1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/layout/base/RestyleTracker.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,420 @@
1.4 +/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
1.5 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.6 + * License, v. 2.0. If a copy of the MPL was not distributed with this
1.7 + * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
1.8 +
1.9 +/**
1.10 + * A class which manages pending restyles. This handles keeping track
1.11 + * of what nodes restyles need to happen on and so forth.
1.12 + */
1.13 +
1.14 +#ifndef mozilla_RestyleTracker_h
1.15 +#define mozilla_RestyleTracker_h
1.16 +
1.17 +#include "mozilla/dom/Element.h"
1.18 +#include "nsDataHashtable.h"
1.19 +#include "nsIFrame.h"
1.20 +#include "mozilla/SplayTree.h"
1.21 +
1.22 +namespace mozilla {
1.23 +
1.24 +class RestyleManager;
1.25 +
1.26 +/**
1.27 + * Helper class that collects a list of frames that need
1.28 + * UpdateOverflow() called on them, and coalesces them
1.29 + * to avoid walking up the same ancestor tree multiple times.
1.30 + */
1.31 +class OverflowChangedTracker
1.32 +{
1.33 +public:
1.34 + enum ChangeKind {
1.35 + /**
1.36 + * The frame was explicitly added as a result of
1.37 + * nsChangeHint_UpdatePostTransformOverflow and hence may have had a style
1.38 + * change that changes its geometry relative to parent, without reflowing.
1.39 + */
1.40 + TRANSFORM_CHANGED,
1.41 + /**
1.42 + * The overflow areas of children have changed
1.43 + * and we need to call UpdateOverflow on the frame.
1.44 + */
1.45 + CHILDREN_CHANGED,
1.46 + /**
1.47 + * The overflow areas of children have changed
1.48 + * and we need to call UpdateOverflow on the frame.
1.49 + * Also call UpdateOverflow on the parent even if the
1.50 + * overflow areas of the frame does not change.
1.51 + */
1.52 + CHILDREN_AND_PARENT_CHANGED
1.53 + };
1.54 +
1.55 + OverflowChangedTracker() :
1.56 + mSubtreeRoot(nullptr)
1.57 + {}
1.58 +
1.59 + ~OverflowChangedTracker()
1.60 + {
1.61 + NS_ASSERTION(mEntryList.empty(), "Need to flush before destroying!");
1.62 + }
1.63 +
1.64 + /**
1.65 + * Add a frame that has had a style change, and needs its
1.66 + * overflow updated.
1.67 + *
1.68 + * If there are pre-transform overflow areas stored for this
1.69 + * frame, then we will call FinishAndStoreOverflow with those
1.70 + * areas instead of UpdateOverflow().
1.71 + *
1.72 + * If the overflow area changes, then UpdateOverflow will also
1.73 + * be called on the parent.
1.74 + */
1.75 + void AddFrame(nsIFrame* aFrame, ChangeKind aChangeKind) {
1.76 + uint32_t depth = aFrame->GetDepthInFrameTree();
1.77 + Entry *entry = nullptr;
1.78 + if (!mEntryList.empty()) {
1.79 + entry = mEntryList.find(Entry(aFrame, depth));
1.80 + }
1.81 + if (entry == nullptr) {
1.82 + // Add new entry.
1.83 + mEntryList.insert(new Entry(aFrame, depth, aChangeKind));
1.84 + } else {
1.85 + // Update the existing entry if the new value is stronger.
1.86 + entry->mChangeKind = std::max(entry->mChangeKind, aChangeKind);
1.87 + }
1.88 + }
1.89 +
1.90 + /**
1.91 + * Remove a frame.
1.92 + */
1.93 + void RemoveFrame(nsIFrame* aFrame) {
1.94 + if (mEntryList.empty()) {
1.95 + return;
1.96 + }
1.97 +
1.98 + uint32_t depth = aFrame->GetDepthInFrameTree();
1.99 + if (mEntryList.find(Entry(aFrame, depth))) {
1.100 + delete mEntryList.remove(Entry(aFrame, depth));
1.101 + }
1.102 + }
1.103 +
1.104 + /**
1.105 + * Set the subtree root to limit overflow updates. This must be set if and
1.106 + * only if currently reflowing aSubtreeRoot, to ensure overflow changes will
1.107 + * still propagate correctly.
