mql-for-begginers/Indicators/Examples/BB.mq5
2025-07-22 18:30:17 +03:00

141 lines
5.5 KiB
MQL5

//+------------------------------------------------------------------+
//| BB.mq5 |
//| Copyright 2000-2025, MetaQuotes Ltd. |
//| https://www.mql5.com |
//+------------------------------------------------------------------+
#property copyright "Copyright 2000-2025, MetaQuotes Ltd."
#property link "https://www.mql5.com"
#property description "Bollinger Bands"
#include <MovingAverages.mqh>
//---
#property indicator_chart_window
#property indicator_buffers 4
#property indicator_plots 3
#property indicator_type1 DRAW_LINE
#property indicator_color1 clrLightSeaGreen
#property indicator_type2 DRAW_LINE
#property indicator_color2 clrLightSeaGreen
#property indicator_type3 DRAW_LINE
#property indicator_color3 clrLightSeaGreen
#property indicator_label1 "Bands middle"
#property indicator_label2 "Bands upper"
#property indicator_label3 "Bands lower"
//--- input parametrs
input int InpBandsPeriod=20; // Period
input int InpBandsShift=0; // Shift
input double InpBandsDeviations=2.0; // Deviation
//--- global variables
int ExtBandsPeriod,ExtBandsShift;
double ExtBandsDeviations;
int ExtPlotBegin=0;
//--- indicator buffer
double ExtMLBuffer[];
double ExtTLBuffer[];
double ExtBLBuffer[];
double ExtStdDevBuffer[];
//+------------------------------------------------------------------+
//| Custom indicator initialization function |
//+------------------------------------------------------------------+
void OnInit()
{
//--- check for input values
if(InpBandsPeriod<2)
{
ExtBandsPeriod=20;
PrintFormat("Incorrect value for input variable InpBandsPeriod=%d. Indicator will use value=%d for calculations.",InpBandsPeriod,ExtBandsPeriod);
}
else
ExtBandsPeriod=InpBandsPeriod;
if(InpBandsShift<0)
{
ExtBandsShift=0;
PrintFormat("Incorrect value for input variable InpBandsShift=%d. Indicator will use value=%d for calculations.",InpBandsShift,ExtBandsShift);
}
else
ExtBandsShift=InpBandsShift;
if(InpBandsDeviations==0.0)
{
ExtBandsDeviations=2.0;
PrintFormat("Incorrect value for input variable InpBandsDeviations=%f. Indicator will use value=%f for calculations.",InpBandsDeviations,ExtBandsDeviations);
}
else
ExtBandsDeviations=InpBandsDeviations;
//--- define buffers
SetIndexBuffer(0,ExtMLBuffer);
SetIndexBuffer(1,ExtTLBuffer);
SetIndexBuffer(2,ExtBLBuffer);
SetIndexBuffer(3,ExtStdDevBuffer,INDICATOR_CALCULATIONS);
//--- set index labels
PlotIndexSetString(0,PLOT_LABEL,"Bands("+string(ExtBandsPeriod)+") Middle");
PlotIndexSetString(1,PLOT_LABEL,"Bands("+string(ExtBandsPeriod)+") Upper");
PlotIndexSetString(2,PLOT_LABEL,"Bands("+string(ExtBandsPeriod)+") Lower");
//--- indicator name
IndicatorSetString(INDICATOR_SHORTNAME,"Bollinger Bands");
//--- indexes draw begin settings
ExtPlotBegin=ExtBandsPeriod-1;
PlotIndexSetInteger(0,PLOT_DRAW_BEGIN,ExtBandsPeriod);
PlotIndexSetInteger(1,PLOT_DRAW_BEGIN,ExtBandsPeriod);
PlotIndexSetInteger(2,PLOT_DRAW_BEGIN,ExtBandsPeriod);
//--- indexes shift settings
PlotIndexSetInteger(0,PLOT_SHIFT,ExtBandsShift);
PlotIndexSetInteger(1,PLOT_SHIFT,ExtBandsShift);
PlotIndexSetInteger(2,PLOT_SHIFT,ExtBandsShift);
//--- number of digits of indicator value
IndicatorSetInteger(INDICATOR_DIGITS,_Digits+1);
}
//+------------------------------------------------------------------+
//| Bollinger Bands |
//+------------------------------------------------------------------+
int OnCalculate(const int rates_total,
const int prev_calculated,
const int begin,
const double &price[])
{
if(rates_total<ExtPlotBegin)
return(0);
//--- indexes draw begin settings, when we've recieved previous begin
if(ExtPlotBegin!=ExtBandsPeriod+begin)
{
ExtPlotBegin=ExtBandsPeriod+begin;
PlotIndexSetInteger(0,PLOT_DRAW_BEGIN,ExtPlotBegin);
PlotIndexSetInteger(1,PLOT_DRAW_BEGIN,ExtPlotBegin);
PlotIndexSetInteger(2,PLOT_DRAW_BEGIN,ExtPlotBegin);
}
//--- starting calculation
int pos;
if(prev_calculated>1)
pos=prev_calculated-1;
else
pos=0;
//--- main cycle
for(int i=pos; i<rates_total && !IsStopped(); i++)
{
//--- middle line
ExtMLBuffer[i]=SimpleMA(i,ExtBandsPeriod,price);
//--- calculate and write down StdDev
ExtStdDevBuffer[i]=StdDev_Func(i,price,ExtMLBuffer,ExtBandsPeriod);
//--- upper line
ExtTLBuffer[i]=ExtMLBuffer[i]+ExtBandsDeviations*ExtStdDevBuffer[i];
//--- lower line
ExtBLBuffer[i]=ExtMLBuffer[i]-ExtBandsDeviations*ExtStdDevBuffer[i];
}
//--- OnCalculate done. Return new prev_calculated.
return(rates_total);
}
//+------------------------------------------------------------------+
//| Calculate Standard Deviation |
//+------------------------------------------------------------------+
double StdDev_Func(const int position,const double &price[],const double &ma_price[],const int period)
{
double std_dev=0.0;
//--- calcualte StdDev
if(position>=period)
{
for(int i=0; i<period; i++)
std_dev+=MathPow(price[position-i]-ma_price[position],2.0);
std_dev=MathSqrt(std_dev/period);
}
//--- return calculated value
return(std_dev);
}
//+------------------------------------------------------------------+