Intersection Observer first draft

Source/core/frame/FrameView.cpp

 /*
  * Copyright (C) 1998, 1999 Torben Weis <weis@kde.org>
  *                     1999 Lars Knoll <knoll@kde.org>
  *                     1999 Antti Koivisto <koivisto@kde.org>
  *                     2000 Dirk Mueller <mueller@kde.org>
  * Copyright (C) 2004, 2005, 2006, 2007, 2008 Apple Inc. All rights reserved.
  *           (C) 2006 Graham Dennis (graham.dennis@gmail.com)
  *           (C) 2006 Alexey Proskuryakov (ap@nypop.com)
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
@@ skipping 1098 matching lines @@
 
 #if ENABLE(ASSERT)
     layoutView()->assertSubtreeClearedPaintInvalidationState();
 #endif
 
     if (m_frame->selection().isCaretBoundsDirty())
         m_frame->selection().invalidateCaretRect();
 
     m_doFullPaintInvalidation = false;
     lifecycle().advanceTo(DocumentLifecycle::PaintInvalidationClean);
+
+    if (RuntimeEnabledFeatures::intersectionObserverEnabled()) {
+        computeIntersectionObservations(paintInvalidationState);
+    }
+}
+
+void FrameView::computeIntersectionObservations(PaintInvalidationState& paintInvalidationState)
+{
+    ASSERT(layoutView());
+
+    if (FrameView* parent = parentFrameView()) {

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

Does this handle clipping correctly if you have multiple levels of nested
frames?

+        m_clippedBounds = IntRect(frameRect().location(), paintInvalidationState.clipRect().pixelSnappedSize());
+        m_clippedBounds = parent->contentsToRootFrame(m_clippedBounds);
+        m_clippedBounds.intersect(parent->contentsToRootFrame(parent->m_clippedBounds));
+        if (!m_clippedBounds.isEmpty()) {

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

Nit: no curlies

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

Done.

+            m_clippedBounds = rootFrameToContents(m_clippedBounds);
+        }
+    } else {
+        m_clippedBounds = pixelSnappedIntRect(paintInvalidationState.clipRect());
+    }
+
+    layoutView()->computeIntersectionObservations(FloatRect(m_clippedBounds));
 }
 
 DocumentLifecycle& FrameView::lifecycle() const
 {
     return m_frame->document()->lifecycle();
 }
 
 LayoutBox* FrameView::embeddedContentBox() const
 {
     LayoutView* layoutView = this->layoutView();
@@ skipping 2834 matching lines @@
 
     if (!graphicsLayer)
         return;
 
     DeprecatedPaintLayer::mapRectToPaintInvalidationBacking(localFrame->contentLayoutObject(), paintInvalidationContainer, viewRect);
 
     graphicsLayerTimingRequests.add(graphicsLayer, Vector<std::pair<int64_t, WebRect>>()).storedValue->value.append(std::make_pair(m_frame->frameID(), enclosingIntRect(viewRect)));
 }
 
 } // namespace blink