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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 */
#include "nsAnimationManager.h"
#include "nsINode.h"
#include "nsTransitionManager.h"
#include "mozilla/AnimationEventDispatcher.h"
#include "mozilla/AnimationUtils.h"
#include "mozilla/EffectCompositor.h"
#include "mozilla/ElementAnimationData.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/ServoStyleSet.h"
#include "mozilla/TimelineCollection.h"
#include "mozilla/dom/AnimationEffect.h"
#include "mozilla/dom/DocumentTimeline.h"
#include "mozilla/dom/KeyframeEffect.h"
#include "mozilla/dom/MutationObservers.h"
#include "mozilla/dom/ScrollTimeline.h"
#include "mozilla/dom/ViewTimeline.h"
#include "nsPresContext.h"
#include "nsPresContextInlines.h"
#include "nsStyleChangeList.h"
#include "nsLayoutUtils.h"
#include "nsIFrame.h"
#include "mozilla/dom/Document.h"
#include "nsDOMMutationObserver.h"
#include "nsRFPService.h"
#include <algorithm> // std::stable_sort
#include <math.h>
using namespace mozilla;
using namespace mozilla::css;
using mozilla::dom::Animation;
using mozilla::dom::AnimationPlayState;
using mozilla::dom::CSSAnimation;
using mozilla::dom::Element;
using mozilla::dom::KeyframeEffect;
using mozilla::dom::MutationObservers;
using mozilla::dom::ScrollTimeline;
using mozilla::dom::ViewTimeline;
////////////////////////// nsAnimationManager ////////////////////////////
// Find the matching animation by |aName| in the old list
// of animations and remove the matched animation from the list.
static already_AddRefed<CSSAnimation> PopExistingAnimation(
const nsAtom* aName,
nsAnimationManager::CSSAnimationCollection* aCollection) {
if (!aCollection) {
return nullptr;
// Animations are stored in reverse order to how they appear in the
// animation-name property. However, we want to match animations beginning
// from the end of the animation-name list, so we iterate *forwards*
// through the collection.
for (size_t idx = 0, length = aCollection->mAnimations.Length();
idx != length; ++idx) {
CSSAnimation* cssAnim = aCollection->mAnimations[idx];
if (cssAnim->AnimationName() == aName) {
RefPtr<CSSAnimation> match = cssAnim;
return match.forget();
return nullptr;
class MOZ_STACK_CLASS ServoCSSAnimationBuilder final {
explicit ServoCSSAnimationBuilder(const ComputedStyle* aComputedStyle)
: mComputedStyle(aComputedStyle) {
bool BuildKeyframes(const Element& aElement, nsPresContext* aPresContext,
nsAtom* aName,
const StyleComputedTimingFunction& aTimingFunction,
nsTArray<Keyframe>& aKeyframes) {
return aPresContext->StyleSet()->GetKeyframesForName(
aElement, *mComputedStyle, aName, aTimingFunction, aKeyframes);
void SetKeyframes(KeyframeEffect& aEffect, nsTArray<Keyframe>&& aKeyframes,
const dom::AnimationTimeline* aTimeline) {
aEffect.SetKeyframes(std::move(aKeyframes), mComputedStyle, aTimeline);
// Currently all the animation building code in this file is based on
// assumption that creating and removing animations should *not* trigger
// additional restyles since those changes will be handled within the same
// restyle.
// While that is true for the Gecko style backend, it is not true for the
// Servo style backend where we want restyles to be triggered so that we
// perform a second animation restyle where we will incorporate the changes
// arising from creating and removing animations.
// Fortunately, our attempts to avoid posting extra restyles as part of the
// processing here are imperfect and most of the time we happen to post
// them anyway. Occasionally, however, we don't. For example, we don't post
// a restyle when we create a new animation whose an animation index matches
// the default value it was given already (which is typically only true when
// the CSSAnimation we create is the first Animation created in a particular
// content process).
