content/renderer/device_sensors/device_sensor_event_pump.cc

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "device_sensor_event_pump.h"
   6
   7 #include "base/logging.h"
   8 #include "content/public/renderer/render_thread.h"
   9
  10 namespace content {
  11
  12 // Default interval between successive polls, should take into account the
  13 // value of |kInertialSensorIntervalMillis| in
  14 // content/browser/device_sensors/inertial_sensor_consts.h.
  15 const int DeviceSensorEventPump::kDefaultPumpDelayMillis = 50;
  16
  17 int DeviceSensorEventPump::GetDelayMillis() const {
  18   return pump_delay_millis_;
  19 }
  20
  21 DeviceSensorEventPump::DeviceSensorEventPump()
  22     : pump_delay_millis_(kDefaultPumpDelayMillis),
  23       state_(STOPPED) {
  24 }
  25
  26 DeviceSensorEventPump::DeviceSensorEventPump(int pump_delay_millis)
  27     : pump_delay_millis_(pump_delay_millis),
  28       state_(STOPPED) {
  29   DCHECK_GE(pump_delay_millis_, 0);
  30 }
  31
  32 DeviceSensorEventPump::~DeviceSensorEventPump() {
  33 }
  34
  35 bool DeviceSensorEventPump::RequestStart() {
  36   DVLOG(2) << "requested start";
  37
  38   if (state_ != STOPPED)
  39     return false;
  40
  41   DCHECK(!timer_.IsRunning());
  42
  43   if (SendStartMessage()) {
  44     state_ = PENDING_START;
  45     return true;
  46   }
  47   return false;
  48 }
  49
  50 bool DeviceSensorEventPump::Stop() {
  51   DVLOG(2) << "stop";
  52
  53   if (state_ == STOPPED)
  54     return true;
  55
  56   DCHECK((state_ == PENDING_START && !timer_.IsRunning()) ||
  57       (state_ == RUNNING && timer_.IsRunning()));
  58
  59   if (timer_.IsRunning())
  60     timer_.Stop();
  61   SendStopMessage();
  62   state_ = STOPPED;
  63   return true;
  64 }
  65
  66 void DeviceSensorEventPump::Attach(RenderThread* thread) {
  67   if (!thread)
  68     return;
  69   thread->AddObserver(this);
  70 }
  71
  72 void DeviceSensorEventPump::OnDidStart(base::SharedMemoryHandle handle) {
  73   DVLOG(2) << "did start sensor event pump";
  74
  75   if (state_ != PENDING_START)
  76     return;
  77
  78   DCHECK(!timer_.IsRunning());
  79
  80   if (InitializeReader(handle)) {
  81     timer_.Start(FROM_HERE, base::TimeDelta::FromMilliseconds(GetDelayMillis()),
  82                  this, &DeviceSensorEventPump::FireEvent);
  83     state_ = RUNNING;
  84   }
  85 }
  86
  87 }  // namespace content