script/dom/document/

animation_manager.rs

/* 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 https://mozilla.org/MPL/2.0/. */

//! The set of animations for a document.

#![cfg_attr(crown, allow(crown::jscontext_first_arg))]

use std::cell::Cell;
use std::sync::Arc;
use std::time::Duration;

use cssparser::ToCss;
use embedder_traits::{AnimationState as AnimationsPresentState, UntrustedNodeAddress};
use js::context::NoGC;
use layout_api::AnimatingImages;
use libc::c_void;
use paint_api::ImageUpdate;
use parking_lot::RwLock;
use rustc_hash::{FxHashMap, FxHashSet};
use script_bindings::cell::DomRefCell;
use script_bindings::codegen::GenericBindings::WindowBinding::WindowMethods;
use script_bindings::refcounted::Trusted;
use serde::{Deserialize, Serialize};
use servo_base::id::PipelineId;
use servo_constellation_traits::ScriptToConstellationMessage;
use style::animation::{
    Animation, AnimationSetKey, AnimationState, DocumentAnimationSet, ElementAnimationSet,
    KeyframesIterationState, Transition,
};
use style::dom::OpaqueNode;
use style::selector_parser::PseudoElement;
use timers::TimerId;

use crate::dom::animationevent::AnimationEvent;
use crate::dom::bindings::codegen::Bindings::AnimationEventBinding::AnimationEventInit;
use crate::dom::bindings::codegen::Bindings::EventBinding::EventInit;
use crate::dom::bindings::codegen::Bindings::TransitionEventBinding::TransitionEventInit;
use crate::dom::bindings::inheritance::Castable;
use crate::dom::bindings::num::Finite;
use crate::dom::bindings::root::{Dom, DomRoot};
use crate::dom::bindings::str::DOMString;
use crate::dom::bindings::trace::NoTrace;
use crate::dom::event::Event;
use crate::dom::node::{Node, NodeDamage, NodeTraits, from_untrusted_node_address};
use crate::dom::transitionevent::TransitionEvent;
use crate::dom::window::Window;
use crate::event_loop::script_thread::with_script_thread;

/// The set of animations for a document.
#[derive(Default, JSTraceable, MallocSizeOf)]
#[cfg_attr(crown, crown::unrooted_must_root_lint::must_root)]
pub(crate) struct AnimationManager {
    /// The map of nodes to their animation states.
    #[no_trace]
    sets: DocumentAnimationSet,

    /// The set of [`AnimatingImages`] which is used to communicate the addition
    /// and removal of animating images from layout.
    #[no_trace]
    #[conditional_malloc_size_of]
    animating_images: Arc<RwLock<AnimatingImages>>,

    /// Whether or not we have animations that are running.
    has_running_animations: Cell<bool>,

    /// A map of nodes with in-progress CSS transitions or pending events.
    rooted_animation_nodes: DomRefCell<FxHashMap<NoTrace<OpaqueNode>, Dom<Node>>>,

    /// A map of nodes with in-progress image animations. This is kept outside
    /// of [`Self::animating_images`] as that data structure is shared with layout.
    rooted_image_nodes: DomRefCell<FxHashMap<NoTrace<OpaqueNode>, Dom<Node>>>,

    /// A list of pending animation-related events.
    pending_events: DomRefCell<Vec<TransitionOrAnimationEvent>>,

    /// The timeline value at the last time all animations were marked dirty.
    /// This is used to prevent marking animations dirty when the timeline
    /// has not changed.
    timeline_value_at_last_dirty: Cell<f64>,

    /// The [`TimerId`] of the currently scheduled animated image update callback.
    #[no_trace]
    image_callback_timer_id: Cell<Option<TimerId>>,
}

impl AnimationManager {
    pub(crate) fn new() -> Self {
        AnimationManager {
            sets: Default::default(),
            animating_images: Default::default(),
            has_running_animations: Cell::new(false),
            rooted_animation_nodes: Default::default(),
            rooted_image_nodes: Default::default(),
            pending_events: Default::default(),
            timeline_value_at_last_dirty: Cell::new(0.0),
            image_callback_timer_id: Default::default(),
        }
    }

    pub(crate) fn animating_images(&self) -> Arc<RwLock<AnimatingImages>> {
        self.animating_images.clone()
    }

    pub(crate) fn sets(&self) -> DocumentAnimationSet {
        self.sets.clone()
    }

    pub(crate) fn clear(&self) {
        self.sets.sets.write().clear();
        self.animating_images.write().node_to_state_map.clear();
        self.rooted_animation_nodes.borrow_mut().clear();
        self.rooted_image_nodes.borrow_mut().clear();
        self.pending_events.borrow_mut().clear();
    }

