display image in fullscreen

public partial class Form3 : Form

    {

        public static string strFileName = string.Empty;

        public Form3()

        {

            InitializeComponent();

        }

        private void button1_Click(object sender, EventArgs e)

        {

            OpenFileDialog dlg = new OpenFileDialog();

            dlg.Filter = "Image files (*.jpg, *.tif, *.bmp)|*.BMP;*.TIF;*.JPG|All files|*.*";

            dlg.RestoreDirectory = true;

            if (dlg.ShowDialog() == DialogResult.OK)

                //showPic(dlg.FileName);

                pictureBox1.Image = new Bitmap(dlg.FileName);

            strFileName = dlg.FileName;

        }

        private void showPic(string fname)

        {

            //linkLabel1.Hide();

            // The size of the image

            int xsize;

            int ysize;

            // The resized image

            int xout;

            int yout;

            // Read the file to memory 

            Bitmap pic = new Bitmap(fname);

            // Get the size of the image

            xsize = pic.Width;

            ysize = pic.Height;

            // Okey up to here we are the same as Tutor 03 now get the screen size

            int x = SystemInformation.PrimaryMonitorSize.Width;

            int y = SystemInformation.PrimaryMonitorSize.Height;

            // Now we know the screen resolution and we set the client to the size of the screen

            ClientSize = new System.Drawing.Size(x, y);

            // Get rid of the window

            FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;

            // Set the background to black which improves the pic display

            BackColor = System.Drawing.Color.Black;

            // Put the picture box at the top left of the screen

            Location = new System.Drawing.Point(0, 0);

            // Make the picture the height of the display and calculate the width to retain aspect

            yout = SystemInformation.PrimaryMonitorSize.Height;

            xout = (int)SystemInformation.PrimaryMonitorSize.Height * xsize / ysize;

            // But what if the width is larger than the display you must recalculate to make the width the size of the display

            // and recalculate the height to retain the aspect

            if (xout > SystemInformation.PrimaryMonitorSize.Width)

            {

                yout = (int)SystemInformation.PrimaryMonitorSize.Width * ysize / xsize;

                xout = SystemInformation.PrimaryMonitorSize.Width;

            }

            // Resize the picture to the display

            pictureBox1.SizeMode = System.Windows.Forms.PictureBoxSizeMode.StretchImage;

            // Center the picture box on the client

            pictureBox1.Location = new System.Drawing.Point((SystemInformation.PrimaryMonitorSize.Width - xout) / 2, (SystemInformation.PrimaryMonitorSize.Height - yout) / 2);

            // Adjust the picture box size to that of the resized picture

            pictureBox1.Size = new System.Drawing.Size(xout, yout);

            // Display the bitmap pic

            pictureBox1.Image = pic;

        }

        private void pictureBox1_Click(object sender, EventArgs e)

        {

            showPic(strFileName);

        }

    }