зеркало из https://github.com/mozilla/gecko-dev.git
394 строки
13 KiB
C++
394 строки
13 KiB
C++
/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/**
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* A class which manages pending restyles. This handles keeping track
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* of what nodes restyles need to happen on and so forth.
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*/
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#ifndef mozilla_RestyleTracker_h
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#define mozilla_RestyleTracker_h
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#include "mozilla/dom/Element.h"
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#include "nsDataHashtable.h"
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#include "nsIFrame.h"
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#include "mozilla/SplayTree.h"
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namespace mozilla {
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class RestyleManager;
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/**
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* Helper class that collects a list of frames that need
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* UpdateOverflow() called on them, and coalesces them
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* to avoid walking up the same ancestor tree multiple times.
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*/
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class OverflowChangedTracker
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{
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public:
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OverflowChangedTracker() :
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mSubtreeRoot(nullptr)
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{}
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~OverflowChangedTracker()
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{
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NS_ASSERTION(mEntryList.empty(), "Need to flush before destroying!");
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}
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/**
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* Add a frame that has had a style change, and needs its
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* overflow updated.
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*
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* If there are pre-transform overflow areas stored for this
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* frame, then we will call FinishAndStoreOverflow with those
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* areas instead of UpdateOverflow().
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*
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* If the overflow area changes, then UpdateOverflow will also
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* be called on the parent.
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*/
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void AddFrame(nsIFrame* aFrame) {
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uint32_t depth = aFrame->GetDepthInFrameTree();
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if (mEntryList.empty() ||
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!mEntryList.find(Entry(aFrame, depth))) {
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// All frames in mEntryList at this stage have STYLE_CHANGED so we don't
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// need to worry about setting the STYLE_CHANGED flag if 'find'
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// returns true.
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mEntryList.insert(new Entry(aFrame, depth, STYLE_CHANGED));
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}
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}
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/**
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* Remove a frame.
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*/
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void RemoveFrame(nsIFrame* aFrame) {
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if (mEntryList.empty()) {
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return;
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}
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uint32_t depth = aFrame->GetDepthInFrameTree();
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if (mEntryList.find(Entry(aFrame, depth))) {
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delete mEntryList.remove(Entry(aFrame, depth));
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}
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}
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/**
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* Set the subtree root to limit overflow updates. This must be set if and
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* only if currently reflowing aSubtreeRoot, to ensure overflow changes will
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* still propagate correctly.
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*/
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void SetSubtreeRoot(const nsIFrame* aSubtreeRoot) {
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mSubtreeRoot = aSubtreeRoot;
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}
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/**
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* Update the overflow of all added frames, and clear the entry list.
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*
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* Start from those deepest in the frame tree and works upwards. This stops
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* us from processing the same frame twice.
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*/
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void Flush() {
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while (!mEntryList.empty()) {
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Entry *entry = mEntryList.removeMin();
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nsIFrame *frame = entry->mFrame;
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bool overflowChanged;
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if (entry->mFlags & CHILDREN_CHANGED) {
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// Need to union the overflow areas of the children.
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overflowChanged = frame->UpdateOverflow();
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} else {
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nsOverflowAreas* pre = static_cast<nsOverflowAreas*>
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(frame->Properties().Get(frame->PreTransformOverflowAreasProperty()));
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if (pre) {
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// Since we have the pre-transform-overflow-areas, we can take a
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// faster path that doesn't require unioning the overflow areas
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// of our children.
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// FinishAndStoreOverflow will change the overflow areas passed in,
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// so make a copy.
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nsOverflowAreas overflowAreas = *pre;
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frame->FinishAndStoreOverflow(overflowAreas, frame->GetSize());
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// We can't tell if the overflow changed, so be conservative
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overflowChanged = true;
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} else {
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// We can't take the faster path here. Do it the hard way.
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overflowChanged = frame->UpdateOverflow();
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}
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}
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// If the frame style changed (e.g. positioning offsets)
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// then we need to update the parent with the overflow areas of its
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// children.
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if (overflowChanged || (entry->mFlags & STYLE_CHANGED)) {
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nsIFrame *parent = frame->GetParent();
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if (parent && parent != mSubtreeRoot) {
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Entry* parentEntry = mEntryList.find(Entry(parent, entry->mDepth - 1));
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if (parentEntry) {
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parentEntry->mFlags |= CHILDREN_CHANGED;
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} else {
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mEntryList.insert(new Entry(parent, entry->mDepth - 1, CHILDREN_CHANGED));
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}
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}
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}
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delete entry;
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}
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}
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private:
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enum {
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/**
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* Set if the overflow areas of children have changed so we need to call
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* UpdateOverflow on the frame.
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*/
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CHILDREN_CHANGED = 0x01,
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/**
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* True if the frame was explicitly added and hence may have had a style
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* change that changes its geometry relative to parent, without reflowing.
