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Posted by Peter Foot [MVP] on March 29, 2007, 8:56 am
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For all the smartphones I've seen it's always been BKL1:, for Pocket PC
2003s I've seen a variety used, though maybe this has improved in more
recent versions, I haven't tried the code on WM5.0 Pocket PCs.
Peter
--
Peter Foot
Device Application Development MVP
www.peterfoot.net | www.inthehand.com
> hmmm.
>
> i've always assumed that the backlight device is BKL1.
>
> the idea of SetPowerRequirement was that applications can programatically
> configure the backlight, rather than use various tricks that are device
> dependent.
>
> if the name of the backlight device is something random that applications
> must guess for each device, then thise would seem to defeat the original
> purpose, no?
>
> if there is a guaranteed method to recover the backlight device name, what
> is it? what registry key must be accessed?
>
> thanks.
>
>> Device names can vary between different device types, you'll need to find
>> an alternative for BKL1: used in the example. Device names are stored in
>> the registry.
>>
>> Peter
>>
>> --
>> Peter Foot
>> Device Application Development MVP
>> www.peterfoot.net | www.inthehand.com
>>
>>> Hi all!
>>>
>>> My device is a HTC P3300 (Phone + GPS) PDA.
>>> I have from http://www.peterfoot.net/KeepYourSmartphoneBacklightOn.aspx
>>> grabbed a class wich should be able to turn the backlight ON/OFF. But
>>> it does'nt work. I got a handle from
>>> SetPowerRequirement(). But no change. Any ideas?
>>>
>>> Thanks
>>> Wolfgang
>>>
>>>
>>> Public Class Backlight
>>> 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
>>> '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
>>> D0 = 0 'full on _
>>> D1 = 1 'low power
>>> D2 = 2 'standby
>>> D3 = 3 'sleep
>>> D4 = 4 'off
>>> 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
>>> 'keep the backlight lit
>>> Public Sub DeActivate()
>>> 'request no power
>>> handle = SetPowerRequirement("BKL1:", PowerState.D4, 1, IntPtr.Zero, 0)
>>> End Sub
>>> Public Function PowerSettingChanged() As Boolean
>>> If handle = IntPtr.Zero Then
>>> Return False
>>> Else
>>> Return True
>>> End If
>>> End Function
>>> '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
>>> End Class
>>>
>>
>
>
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