     spline_context.lineTo(x_to_client(spline_xs[i])-5.5, y_to_client(spline_ys[i])-5.5);
    }
    spline_context.strokeStyle="#AA3311";
    spline_context.stroke();
    spline_context.closePath();
    spline_context.beginPath();
    spline_context.setLineDash([4, 4]);
    for(var i = 0; i < spline_n/2; ++i){
        spline_context.moveTo(x_to_client(spline_xs[2*i]), y_to_client(spline_ys[2*i]));
        spline_context.lineTo(x_to_client(spline_xs[2*i+1]), y_to_client(spline_ys[2*i+1]));
    }
    spline_c