// As a result, when we are using the Servo backend, whenever we have an added
// or removed animation we need to explicitly trigger a restyle.
// This code should eventually disappear along with the Gecko style backend
// and we should simply call Play() / Pause() / Cancel() etc. which will
// post the required restyles.
void NotifyNewOrRemovedAnimation(const Animation& aAnimation) {
dom::AnimationEffect* effect = aAnimation.GetEffect();
if (!effect) {
KeyframeEffect* keyframeEffect = effect->AsKeyframeEffect();
if (!keyframeEffect) {
const ComputedStyle* mComputedStyle;
static void UpdateOldAnimationPropertiesWithNew(
CSSAnimation& aOld, TimingParams&& aNewTiming,
nsTArray<Keyframe>&& aNewKeyframes, bool aNewIsStylePaused,
CSSAnimationProperties aOverriddenProperties,
ServoCSSAnimationBuilder& aBuilder, dom::AnimationTimeline* aTimeline,
dom::CompositeOperation aNewComposite) {
bool animationChanged = false;
// Update the old from the new so we can keep the original object
// identity (and any expando properties attached to it).
if (aOld.GetEffect()) {
dom::AnimationEffect* oldEffect = aOld.GetEffect();
// Copy across the changes that are not overridden
TimingParams updatedTiming = oldEffect->SpecifiedTiming();
if (~aOverriddenProperties & CSSAnimationProperties::Duration) {
if (~aOverriddenProperties & CSSAnimationProperties::IterationCount) {
if (~aOverriddenProperties & CSSAnimationProperties::Direction) {
if (~aOverriddenProperties & CSSAnimationProperties::Delay) {
if (~aOverriddenProperties & CSSAnimationProperties::FillMode) {
animationChanged = oldEffect->SpecifiedTiming() != updatedTiming;
if (KeyframeEffect* oldKeyframeEffect = oldEffect->AsKeyframeEffect()) {
if (~aOverriddenProperties & CSSAnimationProperties::Keyframes) {
aBuilder.SetKeyframes(*oldKeyframeEffect, std::move(aNewKeyframes),
if (~aOverriddenProperties & CSSAnimationProperties::Composition) {
animationChanged = oldKeyframeEffect->Composite() != aNewComposite;
// Checking pointers should be enough. If both are scroll-timeline, we reuse
// the scroll-timeline object if their scrollers and axes are the same.
if (aOld.GetTimeline() != aTimeline) {
animationChanged = true;
// Handle changes in play state. If the animation is idle, however,
// changes to animation-play-state should *not* restart it.
if (aOld.PlayState() != AnimationPlayState::Idle &&
~aOverriddenProperties & CSSAnimationProperties::PlayState) {
bool wasPaused = aOld.PlayState() == AnimationPlayState::Paused;
if (!wasPaused && aNewIsStylePaused) {
animationChanged = true;
} else if (wasPaused && !aNewIsStylePaused) {
animationChanged = true;
// Updating the effect timing above might already have caused the
// animation to become irrelevant so only add a changed record if
// the animation is still relevant.
if (animationChanged && aOld.IsRelevant()) {
static already_AddRefed<dom::AnimationTimeline> GetNamedProgressTimeline(
dom::Document* aDocument, const NonOwningAnimationTarget& aTarget,
nsAtom* aName) {
// A named progress timeline is referenceable in animation-timeline by:
// 1. the declaring element itself
// 2. that element’s descendants
// 3. that element’s following siblings and their descendants
// FIXME: Bug 1823500. Reduce default scoping to ancestors only.
for (Element* curr = AnimationUtils::GetElementForRestyle(
aTarget.mElement, aTarget.mPseudoType);
curr; curr = curr->GetParentElement()) {
// If multiple elements have declared the same timeline name, the matching
// timeline is the one declared on the nearest element in tree order, which
// considers siblings closer than parents.
