gecko-dev/layout/base/RestyleTracker.h

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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* 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/. */
/**
* A class which manages pending restyles. This handles keeping track
* of what nodes restyles need to happen on and so forth.
*/
#ifndef mozilla_RestyleTracker_h
#define mozilla_RestyleTracker_h
#include "mozilla/dom/Element.h"
#include "mozilla/OverflowChangedTracker.h"
#include "nsAutoPtr.h"
#include "nsClassHashtable.h"
#include "nsContainerFrame.h"
#include "nsIContentInlines.h"
#include "mozilla/SplayTree.h"
#include "mozilla/RestyleLogging.h"
#include "GeckoProfiler.h"
#include "mozilla/Maybe.h"
namespace mozilla {
class ElementRestyler;
class GeckoRestyleManager;
class RestyleTracker {
public:
typedef mozilla::dom::Element Element;
friend class ElementRestyler; // for AddPendingRestyleToTable
explicit RestyleTracker(Element::FlagsType aRestyleBits)
: mRestyleBits(aRestyleBits)
, mHaveLaterSiblingRestyles(false)
, mHaveSelectors(false)
{
NS_PRECONDITION((mRestyleBits & ~ELEMENT_ALL_RESTYLE_FLAGS) == 0,
"Why do we have these bits set?");
NS_PRECONDITION((mRestyleBits & ELEMENT_PENDING_RESTYLE_FLAGS) != 0,
"Must have a restyle flag");
NS_PRECONDITION((mRestyleBits & ELEMENT_PENDING_RESTYLE_FLAGS) !=
ELEMENT_PENDING_RESTYLE_FLAGS,
"Shouldn't have both restyle flags set");
NS_PRECONDITION((mRestyleBits & ELEMENT_POTENTIAL_RESTYLE_ROOT_FLAGS) != 0,
"Must have root flag");
NS_PRECONDITION((mRestyleBits & ELEMENT_POTENTIAL_RESTYLE_ROOT_FLAGS) !=
ELEMENT_POTENTIAL_RESTYLE_ROOT_FLAGS,
"Shouldn't have both root flags");
}
void Init(GeckoRestyleManager* aRestyleManager) {
mRestyleManager = aRestyleManager;
}
uint32_t Count() const {
return mPendingRestyles.Count();
}
/**
* Add a restyle for the given element to the tracker. Returns true
* if the element already had eRestyle_LaterSiblings set on it.
*
* aRestyleRoot is the closest restyle root for aElement. If the caller
* does not know what the closest restyle root is, Nothing should be
* passed. A Some(nullptr) restyle root can be passed if there is no
* ancestor element that is a restyle root.
*/
bool AddPendingRestyle(Element* aElement, nsRestyleHint aRestyleHint,
nsChangeHint aMinChangeHint,
const RestyleHintData* aRestyleHintData = nullptr,
const mozilla::Maybe<Element*>& aRestyleRoot =
mozilla::Nothing());
Element* FindClosestRestyleRoot(Element* aElement);
/**
* Process the restyles we've been tracking.
*/
void DoProcessRestyles();
// Return our ELEMENT_HAS_PENDING_(ANIMATION_)RESTYLE bit
uint32_t RestyleBit() const {
return mRestyleBits & ELEMENT_PENDING_RESTYLE_FLAGS;
}
// Return our ELEMENT_IS_POTENTIAL_(ANIMATION_)RESTYLE_ROOT bit
Element::FlagsType RootBit() const {
return mRestyleBits & ELEMENT_POTENTIAL_RESTYLE_ROOT_FLAGS;
}
// Return our ELEMENT_IS_CONDITIONAL_RESTYLE_ANCESTOR bit if present,
// or 0 if it is not.
Element::FlagsType ConditionalDescendantsBit() const {
return mRestyleBits & ELEMENT_IS_CONDITIONAL_RESTYLE_ANCESTOR;
}
struct Hints {
nsRestyleHint mRestyleHint; // What we want to restyle
nsChangeHint mChangeHint; // The minimal change hint for "self"
RestyleHintData mRestyleHintData; // Data associated with mRestyleHint
};
struct RestyleData : Hints {
RestyleData() {
mRestyleHint = nsRestyleHint(0);
mChangeHint = nsChangeHint(0);
}
RestyleData(nsRestyleHint aRestyleHint, nsChangeHint aChangeHint,
const RestyleHintData* aRestyleHintData) {
mRestyleHint = aRestyleHint;
mChangeHint = aChangeHint;
if (aRestyleHintData) {
mRestyleHintData = *aRestyleHintData;
}
}
// Descendant elements we must check that we ended up restyling, ordered
// with the same invariant as mRestyleRoots. The elements here are those
// that we called AddPendingRestyle for and found the element this is
// the RestyleData for as its nearest restyle root.
nsTArray<RefPtr<Element>> mDescendants;
UniqueProfilerBacktrace mBacktrace;
};
/**
* If the given Element has a restyle pending for it, return the
* relevant restyle data. This function will clear everything other
* than a possible eRestyle_LaterSiblings hint for aElement out of
* our hashtable. The returned aData will never have an
* eRestyle_LaterSiblings hint in it.
