Applications can better adapt their behavior to the current power state of the computer by registering for power events. Using the RegisterPowerSettingNotification function, applications can receive PBT_POWERSETTINGCHANGE notifications either with WM_POWERBROADCAST messages sent to a window (for interactive applications) or through the HandlerEx callback function registered with RegisterServiceCtrlHandlerEx (for service applications). The lParam parameter of the WM_POWERBROADCAST message or the lpEventData parameter sent to the HandlerEx callback function is a pointer to a POWERBROADCAST_SETTING structure.

Applications should register for each power change event that may impact their behavior. Here are some common PowerSetting values.

GUID_POWERSCHEME_PERSONALITY - 245d8541-3943-4422-b025-13A7-84F679B7

Notifies each time the active power scheme personality changes. All power schemes map to one of these personalities. The Data member is a GUID that indicates the new active power scheme personality.

GUID_MIN_POWER_SAVINGS - 8c5e7fda-e8bf-4a96-9a85-a6e23a8c635c

High Performance - The scheme is designed to deliver maximum performance at the expense of power consumption savings.

GUID_MAX_POWER_SAVINGS a1841308-3541-4fab-bc81-f71556f20b4a

Power Saver - The scheme is designed to deliver maximum power consumption savings at the expense of system performance and responsiveness.

GUID_TYPICAL_POWER_SAVINGS - 381b4222-f694-41f0-9685-ff5bb260df2e

Automatic - The scheme is designed to automatically balance performance and power consumption savings.

 

GUID_ACDC_POWER_SOURCE - 5d3e9a59-e9D5-4b00-a6bd-ff34ff516548

Notifies each time the system power source changes. The Data member is a DWORD with values from the SYSTEM_POWER_CONDITION enumeration that indicates the current power source.

PoAc (zero)

The computer is powered by an AC power source (or similar, such as a laptop powered by a 12V automotive adapter).

PoDc (one)

The computer is powered by an onboard battery power source.

PoHot (two)

The computer is powered by a short-term power source such as a UPS device.

 

GUID_BATTERY_PERCENTAGE_REMAINING - a7ad8041-b45a-4cae-87a3-eecbb468a9e1

Notifies each time the remaining battery capacity changes. The granularity varies from system to system but the finest granularity is 1 percent. The Data member is a DWORD that indicates the current battery capacity remaining, in percentage from 0 through 100.

GUID_IDLE_BACKGROUND_TASK - 515c31d8-f734-163d-a0fd-11a0-8c91e8f1

The idle/background task notification is delivered when the system is busy. This indicates that the system will not be moving into an idle state in the near future and that the current time is a good time for components to perform background or idle tasks that would otherwise prevent the computer from entering an idle state. There is no notification when the system is able to move into an idle state. The background idle task notification does not indicate if a user is present or not the computer. The Data member has no information and can be ignored.

GUID_SYSTEM_AWAYMODE - 98a7f580-01f7-48aa-9c0f-44352c29e5C0

The away mode notification indicates that the system is entering or exiting away mode. The Data member is a DWORD that indicates the current away mode state.

0x0

The computer is exiting away mode.

0x1

The computer is entering away mode.

 

GUID_MONITOR_POWER_ON - 02731015-4510-4526-99e6-e5a17ebd1aea

The monitor on/off notification indicates when the primary system monitor is on or off. This notification is useful for components that actively render content to the display device, such as media visualization. These applications should register for this notification and stop rendering graphics content when the monitor is off to reduce system power consumption. The Data member is a DWORD that indicates the current monitor state.

0x0

The monitor is off.

0x1

The monitor is on.

 

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Build date: 10/8/2009