1.108 + */
1.109 + void SetSubtreeRoot(const nsIFrame* aSubtreeRoot) {
1.110 + mSubtreeRoot = aSubtreeRoot;
1.111 + }
1.112 +
1.113 + /**
1.114 + * Update the overflow of all added frames, and clear the entry list.
1.115 + *
1.116 + * Start from those deepest in the frame tree and works upwards. This stops
1.117 + * us from processing the same frame twice.
1.118 + */
1.119 + void Flush() {
1.120 + while (!mEntryList.empty()) {
1.121 + Entry *entry = mEntryList.removeMin();
1.122 + nsIFrame *frame = entry->mFrame;
1.123 +
1.124 + bool overflowChanged = false;
1.125 + if (entry->mChangeKind == CHILDREN_AND_PARENT_CHANGED) {
1.126 + // Need to union the overflow areas of the children.
1.127 + // Always update the parent, even if the overflow does not change.
1.128 + frame->UpdateOverflow();
1.129 + overflowChanged = true;
1.130 + } else if (entry->mChangeKind == CHILDREN_CHANGED) {
1.131 + // Need to union the overflow areas of the children.
1.132 + // Only update the parent if the overflow changes.
1.133 + overflowChanged = frame->UpdateOverflow();
1.134 + } else {
1.135 + // Take a faster path that doesn't require unioning the overflow areas
1.136 + // of our children.
1.137 +
1.138 +#ifdef DEBUG
1.139 + bool hasInitialOverflowPropertyApplied = false;
1.140 + frame->Properties().Get(nsIFrame::DebugInitialOverflowPropertyApplied(),
1.141 + &hasInitialOverflowPropertyApplied);
1.142 + NS_ASSERTION(hasInitialOverflowPropertyApplied,
1.143 + "InitialOverflowProperty must be set first.");
1.144 +#endif
1.145 +
1.146 + nsOverflowAreas* overflow =
1.147 + static_cast<nsOverflowAreas*>(frame->Properties().Get(nsIFrame::InitialOverflowProperty()));
1.148 + if (overflow) {
1.149 + // FinishAndStoreOverflow will change the overflow areas passed in,
1.150 + // so make a copy.
1.151 + nsOverflowAreas overflowCopy = *overflow;
1.152 + frame->FinishAndStoreOverflow(overflowCopy, frame->GetSize());
1.153 + } else {
1.154 + nsRect bounds(nsPoint(0, 0), frame->GetSize());
1.155 + nsOverflowAreas boundsOverflow;
1.156 + boundsOverflow.SetAllTo(bounds);
1.157 + frame->FinishAndStoreOverflow(boundsOverflow, bounds.Size());
1.158 + }
1.159 +
1.160 + // We can't tell if the overflow changed, so be conservative
1.161 + overflowChanged = true;
1.162 + }
1.163 +
1.164 + // If the frame style changed (e.g. positioning offsets)
1.165 + // then we need to update the parent with the overflow areas of its
1.166 + // children.
1.167 + if (overflowChanged) {
1.168 + nsIFrame *parent = frame->GetParent();
1.169 + if (parent && parent != mSubtreeRoot) {
1.170 + Entry* parentEntry = mEntryList.find(Entry(parent, entry->mDepth - 1));
1.171 + if (parentEntry) {
1.172 + parentEntry->mChangeKind = std::max(parentEntry->mChangeKind, CHILDREN_CHANGED);
1.173 + } else {
1.174 + mEntryList.insert(new Entry(parent, entry->mDepth - 1, CHILDREN_CHANGED));
1.175 + }
1.176 + }
1.177 + }
1.178 + delete entry;
1.179 + }
1.180 + }
1.181 +
1.182 +private:
1.183 + struct Entry : SplayTreeNode<Entry>
1.184 + {
1.185 + Entry(nsIFrame* aFrame, uint32_t aDepth, ChangeKind aChangeKind = CHILDREN_CHANGED)
1.186 + : mFrame(aFrame)
1.187 + , mDepth(aDepth)
1.188 + , mChangeKind(aChangeKind)
1.189 + {}
1.190 +
1.191 + bool operator==(const Entry& aOther) const
1.192 + {
1.193 + return mFrame == aOther.mFrame;
1.194 + }
1.195 +
1.196 + /**
1.197 + * Sort by *reverse* depth in the tree, and break ties with
1.198 + * the frame pointer.
