gecko-dev/layout/style/AnimationCommon.h

/* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
/* 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_css_AnimationCommon_h
#define mozilla_css_AnimationCommon_h

#include <algorithm> // For <std::stable_sort>
#include "nsChangeHint.h"
#include "nsCSSProperty.h"
#include "nsDisplayList.h" // For nsDisplayItem::Type
#include "mozilla/AnimationComparator.h"
#include "mozilla/EventDispatcher.h"
#include "mozilla/LinkedList.h"
#include "mozilla/MemoryReporting.h"
#include "mozilla/StyleAnimationValue.h"
#include "mozilla/dom/Animation.h"
#include "mozilla/dom/Element.h"
#include "mozilla/dom/Nullable.h"
#include "mozilla/Attributes.h"
#include "mozilla/Assertions.h"
#include "mozilla/FloatingPoint.h"
#include "nsContentUtils.h"
#include "nsCSSPseudoElements.h"
#include "nsCycleCollectionParticipant.h"

class nsIFrame;
class nsPresContext;

namespace mozilla {

struct AnimationCollection;

class CommonAnimationManager {
public:
  explicit CommonAnimationManager(nsPresContext *aPresContext);

  // NOTE:  This can return null after Disconnect().
  nsPresContext* PresContext() const { return mPresContext; }

  /**
   * Notify the manager that the pres context is going away.
   */
  void Disconnect();

  // Returns true if aContent or any of its ancestors has an animation
  // or transition.
  static bool ContentOrAncestorHasAnimation(nsIContent* aContent) {
    do {
      if (aContent->GetProperty(nsGkAtoms::animationsProperty) ||
          aContent->GetProperty(nsGkAtoms::transitionsProperty)) {
        return true;
      }
    } while ((aContent = aContent->GetParent()));

    return false;
  }

  static bool ExtractComputedValueForTransition(
                  nsCSSProperty aProperty,
                  nsStyleContext* aStyleContext,
                  StyleAnimationValue& aComputedValue);

  virtual bool IsAnimationManager() {
    return false;
  }

protected:
  virtual ~CommonAnimationManager();

  void AddElementCollection(AnimationCollection* aCollection);
  void RemoveAllElementCollections();

  bool NeedsRefresh() const;

  virtual nsIAtom* GetAnimationsAtom() = 0;
  virtual nsIAtom* GetAnimationsBeforeAtom() = 0;
  virtual nsIAtom* GetAnimationsAfterAtom() = 0;

public:
  // Get (and optionally create) the collection of animations managed
  // by this class for the given |aElement| and |aPseudoType|.
  AnimationCollection*
  GetAnimationCollection(dom::Element *aElement,
                         nsCSSPseudoElements::Type aPseudoType,
                         bool aCreateIfNeeded);

  // Given the frame |aFrame| with possibly animated content, finds its
  // associated collection of animations. If it is a generated content
  // frame, it may examine the parent frame to search for such animations.
  AnimationCollection*
  GetAnimationCollection(const nsIFrame* aFrame);

protected:
  LinkedList<AnimationCollection> mElementCollections;
  nsPresContext *mPresContext; // weak (non-null from ctor to Disconnect)
};

typedef InfallibleTArray<RefPtr<dom::Animation>> AnimationPtrArray;

struct AnimationCollection : public LinkedListElement<AnimationCollection>
{
  AnimationCollection(dom::Element *aElement, nsIAtom *aElementProperty,
                      CommonAnimationManager *aManager)
    : mElement(aElement)
    , mElementProperty(aElementProperty)
    , mManager(aManager)
    , mCheckGeneration(0)
#ifdef DEBUG
    , mCalledPropertyDtor(false)
#endif
  {
    MOZ_COUNT_CTOR(AnimationCollection);
  }
  ~AnimationCollection()
  {
    MOZ_ASSERT(mCalledPropertyDtor,
               "must call destructor through element property dtor");
    MOZ_COUNT_DTOR(AnimationCollection);
    remove();
  }

  void Destroy()
  {
    // This will call our destructor.
    mElement->DeleteProperty(mElementProperty);
  }

  static void PropertyDtor(void *aObject, nsIAtom *aPropertyName,
                           void *aPropertyValue, void *aData);

  void Tick();

