IntersectionObserver: second cut.

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

Index: third_party/WebKit/Source/core/dom/Element.cpp
diff --git a/third_party/WebKit/Source/core/dom/Element.cpp b/third_party/WebKit/Source/core/dom/Element.cpp
index d54240953a41d9654d01dadb43402f3721bc3ebc..92d52fa4d8ad473a90a16deb8f70d112e717574a 100644
--- a/third_party/WebKit/Source/core/dom/Element.cpp
+++ b/third_party/WebKit/Source/core/dom/Element.cpp
@@ -60,6 +60,8 @@
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/FirstLetterPseudoElement.h"
 #include "core/dom/Fullscreen.h"
+#include "core/dom/IntersectionObserver.h"
+#include "core/dom/IntersectionObserverRegistry.h"
 #include "core/dom/LayoutTreeBuilder.h"
 #include "core/dom/MutationObserverInterestGroup.h"
 #include "core/dom/MutationRecord.h"
@@ -106,6 +108,8 @@
 #include "core/html/HTMLTemplateElement.h"
 #include "core/html/parser/HTMLParserIdioms.h"
 #include "core/inspector/InspectorInstrumentation.h"
+#include "core/layout/LayoutInline.h"
+#include "core/layout/LayoutPart.h"
 #include "core/layout/LayoutTextFragment.h"
 #include "core/layout/LayoutView.h"
 #include "core/loader/DocumentLoader.h"
@@ -1450,8 +1454,21 @@ Node::InsertionNotificationRequest Element::insertedInto(ContainerNode* insertio
     if (!insertionPoint->isInTreeScope())
         return InsertionDone;
 
-    if (hasRareData())
-        elementRareData()->clearClassListValueForQuirksMode();
+    if (hasRareData()) {
+        ElementRareData* rareData = elementRareData();
+        rareData->clearClassListValueForQuirksMode();
+        if (rareData->hasIntersectionObserver()) {
+            IntersectionObserverRegistry* registry = document().intersectionObserverRegistry();
+            for (auto& observer: rareData->intersectionObservers()) {
+                registry->addTrackedObserver(*observer);
+                observer->setActive(true);
+            }
+        }
+        if (rareData->hasIntersectionObservation()) {
+            for (auto& observation: rareData->intersectionObservations())
+                observation->setActive(observation->observer()->isDescendantOfRoot(this));
+        }
+    }
 
     if (isUpgradedCustomElement() && inDocument())
         CustomElement::didAttach(this, document());
@@ -1529,6 +1546,12 @@ void Element::removedFrom(ContainerNode* insertionPoint)
 
         if (ElementAnimations* elementAnimations = data->elementAnimations())
             elementAnimations->cssAnimations().cancel();
+
+        if (data->hasIntersectionObserver()) {
+            document().intersectionObserverRegistry()->removeTrackedObserversForRoot(this);
+            data->deactivateAllIntersectionObservers();
+        }
+        data->deactivateAllIntersectionObservations();
     }
 }
 
@@ -3570,6 +3593,55 @@ bool Element::supportsStyleSharing() const
     return true;
 }
 
+WeakPtrWillBeRawPtr<Element> Element::createWeakPtr()
+{
+#if ENABLE(OILPAN)
+    return this;
+#else
+    return ensureElementRareData().createWeakPtr(this);
+#endif
+}
+
+void Element::addIntersectionObservation(IntersectionObservation& observation)
+{
+    ensureElementRareData().intersectionObservations().add(&observation);
+}
+
+void Element::removeIntersectionObservation(IntersectionObservation& observation)
+{
+    if (!hasRareData() || !elementRareData()->hasIntersectionObservation())
+        return;
+    elementRareData()->intersectionObservations().remove(&observation);
+}
+
+bool Element::computeIntersection(Element* root, LayoutRect& targetRect, LayoutRect& rootRect, LayoutRect& intersectionRect)
+{
+    bool rootIsDocumentElement = (root == root->document().documentElement());
+    LayoutObject* rootLayoutObject = rootIsDocumentElement ? root->document().layoutView() : root->layoutObject();
+    if (!rootLayoutObject->isBoxModelObject())
+        return false;
+    intersectionRect = targetRect = toLayoutBoxModelObject(layoutObject())->visualOverflowRect();
+    layoutObject()->mapRectToPaintInvalidationBacking(toLayoutBoxModelObject(rootLayoutObject), intersectionRect, nullptr);
+    targetRect = LayoutRect(layoutObject()->localToAbsoluteQuad(FloatQuad(FloatRect(targetRect)), UseTransforms | ApplyContainerFlip | TraverseDocumentBoundaries).boundingBox());
+    intersectionRect = LayoutRect(rootLayoutObject->localToAbsoluteQuad(FloatQuad(FloatRect(intersectionRect))).boundingBox());
+    LayoutPoint scrollPosition(root->document().view()->scrollPosition());
+    if (rootIsDocumentElement) {
+        rootRect = LayoutRect(root->document().view()->visibleContentRect());
+        intersectionRect.intersect(rootRect);
+    } else if (rootLayoutObject->isBox()) {
+        rootRect = LayoutRect(toLayoutBox(rootLayoutObject)->absoluteContentBox());
+    } else {
+        rootRect = LayoutRect(rootLayoutObject->absoluteBoundingBoxRect());
+    }
+    targetRect.moveBy(-scrollPosition);
+    intersectionRect.moveBy(-scrollPosition);
+    rootRect.moveBy(-scrollPosition);
+    if (intersectionRect.size().isZero())
+        intersectionRect = LayoutRect();
+
+    return true;
+}
+
 void Element::logEventIfIsolatedWorldAndInDocument(const String& eventName, const String& arg1, const String& arg2)
 {
     if (!inDocument())