| /* |
| * Copyright (c) 2011, Google Inc. All rights reserved. |
| * |
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| * modification, are permitted provided that the following conditions are |
| * met: |
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| * in the documentation and/or other materials provided with the |
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| * this software without specific prior written permission. |
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| */ |
| |
| #ifndef THIRD_PARTY_BLINK_RENDERER_CORE_SCROLL_SCROLL_ANIMATOR_H_ |
| #define THIRD_PARTY_BLINK_RENDERER_CORE_SCROLL_SCROLL_ANIMATOR_H_ |
| |
| #include <memory> |
| #include "base/time/default_tick_clock.h" |
| |
| #include "third_party/blink/renderer/core/scroll/scroll_animator_base.h" |
| #include "third_party/blink/renderer/platform/animation/compositor_animation_client.h" |
| #include "third_party/blink/renderer/platform/animation/compositor_animation_delegate.h" |
| #include "third_party/blink/renderer/platform/animation/compositor_scroll_offset_animation_curve.h" |
| #include "third_party/blink/renderer/platform/timer.h" |
| |
| namespace blink { |
| |
| class CompositorAnimationTimeline; |
| |
| // ScrollAnimator is the Blink-side implementation of user-input scroll offset |
| // animations ("smooth scrolling") on all platforms except for Mac. |
| // |
| // See http://bit.ly/smoothscrolling for general info about user-input smooth |
| // scrolling. For the Mac implementation, see ScrollAnimatorMac. For |
| // programmatic (CSSOM) smooth scrolls, see ProgrammaticScrollAnimator. |
| // |
| // When Blink receives an input event that should start or update a scroll |
| // animation, it calls ScrollAnimator::UserScroll. This will construct an |
| // animation curve object which can report the desired scroll offset as a |
| // function of elapsed time. See cc/animation/scroll_offset_animation_curve.h |
| // for more info about the animation curve logic (including velocity-matched |
| // target updating). |
| // |
| // Having established an animation curve, the logic for servicing the animation |
| // is highly dependent on compositing. There are four scenarios to consider: |
| // |
| // (1) Scroll animation running on the compositor, scheduled by the compositor |
| // (LayerTreeHostImpl::ScrollAnimated) in response to a scroll wheel input |
| // event handled by the compositor thread. Blink doesn't know about these. |
| // |
| // (2) Scroll animation running on the compositor, scheduled by Blink. For |
| // example, a keyboard scroll of a composited scroller. |
| // |
| // (3) Scroll animation of a composited scroller, running on the main thread due |
| // to main-thread scrolling reasons (for example, non-composited fixed- |
| // position elements that need to be repainted on scroll). |
| // |
| // (4) Scroll animation of a non-composited scroller, running on the main |
| // thread. |
| // |
| // In scenarios (1) and (2) the animation is created as a cc::Animation with |
| // TargetProperty::SCROLL_OFFSET and added to a cc::Animation that is |
| // serviced on the compositor thread (in cc::AnimationHost::TickAnimations). |
| // This lets the animation play smoothly even if the main thread is janked. |
| // |
| // In scenarios (3) and (4), we schedule the animation ticks on the main thread |
| // using ScrollableArea::ScheduleAnimation, and update the scroll offset during |
| // ScrollAnimator::TickAnimation. |
| // |
| // There is a special main-thread scrolling reason kHandlingScrollFromMainThread |
| // set in scenarios (2) and (3) for the duration of the scroll, to prevent |
| // interference from events that would otherwise trigger scenario (1). |
| // |
| // There is a complicated handoff from (1) to (3) in the event that a main- |
| // thread scrolling reason is added in the middle of an animation. This is |
| // handled by TakeOverCompositorAnimation, which aborts the animation in cc and |
| // sends an AnimationEvent::TAKEOVER back to the main thread containing a copy |
| // of the curve. That calls back into NotifyAnimationTakeover which starts a |
| // new animation on main to play the "remainder" of the curve. |
| // |
| // The logic for Blink-side scheduling of compositor-serviced scroll offset |
| // animations is shared with ProgrammaticScrollAnimator, and lives mostly in the |
| // common base class ScrollAnimatorCompositorCoordinator. |
| |
| class CORE_EXPORT ScrollAnimator : public ScrollAnimatorBase { |
| public: |
| explicit ScrollAnimator(ScrollableArea*, |
| const base::TickClock* tick_clock = |
| base::DefaultTickClock::GetInstance()); |
| ~ScrollAnimator() override; |
| |
| bool HasRunningAnimation() const override; |
| ScrollOffset ComputeDeltaToConsume(const ScrollOffset& delta) const override; |
| |
| // The callback will be run if the animation is updated by another |
| // UserScroll, otherwise it is called when the animation is finished, |
| // cancelled or reset. |
| ScrollResult UserScroll(ScrollGranularity, |
| const ScrollOffset& delta, |
| ScrollableArea::ScrollCallback on_finish) override; |
| void ScrollToOffsetWithoutAnimation(const ScrollOffset&) override; |
| ScrollOffset DesiredTargetOffset() const override; |
| |
| // ScrollAnimatorCompositorCoordinator implementation. |
| void TickAnimation(double monotonic_time) override; |
| void CancelAnimation() override; |
| void AdjustAnimationAndSetScrollOffset(const ScrollOffset&, |
| mojom::blink::ScrollType) override; |
| void TakeOverCompositorAnimation() override; |
| void ResetAnimationState() override; |
| void UpdateCompositorAnimations() override; |
| void NotifyCompositorAnimationFinished(int group_id) override; |
| void NotifyCompositorAnimationAborted(int group_id) override; |
| void LayerForCompositedScrollingDidChange( |
| CompositorAnimationTimeline*) override; |
| |
| void Trace(Visitor*) override; |
| |
| protected: |
| // Returns whether or not the animation was sent to the compositor. |
| virtual bool SendAnimationToCompositor(); |
| |
| private: |
| // Returns true if the animation was scheduled successfully. If animation |
| // could not be scheduled (e.g. because the frame is detached), scrolls |
| // immediately to the target and returns false. |
| bool RegisterAndScheduleAnimation(); |
| |
| void CreateAnimationCurve(); |
| |
| // Returns true if will animate to the given target offset. Returns false |
| // only when there is no animation running and we are not starting one |
| // because we are already at targetPos. |
| bool WillAnimateToOffset(const ScrollOffset& target_pos); |
| |
| std::unique_ptr<CompositorScrollOffsetAnimationCurve> animation_curve_; |
| const base::TickClock* const tick_clock_; |
| base::TimeTicks start_time_; |
| |
| ScrollOffset target_offset_; |
| ScrollGranularity last_granularity_; |
| |
| // on_finish_ is a callback to call on animation finished, cancelled, or |
| // otherwise interrupted in any way. |
| ScrollableArea::ScrollCallback on_finish_; |
| }; |
| |
| } // namespace blink |
| |
| #endif // THIRD_PARTY_BLINK_RENDERER_CORE_SCROLL_SCROLL_ANIMATOR_H_ |