WebKit & WebCore part of the device motion implementation using the platform layer.

Source/WebCore/platform/chromium/support/WebDeviceMotionEventPump.cpp

+/*
+ * Copyright (C) 2013 Google Inc. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are
+ * met:
+ *
+ *     * Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *     * Redistributions in binary form must reproduce the above
+ * copyright notice, this list of conditions and the following disclaimer
+ * in the documentation and/or other materials provided with the
+ * distribution.
+ *     * Neither the name of Google Inc. nor the names of its
+ * contributors may be used to endorse or promote products derived from
+ * this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+ * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "config.h"
+#include "WebDeviceMotionEventPump.h"
+
+#include <public/Platform.h>
+#include <public/WebDeviceMotionData.h>
+#include <public/WebDeviceMotionReader.h>
+#include <wtf/CurrentTime.h>
+
+namespace WebKit {
+
+// static
+WebDeviceMotionEventPump& WebDeviceMotionEventPump::shared()
+{
+    DEFINE_STATIC_LOCAL(WebDeviceMotionEventPump, webDeviceMotionEventPump, (kPumpDelayMilliseconds / 1000.0f));
+    return webDeviceMotionEventPump;
+}
+
+WebDeviceMotionEventPump::WebDeviceMotionEventPump(double delaySeconds) :
+    m_delaySeconds(delaySeconds),
+    m_lastFireEventTimeMonotonic(0),
+    m_stopped(true),
+    m_lastDeviceMotionData(0),
+    m_pumpTimer(this, &WebDeviceMotionEventPump::fireEvent)
+{
+}
+
+void WebDeviceMotionEventPump::fireEvent(Timer<WebDeviceMotionEventPump>*)
+{
+    if (m_stopped)

[eseidel, 2013/04/23 15:21:24]

This shoudl be an ASSERT.  When you cancel a timer, it can't fire.

[timvolodine, 2013/04/23 18:10:40]

Done.

+        return;
+
+    m_lastFireEventTimeMonotonic = monotonicallyIncreasingTime();
+    WebDeviceMotionReader* reader = WebKit::Platform::current()->deviceMotionReader();
+    WebDeviceMotionData data;
+    if (reader->latestDeviceMotionData(data)) {
+        m_lastDeviceMotionData = PassRefPtr<WebCore::DeviceMotionData>(data);
+
+        if (shouldFireEvent()) {
+            Vector<RefPtr<DeviceMotionController> > listenerVector;
+            copyToVector(m_listeners, listenerVector);
+            for (size_t i = 0;i < listenerVector.size(); ++i)
+                listenerVector[i]->didChangeDeviceMotion(m_lastDeviceMotionData.get());
+        }
+    }
+
+    scheduleFireEvent();
+}
+
+void WebDeviceMotionEventPump::scheduleFireEvent()
+{
+    if (m_pumpTimer.isActive())

[eseidel, 2013/04/23 15:21:24]

This can be an ASSERT I believe.

[timvolodine, 2013/04/23 18:10:40]

Done.

+        return;
+
+    double scheduleDelay = std::max<double>(m_delaySeconds - (monotonicallyIncreasingTime() - m_lastFireEventTimeMonotonic), 0);
+    m_pumpTimer.startOneShot(scheduleDelay);
+}
+
+WebCore::DeviceMotionData* WebDeviceMotionEventPump::latestDeviceMotionData()
+{
+    return m_lastDeviceMotionData.get();
+}
+
+bool WebDeviceMotionEventPump::shouldFireEvent()
+{
+    // FIXME motion event should be fired only when values are different from the values
+    // of the previously fired event.
+    return true;
+}
+
+void WebDeviceMotionEventPump::addListener(DeviceMotionController* controller)
+{
+    bool wasEmpty = m_listeners.isEmpty();
+    m_listeners.add(controller);
+    if (wasEmpty)
+        start();
+}
+
+void WebDeviceMotionEventPump::removeListener(DeviceMotionController* controller)
+{
+    m_listeners.remove(controller);
+    if (m_listeners.isEmpty())
+        stop();
+}
+
+void WebDeviceMotionEventPump::start()
+{
+    WebDeviceMotionReader* reader = WebKit::Platform::current()->deviceMotionReader();
+    ASSERT(reader);
+    reader->startUpdating();
+    m_stopped = false;
+    scheduleFireEvent();
+}
+
+void WebDeviceMotionEventPump::stop()
+{
+    WebDeviceMotionReader* reader = WebKit::Platform::current()->deviceMotionReader();
+    ASSERT(reader);
+    reader->stopUpdating();
+    m_stopped = true;

[eseidel, 2013/04/23 15:21:24]

You should just cancel the timer here.

[timvolodine, 2013/04/23 18:10:40]

Done.

+}
+
+} // namespace WebKit