Source code

Revision control

Copy as Markdown

Other Tools

/* -*- 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 "mozilla/Attributes.h"
#include "mozilla/SMILCompositorTable.h"
#include "mozilla/SMILMilestone.h"
#include "mozilla/SMILTimeContainer.h"
#include "mozilla/UniquePtr.h"
#include "nsCOMPtr.h"
#include "nsTArray.h"
#include "nsTHashtable.h"
#include "nsHashKeys.h"
#include "nsRefreshObservers.h"
class nsRefreshDriver;
namespace mozilla {
struct SMILTargetIdentifier;
namespace dom {
class Element;
class SVGAnimationElement;
} // namespace dom
// SMILAnimationController
// The animation controller maintains the animation timer and determines the
// sample times and sample rate for all SMIL animations in a document. There is
// at most one animation controller per document so that frame-rate tuning can
// be performed at a document-level.
// The animation controller can contain many child time containers (timed
// document root objects) which may correspond to SVG document fragments within
// a compound document. These time containers can be paused individually or
// here, at the document level.
class SMILAnimationController final : public SMILTimeContainer,
public nsARefreshObserver {
explicit SMILAnimationController(mozilla::dom::Document* aDoc);
// Clears mDocument pointer. (Called by our mozilla::dom::Document when it's
// going away)
void Disconnect();
// SMILContainer
void Pause(uint32_t aType) override;
void Resume(uint32_t aType) override;
SMILTime GetParentTime() const override;
// nsARefreshObserver
NS_IMETHOD_(MozExternalRefCountType) AddRef() override;
NS_IMETHOD_(MozExternalRefCountType) Release() override;
void WillRefresh(mozilla::TimeStamp aTime) override;
// Methods for registering and enumerating animation elements
void RegisterAnimationElement(
mozilla::dom::SVGAnimationElement* aAnimationElement);
void UnregisterAnimationElement(
mozilla::dom::SVGAnimationElement* aAnimationElement);
// Methods for resampling all animations
// (A resample performs the same operations as a sample but doesn't advance
// the current time and doesn't check if the container is paused)
// This will flush pending style changes for the document.
void Resample() { DoSample(false); }
void SetResampleNeeded() {
if (!mRunningSample && !mResampleNeeded) {
mResampleNeeded = true;
// This will flush pending style changes for the document.
void FlushResampleRequests() {
if (!mResampleNeeded) return;
// Methods for handling page transitions
void OnPageShow();
void OnPageHide();
// Methods for supporting cycle-collection
void Traverse(nsCycleCollectionTraversalCallback* aCallback);
void Unlink();
// Methods for relaying the availability of the refresh driver
void NotifyRefreshDriverCreated(nsRefreshDriver* aRefreshDriver);
void NotifyRefreshDriverDestroying(nsRefreshDriver* aRefreshDriver);
// Helper to check if we have any animation elements at all
bool HasRegisteredAnimations() const {
return mAnimationElementTable.Count() != 0;
bool MightHavePendingStyleUpdates() const {
return mMightHavePendingStyleUpdates;
void PreTraverse();
void PreTraverseInSubtree(mozilla::dom::Element* aRoot);
// alias declarations
using TimeContainerPtrKey = nsPtrHashKey<SMILTimeContainer>;
using TimeContainerHashtable = nsTHashtable<TimeContainerPtrKey>;
using AnimationElementPtrKey = nsPtrHashKey<dom::SVGAnimationElement>;
using AnimationElementHashtable = nsTHashtable<AnimationElementPtrKey>;
// Returns mDocument's refresh driver, if it's got one.
nsRefreshDriver* GetRefreshDriver();
// Methods for controlling whether we're sampling
void UpdateSampling();
bool ShouldSample() const;
void StopSampling(nsRefreshDriver* aRefreshDriver);
// Wrapper for StartSampling that defers if no animations are registered.
void MaybeStartSampling(nsRefreshDriver* aRefreshDriver);
// Sample-related callbacks and implementation helpers
void DoSample() override;
void DoSample(bool aSkipUnchangedContainers);
void RewindElements();
void DoMilestoneSamples();
static void SampleTimedElement(mozilla::dom::SVGAnimationElement* aElement,
TimeContainerHashtable* aActiveContainers);
static void AddAnimationToCompositorTable(
mozilla::dom::SVGAnimationElement* aElement,
SMILCompositorTable* aCompositorTable);
static bool GetTargetIdentifierForAnimation(
mozilla::dom::SVGAnimationElement* aAnimElem,
SMILTargetIdentifier& aResult);
// Methods for adding/removing time containers
nsresult AddChild(SMILTimeContainer& aChild) override;
void RemoveChild(SMILTimeContainer& aChild) override;
void FlagDocumentNeedsFlush();
// Members
nsAutoRefCnt mRefCnt;
AnimationElementHashtable mAnimationElementTable;
TimeContainerHashtable mChildContainerTable;
mozilla::TimeStamp mCurrentSampleTime;
mozilla::TimeStamp mStartTime;
// Average time between samples from the refresh driver. This is used to
// detect large unexpected gaps between samples such as can occur when the
// computer sleeps. The nature of the SMIL model means that catching up these
// large gaps can be expensive as, for example, many events may need to be
// dispatched for the intervening time when no samples were received.
// In such cases, we ignore the intervening gap and continue sampling from
// when we were expecting the next sample to arrive.
// Note that we only do this for SMIL and not CSS transitions (which doesn't
// have so much work to do to catch up) nor scripted animations (which expect
// animation time to follow real time).
// This behaviour does not affect pausing (since we're not *expecting* any
// samples then) nor seeking (where the SMIL model behaves somewhat
// differently such as not dispatching events).
SMILTime mAvgTimeBetweenSamples = 0;
bool mResampleNeeded = false;
bool mRunningSample = false;
// Are we registered with our document's refresh driver?
bool mRegisteredWithRefreshDriver = false;
// Have we updated animated values without adding them to the restyle tracker?
bool mMightHavePendingStyleUpdates = false;
// Store raw ptr to mDocument. It owns the controller, so controller
// shouldn't outlive it
mozilla::dom::Document* mDocument;
// Contains compositors used in our last sample. We keep this around
// so we can detect when an element/attribute used to be animated,
// but isn't anymore for some reason. (e.g. if its <animate> element is
// removed or retargeted)
UniquePtr<SMILCompositorTable> mLastCompositorTable;
} // namespace mozilla