MQL4 How to alert when a price reaches certain levels?

Question

I have this free indicator is the name is FiboPiv_v2.mq4.

It's a tool I use with good result in trading scalping. I set normally the alert by hand, but I see that the code is open and so I'd like to do a modification but I'm quite newbie in programming MQL4.

I would like to add a pop-up and sound that says something like "AUDUSD has reached S1".

Code of the indicator:

#property indicator_chart_window
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int init()
{
//---- indicators
return(0);
}
//+------------------------------------------------------------------+
//| Custom indicator deinitialization function                       |
//+------------------------------------------------------------------+
int deinit()
{
//----
ObjectDelete("S1");
ObjectDelete("S2");
ObjectDelete("S3");
ObjectDelete("R1");
ObjectDelete("R2");
ObjectDelete("R3");
ObjectDelete("PIVIOT");
ObjectDelete("Support 1");
ObjectDelete("Support 2");
ObjectDelete("Support 3");
ObjectDelete("Piviot level");
ObjectDelete("Resistance 1");
ObjectDelete("Resistance 2");
ObjectDelete("Resistance 3");
Comment(" ");
//----
return(0);
}
//+------------------------------------------------------------------+
//| Custom indicator iteration function                              |
//+------------------------------------------------------------------+
int start()
{
double rates[1][6],yesterday_close,yesterday_high,yesterday_low;
ArrayCopyRates(rates,Symbol(),PERIOD_D1);
//----
if(DayOfWeek()==1)
 {
  if(TimeDayOfWeek(iTime(Symbol(),PERIOD_D1,1))==5)
    {
     yesterday_close= rates[1][4];
     yesterday_high = rates[1][3];
     yesterday_low=rates[1][2];
    }
  else
    {
     for(int d=5;d>=0;d--)
       {
        if(TimeDayOfWeek(iTime(Symbol(),PERIOD_D1,d))==5)
          {
           yesterday_close= rates[d][4];
           yesterday_high = rates[d][3];
           yesterday_low=rates[d][2];
          }

       }
    }
 }
else
 {
  yesterday_close= rates[1][4];
  yesterday_high = rates[1][3];
  yesterday_low=rates[1][2];
 }
//---- Calculate Pivots
Comment("\nYesterday quotations:\nH ",yesterday_high,"\nL 
",yesterday_low,"\nC ",yesterday_close);
double R=yesterday_high-yesterday_low;//range
double p=(yesterday_high+yesterday_low+yesterday_close)/3;// Standard Pivot
double r3 = p + (R * 1.000);
double r2 = p + (R * 0.618);
double r1 = p + (R * 0.382);
double s1 = p - (R * 0.382);
double s2 = p - (R * 0.618);
double s3 = p - (R * 1.000);
//----
drawLine(r3,"R3",Lime,0);
drawLabel("Resistance 3",r3,Lime);
drawLine(r2,"R2",Green,0);
drawLabel("Resistance 2",r2,Green);
drawLine(r1,"R1",DarkGreen,0);
drawLabel("Resistance 1",r1,DarkGreen);
drawLine(p,"PIVIOT",Blue,1);
drawLabel("Piviot level",p,Blue);
drawLine(s1,"S1",Maroon,0);
drawLabel("Support 1",s1,Maroon);
drawLine(s2,"S2",Crimson,0);
drawLabel("Support 2",s2,Crimson);
drawLine(s3,"S3",Red,0);
drawLabel("Support 3",s3,Red);
//----
return(0);
}
//+------------------------------------------------------------------+
void drawLabel(string name,double lvl,color Color)
{
if(ObjectFind(name)!=0)
 {
  if(Bars<10) return;
  ObjectCreate(name,OBJ_TEXT,0,Time[10],lvl);
  ObjectSetText(name,name,8,"Arial",EMPTY);
  ObjectSet(name,OBJPROP_COLOR,Color);
 }
else
 {
  if(Bars<10) return;
  ObjectMove(name,0,Time[10],lvl);
 }
}
 //----
 void drawLine(double lvl,string name,color Col,int type)
 {
 if(ObjectFind(name)!=0)
  {
   ObjectCreate(name,OBJ_HLINE,0,Time[0],lvl,Time[0],lvl);
   if(type==1)
     ObjectSet(name,OBJPROP_STYLE,STYLE_SOLID);
   else
     ObjectSet(name,OBJPROP_STYLE,STYLE_DOT);
   ObjectSet(name,OBJPROP_COLOR,Col);
   ObjectSet(name,OBJPROP_WIDTH,1);
   }
   else
    {
    ObjectDelete(name);
    ObjectCreate(name,OBJ_HLINE,0,Time[0],lvl,Time[0],lvl);
    if(type==1)
     ObjectSet(name,OBJPROP_STYLE,STYLE_SOLID);
  else
     ObjectSet(name,OBJPROP_STYLE,STYLE_DOT);
  ObjectSet(name,OBJPROP_COLOR,Col);
  ObjectSet(name,OBJPROP_WIDTH,1);
 }
  }
//+--------------------------------------------------------------------+

