The class for drawing the MFI using the ring buffer - indicator for MetaTrader 5

Description

The CMFIOnRingBuffer class is designed to calculate the technical indicator Money Flow Index (Money Flow Index, MFI) using the algorithm of  the ring buffer. 

Declaration

class CMFIOnRingBuffer : public CArrayRing

Title

#include <IncOnRingBuffer\CMFIOnRingBuffer.mqh>

File of the CMFIOnRingBuffer.mqh class must be placed in IncOnRingBuffer folder that need to be established in MQL5\Include\. Two files with the examples used by the class from this folder are attached to the description. File with the class of the ring buffer and the class of Moving Average also must be in this folder.

Class methods

//--- initialization method:
bool Init(                                             // if error it returns false,
                                                       // if successful - true
   int                 period         = 14,            // the period of the MFI
   ENUM_MA_METHOD      method         = MODE_SMA,      // the method of smoothibg  
   ENUM_APPLIED_PRICE  applied_price  = PRICE_TYPICAL, // price used for calculation
   ENUM_APPLIED_VOLUME applied_volume = VOLUME_TICK,   // volume used for calculation
   int                 size_buffer    = 256,           // the size of the ring buffer
   bool                as_series      = false          // true, if a time series, otherwise - false
   );

//--- the method of calculation based on the time series or indicator buffers:          
int MainOnArray(                  // returns the number of the processed elements  
   const int     rates_total,     // the size of the arrays
   const int     prev_calculated, // processed elements on the previous call
   const double& open[],          // open prices
   const double& high[],          // the maximum prices
   const double& low[],           // the minimum prices
   const double& close[],         // close prices
   const long&   tick_volume[],   // tick volume
   const long&   volume[]);       // stock volume
   );

//--- method of calculation on the basis of the separate series elements of the array           
double MainOnValue(              // returns the MFI value for the set element (bar)
   const int    rates_total,     // the size of the array
   const int    prev_calculated, // processed elements of the array
   const int    begin,           // from where the significant data of the array starts
   const double open,            // price of bar opening
   const double high,            // the maximum price of the bar
   const double low,             // the minimum price of the bar
   const double close,           // price of bar closing
   const long   tick_volume,     // tick volume of the bar
   const long   volume,          // stock volume of the bar
   const int    index            // the element (bar) index
   );

//--- the methods of access to the data:
int                 BarsRequired(); // Returns the necessary number of bars to draw the indicator
string              Name();         // Returns the name of the indicator
int                 Period();       // Returns the period 
string              Method();       // Returns the method in the form of the text line 
ENUM_APPLIED_PRICE  Price();        // Returns the type of the used price
ENUM_APPLIED_VOLUME Volume();       // Returns the type of the used volume
int                 Size();         // Returns the size of the ring buffer

To get the calculated data of the indicator from the ring buffer is possible as from the usual array. For example:

//--- the class with the methods of calculation of the MFI indicator:
#include <IncOnRingBuffer\CMFIOnRingBuffer.mqh>
CMFIOnRingBuffer mfi;

...

//+------------------------------------------------------------------+
//| Custom indicator iteration function                              |
//+------------------------------------------------------------------+
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[])
  {
//--- calculation of the indicator based on time series:
   mfi.MainOnArray(rates_total,prev_calculated,open,high,low,close,tick_volume,volume);

...

//--- use data from the ring buffers "mfi",
//    for example, copy data in the indicator buffer:
   for(int i=start;i<rates_total && !IsStopped();i++)
      MFI_Buffer[i] = mfi[rates_total-1-i]; // indicator line

...

//--- return value of prev_calculated for next call:
   return(rates_total);
  }

Examples

1. The Test_MFI_OnArrayRB.mq5 file calculates the indicator based on the price time series. The MainOnArray() method application is demonstrated
2. The Test_MFI_OnValueRB.mq5 file demonstrates the use of the MainOnValue() method. At first the MFI indicator is calculated and drawn. Then on the basis of this ring buffer of this indicator one more MFI indicator is drawn. 

The result of the work of the Test_MFI_OnArrayRB.mq5 with the size of the ring buffer of 256 elements

The result of the work of the Test_MFI_OnValueRB.mq5 with the size of the ring buffer of 256 elements

When writing code the developments of MetaQuotes Software Corp., Integer and GODZILLA were used.