device/battery/battery_status_manager_win.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/battery/battery_status_manager_win.h"
   6
   7 #include "base/bind.h"
   8 #include "base/memory/scoped_ptr.h"
   9 #include "base/metrics/histogram.h"
  10 #include "base/strings/string16.h"
  11 #include "base/win/message_window.h"
  12 #include "base/win/windows_version.h"
  13 #include "device/battery/battery_status_manager.h"
  14
  15 namespace device {
  16
  17 namespace {
  18
  19 typedef BatteryStatusService::BatteryUpdateCallback BatteryCallback;
  20
  21 const wchar_t kWindowClassName[] = L"BatteryStatusMessageWindow";
  22
  23 // This enum is used for histogram. Don't change the order of the existing
  24 // values.
  25 enum NumberBatteriesType {
  26   UNKNOWN_BATTERIES = 0,
  27   NO_BATTERY = 1,
  28   ONE_OR_MORE_BATTERIES = 2,
  29   BATTERY_TYPES_COUNT = 3,
  30 };
  31
  32 void UpdateNumberBatteriesHistogram(NumberBatteriesType count) {
  33   UMA_HISTOGRAM_ENUMERATION("BatteryStatus.NumberBatteriesWin",
  34                             count,
  35                             BATTERY_TYPES_COUNT);
  36 }
  37
  38 void UpdateNumberBatteriesHistogram() {
  39   SYSTEM_POWER_STATUS win_status;
  40   if (!GetSystemPowerStatus(&win_status)) {
  41     UpdateNumberBatteriesHistogram(UNKNOWN_BATTERIES);
  42     return;
  43   }
  44
  45   if (win_status.BatteryFlag == 255)
  46     UpdateNumberBatteriesHistogram(UNKNOWN_BATTERIES);
  47   else if (win_status.BatteryFlag == 128)
  48     UpdateNumberBatteriesHistogram(NO_BATTERY);
  49   else
  50     UpdateNumberBatteriesHistogram(ONE_OR_MORE_BATTERIES);
  51 }
  52
  53 // Message-only window for handling battery changes on Windows.
  54 class BatteryStatusObserver {
  55  public:
  56   explicit BatteryStatusObserver(const BatteryCallback& callback)
  57       : power_handle_(NULL),
  58         battery_change_handle_(NULL),
  59         callback_(callback) {
  60   }
  61
  62   ~BatteryStatusObserver() { DCHECK(!window_); }
  63
  64   void Start() {
  65     if (CreateMessageWindow()) {
  66       BatteryChanged();
  67       // RegisterPowerSettingNotification function work from Windows Vista
  68       // onwards. However even without them we will receive notifications,
  69       // e.g. when a power source is connected.
  70       // TODO(timvolodine) : consider polling for battery changes on windows
  71       // versions prior to Vista, see crbug.com/402466.
  72       power_handle_ =
  73           RegisterNotification(&GUID_ACDC_POWER_SOURCE);
  74       battery_change_handle_ =
  75           RegisterNotification(&GUID_BATTERY_PERCENTAGE_REMAINING);
  76     } else {
  77       // Could not create a message window, execute callback with the default
  78       // values.
