Source/modules/device_orientation/DeviceMotionDispatcher.cpp

/*
 * Copyright (C) 2013 Google Inc. All rights reserved.
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 * modification, are permitted provided that the following conditions are
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 *
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 * in the documentation and/or other materials provided with the
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 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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#include "config.h"
#include "DeviceMotionDispatcher.h"

#include "core/platform/NotImplemented.h"
#include "modules/device_orientation/DeviceMotionController.h"
#include "modules/device_orientation/DeviceMotionData.h"
#include "public/platform/Platform.h"
#include "public/platform/WebDeviceMotionData.h"

namespace WebCore {

DeviceMotionDispatcher& DeviceMotionDispatcher::instance()
{
    DEFINE_STATIC_LOCAL(DeviceMotionDispatcher, deviceMotionDispatcher, ());
    return deviceMotionDispatcher;
}

DeviceMotionDispatcher::DeviceMotionDispatcher()
{
}

DeviceMotionDispatcher::~DeviceMotionDispatcher()
{
}

void DeviceMotionDispatcher::addController(DeviceMotionController* controller)
{
    bool wasEmpty = m_controllers.isEmpty();
    if (!m_controllers.contains(controller))
        m_controllers.append(controller);
    if (wasEmpty)
        startListening();
}

void DeviceMotionDispatcher::removeController(DeviceMotionController* controller)
{
    // Do not actually remove controller from the vector, instead zero them out.
    // The zeros are removed after didChangeDeviceMotion has dispatched all events.
    // This is to prevent re-entrancy case when a controller is destroyed while in the
    // didChangeDeviceMotion method.
    size_t index = m_controllers.find(controller);
    if (index != notFound)
        m_controllers[index] = 0;
}

void DeviceMotionDispatcher::startListening()
{
    WebKit::Platform::current()->setDeviceMotionListener(this);
}

void DeviceMotionDispatcher::stopListening()
{
    WebKit::Platform::current()->setDeviceMotionListener(0);
}

void DeviceMotionDispatcher::didChangeDeviceMotion(const WebKit::WebDeviceMotionData& motion)
{
    m_lastDeviceMotionData = DeviceMotionData::create(motion);
    bool needsPurge = false;
    for (size_t i = 0; i < m_controllers.size(); ++i) {
        if (m_controllers[i])
            m_controllers[i]->didChangeDeviceMotion(m_lastDeviceMotionData.get());
        else
            needsPurge = true;
    }

    if (needsPurge)
        purgeControllers();
}

DeviceMotionData* DeviceMotionDispatcher::latestDeviceMotionData()
{
    return m_lastDeviceMotionData.get();
}

void DeviceMotionDispatcher::purgeControllers()
{
    size_t i = 0;
    while (i < m_controllers.size()) {
        if (!m_controllers[i]) {
            m_controllers[i] = m_controllers.last();
            m_controllers.removeLast();
        } else
            ++i;
    }

    if (m_controllers.isEmpty())
        stopListening();
}

} // namespace WebCore