// Note: This is fine for parallel traversal because we update animations by
// SequentialTask.
for (Element* e = curr; e; e = e->GetPreviousElementSibling()) {
// In case of a name conflict on the same element, scroll progress
// timelines take precedence over view progress timelines.
const auto [element, pseudoType] =
if (auto* collection =
TimelineCollection<ScrollTimeline>::Get(element, pseudoType)) {
if (RefPtr<ScrollTimeline> timeline = collection->Lookup(aName)) {
return timeline.forget();
if (auto* collection =
TimelineCollection<ViewTimeline>::Get(element, pseudoType)) {
if (RefPtr<ViewTimeline> timeline = collection->Lookup(aName)) {
return timeline.forget();
// If we cannot find a matched scroll-timeline-name, this animation is not
// associated with a timeline.
return nullptr;
static already_AddRefed<dom::AnimationTimeline> GetTimeline(
const StyleAnimationTimeline& aStyleTimeline, nsPresContext* aPresContext,
const NonOwningAnimationTarget& aTarget) {
switch (aStyleTimeline.tag) {
case StyleAnimationTimeline::Tag::Timeline: {
// Check scroll-timeline-name property or view-timeline-property.
nsAtom* name = aStyleTimeline.AsTimeline().AsAtom();
return name != nsGkAtoms::_empty
? GetNamedProgressTimeline(aPresContext->Document(), aTarget,
: nullptr;
case StyleAnimationTimeline::Tag::Scroll: {
const auto& scroll = aStyleTimeline.AsScroll();
return ScrollTimeline::MakeAnonymous(aPresContext->Document(), aTarget,
scroll.axis, scroll.scroller);
case StyleAnimationTimeline::Tag::View: {
const auto& view = aStyleTimeline.AsView();
return ViewTimeline::MakeAnonymous(aPresContext->Document(), aTarget,
view.axis, view.inset);
case StyleAnimationTimeline::Tag::Auto:
return do_AddRef(aTarget.mElement->OwnerDoc()->Timeline());
MOZ_ASSERT_UNREACHABLE("Unknown animation-timeline value?");
return nullptr;
// Returns a new animation set up with given StyleAnimation.
// Or returns an existing animation matching StyleAnimation's name updated
// with the new StyleAnimation.
static already_AddRefed<CSSAnimation> BuildAnimation(
nsPresContext* aPresContext, const NonOwningAnimationTarget& aTarget,
const nsStyleUIReset& aStyle, uint32_t animIdx,
ServoCSSAnimationBuilder& aBuilder,
nsAnimationManager::CSSAnimationCollection* aCollection) {
nsAtom* animationName = aStyle.GetAnimationName(animIdx);
nsTArray<Keyframe> keyframes;
if (!aBuilder.BuildKeyframes(*aTarget.mElement, aPresContext, animationName,
keyframes)) {
return nullptr;
TimingParams timing = TimingParamsFromCSSParams(
bool isStylePaused =
aStyle.GetAnimationPlayState(animIdx) == StyleAnimationPlayState::Paused;
RefPtr<dom::AnimationTimeline> timeline =
GetTimeline(aStyle.GetTimeline(animIdx), aPresContext, aTarget);
// Find the matching animation with animation name in the old list
// of animations and remove the matched animation from the list.
RefPtr<CSSAnimation> oldAnim =
PopExistingAnimation(animationName, aCollection);
const auto composition = StyleToDom(aStyle.GetAnimationComposition(animIdx));
if (oldAnim) {
// Copy over the start times and (if still paused) pause starts
// for each animation (matching on name only) that was also in the
// old list of animations.
// This means that we honor dynamic changes, which isn't what the
// spec says to do, but WebKit seems to honor at least some of
// them. See
// In order to honor what the spec said, we'd copy more data over.
