c# GDI basic

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;
using System.Drawing.Drawing2D;

namespace gdi
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Paint(object sender, PaintEventArgs e)
        {
            Graphics g = e.Graphics;
            Rectangle rect = this.ClientRectangle;

            LinearGradientBrush lbrush = new LinearGradientBrush(rect, Color.Red, Color.Yellow, LinearGradientMode.BackwardDiagonal);
            g.FillRectangle(lbrush, rect);

            Pen pn = new Pen(Color.Blue);
            rect = new Rectangle(50, 50, 200, 100);
            g.DrawArc(pn, rect, 12, 84);

            Pen pn2 = new Pen(Color.BlueViolet);
            Point pt1 = new Point(30, 30);
            Point pt2 = new Point(110, 100);
            g.DrawLine(pn2, pt1, pt2);

            g.DrawString("welcome to the graphics world", this.Font, new SolidBrush(Color.Azure), 10, 10);

            Pen pn3 = new Pen(Color.Aqua, 5);
            rect=new Rectangle(ClientRectangle.Right-60,ClientRectangle.Bottom-60,50,50);
            g.DrawEllipse(pn3,rect);

            GraphicsPath path = new GraphicsPath(new Point[]
            {
                new Point(40,140),new Point(275,200),new Point(105,225),new Point(190,ClientRectangle.Bottom),
                new Point(50,ClientRectangle.Bottom),new Point(20,180),
            },

            new byte[]
            {
                (byte)PathPointType.Start,
                (byte)PathPointType.Bezier,
                (byte)PathPointType.Bezier,
                (byte)PathPointType.Bezier,
                (byte)PathPointType.Line,
                (byte)PathPointType.Line,
            });

            PathGradientBrush pgb = new PathGradientBrush(path);
            pgb.SurroundColors = new Color[] { Color.Green, Color.Yellow, Color.Red, Color.Blue, Color.Orange, Color.White, };
            g.FillPath(pgb, path);


        }
    }
}