Hi, I have a Windows Mobile application (written in C#) that only works on portrait mode. Is there anyway programmatically to prevent the system from automatically rotating my application to landscape mode without having to change Windows Mobile system settings?
Platform: Windows Mobile 6.1 Professional
No, and even if there were it would involve hooks, which is a really, really bad idea on an embedded device.
But you can change the screen orientation to whatever you like, since you obviously know what it should be. See Developing Screen Orientation-Aware Applications -> Changing Screen Orientation for more details.
Edit: Just realized you're stuck with C# / .NETCF. Don't know that part of the framework, but I'll leave the answer here for reference, perhaps it will point you in the right direction. The concepts explained in tat article are still valid, of course.
What version of windows mobile?
Is your application going to be only used by a controlled group of users (e.g. an internal company application) where the hardware can be controlled?
Windows mobile supports different screen sizes and orientations. For example a device may be designed with a portrait, square or landscape screen. Your software being designed to only run in portrait mode could cause a problem if you are not controlling the hardware that runs it.
If you do want to set portrait mode you can do so by calling
SystemSettings.ScreenOrientation = ScreenOrientation.Angle0;
This will set the whole device to be in portrait mode. If you do chose to go ahead with this I'd recommend setting the orientation in your form activated event and checking the orientation in the resize event. This will reset the device back to portrait when your application gets focus if anyone changes it to landscape.
It may also be useful to store the initial orientation when your application starts and re-set the device to this when your application exits.
This is a bad, bad, bad idea. The device is a general purpose device intended to run multiple applications. The platform should not be a slave to your application. That's like saying that you have a desktop application that only runs at 640x480, so you should be able to lock someone's PC to that resolution.
The better solution is to either actually fix your software (gasp) to support both orientations (and you are aware that there are also different resolutions as well as square-screen devices, right?) or to have your app at least pop up some sort of message box to inform the user about compatibility when an unsupported resolution or orientation is selected.
As for the "how" to do it - you can't. Rotation is handled by the display driver, specifically by calling ExtEscape with DRVESC_SETSCREENROTATION. In the standard GPEFlat driver that ships with PB, this in turn calls DynRotate and goes on to call SetRotation (you can look at the public source in the eval edition is you really want to know how it all works).
The short of this is that to intercept that call, you'd have to either create a replacement display driver, or at least some shim that you insert as the driver that in turns calls the existing one. Neither of these are going to happen in managed code.