indicator is fine but not clear what is the problem? have you tried to modify it? if not, then please modify and mention what is the problem — Daniel Kniaz
Hi Daniel Kniaz, the problem is that I don't know how to modify as required. Thanks — user5351312
( The real problem is, the original code has performance-wise & risk-of-blocking-wise a rather poor design ) — user3666197

user3666197 user3666197 · Accepted Answer · 2018-04-18T17:01:07

First:

Forget to have an Alert() call inside an Indicator type of MQL4-code. For details ref. below + MQL4 Documentation on such and similarly forbidden blocking calls.

Next :
The original code was awfully inefficient

_{( see details in documentation on New-MQL4.56789, in 2018/Q2 still runs all ( indeed ALL platform's instances of concurrently operated CustomIndicator + Indicators inside one, single, solo, blocking-vulnerable, SPOF-thread (!!) )}

A sort of efficiency-repaired code that does not "shaking all trees" bottom up per each QUOTE-arrival, that yet performs all the necessary updates and shows the beeping-alarm scheme:

#property indicator_chart_window

double R, r3, r2, r1, p, s1, s2, s3;                                    // SEMI-GLOBALs for easy runPriceCHECKs()

//+------------------------------------------------------------------+
//| Custom indicator iteration function                              |
//+------------------------------------------------------------------+
int start()
{   
    static int  aLastVisitedBAR =  EMPTY;                               // INIT
    if (        aLastVisitedBAR == iBars( _Symbol, PERIOD_D1 ) )        // TEST:
    {                              runPriceCHECKs();                    //        Check Price v/s PIVOT levels
                                   return( 0 );                         //                    but PIVOTs never change during the same day ... so JIT/RET--^
    }
    else        aLastVisitedBAR == iBars( _Symbol, PERIOD_D1 );         // SYNC & RE-CALC:

    double rates[][6], yesterday_close,
                       yesterday_high,
                       yesterday_low;
    ArrayCopyRates( rates,
                    _Symbol,
                    PERIOD_D1
                    );
//----
    if (  DayOfWeek() == 1 )
    {     
          if (  TimeDayOfWeek( iTime( _Symbol, PERIOD_D1, 1 ) ) == 5 )
          {     
                yesterday_close = rates[1][4];
                yesterday_high  = rates[1][3];
                yesterday_low   = rates[1][2];
          }
          else
          {     
                for ( int d = 5; d >= 0; d-- )
                {       
                      if (  TimeDayOfWeek( iTime( _Symbol, PERIOD_D1, d ) ) == 5 )
                      {     
                            yesterday_close = rates[d][4];
                            yesterday_high  = rates[d][3];
                            yesterday_low   = rates[d][2];
                      }
                }
          }
    }
    else
    {     
          yesterday_close = rates[1][4];
          yesterday_high  = rates[1][3];
          yesterday_low   = rates[1][2];
    }
//---- Calculate Pivots
    Comment( "\nYesterday quotations:\nH ",
                yesterday_high,     "\nL ",
                yesterday_low,      "\nC ",
                yesterday_close
                );

    R  =   yesterday_high - yesterday_low;                       // a Day range
    p  = ( yesterday_high + yesterday_low + yesterday_close ) /3;// a Standard Pivot

    r3 = p + ( R * 1.000 ); drawLine( r3, "R3",    clrLime,      0 ); drawLabel( "Resistance 3", r3, clrLime      );
    r2 = p + ( R * 0.618 ); drawLine( r2, "R2",    clrGreen,     0 ); drawLabel( "Resistance 2", r2, clrGreen     );
    r1 = p + ( R * 0.382 ); drawLine( r1, "R1",    clrDarkGreen, 0 ); drawLabel( "Resistance 1", r1, clrDarkGreen );
                            drawLine( p,  "PIVOT", clrBlue,      1 ); drawLabel( "Pivot level",  p,  clrBlue      );
    s1 = p - ( R * 0.382 ); drawLine( s1, "S1",    clrMaroon,    0 ); drawLabel( "Support 1",    s1, clrMaroon    );
    s2 = p - ( R * 0.618 ); drawLine( s2, "S2",    clrCrimson,   0 ); drawLabel( "Support 2",    s2, clrCrimson   );
    s3 = p - ( R * 1.000 ); drawLine( s3, "S3",    clrRed,       0 ); drawLabel( "Support 3",    s3, clrRed       );
//----
    runPriceCHECKs();                                                   //        Check Price v/s PIVOT levels    
//----
    return( 0 );
  }

