Windows Mobile - detecting when power off button is pressed

Question

Is there an easy way to get notified when user presses Power Off button on it's Windows Mobile device? Using C# of course.

Thanks!

Answer 1

When the power button is pressed, the power manager will send out a notification of a state change. You can request that the PM send you a notification by calling RequestPowerNotifications You have to send in a handle to a point-to-point messgae queue (managed version here ) that will get the notification.

For thos who don't want to write all of the glue to make this work, all of this is already pre-done for you in the SDF's PowerManagement class .

Also be forewarned that just becasue you request the notification does not mean that your app will get the notification before the state change occurs. For example on pwer down it's pretty common that an app won't see the notification, and almost certain that even if you do see it you won't have time to execute anything before suspend actually occurs. Typically your handler will run when the device resumes (followed by any handler for the resume state).

The power manager doesn't wait for you, it simply broadcasts a message. You cannot use this to run code before a shutdown.

Answer 2

I just place CreateMsgQueue() into the XIP RPM binaries, without need for source code or OEM help. you need to use a hex editor and a few tools from XDA forums.

<DllImport("coredll.dll", SetLastError:=True)> _
Public Shared Function CreateMsgQueue(ByVal lpszName As String, ByVal lpOptions As MsgQueueOptions) As IntPtr
End Function

also you should just create a simple driver for blocking the power down event, your driver is allowed to hold up the power down process in the PowerDown device Event. that way you get a guaranteed event that you can set the flag and stop your background running process, and store any variables, and then restore them on ther PowerUp event, which is also a standard evc++ event for winCE device driver. Pretty simple really. there is 100s of demo source code on the internet for this, I've seen it on 100s of sites.

Answer 3

Unfortunately, on the Windows CE 6 device i am using, CreateMsgQueue does not exist in CoreDll. Any other suggestions?

The only thing i can think of is continually checking Environment.TickCount against the device's real time clock. If time has moved forward but not the tick count, then presumably the device was sleeping.

Dont like this solution because it will get tricked if the time jumps due to a failure in the device's real time clock