third_party/WebKit/Source/modules/sensor/SensorReading.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 "modules/sensor/SensorReading.h"

#include "core/dom/ExecutionContext.h"
#include "core/frame/LocalDOMWindow.h"
#include "core/timing/DOMWindowPerformance.h"
#include "core/timing/Performance.h"

namespace blink {

SensorReading::SensorReading(SensorProxy* sensorProxy)
    : m_sensorProxy(sensorProxy)
{
}

SensorReading::~SensorReading() = default;

DEFINE_TRACE(SensorReading)
{
    visitor->trace(m_sensorProxy);
}

DOMHighResTimeStamp SensorReading::timeStamp(ScriptState* scriptState) const
{
    LocalDOMWindow* window = scriptState->domWindow();
    if (!window)
        return 0.0;

    Performance* performance = DOMWindowPerformance::performance(*window);
    DCHECK(performance);

    if (!m_sensorProxy) {
        // In cases when SensorReading derived classes are constructed from JS
        // side, e.g. to create syntetic SensorReadingEvent for testing
        // purposes, |m_sensorProxy| will be null and SensorReading.timeStamp
        // would return current DOMHighResTimeStamp, while reading value should
        // be provided by derived classes.
        return performance->now();
    }

    return performance->monotonicTimeToDOMHighResTimeStamp(m_sensorProxy->reading().timestamp);
}

} // namespace blink