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IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #ifndef THIRD_PARTY_BLINK_RENDERER_CORE_SCROLL_SCROLL_ANIMATOR_H_ #define THIRD_PARTY_BLINK_RENDERER_CORE_SCROLL_SCROLL_ANIMATOR_H_ #include #include "base/time/default_tick_clock.h" #include "build/build_config.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 { // 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 MainThreadScrollingDidChange() override; void Trace(Visitor*) const override; #if defined(OS_MAC) bool HaveScrolledSincePageLoad() { return have_scrolled_since_page_load_; } #endif 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 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_; // TODO(crbug.com/1183387): investigate usage scenarios of this flag to verify // if it is still useful. // TODO(crbug.com/1122682): This is necessary for fade-in/out animations // on Mac scrollbars. Remove this when MacScrollbarAnimatorImpl is removed. #if defined(OS_MAC) bool have_scrolled_since_page_load_; #endif }; } // namespace blink #endif // THIRD_PARTY_BLINK_RENDERER_CORE_SCROLL_SCROLL_ANIMATOR_H_