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CBattery Non-MFC Class

Environment: Visual C++ 6 SP3

CBattery is a non-MFC class wrapper for the battery related Windows Power Management API functions. It may be used by notebook/laptops system utilities developed with Visual C++.



CBattery implements the following public methods:
 - BOOL SystemPowerStatusLoaded()
 - BOOL ReloadSystemPowerStatus()
 - SYSTEM_POWER_STATUS SystemPowerStatus()
 - CBattery::AC_LINE_STATUS ACLineStatus()
 - CBattery::BATTERY_FLAG BatteryFlag()
 - CBattery::BOOL BatteryCharging()
 - BYTE BatteryLifePercent()
 - long BatteryFullTime()
 - long BatteryLifeTime()
 - BOOL BatteryIsUnknown()
 - BOOL BatteryIsCharging()
 - CBattery::DEVICE_POWER_STATE GetDevicePowerState()
 - void SetDevice(HANDLE hDevice)
 - HANDLE GetDevice()

CBattery contains the following public constants:
 - Line status:
   ACLS_OFFLINE
   ACLS_ONLINE
   ACLS_UNKNOWN

 - Battery status flags:
   BF_HIGH
   BF_LOW
   BF_CRITICAL
   BF_CHARGING
   BF_NO_BATTERY
   BF_UNKNOWN
 
- Device power state:
   DPS_OFF
   DPS_ON
   DPS_UNKNOWN

 - General constants:
   UNKNOWN_BATTERY_LIFE_PERCENT
   UNKNOWN_BATTERY_FULL_TIME
   UNKNOWN_BATTERY_LIFE_TIME
   UNKNOWN_DEVICE_POWER_STATE


Notes:
 
- The system is only capable of estimating BatteryFullTime based on calculations on BatteryLifeTime and BatteryLifePercent. Without smart battery subsystems, this value may not be accurate enough to be useful.
 - The class does not use the Sysinfo OCX control.
 - The system broadcasts the PBT_APMPOWERSTATUSCHANGE event to all applications when the power status changes. When your application receives this event, it should call the methods of the class again to determine what changed.
 - Power management specifications and white papers from the OnNow initiative home page are located at www.microsoft.com/hwdev/onnow.htm.
 - The PBT_* messages are documented in the SDKs PBT.H.
 - An application can use CBattery::GetDevicePowerState to determine whether a disk or other device is spun up. If the device is not spun up, the application should defer accessing it.
 - For more details about APM, one should check the Platform SDK: Hardware.
 - Unfortunately, power management features dont work in Windows NT 4.0! However, if youre using a specialized version of Windows NT, modified by your computer manufacturer, the methods may work.
 - The demo included application does not use all the all methods implemented in the CBattery class. Check the Battery.cpp and Battery.h files for the class source code.

Downloads

Download source - 2 Kb
Download demo application - 40 Kb


This article was originally published on July 21st, 2000

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