1 files changed, 38 insertions, 9 deletions

diff --git a/gfx/layers/apz/util/ActiveElementManager.h b/gfx/layers/apz/util/ActiveElementManager.h
index f8a6f07261..1f2e1e4aad 100644
--- a/gfx/layers/apz/util/ActiveElementManager.h
+++ b/gfx/layers/apz/util/ActiveElementManager.h
@@ -9,6 +9,7 @@
 
 #include "nsCOMPtr.h"
 #include "nsISupportsImpl.h"
+#include "mozilla/EnumSet.h"
 
 namespace mozilla {
 
@@ -23,6 +24,10 @@ namespace layers {
 
 class DelayedClearElementActivation;
 
+namespace apz {
+enum class SingleTapState : uint8_t;
+}  // namespace apz
+
 /**
  * Manages setting and clearing the ':active' CSS pseudostate in the presence
  * of touch input.
@@ -46,9 +51,9 @@ class ActiveElementManager final {
   /**
    * Handle a touch-start state notification from APZ. This notification
    * may be delayed until after touch listeners have responded to the APZ.
-   * @param aCanBePan whether the touch can be a pan
+   * @param aCanBePanOrZoom whether the touch can be a pan or double-tap-to-zoom
    */
-  void HandleTouchStart(bool aCanBePan);
+  void HandleTouchStart(bool aCanBePanOrZoom);
   /**
    * Clear the active element.
    */
@@ -57,12 +62,12 @@ class ActiveElementManager final {
    * Handle a touch-end or touch-cancel event.
    * @param aWasClick whether the touch was a click
    */
-  void HandleTouchEndEvent(bool aWasClick);
+  bool HandleTouchEndEvent(apz::SingleTapState aState);
   /**
    * Handle a touch-end state notification from APZ. This notification may be
    * delayed until after touch listeners have responded to the APZ.
    */
-  void HandleTouchEnd();
+  bool HandleTouchEnd(apz::SingleTapState aState);
   /**
    * Possibly clear active element sate in response to a single tap.
    */
@@ -76,17 +81,39 @@ class ActiveElementManager final {
   /**
    * The target of the first touch point in the current touch block.
    */
-  nsCOMPtr<dom::Element> mTarget;
+  RefPtr<dom::Element> mTarget;
   /**
-   * Whether the current touch block can be a pan. Set in HandleTouchStart().
+   * Whether the current touch block can be a pan or double-tap-to-zoom. Set in
+   * HandleTouchStart().
    */
-  bool mCanBePan;
+  bool mCanBePanOrZoom;
   /**
-   * Whether mCanBePan has been set for the current touch block.
+   * Whether mCanBePanOrZoom has been set for the current touch block.
    * We need to keep track of this to allow HandleTouchStart() and
    * SetTargetElement() to be called in either order.
    */
-  bool mCanBePanSet;
+  bool mCanBePanOrZoomSet;
+
+  bool mSingleTapBeforeActivation;
+
+  enum class TouchEndState : uint8_t {
+    GotTouchEndNotification,
+    GotTouchEndEvent,
+  };
+  using TouchEndStates = EnumSet<TouchEndState>;
+
+  /**
+   * A flag tracks whether `APZStateChange::eEndTouch` notification has arrived
+   * and whether `eTouchEnd` event has arrived.
+   */
+  TouchEndStates mTouchEndState;
+
+  /**
+   * A tri-state variable to represent the single tap state when both of
+   * `APZStateChange::eEndTouch` notification and `eTouchEnd` event arrived.
+   */
+  apz::SingleTapState mSingleTapState;
+
   /**
    * A task for calling SetActive() after a timeout.
    */
@@ -103,6 +130,8 @@ class ActiveElementManager final {
   void ResetTouchBlockState();
   void SetActiveTask(const nsCOMPtr<dom::Element>& aTarget);
   void CancelTask();
+  // Returns true if the function changed the active element state.
+  bool MaybeChangeActiveState(apz::SingleTapState aState);
 };
 
 }  // namespace layers