1.199 + */
1.200 + bool operator<(const Entry& aOther) const
1.201 + {
1.202 + if (mDepth == aOther.mDepth) {
1.203 + return mFrame < aOther.mFrame;
1.204 + }
1.205 + return mDepth > aOther.mDepth; /* reverse, want "min" to be deepest */
1.206 + }
1.207 +
1.208 + static int compare(const Entry& aOne, const Entry& aTwo)
1.209 + {
1.210 + if (aOne == aTwo) {
1.211 + return 0;
1.212 + } else if (aOne < aTwo) {
1.213 + return -1;
1.214 + } else {
1.215 + return 1;
1.216 + }
1.217 + }
1.218 +
1.219 + nsIFrame* mFrame;
1.220 + /* Depth in the frame tree */
1.221 + uint32_t mDepth;
1.222 + ChangeKind mChangeKind;
1.223 + };
1.224 +
1.225 + /* A list of frames to process, sorted by their depth in the frame tree */
1.226 + SplayTree<Entry, Entry> mEntryList;
1.227 +
1.228 + /* Don't update overflow of this frame or its ancestors. */
1.229 + const nsIFrame* mSubtreeRoot;
1.230 +};
1.231 +
1.232 +class RestyleTracker {
1.233 +public:
1.234 + typedef mozilla::dom::Element Element;
1.235 +
1.236 + RestyleTracker(uint32_t aRestyleBits) :
1.237 + mRestyleBits(aRestyleBits),
1.238 + mHaveLaterSiblingRestyles(false)
1.239 + {
1.240 + NS_PRECONDITION((mRestyleBits & ~ELEMENT_ALL_RESTYLE_FLAGS) == 0,
1.241 + "Why do we have these bits set?");
1.242 + NS_PRECONDITION((mRestyleBits & ELEMENT_PENDING_RESTYLE_FLAGS) != 0,
1.243 + "Must have a restyle flag");
1.244 + NS_PRECONDITION((mRestyleBits & ELEMENT_PENDING_RESTYLE_FLAGS) !=
1.245 + ELEMENT_PENDING_RESTYLE_FLAGS,
1.246 + "Shouldn't have both restyle flags set");
1.247 + NS_PRECONDITION((mRestyleBits & ~ELEMENT_PENDING_RESTYLE_FLAGS) != 0,
1.248 + "Must have root flag");
1.249 + NS_PRECONDITION((mRestyleBits & ~ELEMENT_PENDING_RESTYLE_FLAGS) !=
1.250 + (ELEMENT_ALL_RESTYLE_FLAGS & ~ELEMENT_PENDING_RESTYLE_FLAGS),
1.251 + "Shouldn't have both root flags");
1.252 + }
1.253 +
1.254 + void Init(RestyleManager* aRestyleManager) {
1.255 + mRestyleManager = aRestyleManager;
1.256 + }
1.257 +
1.258 + uint32_t Count() const {
1.259 + return mPendingRestyles.Count();
1.260 + }
1.261 +
1.262 + /**
1.263 + * Add a restyle for the given element to the tracker. Returns true
1.264 + * if the element already had eRestyle_LaterSiblings set on it.
1.265 + */
1.266 + bool AddPendingRestyle(Element* aElement, nsRestyleHint aRestyleHint,
1.267 + nsChangeHint aMinChangeHint);
1.268 +
1.269 + /**
1.270 + * Process the restyles we've been tracking.
