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+/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* 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_layers_ActiveElementManager_h
+#define mozilla_layers_ActiveElementManager_h
+
+#include "nsCOMPtr.h"
+#include "nsISupportsImpl.h"
+
+namespace mozilla {
+
+class CancelableRunnable;
+
+namespace dom {
+class Element;
+class EventTarget;
+} // namespace dom
+
+namespace layers {
+
+/**
+ * Manages setting and clearing the ':active' CSS pseudostate in the presence
+ * of touch input.
+ */
+class ActiveElementManager {
+ ~ActiveElementManager();
+public:
+ NS_INLINE_DECL_REFCOUNTING(ActiveElementManager)
+
+ ActiveElementManager();
+
+ /**
+ * Specify the target of a touch. Typically this should be called right
+ * after HandleTouchStart(), but in cases where the APZ needs to wait for
+ * a content response the HandleTouchStart() may be delayed, in which case
+ * this function can be called first.
+ * |aTarget| may be nullptr.
+ */
+ void SetTargetElement(dom::EventTarget* aTarget);
+ /**
+ * 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
+ */
+ void HandleTouchStart(bool aCanBePan);
+ /**
+ * Clear the active element.
+ */
+ void ClearActivation();
+ /**
+ * Handle a touch-end or touch-cancel event.
+ * @param aWasClick whether the touch was a click
+ */
+ void HandleTouchEndEvent(bool aWasClick);
+ /**
+ * Handle a touch-end state notification from APZ. This notification may be
+ * delayed until after touch listeners have responded to the APZ.
+ */
+ void HandleTouchEnd();
+ /**
+ * @return true iff the currently active element (or one of its ancestors)
+ * actually had a style for the :active pseudo-class. The currently active
+ * element is the root element if no other elements are active.
+ */
+ bool ActiveElementUsesStyle() const;
+private:
+ /**
+ * The target of the first touch point in the current touch block.
+ */
+ nsCOMPtr<dom::Element> mTarget;
+ /**
+ * Whether the current touch block can be a pan. Set in HandleTouchStart().
+ */
+ bool mCanBePan;
+ /**
+ * Whether mCanBePan 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;
+ /**
+ * A task for calling SetActive() after a timeout.
+ */
+ RefPtr<CancelableRunnable> mSetActiveTask;
+ /**
+ * See ActiveElementUsesStyle() documentation.
+ */
+ bool mActiveElementUsesStyle;
+
+ // Helpers
+ void TriggerElementActivation();
+ void SetActive(dom::Element* aTarget);
+ void ResetActive();
+ void ResetTouchBlockState();
+ void SetActiveTask(const nsCOMPtr<dom::Element>& aTarget);
+ void CancelTask();
+};
+
+} // namespace layers
+} // namespace mozilla
+
+#endif /* mozilla_layers_ActiveElementManager_h */