System Drawing Drawing2d C# by API

/*
Professional Windows GUI Programming Using C#
by Jay Glynn, Csaba Torok, Richard Conway, Wahid Choudhury, 
   Zach Greenvoss, Shripad Kulkarni, Neil Whitlow
Publisher: Peer Information
ISBN: 1861007663
*/
using System;
using System.Drawing;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.Data;
using System.Drawing.Drawing2D;  // LinearGradientBrush
namespace LinGradient
{
    /// 
    /// Summary description for LinGradient.
    /// 

    public class LinGradient : System.Windows.Forms.Form
    {
        /// 
        /// Required designer variable.
        /// 

        private System.ComponentModel.Container components = null;
        public LinGradient()
        {
            //
            // Required for Windows Form Designer support
            //
            InitializeComponent();
            this.Text = "LinearGradientMode";
            //
            // TODO: Add any constructor code after InitializeComponent call
            //
        }
        /// 
        /// Clean up any resources being used.
        /// 

        protected override void Dispose( bool disposing )
        {
            if( disposing )
            {
                if (components != null) 
                {
                    components.Dispose();
                }
            }
            base.Dispose( disposing );
        }
        #region Windows Form Designer generated code
        /// 
        /// Required method for Designer support - do not modify
        /// the contents of this method with the code editor.
        /// 

        private void InitializeComponent()
        {
            // 
            // LinGradient
            // 
            this.AutoScaleBaseSize = new System.Drawing.Size(5, 13);
            this.ClientSize = new System.Drawing.Size(256, 205);
            this.Name = "LinGradient";
            this.Text = "LinGradient";
        }
        #endregion
        /// 
        /// The main entry point for the application.
        /// 

        [STAThread]
        static void Main() 
        {
            Application.Run(new LinGradient());
        }
        protected override void OnPaint(PaintEventArgs e)
        {   
            Graphics g = e.Graphics;
            Font f = new Font(new FontFamily("Times New Roman"), 10);
            Brush fb = new SolidBrush(Color.Black);
            LinearGradientBrush lGB;  // namespace System.Drawing.Drawing2D;
            Color cR = Color.Red, cW = Color.White;
            int w = 100, h = 70;
            // Left upper rectangle:
            g.DrawString("Horizontal", f, fb, 10, 5);
            Rectangle rec = new Rectangle(10, 20, w, h);
            LinearGradientMode lGM = LinearGradientMode.Horizontal;
            lGB = new LinearGradientBrush(rec, cR, cW, lGM);
            g.FillRectangle(lGB, rec);
         
            // Right upper rectangle:
            g.DrawString("Vertical", f, fb, w + 20, 5);
            rec.Offset(w + 10, 0);
            lGM = LinearGradientMode.Vertical;
            lGB = new LinearGradientBrush(rec, cR, cW, lGM);
            g.FillRectangle(lGB, rec);
            // Left down rectangle:
            g.DrawString("ForwardDiagonal", f, fb, 10, h + 25);
            rec.Offset(-w - 10, h + 20);
            lGM = LinearGradientMode.ForwardDiagonal;
            lGB = new LinearGradientBrush(rec, cR, cW, lGM);
            g.FillRectangle(lGB, rec);
            // Right down rectangle:
            g.DrawString("BackwardDiagonal", f, fb, w + 20, h + 25);
            rec.Offset(w + 10, 0);
            lGM = LinearGradientMode.BackwardDiagonal;
            lGB = new LinearGradientBrush(rec, cR, cW, lGM);
            g.FillRectangle(lGB, rec);
            fb.Dispose();
            g.Dispose();
        }
    }
}