*oldAnim, std::move(timing), std::move(keyframes), isStylePaused,
oldAnim->GetOverriddenProperties(), aBuilder, timeline, composition);
return oldAnim.forget();
KeyframeEffectParams effectOptions(composition);
auto effect = MakeRefPtr<dom::CSSAnimationKeyframeEffect>(
OwningAnimationTarget(aTarget.mElement, aTarget.mPseudoType),
std::move(timing), effectOptions);
aBuilder.SetKeyframes(*effect, std::move(keyframes), timeline);
auto animation = MakeRefPtr<CSSAnimation>(
aPresContext->Document()->GetScopeObject(), animationName);
OwningElementRef(*aTarget.mElement, aTarget.mPseudoType));
if (isStylePaused) {
} else {
return animation.forget();
static nsAnimationManager::OwningCSSAnimationPtrArray BuildAnimations(
nsPresContext* aPresContext, const NonOwningAnimationTarget& aTarget,
const nsStyleUIReset& aStyle, ServoCSSAnimationBuilder& aBuilder,
nsAnimationManager::CSSAnimationCollection* aCollection,
nsTHashSet<RefPtr<nsAtom>>& aReferencedAnimations) {
nsAnimationManager::OwningCSSAnimationPtrArray result;
for (size_t animIdx = aStyle.mAnimationNameCount; animIdx-- != 0;) {
nsAtom* name = aStyle.GetAnimationName(animIdx);
// CSS Animations whose animation-name does not match a @keyframes rule do
// not generate animation events. This includes when the animation-name is
// "none" which is represented by an empty name in the StyleAnimation.
// Since such animations neither affect style nor dispatch events, we do
// not generate a corresponding CSSAnimation for them.
if (name == nsGkAtoms::_empty) {
RefPtr<CSSAnimation> dest = BuildAnimation(aPresContext, aTarget, aStyle,
animIdx, aBuilder, aCollection);
if (!dest) {
return result;
void nsAnimationManager::UpdateAnimations(dom::Element* aElement,
PseudoStyleType aPseudoType,
const ComputedStyle* aComputedStyle) {
"Should not update animations for print or print preview");
"Should not update animations that are not attached to the "
"document tree");
if (!aComputedStyle ||
aComputedStyle->StyleDisplay()->mDisplay == StyleDisplay::None) {
// If we are in a display:none subtree we will have no computed values.
// However, if we are on the root of display:none subtree, the computed
// values might not have been cleared yet.
// In either case, since CSS animations should not run in display:none
// subtrees we should stop (actually, destroy) any animations on this
// element here.
StopAnimationsForElement(aElement, aPseudoType);
NonOwningAnimationTarget target(aElement, aPseudoType);
ServoCSSAnimationBuilder builder(aComputedStyle);
DoUpdateAnimations(target, *aComputedStyle->StyleUIReset(), builder);
void nsAnimationManager::DoUpdateAnimations(
const NonOwningAnimationTarget& aTarget, const nsStyleUIReset& aStyle,
ServoCSSAnimationBuilder& aBuilder) {
// Everything that causes our animation data to change triggers a
// style change, which in turn triggers a non-animation restyle.
// Likewise, when we initially construct frames, we're not in a
// style change, but also not in an animation restyle.
auto* collection =
CSSAnimationCollection::Get(aTarget.mElement, aTarget.mPseudoType);
if (!collection && aStyle.mAnimationNameCount == 1 &&
aStyle.mAnimations[0].GetName() == nsGkAtoms::_empty) {
nsAutoAnimationMutationBatch mb(aTarget.mElement->OwnerDoc());
// Build the updated animations list, extracting matching animations from
// the existing collection as we go.
OwningCSSAnimationPtrArray newAnimations =
BuildAnimations(mPresContext, aTarget, aStyle, aBuilder, collection,
if (newAnimations.IsEmpty()) {
if (collection) {
if (!collection) {
collection =
*aTarget.mElement, aTarget.mPseudoType);
if (!collection->isInList()) {
// Cancel removed animations
for (size_t newAnimIdx = newAnimations.Length(); newAnimIdx-- != 0;) {