Sending keyboard events to DirectX application from C#

Hello,

I am writing some code in c# to enable me to send keyboard input to a third party DirectX application.

I am able to use :

        // Get a handle to an application window.
        [DllImport("USER32.DLL", CharSet = CharSet.Unicode)]
        public static extern IntPtr FindWindow(string lpClassName,
            IntPtr WindowName);

        // Activate an application window.
        [DllImport("USER32.DLL")]
        public static extern bool SetForegroundWindow(IntPtr hWnd);

To get a handle to application window, and set it to be the foreground application, but the SendKeys methods fail to send the keyboard events to the application, ie:

SendKeys.SendWait("K")

does not raise a new dialog as expected. Pressing K on the keyboard however does. I have also tried the

        [DllImport("User32.Dll")]
        static extern bool SendMessage(IntPtr hWnd, uint msg, int wParam, int lParam);

        [DllImport("user32.dll")]
        static extern byte VkKeyScan(char ch);

methods to accomplish this, by calling:

 const uint WM_KEYDOWN = 0x100;
 SendMessage(handle, WM_KEYDOWN, VkKeyScan('K'), 0);

which does not yield any results either.

However both methods seem to work fine with other applications such as Notepad, Calculator etc.

I have been reading up on the issue and it seems that the only way to do what I want is by using DirectInput events. I could not however find a concrete example on how to use them.  Which methods/dlls would I have to import to do this ?

I'd appreciate any help, as I'm getting close to the point of bursting into tears!!!

Thanks
Antonis