using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace WindowsApplication2
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            this.MouseClick+=new MouseEventHandler(Form1_MouseClick);
        }

        void Form1_MouseClick(object sender, MouseEventArgs e)
        {
            MessageBox.Show("X :" + e.X.ToString() + "Y :" + e.Y.ToString());

        }

        private void button1_Click(object sender, EventArgs e)
        {
            int x=58;
            int y=32;

            //写法1
            PostMessage(this.Handle, WM_LBUTTONDOWN, 0, (x & 0xFFFF) + (y & 0xFFFF) * 0x10000);
            PostMessage(this.Handle, WM_LBUTTONUP, 0, (x & 0xFFFF) + (y & 0xFFFF) * 0x10000);

            //简化下  其实就是Y坐标左移16位,然后再加上X坐标
            PostMessage(this.Handle, WM_LBUTTONDOWN, 0, x + (y<<16));
            PostMessage(this.Handle, WM_LBUTTONUP, 0, x+(y<<16));

        }


          uint WM_LBUTTONDOWN  = 0x201;
          uint WM_LBUTTONUP  = 0x202;

        
        [DllImport("user32.dll", SetLastError = true)]
        static extern bool PostMessage(IntPtr hWnd, uint Msg, int wParam, int lParam);
    }
}

Virtual mouse click c#
Int32 word = MakeLParam(x, y);
 
private int MakeLParam(int LoWord, int HiWord)
     {
         return ((HiWord << 16) | (LoWord & 0xffff));
     }
       
public static class SimInput
{
    [DllImport("user32.dll")]
    static extern void mouse_event(uint dwFlags, uint dx, uint dy, uint dwData, UIntPtr dwExtraInfo);
 
    [Flags]
    public enum MouseEventFlags : uint
    {
        Move = 0x0001,
        LeftDown = 0x0002,
        LeftUp = 0x0004,
        RightDown = 0x0008,
        RightUp = 0x0010,
        MiddleDown = 0x0020,
        MiddleUp = 0x0040,
        Absolute = 0x8000
    }
 
    public static void MouseEvent(MouseEventFlags e, uint x, uint y)
    {
        mouse_event((uint)e, x, y, 0, UIntPtr.Zero);
    }
 
    public static void LeftClick(Point p)
    {
        LeftClick((double)p.X, (double)p.Y);
    }
 
    public static void LeftClick(double x, double y)
    {
        var scr = Screen.PrimaryScreen.Bounds;
        MouseEvent(MouseEventFlags.LeftDown | MouseEventFlags.LeftUp | MouseEventFlags.Move | MouseEventFlags.Absolute,
            (uint)Math.Round(x / scr.Width * 65535),
            (uint)Math.Round(y / scr.Height * 65535));
    }
 
    public static void LeftClick(int x, int y)
    {
        LeftClick((double)x, (double)y);
    }
}
       
public static void MouseLeftClick(Point p, int handle = 0)
{
    //build coordinates
    int coordinates = p.X | (p.Y << 16);
    //send left button down
    SendMessage(handle, 0x201, 0x1, coordinates);
    //send left button up
    SendMessage(handle, 0x202, 0x1, coordinates);
}