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* In this case we must update overflow on the frame's parent even if
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* this frame's overflow did not change.
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*/
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STYLE_CHANGED = 0x02
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};
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struct Entry : SplayTreeNode<Entry>
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{
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Entry(nsIFrame* aFrame, uint32_t aDepth, uint8_t aFlags = 0)
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: mFrame(aFrame)
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, mDepth(aDepth)
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, mFlags(aFlags)
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{}
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bool operator==(const Entry& aOther) const
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{
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return mFrame == aOther.mFrame;
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}
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/**
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* Sort by *reverse* depth in the tree, and break ties with
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* the frame pointer.
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*/
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bool operator<(const Entry& aOther) const
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{
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if (mDepth == aOther.mDepth) {
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return mFrame < aOther.mFrame;
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}
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return mDepth > aOther.mDepth; /* reverse, want "min" to be deepest */
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}
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static int compare(const Entry& aOne, const Entry& aTwo)
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{
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if (aOne == aTwo) {
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return 0;
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} else if (aOne < aTwo) {
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return -1;
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} else {
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return 1;
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}
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}
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nsIFrame* mFrame;
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/* Depth in the frame tree */
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uint32_t mDepth;
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uint8_t mFlags;
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};
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/* A list of frames to process, sorted by their depth in the frame tree */
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SplayTree<Entry, Entry> mEntryList;
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/* Don't update overflow of this frame or its ancestors. */
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const nsIFrame* mSubtreeRoot;
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};
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class RestyleTracker {
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public:
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typedef mozilla::dom::Element Element;
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RestyleTracker(uint32_t aRestyleBits) :
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mRestyleBits(aRestyleBits),
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mHaveLaterSiblingRestyles(false)
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{
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NS_PRECONDITION((mRestyleBits & ~ELEMENT_ALL_RESTYLE_FLAGS) == 0,
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"Why do we have these bits set?");
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NS_PRECONDITION((mRestyleBits & ELEMENT_PENDING_RESTYLE_FLAGS) != 0,
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"Must have a restyle flag");
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NS_PRECONDITION((mRestyleBits & ELEMENT_PENDING_RESTYLE_FLAGS) !=
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ELEMENT_PENDING_RESTYLE_FLAGS,
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"Shouldn't have both restyle flags set");
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NS_PRECONDITION((mRestyleBits & ~ELEMENT_PENDING_RESTYLE_FLAGS) != 0,
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"Must have root flag");
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NS_PRECONDITION((mRestyleBits & ~ELEMENT_PENDING_RESTYLE_FLAGS) !=
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(ELEMENT_ALL_RESTYLE_FLAGS & ~ELEMENT_PENDING_RESTYLE_FLAGS),
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"Shouldn't have both root flags");
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}
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void Init(RestyleManager* aRestyleManager) {
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mRestyleManager = aRestyleManager;
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}
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uint32_t Count() const {
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return mPendingRestyles.Count();
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}
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/**
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* Add a restyle for the given element to the tracker. Returns true
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* if the element already had eRestyle_LaterSiblings set on it.
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*/
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bool AddPendingRestyle(Element* aElement, nsRestyleHint aRestyleHint,
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nsChangeHint aMinChangeHint);
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/**
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* Process the restyles we've been tracking.
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*/
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void ProcessRestyles() {
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// Fast-path the common case (esp. for the animation restyle
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// tracker) of not having anything to do.
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if (mPendingRestyles.Count()) {
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DoProcessRestyles();
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}
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}
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// Return our ELEMENT_HAS_PENDING_(ANIMATION_)RESTYLE bit
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uint32_t RestyleBit() const {
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return mRestyleBits & ELEMENT_PENDING_RESTYLE_FLAGS;
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}
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// Return our ELEMENT_IS_POTENTIAL_(ANIMATION_)RESTYLE_ROOT bit
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uint32_t RootBit() const {
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return mRestyleBits & ~ELEMENT_PENDING_RESTYLE_FLAGS;
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}
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struct RestyleData {
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nsRestyleHint mRestyleHint; // What we want to restyle
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nsChangeHint mChangeHint; // The minimal change hint for "self"
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};
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/**
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* If the given Element has a restyle pending for it, return the
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* relevant restyle data. This function will clear everything other
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* than a possible eRestyle_LaterSiblings hint for aElement out of
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* our hashtable. The returned aData will never have an
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* eRestyle_LaterSiblings hint in it.
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*
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* The return value indicates whether any restyle data was found for
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* the element. If false is returned, then the state of *aData is
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* undefined.
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*/
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bool GetRestyleData(Element* aElement, RestyleData* aData);
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/**
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* The document we're associated with.
