---

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace WinFormsBezier
{
    public partial class Form1 : Form
    {
        protected Point[] apt = new Point[4];
        public Form1()
        {
            InitializeComponent();
            Text = "Bezier (Mouse Defines Control Points)";
            BackColor = SystemColors.Window;
            ForeColor = SystemColors.WindowText;
            ResizeRedraw = true;

            OnResize(EventArgs.Empty);
        }

        private void Form1_Resize(object sender, EventArgs e)
        {
            int cx = ClientSize.Width;
            int cy = ClientSize.Height;

            apt[0] = new Point(cx / 4, cy / 2);
            apt[1] = new Point(cx / 2, cy / 4);
            apt[2] = new Point(cx / 2, 3 * cy / 4);
            apt[3] = new Point(3 * cx / 4, cy / 2);
        }

        private void Form1_MouseDown(object sender, MouseEventArgs mea)
        {
            Point pt;

            if (mea.Button == MouseButtons.Left)
                pt = apt[1];

            else if (mea.Button == MouseButtons.Right)
                pt = apt[2];

            else
                return;

            Cursor.Position = PointToScreen(pt);
        }

        private void Form1_Paint(object sender, PaintEventArgs pea)
        {
            Graphics grfx = pea.Graphics;

            grfx.DrawBeziers(new Pen(ForeColor), apt);

            Pen pen = new Pen(Color.FromArgb(0x80, ForeColor));

            grfx.DrawLine(pen, apt[0], apt[1]);
            grfx.DrawLine(pen, apt[2], apt[3]);
        }

        private void Form1_MouseMove(object sender, MouseEventArgs mea)
        {
            if (mea.Button == MouseButtons.Left)
            {
                apt[1] = new Point(mea.X, mea.Y);
                Invalidate();
            }
            else if (mea.Button == MouseButtons.Right)
            {
                apt[2] = new Point(mea.X, mea.Y);
                Invalidate();
            }
        }
    }
}