如何在mql4中绘制曲线进度图？

#property indicator_chart_window
#property indicator_buffers 1
#property indicator_color1 Blue

input int period = 14;

double buffer[];

int OnInit()
{
    SetIndexBuffer(0, buffer);
    return(INIT_SUCCEEDED);
}

void OnCalculate(const int rates_total,
                 const int prev_calculated,
                 const datetime &time[],
                 const double &open[],
                 const double &high[],
                 const double &low[],
                 const double &close[],
                 const long &tick_volume[],
                 const long &volume[],
                 const int &spread[])
{
    int limit = rates_total - prev_calculated;
    if (prev_calculated > 0)
        limit++;

    for (int i = 0; i < limit; i++)
    {
        // 计算曲线数值
        buffer[i] = iCustom(NULL, 0, "CustomIndicator", period, i);
    }
}