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
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+ * in the documentation and/or other materials provided with the
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+ * 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>
+
+

[Peter Beverloo, 2013/04/09 17:29:53]

nit: two blank lines?

[timvolodine, 2013/04/10 19:06:12]

Done.

+namespace WebKit {
+
+WebDeviceMotionEventPump& WebDeviceMotionEventPump::shared()
+{
+    DEFINE_STATIC_LOCAL(WebDeviceMotionEventPump, webDeviceMotionEventPump, (kPumpDelaySeconds));
+    return webDeviceMotionEventPump;
+}
+
+WebDeviceMotionEventPump::WebDeviceMotionEventPump(double delay_seconds) :
+    m_delaySeconds(delay_seconds), m_lastFireEventTimeMonotonic(0), m_stopped(true),

[Peter Beverloo, 2013/04/09 17:29:53]

nit: please have a single initializer per line.

[timvolodine, 2013/04/10 19:06:12]

Done.

+    m_lastDeviceMotionData(0), m_pumpTimer(this, &WebDeviceMotionEventPump::fireEvent)
+{
+}
+
+void WebDeviceMotionEventPump::fireEvent(Timer<WebDeviceMotionEventPump>* timer)

[Peter Beverloo, 2013/04/09 17:29:53]

The timer is not being used in this method, can we remove the argument?

[timvolodine, 2013/04/10 19:06:12]

I've removed the name, but looks like it's not possible to remove the pointer as
it is required by the Timer class, same construction is done elsewhere in the
code e.g. DocumentLoader.cpp

+{
+    if (m_stopped)
+        return;
+
+    m_lastFireEventTimeMonotonic = monotonicallyIncreasingTime();
+    WebDeviceMotionReader* reader = WebKit::Platform::current()->deviceMotionReader();
+    WebDeviceMotionData data;

[Peter Beverloo, 2013/04/09 17:29:53]

Do we need a temporary variable for the reader? We do need a NULL check here in
case it's not implemented.

[timvolodine, 2013/04/10 19:06:12]

added asserts.

+    reader->lastDeviceMotionData(data);
+    m_lastDeviceMotionData = PassRefPtr<WebCore::DeviceMotionData>(data);
+
+    if (shouldFireEvent())
+        DeviceMotionController::shared().didChangeDeviceMotion(m_lastDeviceMotionData.get());

[Peter Beverloo, 2013/04/09 17:29:53]

It's a bit odd that we update m_lastFireEventTimeMonotonic even if we don't have
to fire the event.

[timvolodine, 2013/04/10 19:06:12]

the if (shouldFireEvent()) is meant as an optimization (e.g. if the values are
equal), we need to update the m_lastFireEventTimeMonotonic anyway to keep
properly firing

+
+    scheduleFireEvent();
+}
+
+void WebDeviceMotionEventPump::scheduleFireEvent()
+{
+    if (m_pumpTimer.isActive())
+        return;
+    double scheduleDelay = std::max<double>(m_delaySeconds - (monotonicallyIncreasingTime() - m_lastFireEventTimeMonotonic), 0);

[Peter Beverloo, 2013/04/09 17:29:53]

nit: newline above this for readability.

[Peter Beverloo, 2013/04/09 17:29:53]

This also assumes we'll fire at 10Hz for Device Motion.  Since we don't have
Chromium-side plumbing here, can we just increase this to the 50-60Hz we want?

[timvolodine, 2013/04/10 19:06:12]

Done.

[timvolodine, 2013/04/10 19:06:12]

we can change the delay value as we want, but for now I've kept it at 100ms.

+    m_pumpTimer.startOneShot(scheduleDelay);
+}
+
+WebCore::DeviceMotionData* WebDeviceMotionEventPump::lastDeviceMotionData()

[Peter Beverloo, 2013/04/09 17:29:53]

The pointer ownership situation is a bit unclear here.  Should we return a const
WebCore::DeviceMotionData* and clarify in this class (with a comment in the
header) that the pump continues to own it?

[timvolodine, 2013/04/10 19:06:12]

ok, done.

+{
+    return m_lastDeviceMotionData.get();
+}
+
+bool WebDeviceMotionEventPump::shouldFireEvent()
+{
+    // TODO(timvolodine): motion event should be fired only when values are different from the values

[Peter Beverloo, 2013/04/09 17:29:53]

nit: Blink style uses unattribute FIXMEs.

[timvolodine, 2013/04/10 19:06:12]

Done.

+    // of the previously fired event.
+    return true;
+}
+
+void WebDeviceMotionEventPump::start()
+{
+    WebDeviceMotionReader* reader = WebKit::Platform::current()->deviceMotionReader();

[Peter Beverloo, 2013/04/09 17:29:53]

Needs a NULL check.

[timvolodine, 2013/04/10 19:06:12]

Done.

+    reader->startUpdating();
+    m_stopped = false;
+    scheduleFireEvent();
+}
+
+void WebDeviceMotionEventPump::stop()
+{
+    WebDeviceMotionReader* reader = WebKit::Platform::current()->deviceMotionReader();

[Peter Beverloo, 2013/04/09 17:29:53]

Needs a NULL check.

[timvolodine, 2013/04/10 19:06:12]

Done.

+    reader->stopUpdating();
+    m_stopped = true;
+}
+
+} // namespace WebKit