gecko-dev/layout/base/RestyleManager.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_RestyleManager_h
#define mozilla_RestyleManager_h

#include "mozilla/OverflowChangedTracker.h"
#include "nsChangeHint.h"
#include "nsPresContext.h"
#include "nsStringFwd.h"

class nsCSSFrameConstructor;
class nsStyleChangeList;

namespace mozilla {

class EventStates;
class GeckoRestyleManager;
class ServoRestyleManager;

namespace dom {
class Element;
}

/**
 * Class for sharing data and logic common to both GeckoRestyleManager and
 * ServoRestyleManager.
 */
class RestyleManager
{
public:
  typedef mozilla::dom::Element Element;

  NS_INLINE_DECL_REFCOUNTING(mozilla::RestyleManager)

  // Get an integer that increments every time we process pending restyles.
  // The value is never 0.
  uint64_t GetRestyleGeneration() const { return mRestyleGeneration; }
  // Unlike GetRestyleGeneration, which means the actual restyling count,
  // GetUndisplayedRestyleGeneration represents any possible DOM changes that
  // can cause restyling. This is needed for getComputedStyle to work with
  // non-styled (e.g. display: none) elements.
  uint64_t GetUndisplayedRestyleGeneration() const {
    return mUndisplayedRestyleGeneration;
  }

  // Get an integer that increments every time there is a style change
  // as a result of a change to the :hover content state.
  uint32_t GetHoverGeneration() const { return mHoverGeneration; }

  void Disconnect() { mPresContext = nullptr; }

  static nsCString RestyleHintToString(nsRestyleHint aHint);

#ifdef DEBUG
  static nsCString ChangeHintToString(nsChangeHint aHint);

  /**
   * DEBUG ONLY method to verify integrity of style tree versus frame tree
   */
  void DebugVerifyStyleTree(nsIFrame* aFrame);
#endif

  void FlushOverflowChangedTracker() {
    mOverflowChangedTracker.Flush();
  }

  // Should be called when a frame is going to be destroyed and
  // WillDestroyFrameTree hasn't been called yet.
  void NotifyDestroyingFrame(nsIFrame* aFrame) {
    mOverflowChangedTracker.RemoveFrame(aFrame);
    // If ProcessRestyledFrames is tracking frames which have been
    // destroyed (to avoid re-visiting them), add this one to its set.
    if (mDestroyedFrames) {
      mDestroyedFrames->PutEntry(aFrame);
    }
  }

  // Note: It's the caller's responsibility to make sure to wrap a
  // ProcessRestyledFrames call in a view update batch and a script blocker.
  // This function does not call ProcessAttachedQueue() on the binding manager.
  // If the caller wants that to happen synchronously, it needs to handle that
  // itself.
  void ProcessRestyledFrames(nsStyleChangeList& aChangeList);

  bool IsInStyleRefresh() const { return mInStyleRefresh; }

  // AnimationsWithDestroyedFrame is used to stop animations and transitions
  // on elements that have no frame at the end of the restyling process.
  // It only lives during the restyling process.
  class MOZ_STACK_CLASS AnimationsWithDestroyedFrame final {
  public:
    // Construct a AnimationsWithDestroyedFrame object.  The caller must
    // ensure that aRestyleManager lives at least as long as the
    // object.  (This is generally easy since the caller is typically a
    // method of RestyleManager.)
    explicit AnimationsWithDestroyedFrame(RestyleManager* aRestyleManager);

    // This method takes the content node for the generated content for
    // animation/transition on ::before and ::after, rather than the
    // content node for the real element.
    void Put(nsIContent* aContent, ComputedStyle* aComputedStyle) {
      MOZ_ASSERT(aContent);
      CSSPseudoElementType pseudoType = aComputedStyle->GetPseudoType();
      if (pseudoType == CSSPseudoElementType::NotPseudo) {
        mContents.AppendElement(aContent);
      } else if (pseudoType == CSSPseudoElementType::before) {
        MOZ_ASSERT(aContent->NodeInfo()->NameAtom() ==
                     nsGkAtoms::mozgeneratedcontentbefore);
        mBeforeContents.AppendElement(aContent->GetParent());
      } else if (pseudoType == CSSPseudoElementType::after) {
        MOZ_ASSERT(aContent->NodeInfo()->NameAtom() ==
                     nsGkAtoms::mozgeneratedcontentafter);
        mAfterContents.AppendElement(aContent->GetParent());
      }
    }

    void StopAnimationsForElementsWithoutFrames();

  private:
    void StopAnimationsWithoutFrame(nsTArray<RefPtr<nsIContent>>& aArray,
                                    CSSPseudoElementType aPseudoType);

    RestyleManager* mRestyleManager;
    AutoRestore<AnimationsWithDestroyedFrame*> mRestorePointer;

    // Below three arrays might include elements that have already had their
    // animations or transitions stopped.
    //
    // mBeforeContents and mAfterContents hold the real element rather than
    // the content node for the generated content (which might change during
    // a reframe)
    nsTArray<RefPtr<nsIContent>> mContents;
    nsTArray<RefPtr<nsIContent>> mBeforeContents;
    nsTArray<RefPtr<nsIContent>> mAfterContents;
  };

  /**
   * Return the current AnimationsWithDestroyedFrame struct, or null if we're
   * not currently in a restyling operation.
   */
  AnimationsWithDestroyedFrame* GetAnimationsWithDestroyedFrame() {
    return mAnimationsWithDestroyedFrame;
  }

  void ContentInserted(nsIContent* aChild);
  void ContentAppended(nsIContent* aFirstNewContent);

