Question

I’m using a Winform to give Buttons in a DirectX Game. Therefore I’m using this class:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;

namespace DirectInput
{
    public class cDirectInput
    {
        [DllImport("user32.dll")]
        static extern UInt32 SendInput(UInt32 nInputs, [MarshalAs(UnmanagedType.LPArray, SizeConst = 1)] INPUT[] pInputs, Int32 cbSize);

        [StructLayout(LayoutKind.Sequential)]
        struct MOUSEINPUT
        {
            public int dx;
            public int dy;
            public int mouseData;
            public int dwFlags;
            public int time;
            public IntPtr dwExtraInfo;
        }

        [StructLayout(LayoutKind.Sequential)]
        struct KEYBDINPUT
        {
            public short wVk;
            public short wScan;
            public int dwFlags;
            public int time;
            public IntPtr dwExtraInfo;
        }

        [StructLayout(LayoutKind.Sequential)]
        struct HARDWAREINPUT
        {
            public int uMsg;
            public short wParamL;
            public short wParamH;
        }

        [StructLayout(LayoutKind.Explicit)]
        struct INPUT
        {
            [FieldOffset(0)]
            public int type;
            [FieldOffset(4)]
            public MOUSEINPUT mi;
            [FieldOffset(4)]
            public KEYBDINPUT ki;
            [FieldOffset(4)]
            public HARDWAREINPUT hi;
        }

        const int KEYEVENTF_EXTENDEDKEY = 0x0001;
        const int KEYEVENTF_KEYUP = 0x0002;
        const int KEYEVENTF_UNICODE = 0x0004;
        const int KEYEVENTF_SCANCODE = 0x0008;


        public void Send_Key(short Keycode, int KeyUporDown)
        {
            INPUT[] InputData = new INPUT[1];

            InputData[0].type = 1;
            InputData[0].ki.wScan = Keycode;
            InputData[0].ki.dwFlags = KeyUporDown;
            InputData[0].ki.time = 0;
            InputData[0].ki.dwExtraInfo = IntPtr.Zero;

            SendInput(1, InputData, Marshal.SizeOf(typeof(INPUT)));
        }

    }
}

Then I’m sending Buttons with this:

DirectInput.cDirectInput d = new DirectInput.cDirectInput();
d.Send_Key(0x11, 0x0008);

But when I send it it is permanent. When I send w the player is moving forward forever. I can stop that by pressing w on the keyboard. Why isn’t it stopping? When I send it to an editor it stops when I stop sending, ingame it doesn’t stop. What is the problem?
Thank you in advance!

Answer 1

You’re sending a key down message, but not sending a key up message following it. From the documentation:

KEYBDINPUT.dwFlags:

• KEYEVENTF_KEYUP (0x0002)
  If specified, the key is being released. If not specified, the key is being pressed.

To move forward for 1 second, try:

d.Send_Key(0x11, 0x0008);
Thread.Sleep(1000);
d.Send_Key(0x11, 0x000A);

Note that the reason pressing w fixes the problem is it sends a keydown event (which would be ignored) and then a keyup event, finally releasing the key.