public:
  // True if this animation can be performed on the compositor thread.
  //
  // Returns whether the state of this element's animations at the current
  // refresh driver time contains animation data that can be done on the
  // compositor thread.  (This is used for determining whether a layer
  // should be active, or whether to send data to the layer.)
  //
  // Note that this does not test whether the element's layer uses
  // off-main-thread compositing, although it does check whether
  // off-main-thread compositing is enabled as a whole.
  bool CanPerformOnCompositorThread(const nsIFrame* aFrame) const;

  bool HasCurrentAnimationOfProperty(nsCSSProperty aProperty) const;

  bool IsForElement() const { // rather than for a pseudo-element
    return mElementProperty == nsGkAtoms::animationsProperty ||
           mElementProperty == nsGkAtoms::transitionsProperty;
  }

  bool IsForBeforePseudo() const {
    return mElementProperty == nsGkAtoms::animationsOfBeforeProperty ||
           mElementProperty == nsGkAtoms::transitionsOfBeforeProperty;
  }

  bool IsForAfterPseudo() const {
    return mElementProperty == nsGkAtoms::animationsOfAfterProperty ||
           mElementProperty == nsGkAtoms::transitionsOfAfterProperty;
  }

  bool IsForTransitions() const {
    return mElementProperty == nsGkAtoms::transitionsProperty ||
           mElementProperty == nsGkAtoms::transitionsOfBeforeProperty ||
           mElementProperty == nsGkAtoms::transitionsOfAfterProperty;
  }

  bool IsForAnimations() const {
    return mElementProperty == nsGkAtoms::animationsProperty ||
           mElementProperty == nsGkAtoms::animationsOfBeforeProperty ||
           mElementProperty == nsGkAtoms::animationsOfAfterProperty;
  }

  nsCSSPseudoElements::Type PseudoElementType() const
  {
    if (IsForElement()) {
      return nsCSSPseudoElements::ePseudo_NotPseudoElement;
    }
    if (IsForBeforePseudo()) {
      return nsCSSPseudoElements::ePseudo_before;
    }
    MOZ_ASSERT(IsForAfterPseudo(),
               "::before & ::after should be the only pseudo-elements here");
    return nsCSSPseudoElements::ePseudo_after;
  }

  static nsString PseudoTypeAsString(nsCSSPseudoElements::Type aPseudoType);

  dom::Element* GetElementToRestyle() const;

  dom::Element *mElement;

  // the atom we use in mElement's prop table (must be a static atom,
  // i.e., in an atom list)
  nsIAtom *mElementProperty;

  CommonAnimationManager *mManager;

  AnimationPtrArray mAnimations;

  // For CSS transitions only, we record the most recent generation
  // for which we've done the transition update, so that we avoid doing
  // it more than once per style change.
  // (Note that we also store an animation generation on each EffectSet in
  // order to track when we need to update animations on layers.)
  uint64_t mCheckGeneration;
  // Update mCheckGeneration to RestyleManager's count
  void UpdateCheckGeneration(nsPresContext* aPresContext);

private:
#ifdef DEBUG
  bool mCalledPropertyDtor;
#endif
};

/**
 * Utility class for referencing the element that created a CSS animation or
 * transition. It is non-owning (i.e. it uses a raw pointer) since it is only
 * expected to be set by the owned animation while it actually being managed
 * by the owning element.
 *
 * This class also abstracts the comparison of an element/pseudo-class pair
 * for the sake of composite ordering since this logic is common to both CSS
 * animations and transitions.
 *
 * (We call this OwningElementRef instead of just OwningElement so that we can
 * call the getter on CSSAnimation/CSSTransition OwningElement() without
 * clashing with this object's contructor.)
 */
class OwningElementRef final
{
public:
  OwningElementRef()
    : mElement(nullptr)
    , mPseudoType(nsCSSPseudoElements::ePseudo_NotPseudoElement)
  { }