    // Mark all animations dirty, if they haven't been marked dirty since the
    // specified `current_timeline_value`. Returns true if animations were marked
    // dirty or false otherwise.
    pub(crate) fn mark_animating_nodes_as_dirty(
        &self,
        no_gc: &NoGC,
        current_timeline_value: f64,
    ) -> bool {
        if current_timeline_value <= self.timeline_value_at_last_dirty.get() {
            return false;
        }
        self.timeline_value_at_last_dirty
            .set(current_timeline_value);

        let sets = self.sets.sets.read();
        let rooted_nodes = self.rooted_animation_nodes.borrow();
        for node in sets
            .keys()
            .filter_map(|key| rooted_nodes.get(&NoTrace(key.node)))
        {
            node.dirty(no_gc, NodeDamage::Style);
        }

        true
    }

    pub(crate) fn update_for_new_timeline_value(&self, window: &Window, now: f64) {
        let pipeline_id = window.pipeline_id();
        let mut sets = self.sets.sets.write();

        for (key, set) in sets.iter_mut() {
            self.start_pending_animations(key, set, now, pipeline_id);

            // When necessary, iterate our running animations to the next iteration.
            if now > self.timeline_value_at_last_dirty.get() {
                for animation in set.animations.iter_mut() {
                    if animation.iterate_if_necessary(now) {
                        self.add_animation_event(
                            key,
                            animation,
                            TransitionOrAnimationEventType::AnimationIteration,
                            now,
                            pipeline_id,
                        );
                    }
                }
            }

            self.finish_running_animations(key, set, now, pipeline_id);
        }

        self.unroot_unused_nodes(&sets);
    }

    /// Cancel animations for the given node, if any exist.
    pub(crate) fn cancel_animations_for_node(&self, node: &Node) {
        let opaque_node = node.to_opaque();

        let animation_keys = [
            AnimationSetKey::new_for_non_pseudo(opaque_node),
            AnimationSetKey::new_for_pseudo(opaque_node, PseudoElement::Before),
            AnimationSetKey::new_for_pseudo(opaque_node, PseudoElement::After),
        ];

        let mut animations = self.sets.sets.write();
        for key in animation_keys {
            if let Some(set) = animations.get_mut(&key) {
                set.cancel_all_animations();
            }
        }

        self.animating_images().write().remove(opaque_node);
        self.rooted_image_nodes
            .borrow_mut()
            .remove(&NoTrace(opaque_node));
    }

    /// This does five things:
    ///  - Cancel animations for any nodes that are no longer being rendered or delegating rendering.
    ///  - Process any new animations that were discovered after reflow.
    ///  - Collect pending events for any animations that changed state.
    ///  - Root any nodes with newly animating images
    ///  - Schedule an image update for newly animating images
    pub(crate) fn do_post_reflow_update(&self, window: &Window, now: f64) {
        let mut sets = self.sets.sets.write();
        {
            let rooted_nodes = self.rooted_animation_nodes.borrow();
            for (key, set) in sets.iter_mut() {
                if rooted_nodes.get(&NoTrace(key.node)).is_some_and(|node| {
                    !node.is_being_rendered_or_delegates_rendering(key.pseudo_element)
                }) {
                    set.cancel_all_animations();
                }
            }
        }

        let pipeline_id = window.pipeline_id();
        self.root_newly_animating_dom_nodes(&sets);

        for (key, set) in sets.iter_mut() {
            self.handle_canceled_animations(key, set, now, pipeline_id);
            self.handle_new_animations(key, set, now, pipeline_id);
        }

        // Remove empty states from our collection of states in order to free
        // up space as soon as we are no longer tracking any animations for
        // a node.
        sets.retain(|_, state| !state.is_empty());
        let have_running_animations = sets.values().any(|state| state.needs_animation_ticks());

        self.update_running_animations_presence(window, have_running_animations);

