ATR CountBack

//+------------------------------------------------------------------+
//|                                                ATR CountBack.mq4 |
//|                      Copyright © 2005, MetaQuotes Software Corp. |
//|                                       http://www.metaquotes.net/ |
//+------------------------------------------------------------------+
#property copyright "Altered by cja"
#property link      "http://www.metaquotes.net/"

#property indicator_separate_window
#property indicator_buffers 1
#property indicator_color1 DodgerBlue
//---- input parameters
extern int AtrPeriod=14;
extern int ATR_TF = 60;
extern int CountBack = 0;

//---- buffers
double AtrBuffer[];
double TempBuffer[];

string TimeFrameStr;
extern int Maxbars   = 24;
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int init()
  {
    
    switch(ATR_TF)
   {
      case 1 : TimeFrameStr="Period M1"; break;
      case 5 : TimeFrameStr="Period M5"; break;
      case 15 : TimeFrameStr="Period M15"; break;
      case 30 : TimeFrameStr="Period M30"; break;
      case 60 : TimeFrameStr="Period H1"; break;
      case 240 : TimeFrameStr="Period H4"; break;
      case 1440 : TimeFrameStr="Period D1"; break;
      case 10080 : TimeFrameStr="Period W1"; break;
      case 43200 : TimeFrameStr="Period MN1"; break;
      default : TimeFrameStr=" Current Timeframe "; ATR_TF=0;
   }
  
   string short_name;
//---- 1 additional buffer used for counting.
   IndicatorBuffers(2);
//---- indicator line
   SetIndexStyle(0,DRAW_LINE);
   SetIndexBuffer(0,AtrBuffer);
   SetIndexBuffer(1,TempBuffer);
//---- name for DataWindow and indicator subwindow label
   short_name="ATR( "+AtrPeriod+" )( "+TimeFrameStr+" )( "+CountBack+" )";
   IndicatorShortName(short_name);
   SetIndexLabel(0,short_name);
//----
   SetIndexDrawBegin(0,AtrPeriod);
//----
   return(0);
  }
//+------------------------------------------------------------------+
//| Average True Range                                               |
//+------------------------------------------------------------------+
int start()
  {
   int i,counted_bars=IndicatorCounted();
   
    int limit;
   limit = MathMin(counted_bars,Maxbars);
   if (limit ==0)
      limit = Maxbars;
   
  //----
   if(Bars<=AtrPeriod) return(0);
//---- initial zero
   if(counted_bars<1)
      for(i=1;i<=AtrPeriod;i++) AtrBuffer[Bars-i]=0.0;
//----
   i=Bars-counted_bars-1;
   while(i>=0)
     {
      double high=iHigh(NULL,ATR_TF,i+CountBack);
      double low =iLow(NULL,ATR_TF,i+CountBack);
      if(i==Bars-1) TempBuffer[i]=high-low;
      else
        {
         double prevclose=iClose(NULL,ATR_TF,i+1+CountBack);
         TempBuffer[i]=MathMax(high,prevclose)-MathMin(low,prevclose);
        }
      i--;
     }
//----
   if(counted_bars>0) counted_bars--;
   //int limit=Bars-counted_bars;
   for(i=0; i<limit; i++)
      AtrBuffer[i]=iMAOnArray(TempBuffer,Bars,AtrPeriod,0,MODE_SMA,i);
      
//----
   return(0);
  }
//+------------------------------------------------------------------+