Intersection Observer first draft

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

 /*
  * Copyright (C) 1999 Lars Knoll (knoll@kde.org)
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Library General Public
  * License as published by the Free Software Foundation; either
  * version 2 of the License, or (at your option) any later version.
  *
  * This library is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * Library General Public License for more details.
  *
  * You should have received a copy of the GNU Library General Public License
  * along with this library; see the file COPYING.LIB.  If not, write to
  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  * Boston, MA 02110-1301, USA.
  */
 
 #include "config.h"
 #include "core/layout/LayoutView.h"
 
 #include "core/dom/Document.h"
 #include "core/dom/Element.h"
+#include "core/dom/IntersectionObserver.h"
 #include "core/editing/FrameSelection.h"
 #include "core/frame/LocalFrame.h"
 #include "core/frame/Settings.h"
 #include "core/html/HTMLFrameOwnerElement.h"
 #include "core/html/HTMLIFrameElement.h"
 #include "core/inspector/InspectorTraceEvents.h"
 #include "core/layout/HitTestResult.h"
 #include "core/layout/LayoutFlowThread.h"
 #include "core/layout/LayoutGeometryMap.h"
 #include "core/layout/LayoutPart.h"
@@ skipping 911 matching lines @@
     float scale = m_frameView ? m_frameView->frame().pageZoomFactor() : 1;
     return viewHeight(IncludeScrollbars) / scale;
 }
 
 void LayoutView::willBeDestroyed()
 {
     LayoutBlockFlow::willBeDestroyed();
     m_compositor.clear();
 }
 
+void LayoutView::addIntersectionObserverTarget(LayoutObject* obj)
+{
+    m_intersectionObserverTargets.add(obj, IntRect());
+}
+
+void LayoutView::removeIntersectionObserverTarget(LayoutObject* obj)
+{
+    m_intersectionObserverTargets.remove(obj);
+}
+
+void LayoutView::computeIntersectionObservations(const FloatRect& rootBounds)
+{
+    for (auto& obj : m_intersectionObserverTargets) {
+        LayoutObject* layoutObject = obj.key;
+        Node* node = layoutObject->node();
+        if (!node || !node->isElementNode())
+            continue;
+        FloatRect bounds = layoutObject->absoluteBoundingBoxFloatRect();
+        FloatRect intersection(bounds);
+        intersection.intersect(rootBounds);
+        const FloatRect& oldIntersection = obj.value;
+        if (oldIntersection == intersection)
+            continue;
+        obj.value = intersection;
+        Element* element = toElement(node);
+        for (auto& observer : element->intersectionObservers()) {
+            observer->enqueueIntersectionObserverEntry(IntersectionObserverEntry::create(0, bounds, rootBounds, intersection, element));
+        }
+    }
+}
+
 } // namespace blink