如何在MQL4中使用指标计数和如何将按键事件转换为代码

//+------------------------------------------------------------------+
//|                                                      Keyboard.mq4 |
//|                        Copyright 2021, MetaQuotes Software Corp. |
//|                                             https://www.mql5.com |
//+------------------------------------------------------------------+
#property copyright "2021, MetaQuotes Software Corp."
#property link      "https://www.mql5.com"
#property version   "1.00"
#property strict

//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int OnInit()
{
   // 监听按键事件
   EventSetTimer(1);
   return(INIT_SUCCEEDED);
}

//+------------------------------------------------------------------+
//| Custom indicator iteration function                              |
//+------------------------------------------------------------------+
int 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[])
{
   // 在这里执行指标计算和交易逻辑

   return(rates_total);
}

//+------------------------------------------------------------------+
//| Custom event function                                            |
//+------------------------------------------------------------------+
void OnTimer()
{
   // 检查是否有按键按下
   if (EventKeyPressed())
   {
      // 获取按下的按键码
      int key = EventKeyboardKey();
      
      // 根据按键码执行相应的操作
      switch (key)
      {
         case KEY_UP:
            // 执行向上操作
            break;
         case KEY_DOWN:
            // 执行向下操作
            break;
         case KEY_LEFT:
            // 执行向左操作
            break;
         case KEY_RIGHT:
            // 执行向右操作
            break;
         default:
            // 其他按键操作
            break;
      }
   }
}