  79       callback_.Run(BatteryStatus());
  80     }
  81
  82     UpdateNumberBatteriesHistogram();
  83   }
  84
  85   void Stop() {
  86     if (power_handle_) {
  87       UnregisterNotification(power_handle_);
  88       power_handle_ = NULL;
  89     }
  90     if (battery_change_handle_) {
  91       UnregisterNotification(battery_change_handle_);
  92       battery_change_handle_ = NULL;
  93     }
  94     window_.reset();
  95   }
  96
  97  private:
  98   void BatteryChanged() {
  99     SYSTEM_POWER_STATUS win_status;
 100     if (GetSystemPowerStatus(&win_status))
 101       callback_.Run(ComputeWebBatteryStatus(win_status));
 102     else
 103       callback_.Run(BatteryStatus());
 104   }
 105
 106   bool HandleMessage(UINT message,
 107                      WPARAM wparam,
 108                      LPARAM lparam,
 109                      LRESULT* result) {
 110     switch(message) {
 111       case WM_POWERBROADCAST:
 112         if (wparam == PBT_APMPOWERSTATUSCHANGE ||
 113             wparam == PBT_POWERSETTINGCHANGE) {
 114           BatteryChanged();
 115         }
 116         *result = NULL;
 117         return true;
 118       default:
 119         return false;
 120     }
 121   }
 122
 123   HPOWERNOTIFY RegisterNotification(LPCGUID power_setting) {
 124     if (base::win::GetVersion() < base::win::VERSION_VISTA)
 125       return NULL;
 126
 127     return RegisterPowerSettingNotification(window_->hwnd(), power_setting,
 128                                      DEVICE_NOTIFY_WINDOW_HANDLE);
 129   }
 130
 131   BOOL UnregisterNotification(HPOWERNOTIFY handle) {
 132     if (base::win::GetVersion() < base::win::VERSION_VISTA)
 133       return FALSE;
 134
 135     return UnregisterPowerSettingNotification(handle);
 136   }
 137
 138   bool CreateMessageWindow() {
 139     // TODO(timvolodine): consider reusing the message window of PowerMonitor.
 140     window_.reset(new base::win::MessageWindow());
 141     if (!window_->CreateNamed(base::Bind(&BatteryStatusObserver::HandleMessage,
 142                                          base::Unretained(this)),
 143                               base::string16(kWindowClassName))) {
 144       LOG(ERROR) << "Failed to create message window: " << kWindowClassName;
 145       window_.reset();
 146       return false;
 147     }
 148     return true;
 149   }
 150
 151   HPOWERNOTIFY power_handle_;
 152   HPOWERNOTIFY battery_change_handle_;
 153   BatteryCallback callback_;
 154   scoped_ptr<base::win::MessageWindow> window_;
 155
 156   DISALLOW_COPY_AND_ASSIGN(BatteryStatusObserver);
 157 };
 158
 159 class BatteryStatusManagerWin : public BatteryStatusManager {
 160  public:
 161   explicit BatteryStatusManagerWin(const BatteryCallback& callback)
 162       : battery_observer_(new BatteryStatusObserver(callback)) {}
 163   ~BatteryStatusManagerWin() override { battery_observer_->Stop(); }
 164
 165  public:
 166   // BatteryStatusManager:
 167   bool StartListeningBatteryChange() override {
 168     battery_observer_->Start();
 169     return true;
 170   }
 171
 172   void StopListeningBatteryChange() override { battery_observer_->Stop(); }
 173
 174  private:
 175   scoped_ptr<BatteryStatusObserver> battery_observer_;
 176
 177   DISALLOW_COPY_AND_ASSIGN(BatteryStatusManagerWin);
 178 };
 179
 180 }  // namespace
 181
 182 BatteryStatus ComputeWebBatteryStatus(const SYSTEM_POWER_STATUS& win_status) {
 183   BatteryStatus status;
 184   status.charging = win_status.ACLineStatus != WIN_AC_LINE_STATUS_OFFLINE;
 185
 186   // Set level if available. Otherwise keep the default value which is 1.
 187   if (win_status.BatteryLifePercent != 255) {
 188     // Convert percentage to a value between 0 and 1 with 2 significant digits.
 189     status.level = static_cast<double>(win_status.BatteryLifePercent) / 100.;
 190   }
 191
 192   if (!status.charging) {
 193     // Set discharging_time if available otherwise keep the default value,
 194     // which is +Infinity.
 195     if (win_status.BatteryLifeTime != (DWORD)-1)
 196       status.discharging_time = win_status.BatteryLifeTime;
 197     status.charging_time = std::numeric_limits<double>::infinity();
 198   } else {
 199     // Set charging_time to +Infinity if not fully charged, otherwise leave the
 200     // default value, which is 0.
 201     if (status.level < 1)
 202       status.charging_time = std::numeric_limits<double>::infinity();
 203   }
 204   return status;
 205 }
 206
 207 // static
 208 scoped_ptr<BatteryStatusManager> BatteryStatusManager::Create(
 209     const BatteryStatusService::BatteryUpdateCallback& callback) {
 210   return scoped_ptr<BatteryStatusManager>(
 211       new BatteryStatusManagerWin(callback));
 212 }
 213
 214 }  // namespace device