C#

<pre lang="c#">

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 WindowsFormsApplication2
{
    public partial class Form3 : Form
    {
        private Boolean _calculateDouglasPeuckerReduction = false;
        private List<WindowsFormsApplication2.PointEnhanced> _amerenPoints = new List<WindowsFormsApplication2.PointEnhanced>();


        public Form3()
        {
            InitializeComponent();
        }


        protected override void OnPaint(PaintEventArgs e)
        {

            List<System.Drawing.Point> drawingPoints = new List<System.Drawing.Point>();
            foreach (WindowsFormsApplication2.PointEnhanced point in _amerenPoints)
            {
                drawingPoints.Add(new System.Drawing.Point(Convert.ToInt32(point.X), Convert.ToInt32(point.Y)));

            }

            if (drawingPoints.Count > 2)
            {
                e.Graphics.DrawLines(new Pen(Brushes.Black, 2), drawingPoints.ToArray());
                lblOriginal2.Text = drawingPoints.Count.ToString();

                if (_calculateDouglasPeuckerReduction)
                {
                    List<WindowsFormsApplication2.PointEnhanced> points = Utility2.DouglasPeuckerReduction(_amerenPoints, Convert.ToDouble(nudTolerance2.Value));
                    drawingPoints = new List<System.Drawing.Point>();
                    foreach (WindowsFormsApplication2.PointEnhanced point in points)
                    {
                        drawingPoints.Add(new System.Drawing.Point(Convert.ToInt32(point.X), Convert.ToInt32(point.Y)));
                    }

                    e.Graphics.DrawLines(new Pen(Brushes.Red, 2), drawingPoints.ToArray());
                    lblSimplified2.Text = drawingPoints.Count.ToString();
                }
            }


            base.OnPaint(e);
        }
        private void Form3_MouseMove(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                _amerenPoints.Add(new WindowsFormsApplication2.PointEnhanced(e.X, e.Y));
                this.Invalidate();
            }
        }

        private void Form3_MouseUp(object sender, MouseEventArgs e)
        {
            //DO the calculation
            _calculateDouglasPeuckerReduction = true;
            this.Invalidate();
        }

        private void Form3_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                _amerenPoints.Clear();
                _calculateDouglasPeuckerReduction = false;
            }
        }

        private void nudTolerance2_ValueChanged(object sender, EventArgs e)
        {
            this.Invalidate();
        }

        private void Form3_Load(object sender, EventArgs e)
        {

        }

    }
}