*
* The return value indicates whether any restyle data was found for
* the element. aData is set to nullptr iff false is returned.
*/
bool GetRestyleData(Element* aElement, nsAutoPtr<RestyleData>& aData);
/**
* Returns whether there is a RestyleData entry in mPendingRestyles
* for the given element.
*/
bool HasRestyleData(Element* aElement) {
return mPendingRestyles.Contains(aElement);
}
/**
* For each element in aElements, appends it to mRestyleRoots if it
* has its restyle bit set. This is used to ensure we restyle elements
* that we did not add as restyle roots initially (due to there being
* an ancestor with the restyle root bit set), but which we might
* not have got around to restyling due to the restyle process
* terminating early with RestyleResul::eStop (see ElementRestyler::Restyle).
*
* This function must be called with elements in order such that
* appending them to mRestyleRoots maintains its ordering invariant that
* ancestors appear after descendants.
*/
void AddRestyleRootsIfAwaitingRestyle(
const nsTArray<RefPtr<Element>>& aElements);
/**
* Converts any eRestyle_SomeDescendants restyle hints in the pending restyle
* table into eRestyle_Subtree hints and clears out the associated arrays of
* nsCSSSelector pointers. This is called in response to a style sheet change
* that might have cause an nsCSSSelector to be destroyed.
*/
void ClearSelectors();
/**
* The document we're associated with.
*/
inline nsIDocument* Document() const;
#ifdef RESTYLE_LOGGING
// Defined in RestyleTrackerInlines.h.
inline bool ShouldLogRestyle();
inline int32_t& LoggingDepth();
#endif
private:
bool AddPendingRestyleToTable(Element* aElement, nsRestyleHint aRestyleHint,
nsChangeHint aMinChangeHint,
const RestyleHintData* aRestyleHintData = nullptr);
/**
* Handle a single mPendingRestyles entry. aRestyleHint must not
* include eRestyle_LaterSiblings; that needs to be dealt with
* before calling this function.
*/
inline void ProcessOneRestyle(Element* aElement,
nsRestyleHint aRestyleHint,
nsChangeHint aChangeHint,
const RestyleHintData& aRestyleHintData);
typedef nsClassHashtable<nsISupportsHashKey, RestyleData> PendingRestyleTable;
typedef AutoTArray< RefPtr<Element>, 32> RestyleRootArray;
// Our restyle bits. These will be a subset of ELEMENT_ALL_RESTYLE_FLAGS, and
// will include one flag from ELEMENT_PENDING_RESTYLE_FLAGS, one flag
// from ELEMENT_POTENTIAL_RESTYLE_ROOT_FLAGS, and might also include
// ELEMENT_IS_CONDITIONAL_RESTYLE_ANCESTOR.
Element::FlagsType mRestyleBits;
GeckoRestyleManager* mRestyleManager; // Owns us
// A hashtable that maps elements to pointers to RestyleData structs. The
// values only make sense if the element's current document is our
// document and it has our RestyleBit() flag set. In particular,
// said bit might not be set if the element had a restyle posted and
// then was moved around in the DOM.
PendingRestyleTable mPendingRestyles;
// An array that keeps track of our possible restyle roots. This
// maintains the invariant that if A and B are both restyle roots
// and A is an ancestor of B then A will come after B in the array.
// We maintain this invariant by checking whether an element has an
// ancestor with the restyle root bit set before appending it to the
// array.
RestyleRootArray mRestyleRoots;
// True if we have some entries with the eRestyle_LaterSiblings
// flag. We need this to avoid enumerating the hashtable looking
// for such entries when we can't possibly have any.
bool mHaveLaterSiblingRestyles;
// True if we have some entries with selectors in the restyle hint data.
