Can't get SendInput() to work

Question

I'm kind of desperate. I have been trying for hours now, but I just can't get SendInput() to work. To be honest, I can't even get it to be recognized. It always says:

Error   1   The type or namespace name 'INPUT' could not be found (are you missing a using directive or an assembly reference?)

And I just can't find out which libraries to use. There's almost zero information about what to include for this, all I can find is for C++ or is simply not existing when I try using it. Please Help!

I'm trying to make my program do a mouseclick... Here's the code, it's one of many versions I found and tried to get to work. In this version, the program also can't find INPUT and SendInputEventType

using System;
using System.Runtime.InteropServices;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Input;

namespace autoPlayer
{
    class Win32
    {
        enum SystemMetric
        {
          SM_CXSCREEN = 0,
          SM_CYSCREEN = 1,
        }

        [DllImport("user32.dll")]
        static extern int GetSystemMetrics(SystemMetric smIndex);

        int CalculateAbsoluteCoordinateX(int x)
        {
          return (x * 65536) / GetSystemMetrics(SystemMetric.SM_CXSCREEN);
        }

        int CalculateAbsoluteCoordinateY(int y)
        {
          return (y * 65536) / GetSystemMetrics(SystemMetric.SM_CYSCREEN);
        }

        public static void ClickLeftMouseButton(int x, int y)
        {
            INPUT mouseInput = new INPUT();
            mouseInput.type = SendInputEventType.InputMouse;
            mouseInput.mkhi.mi.dx = CalculateAbsoluteCoordinateX(x);
            mouseInput.mkhi.mi.dy = CalculateAbsoluteCoordinateY(y);
            mouseInput.mkhi.mi.mouseData = 0;


            mouseInput.mkhi.mi.dwFlags = MouseEventFlags.MOUSEEVENTF_MOVE | MouseEventFlags.MOUSEEVENTF_ABSOLUTE;
            SendInput(1, ref mouseInput, Marshal.SizeOf(new INPUT()));

            mouseInput.mkhi.mi.dwFlags = MouseEventFlags.MOUSEEVENTF_LEFTDOWN;
            SendInput(1, ref mouseInput, Marshal.SizeOf(new INPUT()));

            mouseInput.mkhi.mi.dwFlags = MouseEventFlags.MOUSEEVENTF_LEFTUP;
            SendInput(1, ref mouseInput, Marshal.SizeOf(new INPUT()));
        } 
    }
}

I would be so glad If anyone could help!

Answer 1

You are missing the INPUT structure. It doesn't come from System.Windows.Input if that's what you thought (guessing due to using).

You can find the necessary C# and VB.NET structures here

Your SendInputEventType is really just going to be an enum or a class with constants. PInvoke has that defined as well.

internal enum INPUT_TYPE : uint 
{
      INPUT_MOUSE = 0,
      INPUT_KEYBOARD = 1,
      INPUT_HARDWARE = 2
}

You can update your code to use this name or rename this enum to match your code. It's up to you.

Here is a great answer that has an example of implementing SendInput with those structures defined: how to programatically mouse move,click,right click and keypress, etc. in winform and wpf?