public class piston
    {
        System.Drawing.Graphics zona_des;
        int x0;
        int y0;
        int w;
        int h;

        public void setval(Color culoare_contur, Color culoare_stergere, Color culoare_piston, int alfa_gr)
        {
            // alfa_gr unghiul in grade
            int xc = x0 + w / 2;
            int yc = y0 + w / 2;
            int raza = w / 2;
            int yl;
            zona_des.FillRectangle(new SolidBrush(culoare_stergere), x0 + 1, y0 + 1, w - 1, 3 * w);
            double alfa_r = 2 * System.Math.PI * (alfa_gr) / 360;// unghiul in radiani
            int x = System.Convert.ToInt16(xc + raza * System.Math.Cos(alfa_r));
            int y = System.Convert.ToInt16(yc - raza * System.Math.Sin(alfa_r));
            yl = System.Convert.ToInt16(raza * System.Math.Sin(alfa_r));
            zona_des.DrawEllipse(new Pen(culoare_contur), xc - raza, yc - raza, 2 * raza, 2 * raza);
            zona_des.DrawLine(new Pen(culoare_contur), x, y, xc, y0 + 2 * w - yl);
            zona_des.DrawLine(new Pen(culoare_contur), x, y, xc, yc);
            zona_des.FillRectangle(new SolidBrush(culoare_piston), x0, y0 + 2 * w - yl, w, raza);
            zona_des.DrawRectangle(new Pen(culoare_contur), x0, y0 + w + raza, w, 2 * w - raza / 2);
        }
        public piston(System.Drawing.Graphics desen,int pozx, int pozy, int lat, int inalt)
        {
            zona_des = desen;
            x0 = pozx;
            y0 = pozy;
            w = lat;
            h = inalt;
        }
    }