1.271 + */
1.272 + void ProcessRestyles() {
1.273 + // Fast-path the common case (esp. for the animation restyle
1.274 + // tracker) of not having anything to do.
1.275 + if (mPendingRestyles.Count()) {
1.276 + DoProcessRestyles();
1.277 + }
1.278 + }
1.279 +
1.280 + // Return our ELEMENT_HAS_PENDING_(ANIMATION_)RESTYLE bit
1.281 + uint32_t RestyleBit() const {
1.282 + return mRestyleBits & ELEMENT_PENDING_RESTYLE_FLAGS;
1.283 + }
1.284 +
1.285 + // Return our ELEMENT_IS_POTENTIAL_(ANIMATION_)RESTYLE_ROOT bit
1.286 + uint32_t RootBit() const {
1.287 + return mRestyleBits & ~ELEMENT_PENDING_RESTYLE_FLAGS;
1.288 + }
1.289 +
1.290 + struct RestyleData {
1.291 + nsRestyleHint mRestyleHint; // What we want to restyle
1.292 + nsChangeHint mChangeHint; // The minimal change hint for "self"
1.293 + };
1.294 +
1.295 + /**
1.296 + * If the given Element has a restyle pending for it, return the
1.297 + * relevant restyle data. This function will clear everything other
1.298 + * than a possible eRestyle_LaterSiblings hint for aElement out of
1.299 + * our hashtable. The returned aData will never have an
1.300 + * eRestyle_LaterSiblings hint in it.
1.301 + *
1.302 + * The return value indicates whether any restyle data was found for
1.303 + * the element. If false is returned, then the state of *aData is
1.304 + * undefined.
1.305 + */
1.306 + bool GetRestyleData(Element* aElement, RestyleData* aData);
1.307 +
1.308 + /**
1.309 + * The document we're associated with.
1.310 + */
1.311 + inline nsIDocument* Document() const;
1.312 +
1.313 + struct RestyleEnumerateData : public RestyleData {
1.314 + nsRefPtr<Element> mElement;
1.315 + };
1.316 +
1.317 +private:
1.318 + /**
1.319 + * Handle a single mPendingRestyles entry. aRestyleHint must not
1.320 + * include eRestyle_LaterSiblings; that needs to be dealt with
1.321 + * before calling this function.
1.322 + */
1.323 + inline void ProcessOneRestyle(Element* aElement,
1.324 + nsRestyleHint aRestyleHint,
1.325 + nsChangeHint aChangeHint);
1.326 +
1.327 + /**
1.328 + * The guts of our restyle processing.
1.329 + */
1.330 + void DoProcessRestyles();
1.331 +
1.332 + typedef nsDataHashtable<nsISupportsHashKey, RestyleData> PendingRestyleTable;
1.333 + typedef nsAutoTArray< nsRefPtr<Element>, 32> RestyleRootArray;
1.334 + // Our restyle bits. These will be a subset of ELEMENT_ALL_RESTYLE_FLAGS, and
1.335 + // will include one flag from ELEMENT_PENDING_RESTYLE_FLAGS and one flag
1.336 + // that's not in ELEMENT_PENDING_RESTYLE_FLAGS.
1.337 + uint32_t mRestyleBits;
1.338 + RestyleManager* mRestyleManager; // Owns us
1.339 + // A hashtable that maps elements to RestyleData structs. The
1.340 + // values only make sense if the element's current document is our
1.341 + // document and it has our RestyleBit() flag set. In particular,
1.342 + // said bit might not be set if the element had a restyle posted and
1.343 + // then was moved around in the DOM.
1.344 + PendingRestyleTable mPendingRestyles;
1.345 + // An array that keeps track of our possible restyle roots. This
1.346 + // maintains the invariant that if A and B are both restyle roots
1.347 + // and A is an ancestor of B then A will come after B in the array.
1.348 + // We maintain this invariant by checking whether an element has an
1.349 + // ancestor with the restyle root bit set before appending it to the
1.350 + // array.
