//+------------------------------------------------------------------+
//|         Oscillator of MA                                         |
//+------------------------------------------------------------------+
#property copyright   "2014, Postolache Vitalie"
#property link        "http://www.mql4.com"
#property description "Moving Averages Oscillator"
#property strict
//----
#property  indicator_separate_window
#property  indicator_buffers 1
#property  indicator_color1  clrRed
#property  indicator_width1  2
#property  indicator_level1 0.0
#property  indicator_levelcolor clrSilver
//----
input string pair="NULL";                    //Trading symbol
input ENUM_TIMEFRAMES tf=0;                  //Timeframe
input int period1=13;                        //1st лю period
input int period2=24;                        //2-nd MA period
input int shift=0;                           //2nd MA shift (bars)
input ENUM_MA_METHOD mode=MODE_SMA;          //Averaging method
input ENUM_APPLIED_PRICE price=PRICE_CLOSE;  //Applied price
//----
double    ma[];              
//----
int period=0;
string par,label,name;
//+------------------------------------------------------------------+
//|     Indicator init function                                      |
//+------------------------------------------------------------------+
int OnInit(void)
  {
   if(pair=="NULL") par=Symbol();
   period = MathMax(period1,period2);
   label=StringConcatenate(MQLInfoString(MQL_PROGRAM_NAME)," ,",par);
   name=StringConcatenate(MQLInfoString(MQL_PROGRAM_NAME)," ,",par,", MA",period1," on MA", period2,", shift ",shift,": ");
//----
   SetIndexStyle(0,DRAW_LINE);
   SetIndexBuffer(0,ma);
   SetIndexDrawBegin(0,period+shift);
//----
   IndicatorShortName(name);
   SetIndexLabel(0,label);
   IndicatorDigits(_Digits);
//----
   return(INIT_SUCCEEDED);
  }
//+------------------------------------------------------------------+
//|   Main indicator block starts here                               |
//+------------------------------------------------------------------+
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,limit;
//----if not enough bars, exitting
      if(rates_total-1<=(period+shift))
      return(0);
//----get number of bars to count
   if(prev_calculated>1)
      limit=rates_total-1-prev_calculated;         //if some bars counted already, excluding them
   else
   {
      limit=rates_total-1-period-shift;                         //else - counting all bars
      //zero all indicator buffers
      for(i=0; i<=rates_total-1; i++)
        {
         ma[i]=0.0;                               
        }
   }
   
   for(i=0; i<=limit; i++)
    { 
     double   ma0=iMA(par,tf,period1,0,mode,price,i);       //1st MA calculation
     double   ma1=iMA(par,tf,period2,0,mode,price,i+shift); //2-nd MA calculation
     
      ma[i] = ma0-ma1; //indicator value calculation
    }
   return(rates_total);
  }