[C#] Screen Shot App

using System.Drawing.Imaging;using System.Threading;


///////////////// Declarations ////////////////////////
ImageFormat img; Bitmap bt; Graphics screenShot;


///////////////////// Button1 /////////////////////////////
if (saveFileDialog1.ShowDialog() == DialogResult.OK)
{
    this.Hide();
    // This gives time to the Form to hide before it takes the screenshot. 500 miliseconds are enough.
    Thread.Sleep(500); 
    // Set the image to the size of the screen.
    bt = new Bitmap(Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height, PixelFormat.Format32bppArgb);
    // Creates the graphic object for the image (bt).    
    screenShot = Graphics.FromImage(bt);
    // Takes the screenshot.
    screenShot.CopyFromScreen(Screen.PrimaryScreen.Bounds.X, Screen.PrimaryScreen.Bounds.Y, 0, 0, Screen.PrimaryScreen.Bounds.Size, 


CopyPixelOperation.SourceCopy);
    switch (saveFileDialog1.FilterIndex)
    {
        case 0: img = ImageFormat.Bmp; break;
        case 1: img = ImageFormat.Png; break;
        case 2: img = ImageFormat.Jpeg; break;
    }
    // Saves the image.
    bt.Save(saveFileDialog1.FileName, img);
    // After the screenshot is taken the Form reappears.
    this.Show();
}