Draw multiple vertical lines on MQL5 EA

Question

I would like to draw vertical lines for times when a new signal appears in an EA. For simplicity lets say a signal is simply the close price crossing over an EMA.

I managed to create a vertical line only on the latest signal. For any new signal, all prior Vlines disappear.

Looking over an old POST, I noted that one may have to update the positions of all vertical lines each new candle. The problem with that post, is that it re-runs all the calculations at each new candle, which appears inefficient.

So my solution was to create an array of datetime and store the time each new signal appears, and then loop over that array to place vertical lines over the time of all prior signals. However, as a new line is drawn, the prior one is erased. Any thought what could be wrong, or is there any other way to place such vlines on all crossovers in an EA?

Here is a simplified version of the code:

//General variables
   bool IsNewbar; //Bollean to do calcualtion only on new bar.
   MqlRates Price[]; // to staore price data used in EMA cross over

// Moving average variables
   int              MovAve_Handle;
   double           MovAve_Buffer[]; 

//for marking signals as vertical lines
   datetime TimeLong;
   int NSignalsLongs=0;
   datetime Sig_L_Pos[]; //Array to store datetimes in which signals where reported


int OnInit()
{
   ArraySetAsSeries(Sig_L_Pos,true);
   ArraySetAsSeries(Price,true);

      
   MovAve_Handle= iMA(_Symbol,PERIOD_M1, 100,0, MODE_SMA,PRICE_CLOSE);
   ArraySetAsSeries(MovAve_Buffer,true);
          
   return(INIT_SUCCEEDED);
}



void OnTick()
{
///---check for new bar
      static datetime StartTime;
      datetime ThisBarTime = iTime(_Symbol,PERIOD_M1,0);
      if(StartTime != ThisBarTime) {IsNewbar=true; StartTime = ThisBarTime; } else {IsNewbar=false;}

 
      if(IsNewbar==true){
         //Collect data of signal on new candle
               string SignalEntryType= GetSignal_BBCont_MA();
            
          //Check for signal type 
               if (SignalEntryType=="Long") {
                        NSignalsLongs=ArraySize(Sig_L_Pos);
                        ArrayResize(Sig_L_Pos,NSignalsLongs+1); 
                        Print(NSignalsLongs);
                        Sig_L_Pos[NSignalsLongs]=TimeCurrent();  //store time of signal into array
                        

                        Print(SignalEntryType);
               }
           //Draw vLines for each of the times in which signals arrived.
           for(int i = 0; i<=NSignalsLongs-1; i++){
                   TimeLong=Sig_L_Pos[i];
                   ObjectCreate(0,"Long", OBJ_VLINE,0, TimeLong ,0);
               }
      }   
}


///GETSIGNAL fucntion
string GetSignal_BBCont_MA(){
      
      // close price
            CopyRates(_Symbol,PERIOD_M1,1,2,Price);
            
      //Data from Moving Average
            CopyBuffer(MovAve_Handle,0,1,2,MovAve_Buffer);
               
      //GetSignal  Close Crossover EMA
         if (Price[0].close > MovAve_Buffer[0] && Price[1].close<=MovAve_Buffer[1]) {return("Long");} 
         
      return("None");
}

Answer 1

The reason for drawing only the latest vline, is that the name was not unique.

This fixed the problem:

string name = "L" + IntegerToString(i);
              // ObjectCreate(0, name, OBJ_VLINE, 0, TimeLong,0 ); //Shows bottom labels.
               ObjectCreate(0,name, OBJ_TRENDBYANGLE, 0, TimeLong, 0, TimeLong, 1); // straight lines