MQL4 Reference Standard Constants, Enumerations and Structures Indicator Constants Custom Indicator Properties

Custom Indicators Properties

A custom indicator has a lot of settings to provide convenient displaying. These settings are made through the assignment of corresponding indicator properties using functions IndicatorSetDouble(), IndicatorSetInteger() and IndicatorSetString(). Identifiers of indicator properties are listed in the ENUM_CUSTOMIND_PROPERTY enumeration.

ENUM_CUSTOMIND_PROPERTY_INTEGER

ID

Description

Property type

INDICATOR_DIGITS

Accuracy of drawing of indicator values

int

INDICATOR_HEIGHT

Fixed height of the indicator's window (the preprocessor command #property indicator_height)

int

INDICATOR_LEVELS

Number of levels in the indicator window

int

INDICATOR_LEVELCOLOR

Color of the level line

color                      sets color for all levels

INDICATOR_LEVELSTYLE

Style of the level line

ENUM_LINE_STYLE  sets style for all levels

INDICATOR_LEVELWIDTH

Thickness of the level line

int                         sets width for all levels

ENUM_CUSTOMIND_PROPERTY_DOUBLE

ID

Description

Property type

INDICATOR_MINIMUM

Minimum of the indicator window

double

INDICATOR_MAXIMUM

Maximum of the indicator window

double

INDICATOR_LEVELVALUE

Level value

double                    modifier = level number

ENUM_CUSTOMIND_PROPERTY_STRING

ID

Description

Property type

INDICATOR_SHORTNAME

Short indicator name

string

INDICATOR_LEVELTEXT

Level description

string                    modifier = level number

Example:

#property description "Relative Strength Index"
#property strict
#property indicator_separate_window
#property indicator_buffers 3
#property indicator_color1     clrDodgerBlue
//--- input parameters
input int InpRSIPeriod=14; // RSI Period
//--- buffers
double ExtRSIBuffer[];
double ExtPosBuffer[];
double ExtNegBuffer[];
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int OnInit(void)
  {
   string short_name;
//--- 2 additional buffers are used for calculations.
   IndicatorBuffers(3);
   SetIndexBuffer(0,ExtRSIBuffer);
   SetIndexBuffer(1,ExtPosBuffer);
   SetIndexBuffer(2,ExtNegBuffer);
//--- set levels   
   IndicatorSetInteger(INDICATOR_LEVELS,2);
   IndicatorSetDouble(INDICATOR_LEVELVALUE,0,30);
   IndicatorSetDouble(INDICATOR_LEVELVALUE,1,70);
//--- set maximum and minimum for subwindow 
   IndicatorSetDouble(INDICATOR_MINIMUM,0);
   IndicatorSetDouble(INDICATOR_MAXIMUM,100);
//--- indicator line
   SetIndexStyle(0,DRAW_LINE);
   SetIndexBuffer(0,ExtRSIBuffer);
//--- name for DataWindow and indicator subwindow label
   short_name="RSI("+string(InpRSIPeriod)+")";
   IndicatorShortName(short_name);
   SetIndexLabel(0,short_name);
//--- check for input
   if(InpRSIPeriod<2)
     {
      Print("Incorrect value for input variable InpRSIPeriod = ",InpRSIPeriod);
      return(INIT_FAILED);
     }
//---
   SetIndexDrawBegin(0,InpRSIPeriod);
//--- initialization done
   return(INIT_SUCCEEDED);
  }
//+------------------------------------------------------------------+
//| Relative Strength Index                                          |
//+------------------------------------------------------------------+
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[])
  {
   int    i,pos;
   double diff;
//---
   if(Bars<=InpRSIPeriod || InpRSIPeriod<2)
      return(0);
//--- counting from 0 to rates_total
   ArraySetAsSeries(ExtRSIBuffer,false);
   ArraySetAsSeries(ExtPosBuffer,false);
   ArraySetAsSeries(ExtNegBuffer,false);
   ArraySetAsSeries(close,false);
//--- preliminary calculations
   pos=prev_calculated-1;
   if(pos<=InpRSIPeriod)
     {
      //--- first RSIPeriod values of the indicator are not calculated
      ExtRSIBuffer[0]=0.0;
      ExtPosBuffer[0]=0.0;
      ExtNegBuffer[0]=0.0;
      double sump=0.0;
      double sumn=0.0;
      for(i=1; i<=InpRSIPeriod; i++)
        {
         ExtRSIBuffer[i]=0.0;
         ExtPosBuffer[i]=0.0;
         ExtNegBuffer[i]=0.0;
         diff=close[i]-close[i-1];
         if(diff>0)
            sump+=diff;
         else
            sumn-=diff;
        }
      //--- calculate first visible value
      ExtPosBuffer[InpRSIPeriod]=sump/InpRSIPeriod;
      ExtNegBuffer[InpRSIPeriod]=sumn/InpRSIPeriod;
      if(ExtNegBuffer[InpRSIPeriod]!=0.0)
         ExtRSIBuffer[InpRSIPeriod]=100.0-(100.0/(1.0+ExtPosBuffer[InpRSIPeriod]/ExtNegBuffer[InpRSIPeriod]));
      else
        {
         if(ExtPosBuffer[InpRSIPeriod]!=0.0)
            ExtRSIBuffer[InpRSIPeriod]=100.0;
         else
            ExtRSIBuffer[InpRSIPeriod]=50.0;
        }
      //--- prepare the position value for main calculation
      pos=InpRSIPeriod+1;
     }
//--- the main loop of calculations
   for(i=pos; i<rates_total && !IsStopped(); i++)
     {
      diff=close[i]-close[i-1];
      ExtPosBuffer[i]=(ExtPosBuffer[i-1]*(InpRSIPeriod-1)+(diff>0.0?diff:0.0))/InpRSIPeriod;
      ExtNegBuffer[i]=(ExtNegBuffer[i-1]*(InpRSIPeriod-1)+(diff<0.0?-diff:0.0))/InpRSIPeriod;
      if(ExtNegBuffer[i]!=0.0)
         ExtRSIBuffer[i]=100.0-100.0/(1+ExtPosBuffer[i]/ExtNegBuffer[i]);
      else
        {
         if(ExtPosBuffer[i]!=0.0)
            ExtRSIBuffer[i]=100.0;
         else
            ExtRSIBuffer[i]=50.0;
        }
     }
//---
   return(rates_total);
  }