Initial ResizeObserver implementation

third_party/WebKit/Source/core/observer/ResizeObserver.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/dom/Element.h"
+#include "core/frame/FrameView.h"
+#include "core/frame/LocalFrame.h"
+#include "core/observer/ResizeObservation.h"
+#include "core/observer/ResizeObserverCallback.h"
+#include "core/observer/ResizeObserverController.h"
+#include "core/observer/ResizeObserverEntry.h"
+
+namespace blink {
+
+ResizeObserver* ResizeObserver::create(Document& document, ResizeObserverCallback* callback)
+{
+    auto observer = new ResizeObserver(callback);
+    document.ensureResizeObserverController().addObserver(*observer);
+    return observer;
+}
+
+ResizeObserver::ResizeObserver(ResizeObserverCallback* callback)
+    : m_callback(callback)
+{
+}
+
+void ResizeObserver::observe(Element* target)
+{
+    auto observerMap = target ? target->resizeObserverData() : nullptr;
+    if (observerMap && observerMap->contains(this))
+        return; // Already registered.
+    m_observations.add(new ResizeObservation(target, this));
+
+    if (FrameView* frameView = target->document().view())
+        frameView->scheduleAnimation();
+}
+
+void ResizeObserver::unobserve(Element* target)
+{
+    auto observerMap = target ? target->resizeObserverData() : nullptr;
+    if (!observerMap)
+        return;
+    auto observation = observerMap->find(this);
+    if (observation != observerMap->end()) {
+        m_observations.remove((*observation).value);
+        observerMap->remove(observation);
+    }
+}
+
+void ResizeObserver::disconnect()
+{
+    ObservationList observations;
+    m_observations.swap(observations);
+
+    for (auto observation : observations) {
+        Element* target = (*observation).target();
+        if (target)
+            target->ensureResizeObserverData().remove(this);
+    }
+    m_activeObservations.clear();
+}
+
+bool ResizeObserver::gatherObservations()
+{
+    DCHECK(m_activeObservations.isEmpty());
+
+    for (auto& observation : m_observations) {
+        if (observation->hasResized())
+            m_activeObservations.append(*observation);
+    }
+
+    return !m_activeObservations.isEmpty();
+}
+
+void ResizeObserver::deliverObservations()
+{
+    if (m_activeObservations.size() == 0)
+        return;
+
+    HeapVector<Member<ResizeObserverEntry>> entries;
+
+    for (auto& observation : m_activeObservations) {
+        auto entry = new ResizeObserverEntry(observation->target());
+        entries.append(entry);
+        observation->setBroadcastSize(entry->contentSize());
+    }
+    m_callback->handleEvent(entries, this);
+    m_activeObservations.clear();
+}
+
+void ResizeObserver::clearObservations()
+{
+    m_activeObservations.clear();
+}
+
+DEFINE_TRACE(ResizeObserver)
+{
+    visitor->trace(m_callback);
+    visitor->trace(m_observations);
+    visitor->trace(m_activeObservations);
+}
+
+} // namespace blink