SendInput Example In C#

[onebit]

Here is some code I'm using for SendInput().

Remember to call WindowsAPI.SwitchWindow() before you SendInput() because the window needs focus.

public static void PressKey(char ch, bool press)
        {
            byte vk = WindowsAPI.VkKeyScan(ch);
            ushort scanCode = (ushort)WindowsAPI.MapVirtualKey(vk, 0);

            if (press)
                KeyDown(scanCode);
            else
                KeyUp(scanCode);
        }

        public static void KeyDown(ushort scanCode)
        {
            INPUT[] inputs = new INPUT[1];
            inputs[0].type = WindowsAPI.INPUT_KEYBOARD;
            inputs[0].ki.dwFlags = 0;
            inputs[0].ki.wScan = (ushort)(scanCode & 0xff);

            uint intReturn = WindowsAPI.SendInput(1, inputs, System.Runtime.InteropServices.Marshal.SizeOf(inputs[0]));
            if (intReturn != 1)
            {
                throw new Exception("Could not send key: " + scanCode);
            }
        }

        public static void KeyUp(ushort scanCode)
        {
            INPUT[] inputs = new INPUT[1];
            inputs[0].type = WindowsAPI.INPUT_KEYBOARD;
            inputs[0].ki.wScan = scanCode;
            inputs[0].ki.dwFlags = WindowsAPI.KEYEVENTF_KEYUP;
            uint intReturn = WindowsAPI.SendInput(1, inputs, System.Runtime.InteropServices.Marshal.SizeOf(inputs[0]));
            if (intReturn != 1)
            {
                throw new Exception("Could not send key: " + scanCode);
            }
        }

WindowsAPI functions (32 bit windows only)

using System;
using System.Runtime.InteropServices;
using System.Diagnostics;

    /// <summary>
    /// 
    /// </summary>
    public class WindowsAPI
    {
        /// <summary>
        /// 
        /// </summary>
        public const uint WM_KEYDOWN = 0x100;

        /// <summary>
        /// 
        /// </summary>
        public const uint WM_KEYUP = 0x101;

        /// <summary>
        /// 
        /// </summary>
        public const uint WM_LBUTTONDOWN = 0x201;

        /// <summary>
        /// 
        /// </summary>
        public const uint WM_LBUTTONUP = 0x202;

        public const uint WM_CHAR = 0x102;

        /// <summary>
        /// 
        /// </summary>
        public const int MK_LBUTTON = 0x01;

        /// <summary>
        /// 
        /// </summary>
        public const int VK_RETURN = 0x0d;

        public const int VK_ESCAPE = 0x1b;

        /// <summary>
        /// 
        /// </summary>
        public const int VK_TAB = 0x09;

        /// <summary>
        /// 
        /// </summary>
        public const int VK_LEFT = 0x25;

        /// <summary>
        /// 
        /// </summary>
        public const int VK_UP = 0x26;

        /// <summary>
        /// 
        /// </summary>
        public const int VK_RIGHT = 0x27;

        /// <summary>
        /// 
        /// </summary>
        public const int VK_DOWN = 0x28;

        /// <summary>
        /// 
        /// </summary>
        public const int VK_F5 = 0x74;

        /// <summary>
        /// 
        /// </summary>
        public const int VK_F6 = 0x75;

        /// <summary>
        /// 
        /// </summary>
        public const int VK_F7 = 0x76;

        /// <summary>
        /// The GetForegroundWindow function returns a handle to the foreground window.
        /// </summary>
        [DllImport("user32.dll")]
        public static extern IntPtr GetForegroundWindow();

        [DllImport("kernel32.dll")]
        public static extern uint GetCurrentThreadId();

        [DllImport("user32.dll", SetLastError = true)]
        public static extern uint GetWindowThreadProcessId(IntPtr hWnd, out uint lpdwProcessId);

        [DllImport("user32.dll")]
        public static extern bool AttachThreadInput(uint idAttach, uint idAttachTo, bool fAttach);

        [DllImport("kernel32.dll", SetLastError = true)]
        public static extern bool ReadProcessMemory(
          IntPtr hProcess,
          IntPtr lpBaseAddress,
          [Out()] byte[] lpBuffer,
          int dwSize,
          out int lpNumberOfBytesRead
         );
                
        public static void SwitchWindow(IntPtr windowHandle)
        {
            if (GetForegroundWindow() == windowHandle)
                return;

