Index: third_party/WebKit/Source/modules/sensor/SensorUpdateNotifier.cpp |
diff --git a/third_party/WebKit/Source/modules/sensor/SensorUpdateNotifier.cpp b/third_party/WebKit/Source/modules/sensor/SensorUpdateNotifier.cpp |
new file mode 100644 |
index 0000000000000000000000000000000000000000..2d4248cc3e319415fab2da343c3346cc72b161f0 |
--- /dev/null |
+++ b/third_party/WebKit/Source/modules/sensor/SensorUpdateNotifier.cpp |
@@ -0,0 +1,103 @@ |
+// 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/SensorUpdateNotifier.h" |
+ |
+#include "device/generic_sensor/public/interfaces/sensor.mojom-blink.h" |
+#include "platform/Timer.h" |
+#include "wtf/CurrentTime.h" |
+ |
+namespace blink { |
+ |
+SensorUpdateNotifier::SensorUpdateNotifier( |
+ double frequency, |
+ std::unique_ptr<Function<void()>> func) |
+ : m_period(frequency), m_func(std::move(func)), m_lastTimestamp(0.0) { |
+ DCHECK_GT(frequency, 0.0); |
+ DCHECK(m_func); |
+} |
+ |
+// Implementation for sensors with 'onchange' reporting mode. |
+// Uses a "single-shot" timer to make sure notification is not invoked |
+// more frequently than expected. |
+class SensorUpdateNotifierOnChange : public SensorUpdateNotifier { |
+ public: |
+ SensorUpdateNotifierOnChange(double period, |
+ std::unique_ptr<Function<void()>> func) |
+ : SensorUpdateNotifier(period, std::move(func)), |
+ m_timer(this, &SensorUpdateNotifierOnChange::onTimer) {} |
+ |
+ private: |
+ // SensorUpdateNotifier overrides. |
+ void onSensorReadingChanged(double timestamp) override; |
+ void cancelPendingNotifications() override; |
+ |
+ void onTimer(TimerBase*); |
+ |
+ Timer<SensorUpdateNotifierOnChange> m_timer; |
+}; |
+ |
+void SensorUpdateNotifierOnChange::onSensorReadingChanged(double timestamp) { |
+ if (m_timer.isActive()) |
+ return; // Skipping changes if update notification was already sheduled. |
+ |
+ double elapsedTime = timestamp - m_lastTimestamp; |
+ const double kMinInterval = |
+ 1 / device::mojom::blink::SensorConfiguration::kMaxAllowedFrequency; |
+ double waitingTime = m_period - elapsedTime; |
+ |
+ // Negative or zero 'waitingTime' means that polling period has elapsed. |
+ // We also avoid scheduling if the elapsed time is slightly behind the |
+ // polling period. This is done to reduce using of timer. |
+ if (waitingTime < kMinInterval) { |
+ m_lastTimestamp = timestamp; |
+ (*m_func)(); |
+ } else { |
+ m_timer.startOneShot(waitingTime, BLINK_FROM_HERE); |
+ } |
+} |
+ |
+void SensorUpdateNotifierOnChange::cancelPendingNotifications() { |
+ m_timer.stop(); |
+} |
+ |
+void SensorUpdateNotifierOnChange::onTimer(TimerBase*) { |
+ m_lastTimestamp = WTF::monotonicallyIncreasingTime(); |
+ (*m_func)(); |
+} |
+ |
+// Implementation for sensors with 'continuous' reporting mode. |
+class SensorUpdateNotifierContinuous : public SensorUpdateNotifier { |
+ public: |
+ SensorUpdateNotifierContinuous(double period, |
+ std::unique_ptr<Function<void()>> func) |
+ : SensorUpdateNotifier(period, std::move(func)) {} |
+ |
+ private: |
+ // SensorUpdateNotifier overrides. |
+ void onSensorReadingChanged(double timestamp) override { |
+ if (timestamp - m_lastTimestamp >= m_period) { |
+ m_lastTimestamp = timestamp; |
+ (*m_func)(); |
+ } |
+ } |
+ |
+ void cancelPendingNotifications() override {} |
+}; |
+ |
+// static |
+std::unique_ptr<SensorUpdateNotifier> SensorUpdateNotifier::create( |
+ double frequency, |
+ std::unique_ptr<Function<void()>> func, |
haraken
2016/12/06 02:38:30
func => sensorUpdatingFunction
|
+ device::mojom::blink::ReportingMode mode) { |
+ double period = 1 / frequency; |
+ if (mode == device::mojom::blink::ReportingMode::CONTINUOUS) { |
+ return std::unique_ptr<SensorUpdateNotifier>( |
+ new SensorUpdateNotifierContinuous(period, std::move(func))); |
+ } |
+ return std::unique_ptr<SensorUpdateNotifier>( |
+ new SensorUpdateNotifierOnChange(period, std::move(func))); |
+} |
+ |
+} // namespace blink |