Intersection Observer first draft

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 969 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& viewport)
+{
+    for (auto& obj : m_intersectionObserverTargets) {
+        LayoutObject* layoutObect = obj.key;

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

Typo: layoutObect

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

Done.

+        Node* node = layoutObect->node();
+        if (!node || !node->isElementNode())
+            continue;
+        FloatRect bounds = layoutObect->absoluteBoundingBoxFloatRect();

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

I don't think this handles clipping from ancestor scrollers, does it? Vollick,
what's the right way to get an elements bounding box intersected with all its
ancestor clips? At the moment, the spec just says overflow clips, but we can
consider changing it to include clip-path, etc if that makes more sense.

+        bounds.intersect(viewport);
+        const FloatRect& oldBounds = obj.value;
+        if (oldBounds == bounds)
+            continue;
+        obj.value = bounds;
+        Element* element = toElement(node);
+        Vector<FloatRect> quads;
+        quads.append(bounds);
+        for (auto& observer : element->intersectionObservers()) {
+            observer->enqueueIntersectionObserverEntry(IntersectionObserverEntry::create(0, quads, viewport, element));
+        }
+    }
+}
+
 } // namespace blink