gecko-dev/layout/base/RestyleTracker.h
Cameron McCormack f5e6faa47e Bug 979133 - Add facility to log the restyle process. r=dbaron
Set the MOZ_DEBUG_RESTYLE environment variable and every restyle will have
detailed logging printed to stderr. By default, restyles for animations are
not logged; you can include them by also setting MOZ_DEBUG_RESTYLE_ANIMATIONS.

If you wish to limit restyle logging to a particular change, you can call
nsPresContext::StartRestyleLogging() and nsPresContext::StopRestyleLogging()
at appropriate points. (You might want to add a couple of helper methods
temporarily on nsIDocument and then expose them to your page with Web IDL
to make them easier to call.) You do not need to have set MOZ_DEBUG_RESTYLE
for this to work.
2014-09-25 15:45:36 +10:00

499 lines
17 KiB
C++

/* -*- 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"
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,
/**
* The overflow areas of children have changed
* and we need to call UpdateOverflow on the frame.
* Also call UpdateOverflow on the parent even if the
* overflow areas of the frame does not change.
*/
CHILDREN_AND_PARENT_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_AND_PARENT_CHANGED) {
// Need to union the overflow areas of the children.
// Always update the parent, even if the overflow does not change.
frame->UpdateOverflow();
overflowChanged = true;
} else 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.
#ifdef DEBUG
bool hasInitialOverflowPropertyApplied = false;
frame->Properties().Get(nsIFrame::DebugInitialOverflowPropertyApplied(),
&hasInitialOverflowPropertyApplied);
NS_ASSERTION(hasInitialOverflowPropertyApplied,
"InitialOverflowProperty must be set first.");
#endif
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)
{
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_PENDING_RESTYLE_FLAGS) != 0,
"Must have root flag");
NS_PRECONDITION((mRestyleBits & ~ELEMENT_PENDING_RESTYLE_FLAGS) !=
(ELEMENT_ALL_RESTYLE_FLAGS & ~ELEMENT_PENDING_RESTYLE_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.
*/
bool AddPendingRestyle(Element* aElement, nsRestyleHint aRestyleHint,
nsChangeHint aMinChangeHint);
/**
* Process the restyles we've been tracking.
*/
void ProcessRestyles() {
// Fast-path the common case (esp. for the animation restyle
// tracker) of not having anything to do.
if (mPendingRestyles.Count()) {
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_PENDING_RESTYLE_FLAGS;
}
struct Hints {
nsRestyleHint mRestyleHint; // What we want to restyle
nsChangeHint mChangeHint; // The minimal change hint for "self"
};
struct RestyleData : Hints {
RestyleData() {
mRestyleHint = nsRestyleHint(0);
mChangeHint = NS_STYLE_HINT_NONE;
}
RestyleData(nsRestyleHint aRestyleHint, nsChangeHint aChangeHint) {
mRestyleHint = aRestyleHint;
mChangeHint = aChangeHint;
}
// 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<nsRefPtr<Element>> mDescendants;
};
/**
* 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);
/**
* 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<nsRefPtr<Element>>& aElements);
/**
* 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);
/**
* 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);
/**
* The guts of our restyle processing.
*/
void DoProcessRestyles();
typedef nsClassHashtable<nsISupportsHashKey, RestyleData> PendingRestyleTable;
typedef nsAutoTArray< nsRefPtr<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 and one flag
// that's not in ELEMENT_PENDING_RESTYLE_FLAGS.
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;
};
inline bool
RestyleTracker::AddPendingRestyleToTable(Element* aElement,
nsRestyleHint aRestyleHint,
nsChangeHint aMinChangeHint)
{
RestyleData* existingData;
// 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 (!existingData) {
mPendingRestyles.Put(aElement,
new RestyleData(aRestyleHint, aMinChangeHint));
return false;
}
bool hadRestyleLaterSiblings =
(existingData->mRestyleHint & eRestyle_LaterSiblings) != 0;
existingData->mRestyleHint =
nsRestyleHint(existingData->mRestyleHint | aRestyleHint);
NS_UpdateHint(existingData->mChangeHint, aMinChangeHint);
return hadRestyleLaterSiblings;
}
inline bool
RestyleTracker::AddPendingRestyle(Element* aElement,
nsRestyleHint aRestyleHint,
nsChangeHint aMinChangeHint)
{
bool hadRestyleLaterSiblings =
AddPendingRestyleToTable(aElement, aRestyleHint, aMinChangeHint);
// 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 = 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())) {
mRestyleRoots.AppendElement(aElement);
cur = aElement;
break;
}
cur = parent->AsElement();
}
// 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->mRestyleHint & eRestyle_ForceDescendants)) {
curData->mDescendants.AppendElement(aElement);
}
}
}
mHaveLaterSiblingRestyles =
mHaveLaterSiblingRestyles || (aRestyleHint & eRestyle_LaterSiblings) != 0;
return hadRestyleLaterSiblings;
}
} // namespace mozilla
#endif /* mozilla_RestyleTracker_h */