 + 0.5);
    context.moveTo(client_x_center + 0.5, h);
    context.lineTo(client_x_center + 0.5, 0);
    context.lineTo(client_x_center - 5 + 0.5, 12);
    context.moveTo(client_x_center + 0.5, 0);
    context.lineTo(client_x_center + 5 + 0.5, 12);
    context.fillStyle="#000000";
    for(var i = x_min + 1; i <= x_max - 1; i++){
        if(i != 0) {
            context.moveTo(client_x_center + i*client_x_step + 0.5, client_y_center);
            context.lineTo(client_x_center + i*client_x_step + 0.5, client