Определить середину формы

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
 
namespace WindowsFormsApplication22
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
 
        private int width, height;
        private int centercor1,centercor2;
        private int resultcor1, resultcor2;
 
        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            Form1 fr = new Form1();
            width = fr.Size.Width;
            height = fr.Size.Height;
            centercor1 = width / 2;
            centercor2 = height / 2;
            resultcor1=centercor2-100;
            resultcor2=centercor2+100;
            Point pt1=new Point(centercor1,resultcor1);
            Point pt2=new Point(centercor1,resultcor2);
            e.Graphics.DrawLine(new Pen(Color.Red), pt1, pt2);
        }
 
 
    }
}

width = fr.ClientRectangle.Width;// и т.д

e.Graphics.DrawLine(Pens.Green,
            new Point(this.ClientRectangle.Width >> 1, 0),
            new Point(this.ClientRectangle.Width >> 1, this.ClientRectangle.Height));