draw rectangle and undo

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using System.Drawing.Imaging;
using System.Drawing.Drawing2D;
namespace ControlShapePaint
{
    public partial class DrawShapes : UserControl
    {
        private readonly List<Rectangle> rects = new List<Rectangle>();
        private readonly List<Rectangle> oval = new List<Rectangle>();
        public bool isOval;
        public bool check = false;
        private Point tempStartPoint;
        private Point tempStartPointoval;
        private Rectangle tempRect;
        private Rectangle tempOval;
        public DrawShapes()
        {
            InitializeComponent();
            this.DoubleBuffered = true;
        }

        private void toolStripButtonRectangle_Click(object sender, EventArgs e)
        {
            isOval = true;
            check = true;
        }

        private void toolStripButtonEllipse_Click(object sender, EventArgs e)
        {
            isOval = false;
            check = true;
        }

        private void DrawShapes_MouseDown(object sender, MouseEventArgs e)
        {
            if (check == true)
            {
                if (isOval == true)
                {
                    tempStartPoint = e.Location;
                }
                else if (isOval == false)
                {
                    tempStartPointoval = e.Location;
                }

                Invalidate();
            }

        }

        private void DrawShapes_MouseMove(object sender, MouseEventArgs e)
        {
            if (check == true)
            {
                if (e.Button != MouseButtons.Left)
                    return;

                if (isOval == true)
                {
                    Point tempEndPoint = e.Location;
                    tempRect =

                           new Rectangle(
                               Math.Min(tempStartPoint.X, tempEndPoint.X),
                               Math.Min(tempStartPoint.Y, tempEndPoint.Y),
                               Math.Abs(tempStartPoint.X - tempEndPoint.X),
                               Math.Abs(tempStartPoint.Y - tempEndPoint.Y));
                }
                else if (isOval == false)
                {
                    Point tempEndPoint1 = e.Location;
                    tempOval =
                    new Rectangle(
                        Math.Min(tempStartPointoval.X, tempEndPoint1.X),
                        Math.Min(tempStartPointoval.Y, tempEndPoint1.Y),
                        Math.Abs(tempStartPointoval.X - tempEndPoint1.X),
                        Math.Abs(tempStartPointoval.Y - tempEndPoint1.Y));
                }

                Invalidate();
            }
        }

        private void DrawShapes_MouseUp(object sender, MouseEventArgs e)
        {
            if (check == true)
            {
                // Must be within constraint, prevents tiny invisible rectangles from being added
                if (isOval == true)
                {
                    if (tempRect.Width >= 10 && tempRect.Height >= 10)
                        rects.Add(tempRect);
                }
                else if (isOval == false)
                {
                    if (tempOval.Width >= 10 && tempOval.Height >= 10)
                        oval.Add(tempOval);
                }
            }
        }

        private void DrawShapes_Paint(object sender, PaintEventArgs e)
        {
            using (Pen pen = new Pen(Color.Black, 2))
            {
                // Redraws all existing rectangles onto the form
                foreach (Rectangle rect in rects)
                    e.Graphics.DrawRectangle(pen, rect);

                // Must be within constraint, prevents tiny invisible rectangles from being added
                if (tempRect.Width >= 10 && tempRect.Height >= 10)
                    e.Graphics.DrawRectangle(pen, tempRect);

            }
            using (Pen pen1 = new Pen(Color.Black, 2))
            {
                // Redraws all existing rectangles onto the form
                foreach (Rectangle rectOval in oval)
                    e.Graphics.DrawEllipse(pen1, rectOval);

                // Must be within constraint, prevents tiny invisible rectangles from being added
                if (tempOval.Width >= 10 && tempOval.Height >= 10)
                    e.Graphics.DrawEllipse(pen1, tempOval);
            }


        }





    }
}