Initial ResizeObserver implementation

third_party/WebKit/Source/core/observer/ResizeObserverEntry.cpp

+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "core/observer/ResizeObserverEntry.h"
+
+#include "core/dom/ClientRect.h"
+#include "core/dom/DOMRectReadOnly.h"
+#include "core/dom/Element.h"
+#include "core/layout/LayoutBox.h"
+
+namespace blink {
+
+class ResizeObservation;
+
+ResizeObserverEntry::ResizeObserverEntry(Element* target)
+    : m_target(target)
+{
+    if (!m_target)
+        return;
+    LayoutBox* layout = m_target->layoutBox();
+    if (!layout)
+        return;
+    m_contentRect.setSize(layout->contentSize());

[szager1, 2016/06/02 20:52:41]

m_contentRect = layout->contentBoxRect();

[atotic1, 2016/06/08 18:59:22]

Why? m_contentRect gets the size from layout, and position from padding. I feel
that setting the size explicitly better communicates the intent.

+    m_contentRect.setLocation(LayoutPoint(layout->paddingLeft(), layout->paddingTop()));
+}
+
+ClientRect* ResizeObserverEntry::contentRect() const
+{
+    return ClientRect::create( FloatRect(
+        m_contentRect.x(), m_contentRect.y(),
+        m_contentRect.width(), m_contentRect.height()
+    ));
+    // FIXME(atotic): should return DOMReadOnlyRect once GeometryInterfaces land
+    // return DOMRectReadOnly::create(m_contentRect.x(), m_contentRect.y(),
+    //   m_contentRect.width(), m_contentRect.height());
+
+}
+
+LayoutSize ResizeObserverEntry::contentSize() const
+{
+    return m_contentRect.size();
+}
+
+
+DEFINE_TRACE(ResizeObserverEntry)
+{
+    visitor->trace(m_target);
+}
+
+} // namespace blink