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*/
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inline nsIDocument* Document() const;
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struct RestyleEnumerateData : public RestyleData {
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nsRefPtr<Element> mElement;
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};
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private:
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/**
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* Handle a single mPendingRestyles entry. aRestyleHint must not
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* include eRestyle_LaterSiblings; that needs to be dealt with
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* before calling this function.
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*/
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inline void ProcessOneRestyle(Element* aElement,
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nsRestyleHint aRestyleHint,
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nsChangeHint aChangeHint);
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/**
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* The guts of our restyle processing.
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*/
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void DoProcessRestyles();
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typedef nsDataHashtable<nsISupportsHashKey, RestyleData> PendingRestyleTable;
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typedef nsAutoTArray< nsRefPtr<Element>, 32> RestyleRootArray;
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// Our restyle bits. These will be a subset of ELEMENT_ALL_RESTYLE_FLAGS, and
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// will include one flag from ELEMENT_PENDING_RESTYLE_FLAGS and one flag
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// that's not in ELEMENT_PENDING_RESTYLE_FLAGS.
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uint32_t mRestyleBits;
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RestyleManager* mRestyleManager; // Owns us
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// A hashtable that maps elements to RestyleData structs. The
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// values only make sense if the element's current document is our
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// document and it has our RestyleBit() flag set. In particular,
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// said bit might not be set if the element had a restyle posted and
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// then was moved around in the DOM.
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PendingRestyleTable mPendingRestyles;
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// An array that keeps track of our possible restyle roots. This
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// maintains the invariant that if A and B are both restyle roots
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// and A is an ancestor of B then A will come after B in the array.
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// We maintain this invariant by checking whether an element has an
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// ancestor with the restyle root bit set before appending it to the
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// array.
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RestyleRootArray mRestyleRoots;
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// True if we have some entries with the eRestyle_LaterSiblings
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// flag. We need this to avoid enumerating the hashtable looking
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// for such entries when we can't possibly have any.
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bool mHaveLaterSiblingRestyles;
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};
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inline bool RestyleTracker::AddPendingRestyle(Element* aElement,
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nsRestyleHint aRestyleHint,
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nsChangeHint aMinChangeHint)
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{
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RestyleData existingData;
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existingData.mRestyleHint = nsRestyleHint(0);
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existingData.mChangeHint = NS_STYLE_HINT_NONE;
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// Check the RestyleBit() flag before doing the hashtable Get, since
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// it's possible that the data in the hashtable isn't actually
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// relevant anymore (if the flag is not set).
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if (aElement->HasFlag(RestyleBit())) {
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mPendingRestyles.Get(aElement, &existingData);
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} else {
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aElement->SetFlags(RestyleBit());
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}
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bool hadRestyleLaterSiblings =
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(existingData.mRestyleHint & eRestyle_LaterSiblings) != 0;
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existingData.mRestyleHint =
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nsRestyleHint(existingData.mRestyleHint | aRestyleHint);
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NS_UpdateHint(existingData.mChangeHint, aMinChangeHint);
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mPendingRestyles.Put(aElement, existingData);
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// We can only treat this element as a restyle root if we would
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// actually restyle its descendants (so either call
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// ReResolveStyleContext on it or just reframe it).
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if ((aRestyleHint & (eRestyle_Self | eRestyle_Subtree)) ||
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(aMinChangeHint & nsChangeHint_ReconstructFrame)) {
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for (const Element* cur = aElement; !cur->HasFlag(RootBit()); ) {
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nsIContent* parent = cur->GetFlattenedTreeParent();
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// Stop if we have no parent or the parent is not an element or
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// we're part of the viewport scrollbars (because those are not
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// frametree descendants of the primary frame of the root
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// element).
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// XXXbz maybe the primary frame of the root should be the root scrollframe?
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if (!parent || !parent->IsElement() ||
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// If we've hit the root via a native anonymous kid and that
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// this native anonymous kid is not obviously a descendant
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// of the root's primary frame, assume we're under the root
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// scrollbars. Since those don't get reresolved when
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// reresolving the root, we need to make sure to add the
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// element to mRestyleRoots.
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(cur->IsInNativeAnonymousSubtree() && !parent->GetParent() &&
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cur->GetPrimaryFrame() &&
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cur->GetPrimaryFrame()->GetParent() != parent->GetPrimaryFrame())) {
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mRestyleRoots.AppendElement(aElement);
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break;
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}
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cur = parent->AsElement();
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}
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// At this point some ancestor of aElement (possibly aElement
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// itself) is in mRestyleRoots. Set the root bit on aElement, to
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// speed up searching for an existing root on its descendants.
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aElement->SetFlags(RootBit());
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}
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mHaveLaterSiblingRestyles =
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mHaveLaterSiblingRestyles || (aRestyleHint & eRestyle_LaterSiblings) != 0;
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return hadRestyleLaterSiblings;
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}
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} // namespace mozilla
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#endif /* mozilla_RestyleTracker_h */
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