        // Cancel animations for any images that are no longer rendering.
        self.rooted_image_nodes
            .borrow_mut()
            .retain(|opaque_node, node| {
                if node.is_being_rendered(None) {
                    return true;
                }
                self.animating_images.write().remove(opaque_node.0);
                false
            });

        if self.animating_images().write().clear_dirty() {
            self.root_nodes_with_newly_animating_images();
            self.maybe_schedule_image_animation_update(window, now);
        }
    }

    pub(crate) fn update_active_image_animation_frames(&self, window: &Window, now: f64) {
        if self.animating_images.read().is_empty() {
            return;
        }

        let updates = self
            .animating_images
            .write()
            .node_to_state_map
            .values_mut()
            .filter_map(|state| {
                if !state.update_frame_for_animation_timeline_value(now) {
                    return None;
                }

                let image = &state.image;
                let frame = image
                    .frame_data(state.active_frame)
                    .expect("No frame found")
                    .clone();
                if let Some(mut descriptor) =
                    image.webrender_image_descriptor_and_offset_for_frame()
                {
                    descriptor.offset = frame.byte_range.start as i32;
                    Some(ImageUpdate::UpdateImageForAnimation(
                        image.id.unwrap(),
                        descriptor,
                    ))
                } else {
                    error!("Doing normal image update which will be slow!");
                    None
                }
            })
            .collect();
        window
            .paint_api()
            .update_images(window.webview_id().into(), updates);

        self.maybe_schedule_image_animation_update(window, now);
    }

    fn root_nodes_with_newly_animating_images(&self) {
        let mut rooted_nodes = self.rooted_image_nodes.borrow_mut();
        for opaque_node in self.animating_images.read().node_to_state_map.keys() {
            root_node(&mut rooted_nodes, *opaque_node);
        }
    }

    fn maybe_schedule_image_animation_update(&self, window: &Window, now: f64) {
        with_script_thread(|script_thread| {
            if let Some(current_timer_id) = self.image_callback_timer_id.take() {
                self.image_callback_timer_id.set(None);
                script_thread.cancel_timer(current_timer_id);
            }

            if let Some(duration) = self.duration_to_next_image_animation_frame(now) {
                let trusted_window = Trusted::new(window);
                let timer_id = script_thread.schedule_timer(timers::TimerEventRequest {
                    callback: Box::new(move || {
                        let window = trusted_window.root();
                        window.Document().set_has_pending_animated_image_update();
                    }),
                    duration,
                });
                self.image_callback_timer_id.set(Some(timer_id));
            }
        })
    }

    fn duration_to_next_image_animation_frame(&self, now: f64) -> Option<Duration> {
        self.animating_images
            .read()
            .node_to_state_map
            .values()
            .filter_map(|state| state.duration_to_next_frame(now))
            .min()
    }

    fn update_running_animations_presence(&self, window: &Window, new_value: bool) {
        let had_running_animations = self.has_running_animations.get();
        if new_value == had_running_animations {
            return;
        }

        self.has_running_animations.set(new_value);
        self.handle_animation_presence_or_pending_events_change(window);
    }

    fn handle_animation_presence_or_pending_events_change(&self, window: &Window) {
        let has_running_animations = self.has_running_animations.get();
        let has_pending_events = !self.pending_events.borrow().is_empty();

        // Do not send the AnimationCallbacksAbsent state until all pending
        // animation events are delivered.
        let state = match has_running_animations || has_pending_events {
            true => AnimationsPresentState::AnimationsPresent,
            false => AnimationsPresentState::NoAnimationsPresent,
        };
        window.send_to_constellation(ScriptToConstellationMessage::ChangeRunningAnimationsState(
            state,
        ));
    }

    pub(crate) fn running_animation_count(&self) -> usize {
        self.sets
            .sets
            .read()
            .values()
            .map(|state| state.running_animation_and_transition_count())
            .sum()
    }

    /// Walk through the list of pending animations and start all of the ones that
    /// have left the delay phase.
    fn start_pending_animations(
        &self,
        key: &AnimationSetKey,
        set: &mut ElementAnimationSet,
        now: f64,
        pipeline_id: PipelineId,
    ) {
        for animation in set.animations.iter_mut() {
            if animation.state == AnimationState::Pending && animation.started_at <= now {
                animation.state = AnimationState::Running;
                self.add_animation_event(
                    key,
                    animation,
                    TransitionOrAnimationEventType::AnimationStart,
                    now,
                    pipeline_id,
                );
            }
        }

        for transition in set.transitions.iter_mut() {
            if transition.state == AnimationState::Pending && transition.start_time <= now {
                transition.state = AnimationState::Running;
                self.add_transition_event(
                    key,
                    transition,
                    TransitionOrAnimationEventType::TransitionStart,
                    now,
                    pipeline_id,
                );
            }
        }
    }

