gecko-dev/dom/animation/AnimationTimeline.h

/* -*- 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 mozilla_dom_AnimationTimeline_h
#define mozilla_dom_AnimationTimeline_h

#include "nsISupports.h"
#include "nsWrapperCache.h"
#include "nsCycleCollectionParticipant.h"
#include "js/TypeDecls.h"
#include "mozilla/AnimationUtils.h"
#include "mozilla/Attributes.h"
#include "nsHashKeys.h"
#include "nsIGlobalObject.h"
#include "nsTHashtable.h"

// GetCurrentTime is defined in winbase.h as zero argument macro forwarding to
// GetTickCount().
#ifdef GetCurrentTime
#undef GetCurrentTime
#endif

namespace mozilla {
namespace dom {

class Animation;

class AnimationTimeline
  : public nsISupports
  , public nsWrapperCache
{
public:
  explicit AnimationTimeline(nsIGlobalObject* aWindow)
    : mWindow(aWindow)
  {
    MOZ_ASSERT(mWindow);
  }

protected:
  virtual ~AnimationTimeline()
  {
    mAnimationOrder.clear();
  }

public:
  NS_DECL_CYCLE_COLLECTING_ISUPPORTS
  NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(AnimationTimeline)

  nsIGlobalObject* GetParentObject() const { return mWindow; }

  // AnimationTimeline methods
  virtual Nullable<TimeDuration> GetCurrentTime() const = 0;

  // Wrapper functions for AnimationTimeline DOM methods when called from
  // script.
  Nullable<double> GetCurrentTimeAsDouble() const {
    return AnimationUtils::TimeDurationToDouble(GetCurrentTime());
  }

  /**
   * Returns true if the times returned by GetCurrentTime() are convertible
   * to and from wallclock-based TimeStamp (e.g. from TimeStamp::Now()) values
   * using ToTimelineTime() and ToTimeStamp().
   *
   * Typically this is true, but it will be false in the case when this
   * timeline has no refresh driver or is tied to a refresh driver under test
   * control.
   */
  virtual bool TracksWallclockTime() const = 0;

  /**
   * Converts a TimeStamp to the equivalent value in timeline time.
   * Note that when TracksWallclockTime() is false, there is no correspondence
   * between timeline time and wallclock time. In such a case, passing a
   * timestamp from TimeStamp::Now() to this method will not return a
   * meaningful result.
   */
  virtual Nullable<TimeDuration> ToTimelineTime(const TimeStamp&
                                                  aTimeStamp) const = 0;

  virtual TimeStamp ToTimeStamp(const TimeDuration& aTimelineTime) const = 0;

  /**
   * Inform this timeline that |aAnimation| which is or was observing the
   * timeline, has been updated. This serves as both the means to associate
   * AND disassociate animations with a timeline. The timeline itself will
   * determine if it needs to begin, continue or stop tracking this animation.
   */
  virtual void NotifyAnimationUpdated(Animation& aAnimation);

  /**
   * Returns true if any CSS animations, CSS transitions or Web animations are
   * currently associated with this timeline.  As soon as an animation is
   * applied to an element it is associated with the timeline even if it has a
   * delayed start, so this includes animations that may not be active for some
   * time.
   */
  bool HasAnimations() const {
    return !mAnimations.IsEmpty();
  }

  void RemoveAnimation(Animation* aAnimation);

protected:
  nsCOMPtr<nsIGlobalObject> mWindow;

  // Animations observing this timeline
  //
  // We store them in (a) a hashset for quick lookup, and (b) an array
  // to maintain a fixed sampling order.
  //
  // The hashset keeps a strong reference to each animation since
  // dealing with addref/release with LinkedList is difficult.
  typedef nsTHashtable<nsRefPtrHashKey<dom::Animation>> AnimationSet;
  AnimationSet mAnimations;
  LinkedList<dom::Animation> mAnimationOrder;
};

} // namespace dom
} // namespace mozilla

#endif // mozilla_dom_AnimationTimeline_h