Comment implémenter la copie d'écran en C#

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
using System.Drawing.Drawing2D;
namespace WindowsApplication2
{
  public partial class Form21 : Form
  {
    public Form21()
    {
      InitializeComponent();
    }
    private void button1_Click(object sender, EventArgs e)
    {
      Rectangle screenRect = Screen.PrimaryScreen.WorkingArea;
      Bitmap dumpBitmap = new Bitmap(screenRect.Width, screenRect.Height);
      Graphics tg = Graphics.FromImage(dumpBitmap);
      tg.CopyFromScreen(0, 0, 0, 0, new Size(dumpBitmap.Width, dumpBitmap.Height));
      this.pictureBox1.BackgroundImage = dumpBitmap;
      this.pictureBox1.BackgroundImageLayout = ImageLayout.Stretch;
      dumpBitmap.Save(@"c:/image1.bmp");
    }
  }
}

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace WindowsApplication2
{
  public partial class Form22 : Form
  {
    public Form22()
    {
      InitializeComponent();
    }
    private void button1_Click(object sender, EventArgs e)
    {
      Rectangle rect = new Rectangle(0, 0, this.Size.Width, this.Size.Height);
      Bitmap dumpBitmap = new Bitmap(this.Size.Width, this.Size.Height);
      this.DrawToBitmap(dumpBitmap, rect);
      this.pictureBox1.BackgroundImage = dumpBitmap;
      this.pictureBox1.BackgroundImageLayout = ImageLayout.Stretch;
      dumpBitmap.Save(@"c:/image2.bmp");
    }
  }
}