    /// Walk through the list of running animations and remove all of the ones that
    /// have ended.
    fn finish_running_animations(
        &self,
        key: &AnimationSetKey,
        set: &mut ElementAnimationSet,
        now: f64,
        pipeline_id: PipelineId,
    ) {
        for animation in set.animations.iter_mut() {
            if animation.state == AnimationState::Running && animation.has_ended(now) {
                animation.state = AnimationState::Finished;
                self.add_animation_event(
                    key,
                    animation,
                    TransitionOrAnimationEventType::AnimationEnd,
                    now,
                    pipeline_id,
                );
            }
        }

        for transition in set.transitions.iter_mut() {
            if transition.state == AnimationState::Running && transition.has_ended(now) {
                transition.state = AnimationState::Finished;
                self.add_transition_event(
                    key,
                    transition,
                    TransitionOrAnimationEventType::TransitionEnd,
                    now,
                    pipeline_id,
                );
            }
        }
    }

    /// Send events for canceled animations. Currently this only handles canceled
    /// transitions, but eventually this should handle canceled CSS animations as
    /// well.
    fn handle_canceled_animations(
        &self,
        key: &AnimationSetKey,
        set: &mut ElementAnimationSet,
        now: f64,
        pipeline_id: PipelineId,
    ) {
        for transition in &set.transitions {
            if transition.state == AnimationState::Canceled {
                self.add_transition_event(
                    key,
                    transition,
                    TransitionOrAnimationEventType::TransitionCancel,
                    now,
                    pipeline_id,
                );
            }
        }

        for animation in &set.animations {
            if animation.state == AnimationState::Canceled {
                self.add_animation_event(
                    key,
                    animation,
                    TransitionOrAnimationEventType::AnimationCancel,
                    now,
                    pipeline_id,
                );
            }
        }

        set.clear_canceled_animations();
    }

    fn handle_new_animations(
        &self,
        key: &AnimationSetKey,
        set: &mut ElementAnimationSet,
        now: f64,
        pipeline_id: PipelineId,
    ) {
        for animation in set.animations.iter_mut() {
            animation.is_new = false;
        }

        for transition in set.transitions.iter_mut() {
            if transition.is_new {
                self.add_transition_event(
                    key,
                    transition,
                    TransitionOrAnimationEventType::TransitionRun,
                    now,
                    pipeline_id,
                );
                transition.is_new = false;
            }
        }
    }

    /// Ensure that all nodes with new animations are rooted. This should be called
    /// immediately after a restyle, to ensure that these addresses are still valid.
    fn root_newly_animating_dom_nodes(
        &self,
        sets: &FxHashMap<AnimationSetKey, ElementAnimationSet>,
    ) {
        let mut rooted_nodes = self.rooted_animation_nodes.borrow_mut();
        for (key, set) in sets.iter() {
            let opaque_node = key.node;
            if rooted_nodes.contains_key(&NoTrace(opaque_node)) {
                continue;
            }

            if set.animations.iter().any(|animation| animation.is_new) ||
                set.transitions.iter().any(|transition| transition.is_new)
            {
                root_node(&mut rooted_nodes, opaque_node);
            }
        }
    }

    // Unroot any nodes that we have rooted but are no longer tracking animations for.
    fn unroot_unused_nodes(&self, sets: &FxHashMap<AnimationSetKey, ElementAnimationSet>) {
        let pending_events = self.pending_events.borrow();
        let nodes: FxHashSet<OpaqueNode> = sets.keys().map(|key| key.node).collect();
        self.rooted_animation_nodes.borrow_mut().retain(|node, _| {
            nodes.contains(&node.0) || pending_events.iter().any(|event| event.node == node.0)
        });
    }

    fn add_transition_event(
        &self,
        key: &AnimationSetKey,
        transition: &Transition,
        event_type: TransitionOrAnimationEventType,
        now: f64,
        pipeline_id: PipelineId,
    ) {
        // Calculate the `elapsed-time` property of the event and take the absolute
        // value to prevent -0 values.
        let elapsed_time = match event_type {
            TransitionOrAnimationEventType::TransitionRun |
            TransitionOrAnimationEventType::TransitionStart => transition
                .property_animation
                .duration
                .min((-transition.delay).max(0.)),
            TransitionOrAnimationEventType::TransitionEnd => transition.property_animation.duration,
            TransitionOrAnimationEventType::TransitionCancel => {
                (now - transition.start_time).max(0.)
            },
            _ => unreachable!(),
        }
        .abs();

