ResizeObserver pt3: observation computation

This patch fills in ResizeObservation functionality:
- computing/setting observation size
- determining target depth

ResizeObservation::getTargetSize is static because it will also
get used by ResizeObserverEntry

I've also included basic C++ tests.

BUG=612962

Review-Url: https://codereview.chromium.org/2173203002
Cr-Commit-Position: refs/heads/master@{#407736}

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

@@ -4,18 +4,54 @@
 
 #include "core/observer/ResizeObservation.h"
 
-#include "core/dom/Element.h"
+#include "core/layout/LayoutBox.h"
 #include "core/observer/ResizeObserver.h"
+#include "core/svg/SVGElement.h"
+#include "core/svg/SVGGraphicsElement.h"
 
 namespace blink {
 
 ResizeObservation::ResizeObservation(Element* target, ResizeObserver* observer)
     : m_target(target)
     , m_observer(observer)
+    , m_observationSize(0, 0)
 {
     DCHECK(m_target);
 }
 
+void ResizeObservation::setObservationSize(const LayoutSize& size)
+{
+    m_observationSize = size;
+}
+
+bool ResizeObservation::observationSizeOutOfSync() const
+{
+    return m_observationSize != ResizeObservation::getTargetSize(m_target);
+}
+
+size_t ResizeObservation::targetDepth()
+{
+    unsigned depth = 0;
+    for (Element* parent = m_target; parent; parent = parent->parentElement())
+        ++depth;
+    return depth;
+}
+
+LayoutSize ResizeObservation::getTargetSize(Element* target) // static
+{
+    if (target) {
+        if (target->isSVGElement() && toSVGElement(target)->isSVGGraphicsElement()) {
+            SVGGraphicsElement& svg = toSVGGraphicsElement(*target);
+            return LayoutSize(svg.getBBox().size());
+        }
+        LayoutBox* layout = target->layoutBox();
+        if (layout)
+            return layout->contentSize();
+    }
+    return LayoutSize();
+}
+
+
 DEFINE_TRACE(ResizeObservation)
 {
     visitor->trace(m_target);

third_party/WebKit/Source/core/observer/ResizeObservation.h

@@ -15,18 +15,25 @@ class Element;
 class ResizeObserver;
 
 // ResizeObservation represents an element that is being observed.
-class ResizeObservation final : public GarbageCollected<ResizeObservation> {
+class CORE_EXPORT ResizeObservation final : public GarbageCollected<ResizeObservation> {
 public:
     ResizeObservation(Element* target, ResizeObserver*);
 
     Element* target() const { return m_target; }
+    size_t targetDepth();
+    void setObservationSize(const LayoutSize&);
+    // True if observationSize differs from target's current size.
+    bool observationSizeOutOfSync() const;
+
+    static LayoutSize getTargetSize(Element* target);
 
     DECLARE_TRACE();
 
 private:
     WeakMember<Element> m_target;
-
     Member<ResizeObserver> m_observer;
+    // Target size sent in last observation notification.
+    LayoutSize m_observationSize;
 };
 
 } // namespace blink

third_party/WebKit/Source/core/observer/ResizeObserver.h

@@ -18,7 +18,7 @@ class ResizeObservation;
 
 // ResizeObserver represents ResizeObserver javascript api:
 // https://github.com/WICG/ResizeObserver/
-class ResizeObserver final : public GarbageCollectedFinalized<ResizeObserver>, public ScriptWrappable {
+class CORE_EXPORT ResizeObserver final : public GarbageCollectedFinalized<ResizeObserver>, public ScriptWrappable {
     DEFINE_WRAPPERTYPEINFO();
 public:
 

third_party/WebKit/Source/web/tests/ResizeObserverTest.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/ResizeObserver.h"
+
+#include "core/observer/ResizeObservation.h"
+#include "core/observer/ResizeObserverCallback.h"
+#include "platform/testing/UnitTestHelpers.h"
+#include "web/WebViewImpl.h"
+#include "web/tests/sim/SimCompositor.h"
+#include "web/tests/sim/SimDisplayItemList.h"
+#include "web/tests/sim/SimRequest.h"
+#include "web/tests/sim/SimTest.h"
+#include "wtf/CurrentTime.h"
+
+namespace blink {
+
+namespace {
+
+class TestResizeObserverCallback : public ResizeObserverCallback {
+public:
+    TestResizeObserverCallback(Document& document)
+        : m_document(document)
+        , m_callCount(0)
+    { }
+    void handleEvent(const HeapVector<Member<ResizeObserverEntry>>& entries, ResizeObserver*) override
+    {
+        m_callCount++;
+    }
+    ExecutionContext* getExecutionContext() const { return m_document; }
+    int callCount() const { return m_callCount; }
+
+    DEFINE_INLINE_TRACE() {
+        ResizeObserverCallback::trace(visitor);
+        visitor->trace(m_document);
+    }
+
+private:
+    Member<Document> m_document;
+    int m_callCount;
+};
+
+} // namespace
+
+/* Testing:
+ * getTargetSize
+ * setTargetSize
+ * oubservationSizeOutOfSync == false
+ * modify target size
+ * oubservationSizeOutOfSync == true
+ */
+class ResizeObservationUnitTest : public SimTest { };
+
+TEST_F(ResizeObservationUnitTest, ObserveSchedulesFrame)
+{
+    SimRequest mainResource("https://example.com/", "text/html");
+    loadURL("https://example.com/");
+
+    mainResource.start();
+    mainResource.write(
+        "<div id='domTarget' style='width:100px;height:100px'>yo</div>"
+        "<svg height='200' width='200'>"
+            "<circle id='svgTarget' cx='100' cy='100' r='100'/>"
+        "</svg>"
+    );
+    mainResource.finish();
+
+    ResizeObserverCallback* callback = new TestResizeObserverCallback(document());
+    ResizeObserver* observer = ResizeObserver::create(document(), callback);
+    Element* domTarget = document().getElementById("domTarget");
+    Element* svgTarget = document().getElementById("svgTarget");
+    ResizeObservation* domObservation = new ResizeObservation(domTarget, observer);
+    ResizeObservation* svgObservation = new ResizeObservation(svgTarget, observer);
+
+    // Initial observation is out of sync
+    ASSERT_TRUE(domObservation->observationSizeOutOfSync());
+    ASSERT_TRUE(svgObservation->observationSizeOutOfSync());
+
+    // Target size is correct
+    LayoutSize size = ResizeObservation::getTargetSize(domTarget);
+    ASSERT_EQ(size.width(), 100);
+    ASSERT_EQ(size.height(), 100);
+    domObservation->setObservationSize(size);
+
+    size = ResizeObservation::getTargetSize(svgTarget);
+    ASSERT_EQ(size.width(), 200);
+    ASSERT_EQ(size.height(), 200);
+    svgObservation->setObservationSize(size);
+
+    // Target size is in sync
+    ASSERT_FALSE(domObservation->observationSizeOutOfSync());
+
+    // Target depths
+    ASSERT_EQ(svgObservation->targetDepth() - domObservation->targetDepth(), (size_t)1);
+}
+
+} // namespace blink

third_party/WebKit/Source/web/web.gypi

@@ -265,6 +265,7 @@
       'tests/PrerenderingTest.cpp',
       'tests/ProgrammaticScrollTest.cpp',
       'tests/LayoutGeometryMapTest.cpp',
+      'tests/ResizeObserverTest.cpp',
       'tests/RootScrollerTest.cpp',
       'tests/ScreenWakeLockTest.cpp',
       'tests/ScrollingCoordinatorTest.cpp',