root/base/power_monitor/power_monitor_device_source_win.cc

DEFINITIONS

1. ProcessPowerEventHelper
2. ProcessWmPowerBroadcastMessage
3. IsOnBatteryPowerImpl
4. message_hwnd_
5. WndProcThunk

// 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 "base/power_monitor/power_monitor.h"
#include "base/power_monitor/power_monitor_device_source.h"
#include "base/power_monitor/power_monitor_source.h"
#include "base/win/wrapped_window_proc.h"

namespace base {

void ProcessPowerEventHelper(PowerMonitorSource::PowerEvent event) {
  PowerMonitorSource::ProcessPowerEvent(event);
}

namespace {

const wchar_t kWindowClassName[] = L"Base_PowerMessageWindow";

void ProcessWmPowerBroadcastMessage(WPARAM event_id) {
  PowerMonitorSource::PowerEvent power_event;
  switch (event_id) {
    case PBT_APMPOWERSTATUSCHANGE:  // The power status changed.
      power_event = PowerMonitorSource::POWER_STATE_EVENT;
      break;
    case PBT_APMRESUMEAUTOMATIC:  // Resume from suspend.
      //case PBT_APMRESUMESUSPEND:  // User-initiated resume from suspend.
      // We don't notify for this latter event
      // because if it occurs it is always sent as a
      // second event after PBT_APMRESUMEAUTOMATIC.
      power_event = PowerMonitorSource::RESUME_EVENT;
      break;
    case PBT_APMSUSPEND:  // System has been suspended.
      power_event = PowerMonitorSource::SUSPEND_EVENT;
      break;
    default:
      return;

      // Other Power Events:
      // PBT_APMBATTERYLOW - removed in Vista.
      // PBT_APMOEMEVENT - removed in Vista.
      // PBT_APMQUERYSUSPEND - removed in Vista.
      // PBT_APMQUERYSUSPENDFAILED - removed in Vista.
      // PBT_APMRESUMECRITICAL - removed in Vista.
      // PBT_POWERSETTINGCHANGE - user changed the power settings.
  }

  ProcessPowerEventHelper(power_event);
}

}  // namespace

// Function to query the system to see if it is currently running on
// battery power.  Returns true if running on battery.
bool PowerMonitorDeviceSource::IsOnBatteryPowerImpl() {
  SYSTEM_POWER_STATUS status;
  if (!GetSystemPowerStatus(&status)) {
    DLOG_GETLASTERROR(ERROR) << "GetSystemPowerStatus failed";
    return false;
  }
  return (status.ACLineStatus == 0);
}

PowerMonitorDeviceSource::PowerMessageWindow::PowerMessageWindow()
    : instance_(NULL), message_hwnd_(NULL) {
  if (!MessageLoopForUI::IsCurrent()) {
    // Creating this window in (e.g.) a renderer inhibits shutdown on Windows.
    // See http://crbug.com/230122. TODO(vandebo): http://crbug.com/236031
    DLOG(ERROR)
        << "Cannot create windows on non-UI thread, power monitor disabled!";
    return;
  }
  WNDCLASSEX window_class;
  base::win::InitializeWindowClass(
      kWindowClassName,
      &base::win::WrappedWindowProc<
          PowerMonitorDeviceSource::PowerMessageWindow::WndProcThunk>,
      0, 0, 0, NULL, NULL, NULL, NULL, NULL,
      &window_class);
  instance_ = window_class.hInstance;
  ATOM clazz = RegisterClassEx(&window_class);
  DCHECK(clazz);

  message_hwnd_ = CreateWindowEx(WS_EX_NOACTIVATE, kWindowClassName,
      NULL, WS_POPUP, 0, 0, 0, 0, NULL, NULL, instance_, NULL);
}

PowerMonitorDeviceSource::PowerMessageWindow::~PowerMessageWindow() {
  if (message_hwnd_) {
    DestroyWindow(message_hwnd_);
    UnregisterClass(kWindowClassName, instance_);
  }
}

// static
LRESULT CALLBACK PowerMonitorDeviceSource::PowerMessageWindow::WndProcThunk(
    HWND hwnd,
    UINT message,
    WPARAM wparam,
    LPARAM lparam) {
  switch (message) {
    case WM_POWERBROADCAST:
      ProcessWmPowerBroadcastMessage(wparam);
      return TRUE;
    default:
      return ::DefWindowProc(hwnd, message, wparam, lparam);
  }
}

}  // namespace base