If your application involves displaying screen content you probably have come across the issue where the screen backlight turns off after a few seconds of no keypresses. You can override this behaviour in your application using a couple of underdocumented API Power-Management functions. Here is a VB.NET snippet for .NETCF to keep the backlight on:-
Namespace
OpenNETCF.WindowsCE.Forms
Public
Class Backlight
'ensure the power requirement is released
Protected Overrides Sub Finalize()
Release()
End Sub
'handle to the power requirement
Private handle As IntPtr
Private Enum PowerState
PwrDeviceUnspecified = -1
'full on
D0 = 0
'low power
D1 = 1
'standby
D2 = 2
'sleep
D3 = 3
'off
D4 = 4
PwrDeviceMaximum = 5
End Enum
'keep the backlight lit
Public Sub Activate()
'request full power
handle = SetPowerRequirement("BKL1:", PowerState.D0, 1, IntPtr.Zero, 0)
End Sub
'release power requirement
Public Sub Release()
If handle.ToInt32() <> 0 Then
Dim result As Integer
result = ReleasePowerRequirement(handle)
handle = IntPtr.Zero
End If
End Sub
Private Declare Function SetPowerRequirement Lib "coredll.dll" (ByVal pvDevice As String, ByVal DeviceState As PowerState, ByVal DeviceFlags As Integer, ByVal pvSystemState As IntPtr, ByVal StateFlags As Integer) As IntPtr
Private Declare Function ReleasePowerRequirement Lib "coredll.dll" (ByVal handle As IntPtr) As Integer
End Class
End
Namespace
Thanks to Paul O'Brien from MoDaCo for inspiring and helping test the code.