Web Animations: Introduce ActiveAnimations and AnimationStack

Source/core/animation/TimedItem.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 18 matching lines @@
  */
 
 #ifndef TimedItem_h
 #define TimedItem_h
 
 #include "core/animation/Timing.h"
 #include "wtf/RefCounted.h"
 
 namespace WebCore {
 
+class Player;
+
 static inline bool isNull(double value)
 {
     return std::isnan(value);
 }
 
 static inline double nullValue()
 {
     return std::numeric_limits<double>::quiet_NaN();
 }
 
 class TimedItem : public RefCounted<TimedItem> {
+    friend class Player; // Calls attach/detach, updateInheritedTime.
 public:
     virtual ~TimedItem() { }
 
     bool isScheduled() const { return ensureCalculated().isScheduled; }
     bool isActive() const { return ensureCalculated().isActive; }
     bool isCurrent() const { return ensureCalculated().isCurrent; }
     bool isInEffect() const { return ensureCalculated().isInEffect; }
 
     double startTime() const { return m_startTime; }
 
     double currentIteration() const { return ensureCalculated().currentIteration; }
     double activeDuration() const { return ensureCalculated().activeDuration; }
     double timeFraction() const { return ensureCalculated().timeFraction; }
+    Player* player() const { return m_player; }
 
 protected:
     TimedItem(const Timing&);
 
     // When TimedItem receives a new inherited time via updateInheritedTime
     // it will (if necessary) recalculate timings and (if necessary) call
     // updateChildrenAndEffects.
     void updateInheritedTime(double inheritedTime) const;
     virtual void updateChildrenAndEffects(bool wasActiveOrInEffect) const = 0;
     virtual double intrinsicIterationDuration() const { return 0; };
-
-    friend class Player; // Calls updateInheritedTime.
+    virtual void willDetach() = 0;
 
 private:
+    void attach(Player* player) { m_player = player; };
+    void detach()
+    {
+        ASSERT(m_player);
+        willDetach();
+        m_player = 0;
+    };
+
     // FIXME: m_parent and m_startTime are placeholders, they depend on timing groups.
     TimedItem* const m_parent;
     const double m_startTime;
-
+    Player* m_player;
     Timing m_specified;
 
     // FIXME: Should be versioned by monotonic value on player.
     mutable struct CalculatedTiming {
         CalculatedTiming();
         double activeDuration;
         double currentIteration;
         double timeFraction;
         bool isScheduled;
         bool isActive;
         bool isCurrent;
         bool isInEffect;
     } m_calculated;
 
     // FIXME: Should check the version and reinherit time if inconsistent.
     const CalculatedTiming& ensureCalculated() const { return m_calculated; }
 };
 
 } // namespace WebCore
 
 #endif