static public void Zoom(PictureBox pictureBox, int zoom)
        {
            if (pictureBox.Width != 0)
            {
                if (LastZoom < zoom)
                {
                    pictureBox.Width += zoom;
                    pictureBox.Height += zoom;
                }
                else
                {
                    pictureBox.Width -= zoom;
                    pictureBox.Height -= zoom;
                }
            }
            else
            {
                pictureBox.Width = 10;
                pictureBox.Height = 10;
            }
            LastZoom = zoom;
        }