Call Element::rebuildLayoutTree from Document::updateStyle directly

third_party/WebKit/Source/core/dom/Element.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2001 Peter Kelly (pmk@post.com)
  *           (C) 2001 Dirk Mueller (mueller@kde.org)
  *           (C) 2007 David Smith (catfish.man@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2012, 2013 Apple Inc.
  * All rights reserved.
  *           (C) 2007 Eric Seidel (eric@webkit.org)
  *
@@ skipping 1877 matching lines @@
     if (hasRareData()) {
       ElementRareData* data = elementRareData();
       if (change != IndependentInherit)
         data->clearComputedStyle();
 
       if (change >= IndependentInherit) {
         if (ElementAnimations* elementAnimations = data->elementAnimations())
           elementAnimations->setAnimationStyleChange(false);
       }
     }
-    if (parentComputedStyle())
+    if (parentComputedStyle()) {
       change = recalcOwnStyle(change, nextTextSibling);
-    clearNeedsStyleRecalc();
-    clearNeedsReattachLayoutTree();
+    } else {
+      // In case we don't perform recalcOwnStyle we will never clear the
+      // NeedsReattachLayoutTree flag which is set on the creation of each
+      // Node. Clear that here.
+      clearNeedsReattachLayoutTree();
+    }
+    // If you are going to reattachLayoutTree you need to retain this flag
+    // to determine if detachLayoutTree() needs to happen.
+    if (!needsReattachLayoutTree())
+      clearNeedsStyleRecalc();
   }
 
-  // If we reattached we don't need to recalc the style of our descendants
-  // anymore.
-  if ((change >= UpdatePseudoElements && change < Reattach) ||
-      childNeedsStyleRecalc()) {
+  // If we are going to reattach we don't need to recalc the style of
+  // our descendants anymore.
+  if (change < Reattach &&
+      (change >= UpdatePseudoElements || childNeedsStyleRecalc())) {
     SelectorFilterParentScope filterScope(*this);
     StyleSharingDepthScope sharingScope(*this);
 
     updatePseudoElement(PseudoIdBefore, change);
 
     if (change > UpdatePseudoElements || childNeedsStyleRecalc()) {
       for (ShadowRoot* root = youngestShadowRoot(); root;
            root = root->olderShadowRoot()) {
-        if (root->shouldCallRecalcStyle(change))
+        if (root->shouldCallRecalcStyle(change)) {
           root->recalcStyle(change);
+        } else {
+          // In case we don't perform recalcStyle we will never clear the
+          // NeedsReattachLayoutTree flag which is set on the creation of each
+          // Node. Clear that here.
+          root->clearNeedsReattachLayoutTree();

[esprehn, 2017/02/02 08:37:09]

I wonder how this can happen, how do we get here with the reattach flag set but
without the recalc style flag set?

[nainar, 2017/02/02 23:13:06]

Yup this is redundant code and never executed. Removed. 

+        }
       }
       recalcDescendantStyles(change);
     }
 
     updatePseudoElement(PseudoIdAfter, change);
     updatePseudoElement(PseudoIdBackdrop, change);
 
     // If our children have changed then we need to force the first-letter
     // checks as we don't know if they effected the first letter or not.
     // This can be seen when a child transitions from floating to
     // non-floating we have to take it into account for the first letter.
     updatePseudoElement(PseudoIdFirstLetter,
                         childNeedsStyleRecalc() ? Force : change);
 
     clearChildNeedsStyleRecalc();
-    clearChildNeedsReattachLayoutTree();
   }
 
   if (hasCustomStyleCallbacks())
     didRecalcStyle();
 }
 
 PassRefPtr<ComputedStyle> Element::propagateInheritedProperties(
     StyleRecalcChange change) {
   if (change != IndependentInherit)
     return nullptr;
@@ skipping 39 matching lines @@
   } else {
     INCREMENT_STYLE_STATS_COUNTER(document().styleEngine(), stylesChanged, 1);
   }
 
   if (localChange == Reattach) {
     StyleReattachData styleReattachData;
     styleReattachData.computedStyle = std::move(newStyle);
     styleReattachData.nextTextSibling = nextTextSibling;
     document().addStyleReattachData(*this, styleReattachData);
     setNeedsReattachLayoutTree();
-    return rebuildLayoutTree();
+    return Reattach;
   }
 
   DCHECK(oldStyle);
 
   if (localChange != NoChange)
     updateCallbackSelectors(oldStyle.get(), newStyle.get());
 
   if (LayoutObject* layoutObject = this->layoutObject()) {
     if (localChange != NoChange ||
         pseudoStyleCacheIsInvalid(oldStyle.get(), newStyle.get())) {
@@ skipping 20 matching lines @@
         return Inherit;
       newStyle->copyChildDependentFlagsFrom(*oldStyle);
     }
     if (oldStyle->hasPseudoElementStyle() || newStyle->hasPseudoElementStyle())
       return UpdatePseudoElements;
   }
 
   return localChange;
 }
 
-StyleRecalcChange Element::rebuildLayoutTree() {
+void Element::rebuildLayoutTree() {
   DCHECK(inActiveDocument());
+  DCHECK(parentNode());
+
   StyleReattachData styleReattachData = document().getStyleReattachData(*this);
   AttachContext reattachContext;
   reattachContext.resolvedStyle = styleReattachData.computedStyle.get();
   bool layoutObjectWillChange = needsAttach() || layoutObject();
 
