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 446c4b9c662702900816af142c80273a978b0431..15f36a3dd283dbe644e3cc58a4f57523f5b8051f 100644
--- a/third_party/WebKit/Source/core/dom/Element.cpp
+++ b/third_party/WebKit/Source/core/dom/Element.cpp
@@ -59,6 +59,8 @@
 #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"
@@ -105,6 +107,8 @@
 #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"
@@ -1449,8 +1453,21 @@ 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());
@@ -1528,6 +1545,12 @@ void Element::removedFrom(ContainerNode* insertionPoint)
 
         if (ElementAnimations* elementAnimations = data->elementAnimations())
             elementAnimations->cssAnimations().cancel();
+
+        if (data->hasIntersectionObserver()) {
+            document().intersectionObserverRegistry()->removeTrackedObserversForRoot(this);
+            data->deactivateAllIntersectionObservers();
+        }
+        data->deactivateAllIntersectionObservations();
     }
 }
 
@@ -3561,6 +3584,93 @@ 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)
+{
+    // TODO: support zero-size targetRect
+    intersectionRect = targetRect = toLayoutBoxModelObject(layoutObject())->visualOverflowRect();
+    if (!computeElementIntersection(root, targetRect, intersectionRect))
+        return false;
+
+    LayoutObject* rootLayoutObject = root->layoutObject();
+    rootRect = toLayoutBoxModelObject(rootLayoutObject)->visualOverflowRect();
+
+    // Adjust all rects from root coordinates to document coordinates.
+    rootRect = LayoutRect(rootLayoutObject->localToAbsoluteQuad(FloatQuad(FloatRect(rootRect))).boundingBox());
+    targetRect = LayoutRect(rootLayoutObject->localToAbsoluteQuad(FloatQuad(FloatRect(targetRect))).boundingBox());
+    intersectionRect = LayoutRect(rootLayoutObject->localToAbsoluteQuad(FloatQuad(FloatRect(intersectionRect))).boundingBox());
+
+    return true;
+}
+
+bool Element::computeElementIntersection(Element* root, LayoutRect& targetRect, LayoutRect& intersectionRect)
+{
+    // TODO: mapRectToPaintInvalidationBacking probably doesn't do exactly the clipping we want,
+    // and it doesn't support rootMargin at all.
+    // TODO: Support SVG
+    if (root == this)
+        return true;
+    Element* target = this;
+    while (&target->document() != &root->document()) {
+        target = target->computeFrameIntersection(targetRect, intersectionRect);
+        if (!target)
+            return false;
+        // TODO: adjust for border, padding, scrollbars, writing mode.
+    }
+    ASSERT(target->isDescendantOf(root));
+
+    bool rootIsDocumentElement = (root == root->document().documentElement());
+    LayoutObject* rootLayoutObject = rootIsDocumentElement ? root->document().layoutView() : root->layoutObject();
+    if (!rootLayoutObject->isBoxModelObject())
+        return false;
+    target->layoutObject()->mapRectToPaintInvalidationBacking(toLayoutBoxModelObject(rootLayoutObject), intersectionRect, nullptr);
+    targetRect = LayoutRect(target->layoutObject()->localToContainerQuad(FloatQuad(FloatRect(targetRect)), toLayoutBoxModelObject(rootLayoutObject)).boundingBox());
+    if (rootIsDocumentElement)
+        root->computeFrameIntersection(targetRect, intersectionRect);
+
+    return true;
+}
+
+Element* Element::computeFrameIntersection(LayoutRect& targetRect, LayoutRect& intersectionRect)
+{
+    if (!computeElementIntersection(document().documentElement(), targetRect, intersectionRect))
+        return nullptr;
+    FrameView* frameView = document().view();
+    ASSERT(frameView);
+
+    // Until root layer scrolling is finished, we need to clip to the visible content area of the FrameView.
+    intersectionRect.moveBy(LayoutPoint(-frameView->scrollPosition()));
+    LayoutRect frameClipRect(LayoutPoint(),  LayoutSize(frameView->visibleContentSize()));
+    intersectionRect.intersect(frameClipRect);
+
+    LocalFrame* frame = document().frame();
+    ASSERT(frame);
+    LayoutObject* frameOwner = frame->ownerLayoutObject();
+    if (!frameOwner)
+        return nullptr;
+    return toElement(frameOwner->node());
+}
+
 DEFINE_TRACE(Element)
 {
 #if ENABLE(OILPAN)