Intersection Observer first draft

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/)
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 2468 matching lines @@
 
         if (StyleImage* maskBoxImage = m_style->maskBoxImage().image())
             maskBoxImage->removeClient(this);
 
         removeShapeImageClient(m_style->shapeOutside());
     }
     ResourceLoadPriorityOptimizer::resourceLoadPriorityOptimizer()->removeLayoutObject(this);
 
     if (frameView())
         setIsSlowRepaintObject(false);
+
+    if (view() && hasIntersectionObserver()) {

[ojan, 2015/09/21 03:49:09]

Ditto nits about curlies here and below

[MikeB, 2015/09/24 19:04:04]

Done.

+        view()->removeIntersectionObserverTarget(this);
+    }
 }
 
 void LayoutObject::insertedIntoTree()
 {
     // FIXME: We should ASSERT(isRooted()) here but generated content makes some out-of-order insertion.
 
     // Keep our layer hierarchy updated. Optimize for the common case where we don't have any children
     // and don't have a layer attached to ourselves.
     DeprecatedPaintLayer* layer = nullptr;
     if (slowFirstChild() || hasLayer()) {
         layer = parent()->enclosingLayer();
         addLayers(layer);
     }
 
     // If |this| is visible but this object was not, tell the layer it has some visible content
     // that needs to be drawn and layer visibility optimization can't be used
     if (parent()->style()->visibility() != VISIBLE && style()->visibility() == VISIBLE && !hasLayer()) {
         if (!layer)
             layer = parent()->enclosingLayer();
         if (layer)
             layer->dirtyVisibleContentStatus();
     }
 
     if (parent()->childrenInline())
         parent()->dirtyLinesFromChangedChild(this);
 
     if (LayoutFlowThread* flowThread = flowThreadContainingBlock())
         flowThread->flowThreadDescendantWasInserted(this);
+
+    if (view() && hasIntersectionObserver()) {
+        view()->addIntersectionObserverTarget(this);
+    }
 }
 
 void LayoutObject::willBeRemovedFromTree()
 {
     // FIXME: We should ASSERT(isRooted()) but we have some out-of-order removals which would need to be fixed first.
 
     // If we remove a visible child from an invisible parent, we don't know the layer visibility any more.
     DeprecatedPaintLayer* layer = nullptr;
     if (parent()->style()->visibility() != VISIBLE && style()->visibility() == VISIBLE && !hasLayer()) {
         layer = parent()->enclosingLayer();
         if (layer)
             layer->dirtyVisibleContentStatus();
     }
 
     // Keep our layer hierarchy updated.
     if (slowFirstChild() || hasLayer()) {
         if (!layer)
             layer = parent()->enclosingLayer();
         removeLayers(layer);
     }
 
     if (isOutOfFlowPositioned() && parent()->childrenInline())
         parent()->dirtyLinesFromChangedChild(this);
 
     removeFromLayoutFlowThread();
 
     // Update cached boundaries in SVG layoutObjects if a child is removed.
     if (parent()->isSVG())
         parent()->setNeedsBoundariesUpdate();
+
+    if (view() && hasIntersectionObserver()) {

[ojan, 2015/09/21 03:49:09]

I'm not sure, but I believe this function gets called from
LayoutObject::willBeDestroyed() via the "remove()" call inside it. So, either
this one or the one in willBeDestroyed isn't needed (I think).

+        view()->removeIntersectionObserverTarget(this);
+    }
 }
 
 void LayoutObject::removeFromLayoutFlowThread()
 {
     if (!isInsideFlowThread())
         return;
 
     // Sometimes we remove the element from the flow, but it's not destroyed at that time.
     // It's only until later when we actually destroy it and remove all the children from it.
     // Currently, that happens for firstLetter elements and list markers.
@@ skipping 852 matching lines @@
         const blink::LayoutObject* root = object1;
         while (root->parent())
             root = root->parent();
         root->showLayoutTreeAndMark(object1, "*", object2, "-", 0);
     } else {
         fprintf(stderr, "Cannot showLayoutTree. Root is (nil)\n");
     }
 }
 
 #endif