  // This would be have the same logic as RestyleForInsertOrChange if we got the
  // notification before the removal.  However, we get it after, so we need the
  // following sibling in addition to the old child.
  //
  // aFollowingSibling is the sibling that used to come after aOldChild before
  // the removal.
  void ContentRemoved(nsIContent* aOldChild, nsIContent* aFollowingSibling);

  // Restyling for a ContentInserted (notification after insertion) or
  // for some CharacterDataChanged.
  void RestyleForInsertOrChange(nsIContent* aChild);

  // Restyle for a CharacterDataChanged notification. In practice this can only
  // affect :empty / :-moz-only-whitespace / :-moz-first-node / :-moz-last-node.
  void CharacterDataChanged(nsIContent*, const CharacterDataChangeInfo&);

  MOZ_DECL_STYLO_METHODS(GeckoRestyleManager, ServoRestyleManager)

  inline void PostRestyleEvent(dom::Element* aElement,
                               nsRestyleHint aRestyleHint,
                               nsChangeHint aMinChangeHint);
  inline void RebuildAllStyleData(nsChangeHint aExtraHint,
                                  nsRestyleHint aRestyleHint);
  inline void PostRebuildAllStyleDataEvent(nsChangeHint aExtraHint,
                                           nsRestyleHint aRestyleHint);
  inline void ProcessPendingRestyles();
  inline void ContentStateChanged(nsIContent* aContent,
                                  EventStates aStateMask);
  inline void AttributeWillChange(dom::Element* aElement,
                                  int32_t aNameSpaceID,
                                  nsAtom* aAttribute,
                                  int32_t aModType,
                                  const nsAttrValue* aNewValue);
  inline void AttributeChanged(dom::Element* aElement,
                               int32_t aNameSpaceID,
                               nsAtom* aAttribute,
                               int32_t aModType,
                               const nsAttrValue* aOldValue);
  inline nsresult ReparentComputedStyle(nsIFrame* aFrame);

  inline void UpdateOnlyAnimationStyles();

  // Get a counter that increments on every style change, that we use to
  // track whether off-main-thread animations are up-to-date.
  uint64_t GetAnimationGeneration() const { return mAnimationGeneration; }

  static uint64_t GetAnimationGenerationForFrame(nsIFrame* aFrame);

  // Update the animation generation count to mark that animation state
  // has changed.
  //
  // This is normally performed automatically by ProcessPendingRestyles
  // but it is also called when we have out-of-band changes to animations
  // such as changes made through the Web Animations API.
  void IncrementAnimationGeneration();

  static void AddLayerChangesForAnimation(nsIFrame* aFrame,
                                          nsIContent* aContent,
                                          nsStyleChangeList&
                                            aChangeListToProcess);

protected:
  explicit RestyleManager(nsPresContext* aPresContext);

  virtual ~RestyleManager()
  {
    MOZ_ASSERT(!mAnimationsWithDestroyedFrame,
               "leaving dangling pointers from AnimationsWithDestroyedFrame");
  }

  void RestyleForEmptyChange(Element* aContainer);
  void MaybeRestyleForEdgeChildChange(Element* aContainer, nsIContent* aChangedChild);

  void ContentStateChangedInternal(Element* aElement,
                                   EventStates aStateMask,
                                   nsChangeHint* aOutChangeHint);

  bool IsDisconnected() { return mPresContext == nullptr; }

  void IncrementHoverGeneration() {
    ++mHoverGeneration;
  }

  void IncrementRestyleGeneration() {
    if (++mRestyleGeneration == 0) {
      // Keep mRestyleGeneration from being 0, since that's what
      // nsPresContext::GetRestyleGeneration returns when it no
      // longer has a RestyleManager.
      ++mRestyleGeneration;
    }
    IncrementUndisplayedRestyleGeneration();
  }

  void IncrementUndisplayedRestyleGeneration() {
    if (++mUndisplayedRestyleGeneration == 0) {
      // Ensure mUndisplayedRestyleGeneration > 0, for the same reason as
      // IncrementRestyleGeneration.
      ++mUndisplayedRestyleGeneration;
    }
  }

  nsPresContext* PresContext() const {
    MOZ_ASSERT(mPresContext);
    return mPresContext;
  }

  nsCSSFrameConstructor* FrameConstructor() const {
    return PresContext()->FrameConstructor();
  }

private:
  nsPresContext* mPresContext; // weak, can be null after Disconnect().
  uint64_t mRestyleGeneration;
  uint64_t mUndisplayedRestyleGeneration;
  uint32_t mHoverGeneration;

  // Used to keep track of frames that have been destroyed during
  // ProcessRestyledFrames, so we don't try to touch them again even if
  // they're referenced again later in the changelist.
  mozilla::UniquePtr<nsTHashtable<nsPtrHashKey<const nsIFrame>>> mDestroyedFrames;

protected:
  // True if we're in the middle of a nsRefreshDriver refresh
  bool mInStyleRefresh;

  // The total number of animation flushes by this frame constructor.
  // Used to keep the layer and animation manager in sync.
  uint64_t mAnimationGeneration;

  OverflowChangedTracker mOverflowChangedTracker;

  AnimationsWithDestroyedFrame* mAnimationsWithDestroyedFrame = nullptr;

  friend class mozilla::GeckoRestyleManager;
  friend class mozilla::ServoRestyleManager;
};

} // namespace mozilla

#endif