2D Graphics C#

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Text;
using System.Windows.Forms;
public class Form1 : Form {
    protected override void OnPaint(PaintEventArgs e) {
        Graphics g = e.Graphics;
        GraphicsPath gp = new GraphicsPath();
        gp.AddLine(10, 10, 110, 15);
        gp.AddLine(110, 15, 100, 96);
        gp.AddLine(100, 96, 15, 110);
        gp.CloseFigure();
        g.FillRectangle(Brushes.White, this.ClientRectangle);
        g.SmoothingMode = SmoothingMode.AntiAlias;
        PathGradientBrush pgb = new PathGradientBrush(gp);
        pgb.CenterColor = Color.White;
        pgb.SurroundColors = new Color[] { Color.Blue };
        g.FillPath(pgb, gp);
        g.DrawPath(Pens.Black, gp);
        pgb.Dispose();
        gp.Dispose();
    }
    public static void Main() {
        Application.Run(new Form1());
    }
}