        self.pending_events
            .borrow_mut()
            .push(TransitionOrAnimationEvent {
                pipeline_id,
                event_type,
                node: key.node,
                pseudo_element: key.pseudo_element,
                property_or_animation_name: transition
                    .property_animation
                    .property_id()
                    .name()
                    .into(),
                elapsed_time,
            });
    }

    fn add_animation_event(
        &self,
        key: &AnimationSetKey,
        animation: &Animation,
        event_type: TransitionOrAnimationEventType,
        now: f64,
        pipeline_id: PipelineId,
    ) {
        let iteration_index = match animation.iteration_state {
            KeyframesIterationState::Finite(current, _) |
            KeyframesIterationState::Infinite(current) => current,
        };

        let active_duration = match animation.iteration_state {
            KeyframesIterationState::Finite(_, max) => max * animation.duration,
            KeyframesIterationState::Infinite(_) => f64::MAX,
        };

        // Calculate the `elapsed-time` property of the event and take the absolute
        // value to prevent -0 values.
        let elapsed_time = match event_type {
            TransitionOrAnimationEventType::AnimationStart => {
                (-animation.delay).max(0.).min(active_duration)
            },
            TransitionOrAnimationEventType::AnimationIteration => {
                iteration_index * animation.duration
            },
            TransitionOrAnimationEventType::AnimationEnd => {
                (iteration_index * animation.duration) + animation.current_iteration_duration()
            },
            TransitionOrAnimationEventType::AnimationCancel => {
                (iteration_index * animation.duration) + (now - animation.started_at).max(0.)
            },
            _ => unreachable!(),
        }
        .abs();

        self.pending_events
            .borrow_mut()
            .push(TransitionOrAnimationEvent {
                pipeline_id,
                event_type,
                node: key.node,
                pseudo_element: key.pseudo_element,
                property_or_animation_name: animation.name.to_string(),
                elapsed_time,
            });
    }

    /// An implementation of the final steps of
    /// <https://drafts.csswg.org/web-animations-1/#update-animations-and-send-events>.
    pub(crate) fn send_pending_events(&self, window: &Window, cx: &mut js::context::JSContext) {
        // > 4. Let events to dispatch be a copy of doc’s pending animation event queue.
        // > 5. Clear doc’s pending animation event queue.
        //
        // Take all of the events here, in case sending one of these events
        // triggers adding new events by forcing a layout.
        let events = std::mem::take(&mut *self.pending_events.safe_borrow_mut(cx.no_gc()));
        if events.is_empty() {
            return;
        }

        // > 6. Perform a stable sort of the animation events in events to dispatch as follows:
        // >    1. Sort the events by their scheduled event time such that events that were
        // >       scheduled to occur earlier sort before events scheduled to occur later, and
        // >       events whose scheduled event time is unresolved sort before events with a
        // >       resolved scheduled event time.
        // >    2. Within events with equal scheduled event times, sort by their composite
        // >       order.
        //
        // TODO: Sorting of animation events isn't done yet.

        // 7. Dispatch each of the events in events to dispatch at their corresponding
        // target using the order established in the previous step.
        for event in events.into_iter() {
            // We root the node here to ensure that sending this event doesn't
            // unroot it as a side-effect.
            let node = match self
                .rooted_animation_nodes
                .borrow()
                .get(&NoTrace(event.node))
            {
                Some(node) => DomRoot::from_ref(&**node),
                None => {
                    warn!("Tried to send an event for an unrooted node");
                    continue;
                },
            };

            let event_atom = match event.event_type {
                TransitionOrAnimationEventType::AnimationEnd => atom!("animationend"),
                TransitionOrAnimationEventType::AnimationStart => atom!("animationstart"),
                TransitionOrAnimationEventType::AnimationCancel => atom!("animationcancel"),
                TransitionOrAnimationEventType::AnimationIteration => atom!("animationiteration"),
                TransitionOrAnimationEventType::TransitionCancel => atom!("transitioncancel"),
                TransitionOrAnimationEventType::TransitionEnd => atom!("transitionend"),
                TransitionOrAnimationEventType::TransitionRun => atom!("transitionrun"),
                TransitionOrAnimationEventType::TransitionStart => atom!("transitionstart"),
            };
            let parent = EventInit {
                bubbles: true,
                cancelable: false,
                composed: false,
            };

