C# EM_CHARFROMPOS如何将一个点投射到Intptr？

using System;
using System.Runtime.InteropServices;

public class Program
{
    // 引入user32.dll库
    [DllImport("user32.dll")]
    public static extern IntPtr SendMessage(IntPtr hWnd, int msg, IntPtr wParam, ref Point lParam);

    // 定义Windows消息常量
    public const int EM_CHARFROMPOS = 0x00D7;

    // 定义Point结构体，表示坐标
    [StructLayout(LayoutKind.Sequential)]
    public struct Point
    {
        public int X;
        public int Y;
    }

    public static void Main()
    {
        // 获取目标窗口的句柄，可以使用IntPtr.Zero表示当前活动窗口
        IntPtr hWnd = IntPtr.Zero;

        // 构造一个Point对象，表示需要投射的坐标
        Point position = new Point();
        position.X = 100;
        position.Y = 100;

        // 调用SendMessage函数进行投射
        IntPtr result = SendMessage(hWnd, EM_CHARFROMPOS, IntPtr.Zero, ref position);

        // 输出结果
        Console.WriteLine(result);
    }
}