Fix inline focus ring paint invalidation on continuation change

third_party/WebKit/Source/core/layout/LayoutObject.cpp

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  *           (C) 1999 Antti Koivisto (koivisto@kde.org)
  *           (C) 2000 Dirk Mueller (mueller@kde.org)
  *           (C) 2004 Allan Sandfeld Jensen (kde@carewolf.com)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2011 Apple Inc.
  *               All rights reserved.
  * Copyright (C) 2009 Google Inc. All rights reserved.
  * Copyright (C) 2009 Torch Mobile Inc. All rights reserved.
  *               (http://www.torchmobile.com/)
@@ skipping 3404 matching lines @@
 inline void LayoutObject::markAncestorsForPaintInvalidation() {
   for (LayoutObject* parent = this->paintInvalidationParent();
        parent && !parent->shouldCheckForPaintInvalidation();
        parent = parent->paintInvalidationParent())
     parent->m_bitfields.setMayNeedPaintInvalidation(true);
 }
 
 inline void LayoutObject::setNeedsPaintOffsetAndVisualRectUpdate() {
   if (needsPaintOffsetAndVisualRectUpdate())
     return;
-  m_bitfields.setNeedsPaintOffsetAndVisualRectUpdate(true);
-  for (LayoutObject* parent = paintInvalidationParent();
-       parent && !parent->needsPaintOffsetAndVisualRectUpdate();
-       parent = parent->paintInvalidationParent())
-    parent->m_bitfields.setNeedsPaintOffsetAndVisualRectUpdate(true);
+  for (auto* object = this;
+       object && !object->needsPaintOffsetAndVisualRectUpdate();
+       object = object->paintInvalidationParent()) {

[pdr., 2017/03/21 18:40:49]

Do we need to invalidate both the object and its continuation start? In other
words, could paintInvalidationParent just return the continuation start in this
case?

[Xianzhu, 2017/03/22 02:46:07]

This special case is for focus ring only. Focus ring is the only case that the
visual rect of the start of continuation may depends on continuations. All other
cases just use the normal hierarchy.

+    object->m_bitfields.setNeedsPaintOffsetAndVisualRectUpdate(true);
+
+    // If the object is an anonymous block continuation, mark the start object

[wkorman, 2017/03/21 19:31:52]

Wondered why we only have to mark the start object. Presuming this is an
artifact of how we implement invalidation of continuations, or, the rest of the
continuation will be handled when the other involved objects are invalidated?
Perhaps worth adding to comment.

[Xianzhu, 2017/03/22 02:46:07]

Please see the reply to pdr@'s comment above.

Updated comment to state that this is special case for focus ring only.

+    // of the continuation for paint invalidation if it has focus ring because
+    // change of continuation may change the shape of the focus ring.
+    if (!object->isAnonymous() || !object->isLayoutBlockFlow())
+      continue;
+    auto* blockFlow = toLayoutBlockFlow(object);
+    if (!blockFlow->isAnonymousBlockContinuation())
+      continue;
+
+    if (auto* inlineElementContinuation =
+            blockFlow->inlineElementContinuation()) {
+      auto* startOfContinuations =
+          inlineElementContinuation->node()->layoutObject();
+      if (startOfContinuations &&
+          startOfContinuations->styleRef().outlineStyleIsAuto())
+        startOfContinuations->setMayNeedPaintInvalidation();
+    }
+  }
 }
 
 void LayoutObject::setShouldInvalidateSelection() {
   if (!canUpdateSelectionOnRootLineBoxes())
     return;
   m_bitfields.setShouldInvalidateSelection(true);
   setMayNeedPaintInvalidation();
   frameView()->scheduleVisualUpdateForPaintInvalidationIfNeeded();
 }
 
@@ skipping 185 matching lines @@
     const blink::LayoutObject* root = object1;
     while (root->parent())
       root = root->parent();
     root->showLayoutTreeAndMark(object1, "*", object2, "-", 0);
   } else {
     WTFLogAlways("%s", "Cannot showLayoutTree. Root is (nil)");
   }
 }
 
 #endif