// We use this to skip iterating over mPendingRestyles in ClearSelectors.
bool mHaveSelectors;
};
inline bool
RestyleTracker::AddPendingRestyleToTable(Element* aElement,
nsRestyleHint aRestyleHint,
nsChangeHint aMinChangeHint,
const RestyleHintData* aRestyleHintData)
{
RestyleData* existingData;
if (aRestyleHintData &&
!aRestyleHintData->mSelectorsForDescendants.IsEmpty()) {
mHaveSelectors = true;
}
// Check the RestyleBit() flag before doing the hashtable Get, since
// it's possible that the data in the hashtable isn't actually
// relevant anymore (if the flag is not set).
if (aElement->HasFlag(RestyleBit())) {
mPendingRestyles.Get(aElement, &existingData);
} else {
aElement->SetFlags(RestyleBit());
existingData = nullptr;
}
if (aRestyleHint & eRestyle_SomeDescendants) {
NS_ASSERTION(ConditionalDescendantsBit(),
"why are we getting eRestyle_SomeDescendants in an "
"animation-only restyle?");
aElement->SetFlags(ConditionalDescendantsBit());
}
if (!existingData) {
RestyleData* rd =
new RestyleData(aRestyleHint, aMinChangeHint, aRestyleHintData);
if (profiler_feature_active(ProfilerFeature::Restyle)) {
rd->mBacktrace = profiler_get_backtrace();
}
mPendingRestyles.Put(aElement, rd);
return false;
}
bool hadRestyleLaterSiblings =
(existingData->mRestyleHint & eRestyle_LaterSiblings) != 0;
existingData->mRestyleHint =
nsRestyleHint(existingData->mRestyleHint | aRestyleHint);
existingData->mChangeHint |= aMinChangeHint;
if (aRestyleHintData) {
existingData->mRestyleHintData.mSelectorsForDescendants
.AppendElements(aRestyleHintData->mSelectorsForDescendants);
}
return hadRestyleLaterSiblings;
}
inline mozilla::dom::Element*
RestyleTracker::FindClosestRestyleRoot(Element* aElement)
{
Element* cur = aElement;
while (!cur->HasFlag(RootBit())) {
nsIContent* parent = cur->GetFlattenedTreeParent();
// Stop if we have no parent or the parent is not an element or
// we're part of the viewport scrollbars (because those are not
// frametree descendants of the primary frame of the root
// element).
// XXXbz maybe the primary frame of the root should be the root scrollframe?
if (!parent || !parent->IsElement() ||
// If we've hit the root via a native anonymous kid and that
// this native anonymous kid is not obviously a descendant
// of the root's primary frame, assume we're under the root
// scrollbars. Since those don't get reresolved when
// reresolving the root, we need to make sure to add the
// element to mRestyleRoots.
(cur->IsInNativeAnonymousSubtree() && !parent->GetParent() &&
cur->GetPrimaryFrame() &&
cur->GetPrimaryFrame()->GetParent() != parent->GetPrimaryFrame())) {
return nullptr;
}
cur = parent->AsElement();
}
return cur;
}
inline bool
RestyleTracker::AddPendingRestyle(Element* aElement,
nsRestyleHint aRestyleHint,
nsChangeHint aMinChangeHint,
const RestyleHintData* aRestyleHintData,
const mozilla::Maybe<Element*>& aRestyleRoot)
{
bool hadRestyleLaterSiblings =
AddPendingRestyleToTable(aElement, aRestyleHint, aMinChangeHint,
aRestyleHintData);
// We can only treat this element as a restyle root if we would
// actually restyle its descendants (so either call
// ElementRestyler::Restyle on it or just reframe it).
if ((aRestyleHint & ~eRestyle_LaterSiblings) ||
(aMinChangeHint & nsChangeHint_ReconstructFrame)) {
Element* cur =
aRestyleRoot ? *aRestyleRoot : FindClosestRestyleRoot(aElement);
if (!cur) {
mRestyleRoots.AppendElement(aElement);
cur = aElement;
}
// At this point some ancestor of aElement (possibly aElement
// itself) is in mRestyleRoots. Set the root bit on aElement, to
// speed up searching for an existing root on its descendants.
aElement->SetFlags(RootBit());
if (cur != aElement) {
// We are already going to restyle cur, one of aElement's ancestors,
// but we might not end up restyling all the way down to aElement.
// Record it in the RestyleData so we can ensure it does get restyled
// after we deal with cur.
//
// As with the mRestyleRoots array, mDescendants maintains the
// invariant that if two elements appear in the array and one
// is an ancestor of the other, that the ancestor appears after
// the descendant.
RestyleData* curData;
mPendingRestyles.Get(cur, &curData);
// Even if cur has a ForceDescendants restyle hint, we're not guaranteed
// to reach aElement in the case the PresShell posts a restyle event from
// PostRecreateFramesFor, so we need to track it here.
MOZ_ASSERT(curData, "expected to find a RestyleData for cur");
if (curData) {
curData->mDescendants.AppendElement(aElement);
}
}
}
mHaveLaterSiblingRestyles =
mHaveLaterSiblingRestyles || (aRestyleHint & eRestyle_LaterSiblings) != 0;
return hadRestyleLaterSiblings;
}
} // namespace mozilla
#endif /* mozilla_RestyleTracker_h */