            IntPtr foregroundWindowHandle = GetForegroundWindow();
            uint currentThreadId = GetCurrentThreadId();
            uint temp;
            uint foregroundThreadId = GetWindowThreadProcessId(foregroundWindowHandle, out temp);
            AttachThreadInput(currentThreadId, foregroundThreadId, true);
            SetForegroundWindow(windowHandle);
            AttachThreadInput(currentThreadId, foregroundThreadId, false);

            while (GetForegroundWindow() != windowHandle)
            {
            }
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="hwndParent"></param>
        /// <param name="hwndChildAfter"></param>
        /// <param name="lpszClass"></param>
        /// <param name="lpszWindow"></param>
        /// <returns></returns>
        [DllImport("user32.dll", SetLastError = true)]
        public static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpszClass, string lpszWindow);

        /// <summary>
        /// 
        /// </summary>
        /// <param name="hWnd"></param>
        /// <param name="msg"></param>
        /// <param name="wParam"></param>
        /// <param name="lParam"></param>
        /// <returns></returns>
        [DllImport("User32.Dll", EntryPoint = "PostMessageA")]
        public static extern bool PostMessage(IntPtr hWnd, uint msg, int wParam, int lParam);

        /// <summary>
        /// 
        /// </summary>
        /// <param name="ch"></param>
        /// <returns></returns>
        [DllImport("user32.dll")]
        public static extern byte VkKeyScan(char ch);

        [DllImport("user32.dll")]
        public static extern uint MapVirtualKey(uint uCode, uint uMapType);

        /// <summary>
        /// 
        /// </summary>
        /// <param name="name"></param>
        /// <returns></returns>
        public static IntPtr FindWindow(string name)
        {
            Process[] procs = Process.GetProcesses();

            foreach (Process proc in procs)
            {
                if (proc.MainWindowTitle == name)
                {
                    return proc.MainWindowHandle;
                }
            }

            return IntPtr.Zero;
        }

        [DllImport("user32.dll")]
        public static extern IntPtr SetFocus(IntPtr hWnd);

        [DllImport("user32.dll")]
        [return: MarshalAs(UnmanagedType.Bool)]
        public static extern bool SetForegroundWindow(IntPtr hWnd);

        /// <summary>
        /// 
        /// </summary>
        /// <param name="low"></param>
        /// <param name="high"></param>
        /// <returns></returns>
        public static int MakeLong(int low, int high)
        {
            return (high << 16) | (low & 0xffff);
        }
    
        [DllImport("User32.dll")]
        public static extern uint SendInput(uint numberOfInputs, [MarshalAs(UnmanagedType.LPArray, SizeConst = 1)] INPUT[] input, int structSize); 

        [DllImport("user32.dll")]
        public static extern IntPtr GetMessageExtraInfo();

        public const int INPUT_MOUSE = 0;
        public const int INPUT_KEYBOARD = 1;
        public const int INPUT_HARDWARE = 2;
        public const uint KEYEVENTF_EXTENDEDKEY = 0x0001;
        public const uint KEYEVENTF_KEYUP = 0x0002;
        public const uint KEYEVENTF_UNICODE = 0x0004;
        public const uint KEYEVENTF_SCANCODE = 0x0008;
        public const uint XBUTTON1 = 0x0001;
        public const uint XBUTTON2 = 0x0002;
        public const uint MOUSEEVENTF_MOVE = 0x0001;
        public const uint MOUSEEVENTF_LEFTDOWN = 0x0002;
        public const uint MOUSEEVENTF_LEFTUP = 0x0004;
        public const uint MOUSEEVENTF_RIGHTDOWN = 0x0008;
        public const uint MOUSEEVENTF_RIGHTUP = 0x0010;
        public const uint MOUSEEVENTF_MIDDLEDOWN = 0x0020;
        public const uint MOUSEEVENTF_MIDDLEUP = 0x0040;
        public const uint MOUSEEVENTF_XDOWN = 0x0080;
        public const uint MOUSEEVENTF_XUP = 0x0100;
        public const uint MOUSEEVENTF_WHEEL = 0x0800;
        public const uint MOUSEEVENTF_VIRTUALDESK = 0x4000;
        public const uint MOUSEEVENTF_ABSOLUTE = 0x8000;
    }

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

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

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

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

To get a Window Handle:

Process[] processes = Process.GetProcessesByName("war");

            if (processes.Length == 0)
                throw new Exception("Could not find the Warhammer process; is Warhammer running?");

            
            IntPtr WindowHandle = processes[0].MainWindowHandle;

Credits:
Pickle
apollo
www.pinvoke.net