Generic Sensor API : Ambient Light Sensor API.

third_party/WebKit/Source/modules/sensor/AmbientLightSensor.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/AmbientLightSensor.h"
+
+#include "bindings/core/v8/ScriptPromise.h"
+#include "bindings/core/v8/ScriptPromiseResolver.h"
+#include "core/dom/DOMException.h"
+#include "core/dom/Document.h"
+#include "core/dom/ExceptionCode.h"
+#include "core/events/Event.h"
+
+#include "modules/sensor/AmbientLightSensorDispatcher.h"
+#include "modules/sensor/AmbientLightSensorReading.h"
+#include "modules/sensor/SensorReadingEvent.h"
+#include "modules/sensor/sensor_state_type.h"
+
+namespace blink {
+
+// static
+AmbientLightSensor* AmbientLightSensor::create(ExecutionContext* context, SensorOptions sensorOptions, ExceptionState& exceptionState)
+{
+    AmbientLightSensor* sensor = new AmbientLightSensor(context, sensorOptions);
+    sensor->suspendIfNeeded();
+    return sensor;
+}
+
+// static
+AmbientLightSensor* AmbientLightSensor::create(ExecutionContext* context, ExceptionState& exceptionState)
+{
+    return create(context, SensorOptions(), exceptionState);
+}
+
+AmbientLightSensor::~AmbientLightSensor()
+{
+    stopUpdating();
+}
+
+AmbientLightSensor::AmbientLightSensor(ExecutionContext* executionContext, SensorOptions sensorOptions)
+    : Sensor(executionContext, sensorOptions)
+    , PlatformEventController(toDocument(executionContext)->page())
+{
+}
+
+void AmbientLightSensor::start(ScriptState* scriptState, ExceptionState& exceptionState)
+{
+    if (m_sensorState != SensorState::Idle && m_sensorState != SensorState::Errored)
+        exceptionState.throwDOMException(InvalidStateError, "Invalid State: SensorState is not idle or errored");
+
+    updateState(SensorState::Activating);
+
+    // TODO(riju) : Add Permissions stuff later.
+
+    m_hasEventListener = true;
+    startUpdating();
+}
+
+void AmbientLightSensor::stop(ScriptState* scriptState, ExceptionState& exceptionState)
+{
+    if (m_sensorState == SensorState::Idle || m_sensorState == SensorState::Errored)
+        exceptionState.throwDOMException(InvalidStateError, "Invalid State: SensorState is either idle or errored");
+
+    m_hasEventListener = false;
+    stopUpdating();
+    updateState(SensorState::Idle);
+}
+
+void AmbientLightSensor::updateState(SensorState newState)
+{
+    m_sensorState = newState;
+    dispatchEvent(Event::create(EventTypeNames::statechange));
+}
+
+AmbientLightSensorReading& AmbientLightSensor::reading()
+{
+    return *m_lightReading.get();
+}
+
+void AmbientLightSensor::didUpdateData()
+{
+    if (!m_lightReading)
+        m_lightReading = AmbientLightSensorReading::create();
+
+    AmbientLightSensorReadingProxy oldReading(m_lightReading.get()->timeStamp(), m_lightReading.get()->illuminance());
+    AmbientLightSensorReadingProxy currentReading = *AmbientLightSensorDispatcher::instance().latestData();
+
+    Document* document = toDocument(getExecutionContext());
+    ASSERT(document);
+
+    if (document->activeDOMObjectsAreSuspended() || document->activeDOMObjectsAreStopped())
+        return;
+
+    m_lightReading.get()->setTimeStamp(currentReading.timeStamp);
+    m_lightReading.get()->setIlluminance(currentReading.illuminance);
+
+    // TODO(riju) : Implement threshold when it is specs.
+    if (currentReading.illuminance != oldReading.illuminance)
+        dispatchEvent(SensorReadingEvent::create(EventTypeNames::change, *m_lightReading.get()));
+}
+
+void AmbientLightSensor::registerWithDispatcher()
+{
+    AmbientLightSensorDispatcher::instance().addController(this);
+}
+
+void AmbientLightSensor::unregisterWithDispatcher()
+{
+    AmbientLightSensorDispatcher::instance().removeController(this);
+}
+
+bool AmbientLightSensor::hasLastData()
+{
+    return AmbientLightSensorDispatcher::instance().latestData();
+}
+
+void AmbientLightSensor::suspend()
+{
+    m_hasEventListener = false;

[timvolodine, 2016/05/06 17:05:41]

could this go to the Sensor superclass?

[riju_, 2016/05/16 16:58:51]

I could add the that to Sensor superclass, 
But then Sensor class should inherit PlatformEventController whose primary job
is to be a Base controller class for registering controllers with a dispatcher.

Concrete sensors should have their own Dispatchers, hence this design.

+    stopUpdating();
+}
+
+void AmbientLightSensor::resume()
+{
+    m_hasEventListener = true;
+    startUpdating();
+}
+
+void AmbientLightSensor::stop()
+{
+    m_hasEventListener = false;
+    stopUpdating();
+}
+
+bool AmbientLightSensor::hasPendingActivity() const
+{
+    // Prevent V8 from garbage collecting the wrapper object if there are
+    // event listeners attached to it.
+    return hasEventListeners();
+}
+
+DEFINE_TRACE(AmbientLightSensor)
+{
+    PlatformEventController::trace(visitor);
+    ActiveDOMObject::trace(visitor);
+    Sensor::trace(visitor);
+    visitor->trace(m_lightReading);
+}
+
+} // namespace blink