Drawing Line with Class

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Drawing; // Add to draw
using System.Threading.Tasks;



namespace Line_with_Class
{
    public class Line
    {
        private Point _p1;
        private Point _p2;
        private Color _color;

        public Line(Point p1, Point p2, Color color)
        {
            _p1 = p1;
            _p2 = p2;
            _color = color;
        }

        public Point StartingPoint
        { get { return _p1; } }

        public Point EndingPoint
        { get { return _p2; } }

        private Color color;
        public Color ColorUsing
        {
            get { return _color; }
            set { color = value; }
        }
    }
}
//====================================================
namespace Line_with_Class
{
    public partial class Form1 : Form
    {
        Bitmap bmap;
        Graphics g;

        List<Line> lineList = new List<Line>();
        Point point1, point2;
        Pen shapePen = new Pen(Color.Azure);

        public Form1()
        {
            InitializeComponent();
            bmap = new Bitmap(pictureBox1.Width, pictureBox1.Height);
            g = Graphics.FromImage(bmap);
        }

        private void pictureBox1_MouseDown(object sender, MouseEventArgs e)
        {
            point1 = e.Location;
            point2 = point1;
        }

        private void pictureBox1_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                //Erase previous line
                Pen pen = new Pen(pictureBox1.BackColor);
                g.DrawLine(pen, point1, point2);
                //Capture new Point
                point2 = e.Location;
                pen = new Pen(shapePen.Color);
                g.DrawLine(pen, point1, point2);

                pictureBox1.Image = bmap;
            }
        }

        private void pictureBox1_MouseUp(object sender, MouseEventArgs e)
        {
            point2 = e.Location;
            Line line = new Line(point1, point2, shapePen.Color);
            lineList.Add(line);
            pictureBox1.Invalidate();
        }

        private void pictureBox1_Paint(object sender, PaintEventArgs e)
        {
            foreach (Line line in lineList)
            {
                g.DrawLine(new Pen (line.ColorUsing), line.StartingPoint, line.EndingPoint);
                pictureBox1.Image = bmap;
            }
        }
    }
}
//1. Define class line
//2. Define List<Line>
//3. Mouse Up
//      Create Line object, Save it List<line> Class Line
//      Point p1
//      Ponit p2
//      Color C
//      PictureBox1.Invalidate();

//4. pictureBox_Paint 
//  foreach(Line L in lines)
//  { draw all the line }