center);
    chebyshev_context.lineTo(w - 12, chebyshev_client_y_center + 5);
    chebyshev_context.moveTo(chebyshev_client_x_center, h);
    chebyshev_context.lineTo(chebyshev_client_x_center, 0);
    chebyshev_context.lineTo(chebyshev_client_x_center - 5, 12);
    chebyshev_context.moveTo(chebyshev_client_x_center, 0);
    chebyshev_context.lineTo(chebyshev_client_x_center + 5, 12);
    chebyshev_context.fillStyle="#000000";
    for(var i = x_min + 1; i <= x_max - 1; i++){
        chebyshev_context.moveTo