Sending Key to Game-(Fullscreen)-Application

Question

I use the following Code to send Keystrokes to Windows:

[DllImport("user32.dll", SetLastError = true)]
private static extern void keybd_event(byte bVk, byte bScan, int dwFlags, int dwExtraInfo);

public const int KEYEVENTF_EXTENDEDKEY = 0x0001; //Key down flag 
public const int KEYEVENTF_KEYUP = 0x0002; //Key up flag 
keybd_event((byte)key, 0, KEYEVENTF_EXTENDEDKEY, 0);
keybd_event((byte)key, 0, KEYEVENTF_KEYUP, 0);

"key" can be any keycode. Simple ones like a character or also Function Keys and so on.

This works fine in "simple" Application. For example If I open NotePad++ and my Program runs in the Background everything works as desired.

But when I open a fullscreen-game (e.g. Pinball FX) the Keystrokes do not seem to be received.

I expect that DirectX or something similar is the issue here. Is there another way to send Keys there? Maybe through SharpDX?

Answer 1

I managed to solve this by using a different approach using DirectInput as described here: https://www.codeproject.com/questions/279641/c-sharp-directinput-send-key

[DllImport("user32.dll", SetLastError = true)]
        private static extern uint SendInput(uint numberOfInputs, INPUT[] inputs, int sizeOfInputStructure);

        private static void SendKeyDown(ushort keyCode)
        {
            var input = new KEYBDINPUT
            {
                Vk = keyCode
            };

            SendKeyboardInput(input);
        }

        private static void SendKeyUp(ushort keyCode)
        {
            var input = new KEYBDINPUT
            {
                Vk = keyCode,
                Flags = 2
            };
            SendKeyboardInput(input);
        }

        private static void SendKeyboardInput(KEYBDINPUT keybInput)
        {
            INPUT input = new INPUT
            {
                Type = 1
            };
            input.Data.Keyboard = keybInput;

            if (SendInput(1, new[] { input }, Marshal.SizeOf(typeof(INPUT))) == 0)
            {
                throw new Exception();
            }
        }