//the method adds a figure to the FigureList class, and draws the desired figure (Line)
private void button1_Click(object sender, EventArgs e)
{
figlist.figarray.Add("Lin");
using (grx = Graphics.FromImage(bmp))
{
grx.DrawPolygon(Pens.Black, figlist.GetLine(Convert.ToInt32(textBox1.Text), Convert.ToInt32(textBox2.Text), Convert.ToInt32(textBox4.Text), Convert.ToInt32(textBox3.Text)));
}
pictureBox1.Image = bmp;
}