1 files changed, 142 insertions, 0 deletions
diff --git a/dom/base/ResizeObserverController.h b/dom/base/ResizeObserverController.h
new file mode 100644
index 0000000000..bb6eaa48be
--- /dev/null
+++ b/dom/base/ResizeObserverController.h
@@ -0,0 +1,142 @@
+/* -*- 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_dom_ResizeObserverController_h
+#define mozilla_dom_ResizeObserverController_h
+
+#include "mozilla/dom/Document.h"
+#include "mozilla/dom/ResizeObserver.h"
+#include "mozilla/TimeStamp.h"
+#include "nsRefreshObservers.h"
+#include "nsTObserverArray.h"
+
+class nsRefreshDriver;
+
+namespace mozilla {
+
+class PresShell;
+
+namespace dom {
+
+class ResizeObserverController;
+
+/**
+ * ResizeObserverNotificationHelper will trigger ResizeObserver notifications
+ * by registering with the Refresh Driver.
+ */
+class ResizeObserverNotificationHelper final : public nsARefreshObserver {
+ public:
+  NS_INLINE_DECL_REFCOUNTING(ResizeObserverNotificationHelper, override)
+
+  explicit ResizeObserverNotificationHelper(ResizeObserverController* aOwner)
+      : mOwner(aOwner), mRegistered(false) {
+    MOZ_ASSERT(mOwner, "Need a non-null owner");
+  }
+
+  MOZ_CAN_RUN_SCRIPT void WillRefresh(TimeStamp aTime) override;
+
+  nsRefreshDriver* GetRefreshDriver() const;
+
+  void Register();
+
+  void Unregister();
+
+  bool IsRegistered() const { return mRegistered; }
+
+  void DetachFromOwner() { mOwner = nullptr; }
+
+ private:
+  virtual ~ResizeObserverNotificationHelper();
+
+  ResizeObserverController* mOwner;
+  bool mRegistered;
+};
+
+/**
+ * ResizeObserverController contains the list of ResizeObservers and controls
+ * the flow of notification.
+ */
+class ResizeObserverController final {
+ public:
+  explicit ResizeObserverController(Document* aDocument)
+      : mDocument(aDocument),
+        mResizeObserverNotificationHelper(
+            new ResizeObserverNotificationHelper(this)) {
+    MOZ_ASSERT(mDocument, "Need a non-null document");
+  }
+
+  // Methods for supporting cycle-collection
+  void Traverse(nsCycleCollectionTraversalCallback& aCb);
+  void Unlink();
+
+  void AddSizeOfIncludingThis(nsWindowSizes&) const;
+
+  void ShellDetachedFromDocument();
+  void AddResizeObserver(ResizeObserver& aObserver) {
+    MOZ_ASSERT(!mResizeObservers.Contains(&aObserver));
+    mResizeObservers.AppendElement(&aObserver);
+  }
+
+  void RemoveResizeObserver(ResizeObserver& aObserver) {
+    MOZ_ASSERT(mResizeObservers.Contains(&aObserver));
+    mResizeObservers.RemoveElement(&aObserver);
+  }
+
+  /**
+   * Schedule the notification via ResizeObserverNotificationHelper refresh
+   * observer.
+   */
+  void ScheduleNotification();
+
+  /**
+   * Notify all ResizeObservers by gathering and broadcasting all active
+   * observations.
+   */
+  MOZ_CAN_RUN_SCRIPT void Notify();
+
+  PresShell* GetPresShell() const { return mDocument->GetPresShell(); }
+
+  ~ResizeObserverController();
+
+ private:
+  /**
+   * Calls GatherActiveObservations(aDepth) for all ResizeObservers in this
+   * controller. All observations in each ResizeObserver with element's depth
+   * more than aDepth will be gathered.
+   */
+  void GatherAllActiveObservations(uint32_t aDepth);
+
+  /**
+   * Calls BroadcastActiveObservations() for all ResizeObservers in this
+   * controller. It also returns the shallowest depth of observed target
+   * elements with active observations from all ResizeObservers or
+   * numeric_limits<uint32_t>::max() if there aren't any active observations
+   * at all.
+   */
+  MOZ_CAN_RUN_SCRIPT uint32_t BroadcastAllActiveObservations();
+
+  /**
+   * Returns whether there is any ResizeObserver that has active observations.
+   */
+  bool HasAnyActiveObservations() const;
+
+  /**
+   * Returns whether there is any ResizeObserver that has skipped observations.
+   */
+  bool HasAnySkippedObservations() const;
+
+  // Raw pointer is OK because mDocument strongly owns us & hence must outlive
+  // us.
+  Document* const mDocument;
+
+  RefPtr<ResizeObserverNotificationHelper> mResizeObserverNotificationHelper;
+  nsTArray<RefPtr<ResizeObserver>> mResizeObservers;
+};
+
+}  // namespace dom
+}  // namespace mozilla
+
+#endif  // mozilla_dom_ResizeObserverController_h