  OwningElementRef(dom::Element& aElement,
                   nsCSSPseudoElements::Type aPseudoType)
    : mElement(&aElement)
    , mPseudoType(aPseudoType)
  { }

  bool Equals(const OwningElementRef& aOther) const
  {
    return mElement == aOther.mElement &&
           mPseudoType == aOther.mPseudoType;
  }

  bool LessThan(const OwningElementRef& aOther) const
  {
    MOZ_ASSERT(mElement && aOther.mElement,
               "Elements to compare should not be null");

    if (mElement != aOther.mElement) {
      return nsContentUtils::PositionIsBefore(mElement, aOther.mElement);
    }

    return mPseudoType == nsCSSPseudoElements::ePseudo_NotPseudoElement ||
          (mPseudoType == nsCSSPseudoElements::ePseudo_before &&
           aOther.mPseudoType == nsCSSPseudoElements::ePseudo_after);
  }

  bool IsSet() const { return !!mElement; }

  void GetElement(dom::Element*& aElement,
                  nsCSSPseudoElements::Type& aPseudoType) const {
    aElement = mElement;
    aPseudoType = mPseudoType;
  }

  nsPresContext* GetRenderedPresContext() const;

private:
  dom::Element* MOZ_NON_OWNING_REF mElement;
  nsCSSPseudoElements::Type        mPseudoType;
};

template <class EventInfo>
class DelayedEventDispatcher
{
public:
  DelayedEventDispatcher() : mIsSorted(true) { }

  void QueueEvent(EventInfo&& aEventInfo)
  {
    mPendingEvents.AppendElement(Forward<EventInfo>(aEventInfo));
    mIsSorted = false;
  }

  // This is exposed as a separate method so that when we are dispatching
  // *both* transition events and animation events we can sort both lists
  // once using the current state of the document before beginning any
  // dispatch.
  void SortEvents()
  {
    if (mIsSorted) {
      return;
    }

    // FIXME: Replace with mPendingEvents.StableSort when bug 1147091 is
    // fixed.
    std::stable_sort(mPendingEvents.begin(), mPendingEvents.end(),
                     EventInfoLessThan());
    mIsSorted = true;
  }

  // Takes a reference to the owning manager's pres context so it can
  // detect if the pres context is destroyed while dispatching one of
  // the events.
  //
  // This will call SortEvents automatically if it has not already been
  // called.
  void DispatchEvents(nsPresContext* const & aPresContext)
  {
    if (!aPresContext || mPendingEvents.IsEmpty()) {
      return;
    }

    SortEvents();

    EventArray events;
    mPendingEvents.SwapElements(events);
    // mIsSorted will be set to true by SortEvents above, and we leave it
    // that way since mPendingEvents is now empty
    for (EventInfo& info : events) {
      EventDispatcher::Dispatch(info.mElement, aPresContext, &info.mEvent);

      if (!aPresContext) {
        break;
      }
    }
  }

  void ClearEventQueue()
  {
    mPendingEvents.Clear();
    mIsSorted = true;
  }
  bool HasQueuedEvents() const { return !mPendingEvents.IsEmpty(); }

  // Methods for supporting cycle-collection
  void Traverse(nsCycleCollectionTraversalCallback* aCallback,
                const char* aName)
  {
    for (EventInfo& info : mPendingEvents) {
      ImplCycleCollectionTraverse(*aCallback, info.mElement, aName);
      ImplCycleCollectionTraverse(*aCallback, info.mAnimation, aName);
    }
  }
  void Unlink() { ClearEventQueue(); }

protected:
  class EventInfoLessThan
  {
  public:
    bool operator()(const EventInfo& a, const EventInfo& b) const
    {
      if (a.mTimeStamp != b.mTimeStamp) {
        // Null timestamps sort first
        if (a.mTimeStamp.IsNull() || b.mTimeStamp.IsNull()) {
          return a.mTimeStamp.IsNull();
        } else {
          return a.mTimeStamp < b.mTimeStamp;
        }
      }

      AnimationPtrComparator<RefPtr<dom::Animation>> comparator;
      return comparator.LessThan(a.mAnimation, b.mAnimation);
    }
  };

  typedef nsTArray<EventInfo> EventArray;
  EventArray mPendingEvents;
  bool mIsSorted;
};

template <class EventInfo>
inline void
ImplCycleCollectionUnlink(DelayedEventDispatcher<EventInfo>& aField)
{
  aField.Unlink();
}

template <class EventInfo>
inline void
ImplCycleCollectionTraverse(nsCycleCollectionTraversalCallback& aCallback,
                            DelayedEventDispatcher<EventInfo>& aField,
                            const char* aName,
                            uint32_t aFlags = 0)
{
  aField.Traverse(&aCallback, aName);
}

} // namespace mozilla

#endif /* !defined(mozilla_css_AnimationCommon_h) */