Рисование прямоугольника на picturebox

public void Draw(int width, int height)
        {
            Bitmap bmp;
            bmp = new Bitmap(Graph.Width, Graph.Height);
            Graph.Image = bmp;
            Graphics g = Graphics.FromImage(Graph.Image);
            Rectangle rect = new Rectangle(20,20,width, height);
            g.DrawRectangle(new Pen(Color.Red, .5f), rect);
        }

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            Draw(50, 50);
        }
        public void Draw(int width, int height)
        {
            Bitmap bmp;
            bmp = new Bitmap(pictureBox1.Width, pictureBox1.Height);
            pictureBox1.Image = bmp;
            Graphics g = Graphics.FromImage(pictureBox1.Image);
            Rectangle rect = new Rectangle(20, 20, width, height);
            g.DrawRectangle(new Pen(Color.Red, .5f), rect);
        }

using System;
using System.Drawing;
using System.ComponentModel;
using System.Windows.Forms;
using System.Globalization;
using System.Threading;
 
...
 
public int IColor;
public UInt64 GHeight;
public Pen Perimeter;
public Bitmap Pix;
public Random Rnd = new Random();
 
private void button1_Click(object sender, EventArgs e) {
    Thread.Sleep(40);
 
    GHeight = (UInt64)(pictureBox1.Size.Height - 4);
    IColor = Rnd.Next(16777216);
    pictureBox1.BackColor = Color.FromArgb(~IColor);
    IColor = (int)((UInt32)IColor | 0xFF000000);
    
    Pix = new Bitmap(pictureBox1.Width, pictureBox1.Height);
    using (Graphics f = Graphics.FromImage(Pix)) {
        Perimeter = new Pen(Color.FromArgb(IColor), 1);
 
        f.DrawLine(Perimeter, 4, GHeight, 4, 4);
        f.DrawLine(Perimeter, 4, 4, pictureBox1.Size.Width - 4, 4);
 
        Pix.RotateFlip(RotateFlipType.RotateNoneFlipY); pictureBox1.Image = Pix;
    }
}