text: // Copyright 2017 The Chromium Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  
  #ifndef CC_ANIMATION_WORKLET_ANIMATION_H_
  #define CC_ANIMATION_WORKLET_ANIMATION_H_
  
  #include "base/optional.h"
  #include "base/time/time.h"
  #include "cc/animation/animation_export.h"
  #include "cc/animation/keyframe_effect.h"
  #include "cc/animation/single_keyframe_effect_animation.h"
  
  namespace cc {
  
  class ScrollTimeline;
  
  // A WorkletAnimation is an animation that allows its animation
  // timing to be controlled by an animator instance that is running in a
  // AnimationWorkletGlobalScope.
  class CC_ANIMATION_EXPORT WorkletAnimation final
      : public SingleKeyframeEffectAnimation {
   public:
    WorkletAnimation(int id,
                     const std::string& name,
                     std::unique_ptr<ScrollTimeline> scroll_timeline,
                     bool is_controlling_instance);
    static scoped_refptr<WorkletAnimation> Create(
        int id,
        const std::string& name,
        std::unique_ptr<ScrollTimeline> scroll_timeline);
    scoped_refptr<Animation> CreateImplInstance() const override;
  
    const std::string& name() const { return name_; }
    const ScrollTimeline* scroll_timeline() const {
      return scroll_timeline_.get();
    }
  
    void SetLocalTime(base::TimeDelta local_time);
    bool IsWorkletAnimation() const override;
  
    void Tick(base::TimeTicks monotonic_time) override;
  
    // Returns the current time to be passed into the underlying AnimationWorklet.
    // The current time is based on the timeline associated with the animation.
    double CurrentTime(base::TimeTicks monotonic_time,
                       const ScrollTree& scroll_tree);
  
    // Returns true if the worklet animation needs to be updated which happens iff
    // its current time is going to be different from last time given these input.
    bool NeedsUpdate(base::TimeTicks monotonic_time,
                     const ScrollTree& scroll_tree);
  
   private:
    ~WorkletAnimation() override;
  
    std::string name_;
  
    // The ScrollTimeline associated with the underlying animation. If null, the
    // animation is based on a DocumentTimeline.
    //
    // TODO(crbug.com/780148): A WorkletAnimation should own an AnimationTimeline
    // which must exist but can either be a DocumentTimeline, ScrollTimeline, or
    // some other future implementation.
    std::unique_ptr<ScrollTimeline> scroll_timeline_;
  
    base::TimeDelta local_time_;
  
    base::Optional<double> last_current_time_;
  
    bool is_impl_instance_;
  };
  
  }  // namespace cc
  
  #endif  // CC_ANIMATION_WORKLET_ANIMATION_H_
  