            let property_or_animation_name =
                DOMString::from(event.property_or_animation_name.clone());
            let pseudo_element = event
                .pseudo_element
                .map_or_else(DOMString::new, |pseudo_element| {
                    DOMString::from(pseudo_element.to_css_string())
                });
            let elapsed_time = Finite::new(event.elapsed_time as f32).unwrap();
            let window = node.owner_window();

            if event.event_type.is_transition_event() {
                let event_init = TransitionEventInit {
                    parent,
                    propertyName: property_or_animation_name,
                    elapsedTime: elapsed_time,
                    pseudoElement: pseudo_element,
                };
                TransitionEvent::new(cx, &window, event_atom, &event_init)
                    .upcast::<Event>()
                    .fire(cx, node.upcast());
            } else {
                let event_init = AnimationEventInit {
                    parent,
                    animationName: property_or_animation_name,
                    elapsedTime: elapsed_time,
                    pseudoElement: pseudo_element,
                };
                AnimationEvent::new(cx, &window, event_atom, &event_init)
                    .upcast::<Event>()
                    .fire(cx, node.upcast());
            }
        }

        if self.pending_events.borrow().is_empty() {
            self.handle_animation_presence_or_pending_events_change(window);
        }
    }
}

/// The type of transition event to trigger. These are defined by
/// CSS Transitions § 6.1 and CSS Animations § 4.2
#[derive(Clone, Debug, Deserialize, JSTraceable, MallocSizeOf, Serialize)]
pub(crate) enum TransitionOrAnimationEventType {
    /// "The transitionrun event occurs when a transition is created (i.e., when it
    /// is added to the set of running transitions)."
    TransitionRun,
    /// "The transitionstart event occurs when a transition’s delay phase ends."
    TransitionStart,
    /// "The transitionend event occurs at the completion of the transition. In the
    /// case where a transition is removed before completion, such as if the
    /// transition-property is removed, then the event will not fire."
    TransitionEnd,
    /// "The transitioncancel event occurs when a transition is canceled."
    TransitionCancel,
    /// "The animationstart event occurs at the start of the animation. If there is
    /// an animation-delay then this event will fire once the delay period has expired."
    AnimationStart,
    /// "The animationiteration event occurs at the end of each iteration of an
    /// animation, except when an animationend event would fire at the same time."
    AnimationIteration,
    /// "The animationend event occurs when the animation finishes"
    AnimationEnd,
    /// "The animationcancel event occurs when the animation stops running in a way
    /// that does not fire an animationend event..."
    AnimationCancel,
}

impl TransitionOrAnimationEventType {
    /// Whether or not this event is a transition-related event.
    pub(crate) fn is_transition_event(&self) -> bool {
        match *self {
            Self::TransitionRun |
            Self::TransitionEnd |
            Self::TransitionCancel |
            Self::TransitionStart => true,
            Self::AnimationEnd |
            Self::AnimationIteration |
            Self::AnimationStart |
            Self::AnimationCancel => false,
        }
    }
}

#[derive(Deserialize, JSTraceable, MallocSizeOf, Serialize)]
/// A transition or animation event.
pub(crate) struct TransitionOrAnimationEvent {
    /// The pipeline id of the layout task that sent this message.
    #[no_trace]
    pub(crate) pipeline_id: PipelineId,
    /// The type of transition event this should trigger.
    pub(crate) event_type: TransitionOrAnimationEventType,
    /// The address of the node which owns this transition.
    #[no_trace]
    pub(crate) node: OpaqueNode,
    /// The pseudo element for this transition or animation, if applicable.
    #[no_trace]
    pub(crate) pseudo_element: Option<PseudoElement>,
    /// The name of the property that is transitioning (in the case of a transition)
    /// or the name of the animation (in the case of an animation).
    pub(crate) property_or_animation_name: String,
    /// The elapsed time property to send with this transition event.
    pub(crate) elapsed_time: f64,
}

/// Inserts [opaque_node] into [rooted_nodes], if it isn't already present. This should be
/// called immediately after a restyle, to ensure that these addresses are still valid.
fn root_node(
    rooted_nodes: &mut FxHashMap<NoTrace<OpaqueNode>, Dom<Node>>,
    opaque_node: OpaqueNode,
) {
    #[expect(unsafe_code)]
    rooted_nodes.entry(NoTrace(opaque_node)).or_insert_with(|| {
        // SAFETY: This should be safe as this method is run directly after layout,
        // which should not remove any nodes.
        let address = UntrustedNodeAddress(opaque_node.0 as *const c_void);
        unsafe { Dom::from_ref(&*from_untrusted_node_address(address)) }
    });
}