RestyleTracker.h
/* -*- 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 "nsClassHashtable.h"
#include "nsContainerFrame.h"
#include "mozilla/SplayTree.h"
#include "mozilla/RestyleLogging.h"
#include "GeckoProfiler.h"
#include "mozilla/Maybe.h"
#if defined(MOZ_ENABLE_PROFILER_SPS)
#include "ProfilerBacktrace.h"
#endif
namespace mozilla {
class RestyleManager;
class ElementRestyler;
/**
* Helper class that collects a list of frames that need
* UpdateOverflow() called on them, and coalesces them
* to avoid walking up the same ancestor tree multiple times.
*/
class OverflowChangedTracker
{
public:
enum ChangeKind {
/**
* The frame was explicitly added as a result of
* nsChangeHint_UpdatePostTransformOverflow and hence may have had a style
* change that changes its geometry relative to parent, without reflowing.
*/
TRANSFORM_CHANGED,
/**
* The overflow areas of children have changed
* and we need to call UpdateOverflow on the frame.
*/
CHILDREN_CHANGED,
};
OverflowChangedTracker() :
mSubtreeRoot(nullptr)
{}
~OverflowChangedTracker()
{
NS_ASSERTION(mEntryList.empty(), "Need to flush before destroying!");
}
/**
* Add a frame that has had a style change, and needs its
* overflow updated.
*
* If there are pre-transform overflow areas stored for this
* frame, then we will call FinishAndStoreOverflow with those
* areas instead of UpdateOverflow().
*
* If the overflow area changes, then UpdateOverflow will also
* be called on the parent.
*/
void AddFrame(nsIFrame* aFrame, ChangeKind aChangeKind) {
uint32_t depth = aFrame->GetDepthInFrameTree();
Entry *entry = nullptr;
if (!mEntryList.empty()) {
entry = mEntryList.find(Entry(aFrame, depth));
}
if (entry == nullptr) {
// Add new entry.
mEntryList.insert(new Entry(aFrame, depth, aChangeKind));
} else {
// Update the existing entry if the new value is stronger.
entry->mChangeKind = std::max(entry->mChangeKind, aChangeKind);
}
}
/**
* Remove a frame.
*/
void RemoveFrame(nsIFrame* aFrame) {
if (mEntryList.empty()) {
return;
}
uint32_t depth = aFrame->GetDepthInFrameTree();
if (mEntryList.find(Entry(aFrame, depth))) {
delete mEntryList.remove(Entry(aFrame, depth));
}
}
/**
* Set the subtree root to limit overflow updates. This must be set if and
* only if currently reflowing aSubtreeRoot, to ensure overflow changes will
* still propagate correctly.
*/
void SetSubtreeRoot(const nsIFrame* aSubtreeRoot) {
mSubtreeRoot = aSubtreeRoot;
}
/**
* Update the overflow of all added frames, and clear the entry list.
*
* Start from those deepest in the frame tree and works upwards. This stops
* us from processing the same frame twice.
*/
void Flush() {
while (!mEntryList.empty()) {
Entry *entry = mEntryList.removeMin();
nsIFrame *frame = entry->mFrame;
bool overflowChanged = false;
if (entry->mChangeKind == CHILDREN_CHANGED) {
// Need to union the overflow areas of the children.
// Only update the parent if the overflow changes.
overflowChanged = frame->UpdateOverflow();
} else {
// Take a faster path that doesn't require unioning the overflow areas
// of our children.
NS_ASSERTION(frame->Properties().Get(
nsIFrame::DebugInitialOverflowPropertyApplied()),
"InitialOverflowProperty must be set first.");
nsOverflowAreas* overflow =
static_cast<nsOverflowAreas*>(frame->Properties().Get(nsIFrame::InitialOverflowProperty()));
if (overflow) {
// FinishAndStoreOverflow will change the overflow areas passed in,
// so make a copy.
nsOverflowAreas overflowCopy = *overflow;
frame->FinishAndStoreOverflow(overflowCopy, frame->GetSize());
} else {
nsRect bounds(nsPoint(0, 0), frame->GetSize());
nsOverflowAreas boundsOverflow;
boundsOverflow.SetAllTo(bounds);
frame->FinishAndStoreOverflow(boundsOverflow, bounds.Size());
}
// We can't tell if the overflow changed, so be conservative
overflowChanged = true;
}
// If the frame style changed (e.g. positioning offsets)
// then we need to update the parent with the overflow areas of its
// children.
if (overflowChanged) {
nsIFrame *parent = frame->GetParent();
if (parent && parent != mSubtreeRoot) {
Entry* parentEntry = mEntryList.find(Entry(parent, entry->mDepth - 1));
if (parentEntry) {
parentEntry->mChangeKind = std::max(parentEntry->mChangeKind, CHILDREN_CHANGED);
} else {
mEntryList.insert(new Entry(parent, entry->mDepth - 1, CHILDREN_CHANGED));
}
}
}
delete entry;
}
}
private:
struct Entry : SplayTreeNode<Entry>
{
Entry(nsIFrame* aFrame, uint32_t aDepth, ChangeKind aChangeKind = CHILDREN_CHANGED)
: mFrame(aFrame)
, mDepth(aDepth)
, mChangeKind(aChangeKind)
{}
bool operator==(const Entry& aOther) const
{
return mFrame == aOther.mFrame;
}
/**
* Sort by *reverse* depth in the tree, and break ties with
* the frame pointer.
*/
bool operator<(const Entry& aOther) const
{
if (mDepth == aOther.mDepth) {
return mFrame < aOther.mFrame;
}
return mDepth > aOther.mDepth; /* reverse, want "min" to be deepest */
}
static int compare(const Entry& aOne, const Entry& aTwo)
{
if (aOne == aTwo) {
return 0;
} else if (aOne < aTwo) {
return -1;
} else {
return 1;
}
}
nsIFrame* mFrame;
/* Depth in the frame tree */
uint32_t mDepth;
ChangeKind mChangeKind;
};
/* A list of frames to process, sorted by their depth in the frame tree */
SplayTree<Entry, Entry> mEntryList;
/* Don't update overflow of this frame or its ancestors. */
const nsIFrame* mSubtreeRoot;
};
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(RestyleManager* 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,
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 = NS_STYLE_HINT_NONE;
}
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;
#if defined(MOZ_ENABLE_PROFILER_SPS)
UniquePtr<ProfilerBacktrace> mBacktrace;
#endif
};
/**
* 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 eRestyleResult_Stop (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;
RestyleManager* 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 defined(MOZ_ENABLE_PROFILER_SPS)
if (profiler_feature_active("restyle")) {
rd->mBacktrace.reset(profiler_get_backtrace());
}
#endif
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,
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
// ReResolveStyleContext 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);
NS_ASSERTION(curData, "expected to find a RestyleData for cur");
// If cur has an eRestyle_ForceDescendants restyle hint, then we
// know that we will get to all descendants. Don't bother
// recording the descendant to restyle in that case.
if (curData && !(curData->mRestyleHint & eRestyle_ForceDescendants)) {
curData->mDescendants.AppendElement(aElement);
}
}
}
mHaveLaterSiblingRestyles =
mHaveLaterSiblingRestyles || (aRestyleHint & eRestyle_LaterSiblings) != 0;
return hadRestyleLaterSiblings;
}
} // namespace mozilla
#endif /* mozilla_RestyleTracker_h */