//+------------------------------------------------------------------+
//|  drawLabel( string name, double lvl, color Color )               |
//+------------------------------------------------------------------+
void drawLabel( string name, double lvl, color Color )
{    
     if (  Bars <  10 ) return;

     if (  ObjectFind( name ) == 0 ) ObjectMove(    name,                0, Time[10], lvl );
     else
     {                               ObjectCreate(  name, OBJ_TEXT,      0, Time[10], lvl );
                                     ObjectSet(     name, OBJPROP_COLOR, Color );
                                     ObjectSetText( name, name,          8, "Arial", EMPTY );
     }
  }
//+------------------------------------------------------------------+
//|  drawLine( double lvl, string name, color Col, int type )        |
//+------------------------------------------------------------------+
void drawLine( double lvl, string name, color Col, int type )
{    
     if (  ObjectFind(   name ) == 0 )
           ObjectDelete( name );

     ObjectCreate(       name, OBJ_HLINE, 0,  Time[0], lvl,
                                              Time[0], lvl );
     ObjectSet(          name, OBJPROP_COLOR, Col );
     ObjectSet(          name, OBJPROP_WIDTH, 1 );
     ObjectSet(          name, OBJPROP_STYLE, (  type == 1 ) ? STYLE_SOLID : STYLE_DOT );
  }
//+------------------------------------------------------------------+
//|  runPriceCHECKs()                                                |
//+------------------------------------------------------------------+
void runPriceCHECKs()
{    
#define DEF_PROXIMITY_TRESHOLD_R3    ( 15 * Point )
#define DEF_PROXIMITY_TRESHOLD_R2    ( 10 * Point )
#define DEF_PROXIMITY_TRESHOLD_R1    (  5 * Point )
#define DEF_PROXIMITY_TRESHOLD_P     (  2 * Point )
#define DEF_PROXIMITY_TRESHOLD_S1    (  5 * Point )
#define DEF_PROXIMITY_TRESHOLD_S2    ( 10 * Point )
#define DEF_PROXIMITY_TRESHOLD_S3    ( 15 * Point )

     if (  MathAbs( r3 - Close ) <= DEF_PROXIMITY_TRESHOLD_R3 )
           ...
           PlaySound( aFileNAME_WAV_R3 ); // The file must be located in terminal_directory\Sounds or its sub-directory. Only WAV files are played.
        // Sleep(     250 );              // 250 [ms] AS A LAST RESORT, BETTER MAKE .WAV CUT-SHORT NOT TO LAST LONGER BY ITSELF
        // PlaySound( NULL );
           return;

     if (  MathAbs( r2 - Close ) <= DEF_PROXIMITY_TRESHOLD_R2 )
           ...
           return;

     if (  MathAbs( r1 - Close ) <= DEF_PROXIMITY_TRESHOLD_R1 )
           ...
           return;

     if (  MathAbs( p  - Close ) <= DEF_PROXIMITY_TRESHOLD_P  )
           ...
           return;

     if (  MathAbs( s1 - Close ) <= DEF_PROXIMITY_TRESHOLD_S1 )
           ...
           return;

     if (  MathAbs( s2 - Close ) <= DEF_PROXIMITY_TRESHOLD_S2 )
           ...
           return;

     if (  MathAbs( s3 - Close ) <= DEF_PROXIMITY_TRESHOLD_S3 )
           ...
           return;

  // nop

  }
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int init()
{   return( 0 );
  }
//+------------------------------------------------------------------+
//| Custom indicator deinitialization function                       |
//+------------------------------------------------------------------+
int deinit()
{   
//----
    ObjectDelete( "S1"           );
    ObjectDelete( "S2"           );
    ObjectDelete( "S3"           );
    ObjectDelete( "R1"           );
    ObjectDelete( "R2"           );
    ObjectDelete( "R3"           );
    ObjectDelete( "PIVOT"        );
    ObjectDelete( "Support 1"    );
    ObjectDelete( "Support 2"    );
    ObjectDelete( "Support 3"    );
    ObjectDelete( "Piviot level" );
    ObjectDelete( "Resistance 1" );
    ObjectDelete( "Resistance 2" );
    ObjectDelete( "Resistance 3" );

    Comment( ":o)" );
//----
    return( 0 );
  }
//+------------------------------------------------------------------+

MQL4 How to alert when a price reaches certain levels?

1 Answers

First:

Next :The original code was awfully inefficient

Next :
The original code was awfully inefficient