-  // We are calling Element::rebuildLayoutTree() from inside
-  // Element::recalcOwnStyle where we set the NeedsReattachLayoutTree
-  // flag - so needsReattachLayoutTree() should always be true.
-  DCHECK(parentNode());
-  DCHECK(parentNode()->childNeedsReattachLayoutTree());
-  DCHECK(needsReattachLayoutTree());
-  reattachLayoutTree(reattachContext);
-  // Since needsReattachLayoutTree() is always true we go into
-  // reattachLayoutTree() which reattaches all the descendant
-  // sub-trees. At this point no child should need reattaching.
+  if (needsReattachLayoutTree()) {
+    reattachLayoutTree(reattachContext);
+  } else if (childNeedsReattachLayoutTree()) {
+    DCHECK(!needsReattachLayoutTree());
+    SelectorFilterParentScope filterScope(*this);
+    StyleSharingDepthScope sharingScope(*this);
+    reattachPseudoElementLayoutTree(PseudoIdBefore);
+    rebuildShadowRootLayoutTree();
+    rebuildChildrenLayoutTrees();
+    reattachPseudoElementLayoutTree(PseudoIdAfter);
+    reattachPseudoElementLayoutTree(PseudoIdBackdrop);
+    reattachPseudoElementLayoutTree(PseudoIdFirstLetter);
+  }
+  DCHECK(!needsStyleRecalc());
+  DCHECK(!childNeedsStyleRecalc());
+  DCHECK(!needsReattachLayoutTree());
   DCHECK(!childNeedsReattachLayoutTree());
 
   if (layoutObjectWillChange || layoutObject()) {
     // nextTextSibling is passed on to recalcStyle from recalcDescendantStyles
     // we can either traverse the current subtree from this node onwards
     // or store it.
     // The choice is between increased time and increased memory complexity.
     reattachWhitespaceSiblingsIfNeeded(styleReattachData.nextTextSibling);
-    return Reattach;
   }
-  return ReattachNoLayoutObject;
+}
+
+void Element::rebuildShadowRootLayoutTree() {
+  for (ShadowRoot* root = youngestShadowRoot(); root;
+       root = root->olderShadowRoot()) {
+    if (root->needsReattachLayoutTree() || root->childNeedsReattachLayoutTree())
+      root->rebuildLayoutTree();
+  }
+}
+
+void Element::reattachPseudoElementLayoutTree(PseudoId pseudoId) {
+  if (PseudoElement* element = pseudoElement(pseudoId)) {
+    if (element->needsReattachLayoutTree() ||
+        element->childNeedsReattachLayoutTree())
+      element->rebuildLayoutTree();
+  } else {
+    createPseudoElementIfNeeded(pseudoId);
+  }
 }
 
 void Element::updateCallbackSelectors(const ComputedStyle* oldStyle,
                                       const ComputedStyle* newStyle) {
   Vector<String> emptyVector;
   const Vector<String>& oldCallbackSelectors =
       oldStyle ? oldStyle->callbackSelectors() : emptyVector;
   const Vector<String>& newCallbackSelectors =
       newStyle ? newStyle->callbackSelectors() : emptyVector;
   if (oldCallbackSelectors.isEmpty() && newCallbackSelectors.isEmpty())
@@ skipping 1129 matching lines @@
 Locale& Element::locale() const {
   return document().getCachedLocale(computeInheritedLanguage());
 }
 
 void Element::cancelFocusAppearanceUpdate() {
   if (document().focusedElement() == this)
     document().cancelFocusAppearanceUpdate();
 }
 
 void Element::updatePseudoElement(PseudoId pseudoId, StyleRecalcChange change) {
-  DCHECK(!needsStyleRecalc());
   PseudoElement* element = pseudoElement(pseudoId);
 
   if (element && (change == UpdatePseudoElements ||
                   element->shouldCallRecalcStyle(change))) {
     if (pseudoId == PseudoIdFirstLetter && updateFirstLetter(element))
       return;
 
     // Need to clear the cached style if the PseudoElement wants a recalc so it
     // computes a new style.
     if (element->needsStyleRecalc())
@@ skipping 919 matching lines @@
 }
 
 DEFINE_TRACE_WRAPPERS(Element) {
   if (hasRareData()) {
     visitor->traceWrappers(elementRareData());
   }
   ContainerNode::traceWrappers(visitor);
 }
 
 }  // namespace blink