WM_POWER
The WM_POWER
message is sent when the system, typically a battery-powered personal computer,
is about to enter suspended mode.
The WM_POWER
message is obsolete. It is provided to simplify porting of 16-bit Windows-based
applications. New Win32-based applications should use the WM_POWERBROADCAST message.
WM_POWER
fwPowerEvt = wParam; // power-event notification message
Parameters
fwPowerEvt
Value of wParam.
Specifies a power-event notification message. This parameter can be one of the
following values:
|
Value |
Meaning |
|
PWR_CRITICALRESUME |
Indicates
that the system is resuming operation after entering suspended mode without
first sending a PWR_SUSPENDREQUEST notification message to the application.
An application should perform any necessary recovery actions. |
|
PWR_SUSPENDREQUEST |
Indicates
that the system is about to enter suspended mode. |
|
PWR_SUSPENDRESUME |
Indicates
that the system is resuming operation after having entered suspended mode
normally that is, the system sent a
PWR_SUSPENDREQUEST notification message to the application before the system
was suspended. An application should perform any necessary recovery actions. |
Return Values
The value an
application returns depends on the value of the wParam parameter. If wParam
is PWR_SUSPENDREQUEST, the return value is PWR_FAIL to prevent the system from
entering the suspended state; otherwise, it is PWR_OK. If wParam is
PWR_SUSPENDRESUME or PWR_CRITICALRESUME, the return value is zero.
Remarks
This message
is sent only to an application that is running on a system that conforms to the
Advanced Power Management (APM) basic input/output system (BIOS) specification.
The message is sent by the power-management driver to each window returned by
the EnumWindows function.
The suspended
mode is the state in which the greatest amount of power savings occurs, but all
operational data and parameters are preserved. Random-access memory (RAM)
contents are preserved, but many devices are likely to be turned off.
See Also