POWER_BROADCAST (Compact 2013)

3/26/2014

This structure is used to issue power notification events through message queues.

Syntax

struct {
  DWORD Message;
  DWORD Flags;
  DWORD Length;
  WCHAR SystemPowerState[1];
} POWER_BROADCAST, *PPOWER_BROADCAST;

Members

• Message
  This field defines the event type. Set to one of the events shown in the following table.

  Event type	Description
  PBT_POWERINFOCHANGE	A member of the POWER_BROADCAST_POWER_INFO structure has changed. You should not call GetBatteryStatusEx directly. Instead, register with Power Manager for a PBT_POWERINFOCHANGE that contains the same amount of information. The battery driver polls as necessary to extract data from the driver, and then pushes changes to Power Manager with PowerPolicyNotify.
  PBT_POWERSTATUSCHANGE	Power supply switched to/from AC/DC.
  PBT_RESUME	Resume from previous state.
  PBT_TRANSITION	System power state transition.

• Flags
  Use one of the system power flags shown in the following table.

  System power flag	Description
  POWER_STATE_BACKLIGHTON	Screen backlight is on.
  POWER_STATE_BOOT	Boot state.
  POWER_STATE_CRITICAL	Critical off.
  POWER_STATE_IDLE	Idle state.
  POWER_STATE_ON	On state.
  POWER_STATE_OFF	No power, full off.
  POWER_STATE_RESET	Reset state.
  POWER_STATE_SUSPEND	Suspended state.
  POWER_STATE_UNATTENDED	Unattended state.
  POWER_STATE_USERIDLE	User idle state.

• Length
  The byte count of SystemPowerState.

• SystemPowerState
  The named system power state Flags.

Remarks

Applications and drivers register for power events with RequestPowerNotifications and unregister with StopPowerNotifications. Power notification events are issued in a POWER_BROADCAST structure, through message queues.

These notifications are multicast messages that are sent only to applications and drivers that have registered to receive the messages.

The POWER_BROADCAST structure has a variable length. The SystemPowerState array is a placeholder for data associated with the message being broadcast and is not always WCHAR data. For example, the PBT_POWERINFOCHANGE message embeds a POWER_BROADCAST_POWER_INFO structure.

Requirements

Header

pm.h

See Also

Reference

Power Management Structures
RequestPowerNotifications
StopPowerNotifications