1.351 + RestyleRootArray mRestyleRoots;
1.352 + // True if we have some entries with the eRestyle_LaterSiblings
1.353 + // flag. We need this to avoid enumerating the hashtable looking
1.354 + // for such entries when we can't possibly have any.
1.355 + bool mHaveLaterSiblingRestyles;
1.356 +};
1.357 +
1.358 +inline bool RestyleTracker::AddPendingRestyle(Element* aElement,
1.359 + nsRestyleHint aRestyleHint,
1.360 + nsChangeHint aMinChangeHint)
1.361 +{
1.362 + RestyleData existingData;
1.363 + existingData.mRestyleHint = nsRestyleHint(0);
1.364 + existingData.mChangeHint = NS_STYLE_HINT_NONE;
1.365 +
1.366 + // Check the RestyleBit() flag before doing the hashtable Get, since
1.367 + // it's possible that the data in the hashtable isn't actually
1.368 + // relevant anymore (if the flag is not set).
1.369 + if (aElement->HasFlag(RestyleBit())) {
1.370 + mPendingRestyles.Get(aElement, &existingData);
1.371 + } else {
1.372 + aElement->SetFlags(RestyleBit());
1.373 + }
1.374 +
1.375 + bool hadRestyleLaterSiblings =
1.376 + (existingData.mRestyleHint & eRestyle_LaterSiblings) != 0;
1.377 + existingData.mRestyleHint =
1.378 + nsRestyleHint(existingData.mRestyleHint | aRestyleHint);
1.379 + NS_UpdateHint(existingData.mChangeHint, aMinChangeHint);
1.380 +
1.381 + mPendingRestyles.Put(aElement, existingData);
1.382 +
1.383 + // We can only treat this element as a restyle root if we would
1.384 + // actually restyle its descendants (so either call
1.385 + // ReResolveStyleContext on it or just reframe it).
1.386 + if ((aRestyleHint & (eRestyle_Self | eRestyle_Subtree)) ||
1.387 + (aMinChangeHint & nsChangeHint_ReconstructFrame)) {
1.388 + for (const Element* cur = aElement; !cur->HasFlag(RootBit()); ) {
1.389 + nsIContent* parent = cur->GetFlattenedTreeParent();
1.390 + // Stop if we have no parent or the parent is not an element or
1.391 + // we're part of the viewport scrollbars (because those are not
1.392 + // frametree descendants of the primary frame of the root
1.393 + // element).
1.394 + // XXXbz maybe the primary frame of the root should be the root scrollframe?
1.395 + if (!parent || !parent->IsElement() ||
1.396 + // If we've hit the root via a native anonymous kid and that
1.397 + // this native anonymous kid is not obviously a descendant
1.398 + // of the root's primary frame, assume we're under the root
1.399 + // scrollbars. Since those don't get reresolved when
1.400 + // reresolving the root, we need to make sure to add the
1.401 + // element to mRestyleRoots.
1.402 + (cur->IsInNativeAnonymousSubtree() && !parent->GetParent() &&
1.403 + cur->GetPrimaryFrame() &&
1.404 + cur->GetPrimaryFrame()->GetParent() != parent->GetPrimaryFrame())) {
1.405 + mRestyleRoots.AppendElement(aElement);
1.406 + break;
1.407 + }
1.408 + cur = parent->AsElement();
1.409 + }
1.410 + // At this point some ancestor of aElement (possibly aElement
1.411 + // itself) is in mRestyleRoots. Set the root bit on aElement, to
1.412 + // speed up searching for an existing root on its descendants.
1.413 + aElement->SetFlags(RootBit());
1.414 + }
1.415 +
1.416 + mHaveLaterSiblingRestyles =
1.417 + mHaveLaterSiblingRestyles || (aRestyleHint & eRestyle_LaterSiblings) != 0;
1.418 + return hadRestyleLaterSiblings;
1.419 +}
1.420 +
1.421 +} // namespace mozilla
1.422 +
1.423 +#endif /* mozilla_RestyleTracker_h */
