Implement Device Orientation using shared memory in content/renderer.

content/renderer/device_orientation/device_orientation_event_pump.cc

+// Copyright 2013 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 "device_orientation_event_pump.h"
+
+#include "content/common/device_orientation_messages.h"
+#include "content/public/renderer/render_thread.h"
+#include "third_party/WebKit/public/platform/WebDeviceOrientationListener.h"
+
+namespace content {
+
+DeviceOrientationEventPump::DeviceOrientationEventPump()
+    : DeviceSensorEventPump(), listener_(0) {
+}
+
+DeviceOrientationEventPump::DeviceOrientationEventPump(int pump_delay_millis)
+    : DeviceSensorEventPump(pump_delay_millis), listener_(0) {
+}
+
+DeviceOrientationEventPump::~DeviceOrientationEventPump() {
+}
+
+bool DeviceOrientationEventPump::SetListener(
+    WebKit::WebDeviceOrientationListener* listener) {
+  listener_ = listener;
+  return listener_ ? RequestStart() : Stop();
+}
+
+bool DeviceOrientationEventPump::OnControlMessageReceived(
+    const IPC::Message& message) {
+  bool handled = true;
+  IPC_BEGIN_MESSAGE_MAP(DeviceOrientationEventPump, message)
+    IPC_MESSAGE_HANDLER(DeviceOrientationMsg_DidStartPolling, OnDidStart)
+    IPC_MESSAGE_UNHANDLED(handled = false)
+  IPC_END_MESSAGE_MAP()
+  return handled;
+}
+
+void DeviceOrientationEventPump::FireEvent() {
+  DCHECK(listener_);
+  WebKit::WebDeviceOrientationData data;
+  if (reader_->GetLatestData(&data) && ShouldFireEvent(data)) {
+    memcpy(&data_, &data, sizeof(data));
+    listener_->didChangeDeviceOrientation(data);
+  }
+}
+
+static bool IsSignificantlyDifferent(bool hasAngle1, double angle1,
+    bool hasAngle2, double angle2) {
+  if (hasAngle1 != hasAngle2)
+    return true;
+  return (hasAngle1 && std::fabs(angle1 - angle2) >=
+          DeviceOrientationEventPump::kOrientationThreshold);
+}
+
+bool DeviceOrientationEventPump::ShouldFireEvent(
+    const WebKit::WebDeviceOrientationData& data) const {
+  return data.allAvailableSensorsAreActive &&
+      (IsSignificantlyDifferent(
+          data_.hasAlpha, data_.alpha, data.hasAlpha, data.alpha) ||
+       IsSignificantlyDifferent(
+          data_.hasBeta, data_.beta, data.hasBeta, data.beta) ||
+       IsSignificantlyDifferent(
+          data_.hasGamma, data_.gamma, data.hasGamma, data.gamma));
+}
+
+bool DeviceOrientationEventPump::InitializeReader(
+    base::SharedMemoryHandle handle) {
+  memset(&data_, 0, sizeof(data_));
+  if (!reader_)
+    reader_.reset(new DeviceOrientationSharedMemoryReader());
+  return reader_->Initialize(handle);
+}
+
+bool DeviceOrientationEventPump::SendStartMessage() {
+  return RenderThread::Get()->Send(new DeviceOrientationHostMsg_StartPolling());
+}
+
+bool DeviceOrientationEventPump::SendStopMessage() {
+  return RenderThread::Get()->Send(new DeviceOrientationHostMsg_StopPolling());
+}
+
+}  // namespace content