//+------------------------------------------------------------------+
//|                                                  OnBookEvent.mq5 |
//|                        Copyright 2020, MetaQuotes Software Corp. |
//|                                             https://www.mql5.com |
//+------------------------------------------------------------------+
#property copyright "Copyright 2020, MetaQuotes Software Corp."
#property link      "https://www.mql5.com"
#property version   "1.00"
//+------------------------------------------------------------------+
//| Expert initialization function                                   |
//+------------------------------------------------------------------+
int OnInit()
  {
//---
   MarketBookAdd(_Symbol);

//---
   return(INIT_SUCCEEDED);
  }
//+------------------------------------------------------------------+
//| Expert deinitialization function                                 |
//+------------------------------------------------------------------+
void OnDeinit(const int reason)
  {
//---
   MarketBookRelease(_Symbol);

//---
  }
//+------------------------------------------------------------------+
//| Expert tick function                                             |
//+------------------------------------------------------------------+
void OnTick()
  {
//---

  }
//+------------------------------------------------------------------+
//| BookEvent function                                               |
//+------------------------------------------------------------------+
void OnBookEvent(const string &symbol)
  {
//---
   MqlBookInfo DomArr[];

//---
   MarketBookGet(_Symbol,DomArr);

//---
   string comment="";

//---
   for(int i=0; i<ArraySize(DomArr); i++)
     {
      //---
      string BidOrAsk="";

      //---
      if(DomArr[i].type==1)
        {
         BidOrAsk="Ask";
        }
      else
        {
         BidOrAsk="Bid";
        }

      //---
      if(DomArr[i].volume>150)
        {
         Print("A volume of 150 or more has been found @",DomArr[i].price);
        }

      //---
      comment+="Price: @"+DoubleToString(DomArr[i].price,_Digits)+" Vol: "+IntegerToString(DomArr[i].volume)+" Type: "+BidOrAsk+"\n";
     }

//---
   Comment(comment);
  }
//+------------------------------------------------------------------+