionParticipant.h"
+#include "nsTHashSet.h"
+
+namespace mozilla {
+
+namespace dom {
+class Document;
+}
+
+/**
+ * Handle the pending animations which use scroll timeline while playing or
+ * pausing.
+ */
+class ScrollTimelineAnimationTracker final {
+ public:
+  explicit ScrollTimelineAnimationTracker(dom::Document* aDocument)
+      : mDocument(aDocument) {}
+
+  NS_INLINE_DECL_CYCLE_COLLECTING_NATIVE_REFCOUNTING(
+      ScrollTimelineAnimationTracker)
+  NS_DECL_CYCLE_COLLECTION_NATIVE_CLASS(ScrollTimelineAnimationTracker)
+
+  void AddPending(dom::Animation& aAnimation) {
+    mPendingSet.Insert(&aAnimation);
+  }
+
+  void RemovePending(dom::Animation& aAnimation) {
+    mPendingSet.Remove(&aAnimation);
+  }
+
+  bool HasPendingAnimations() const { return mPendingSet.Count() > 0; }
+
+  bool IsWaiting(const dom::Animation& aAnimation) const {
+    return mPendingSet.Contains(const_cast<dom::Animation*>(&aAnimation));
+  }
+
+  void TriggerPendingAnimations();
+
+ private:
+  ~ScrollTimelineAnimationTracker() = default;
+
+  nsTHashSet<nsRefPtrHashKey<dom::Animation>> mPendingSet;
+  RefPtr<dom::Document> mDocument;
+};
+
+}  // namespace mozilla
+
+#endif  // mozilla_ScrollTimelineAnimationTracker_h