SMILAnimationController.h

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

#ifndef DOM_SMIL_SMILANIMATIONCONTROLLER_H_

#define DOM_SMIL_SMILANIMATIONCONTROLLER_H_

#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 {

 public:

  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) {

      FlagDocumentNeedsFlush();

      mResampleNeeded = true;

  // This will flush pending style changes for the document.

  void FlushResampleRequests() {

    if (!mResampleNeeded) return;

    Resample();

  // 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);

 protected:

  ~SMILAnimationController();

  // 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;

  NS_DECL_OWNINGTHREAD

  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

#endif  // DOM_SMIL_SMILANIMATIONCONTROLLER_H_