//+------------------------------------------------------------------+
//| Demo_iStdDev.mq5 |
//| Copyright 2011, MetaQuotes Software Corp. |
//| https://www.mql5.com |
//+------------------------------------------------------------------+
#property copyright "Copyright 2000-2024, MetaQuotes Ltd."
#property link "https://www.mql5.com"
#property version "1.00"
#property description "The indicator demonstrates how to obtain data"
#property description "of indicator buffers for the iStdDev technical indicator."
#property description "A symbol and timeframe used for calculation of the indicator,"
#property description "are set by the symbol and period parameters."
#property description "The method of creation of the handle is set through the 'type' parameter (function type)."
#property description "All the other parameters are similar to the normal Standard Deviation."
#property indicator_separate_window
#property indicator_buffers 1
#property indicator_plots 1
//--- the iStdDev plot
#property indicator_label1 "iStdDev"
#property indicator_type1 DRAW_LINE
#property indicator_color1 clrMediumSeaGreen
#property indicator_style1 STYLE_SOLID
#property indicator_width1 1
//+------------------------------------------------------------------+
//| Enumeration of the methods of handle creation |
//+------------------------------------------------------------------+
enum Creation
{
Call_iStdDev, // use iStdDev
Call_IndicatorCreate // use IndicatorCreate
};
//--- input parameters
input Creation type=Call_iStdDev; // type of the function
input int ma_period=20; // period of averaging
input int ma_shift=0; // shift
input ENUM_MA_METHOD ma_method=MODE_SMA; // type of smoothing
input ENUM_APPLIED_PRICE applied_price=PRICE_CLOSE; // type of price
input string symbol=" "; // symbol
input ENUM_TIMEFRAMES period=PERIOD_CURRENT; // timeframe
//--- indicator buffer
double iStdDevBuffer[];
//--- variable for storing the handle of the iStdDev indicator
int handle;
//--- variable for storing
string name=symbol;
//--- name of the indicator on a chart
string short_name;
//--- we will keep the number of values in the Standard Deviation indicator
int bars_calculated=0;
//+------------------------------------------------------------------+
//| Custom indicator initialization function |
//+------------------------------------------------------------------+
int OnInit()
{
//--- assignment of array to indicator buffer
SetIndexBuffer(0,iStdDevBuffer,INDICATOR_DATA);
//--- set shift
PlotIndexSetInteger(0,PLOT_SHIFT,ma_shift);
//--- determine the symbol the indicator is drawn for
name=symbol;
//--- delete spaces to the right and to the left
StringTrimRight(name);
StringTrimLeft(name);
//--- if it results in zero length of the 'name' string
if(StringLen(name)==0)
{
//--- take the symbol of the chart the indicator is attached to
name=_Symbol;
}
//--- create handle of the indicator
if(type==Call_iStdDev)
handle=iStdDev(name,period,ma_period,ma_shift,ma_method,applied_price);
else
{
//--- fill the structure with parameters of the indicator
MqlParam pars[4];
//--- period
pars[0].type=TYPE_INT;
pars[0].integer_value=ma_period;
//--- shift
pars[1].type=TYPE_INT;
pars[1].integer_value=ma_shift;
//--- type of smoothing
pars[2].type=TYPE_INT;
pars[2].integer_value=ma_method;
//--- type of price
pars[3].type=TYPE_INT;
pars[3].integer_value=applied_price;
handle=IndicatorCreate(name,period,IND_STDDEV,4,pars);
}
//--- if the handle is not created
if(handle==INVALID_HANDLE)
{
//--- tell about the failure and output the error code
PrintFormat("Failed to create handle of the iStdDev indicator for the symbol %s/%s, error code %d",
name,
EnumToString(period),
GetLastError());
//--- the indicator is stopped early
return(INIT_FAILED);
}
//--- show the symbol/timeframe the Standard Deviation indicator is calculated for
short_name=StringFormat("iStdDev(%s/%s, %d, %d, %s, %s)",name,EnumToString(period),
ma_period,ma_shift,EnumToString(ma_method),EnumToString(applied_price));
IndicatorSetString(INDICATOR_SHORTNAME,short_name);
//--- normal initialization of the indicator
return(INIT_SUCCEEDED);
}
//+------------------------------------------------------------------+
//| 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[])
{
//--- number of values copied from the iStdDev indicator
int values_to_copy;
//--- determine the number of values calculated in the indicator
int calculated=BarsCalculated(handle);
if(calculated<=0)
{
PrintFormat("BarsCalculated() returned %d, error code %d",calculated,GetLastError());
return(0);
}
//--- if it is the first start of calculation of the indicator or if the number of values in the iStdDev indicator changed
//---or if it is necessary to calculated the indicator for two or more bars (it means something has changed in the price history)
if(prev_calculated==0 || calculated!=bars_calculated || rates_total>prev_calculated+1)
{
//--- if the iStdDevBuffer array is greater than the number of values in the iStdDev indicator for symbol/period, then we don't copy everything
//--- otherwise, we copy less than the size of indicator buffers
if(calculated>rates_total) values_to_copy=rates_total;
else values_to_copy=calculated;
}
else
{
//--- it means that it's not the first time of the indicator calculation, and since the last call of OnCalculate()
//--- for calculation not more than one bar is added
values_to_copy=(rates_total-prev_calculated)+1;
}
//--- fill the array with values of the Standard Deviation indicator
//--- if FillArrayFromBuffer returns false, it means the information is nor ready yet, quit operation
if(!FillArrayFromBuffer(iStdDevBuffer,ma_shift,handle,values_to_copy)) return(0);
//--- form the message
string comm=StringFormat("%s ==> Updated value in the indicator %s: %d",
TimeToString(TimeCurrent(),TIME_DATE|TIME_SECONDS),
short_name,
values_to_copy);
//--- display the service message on the chart
Comment(comm);
//--- memorize the number of values in the Standard Deviation indicator
bars_calculated=calculated;
//--- return the prev_calculated value for the next call
return(rates_total);
}
//+------------------------------------------------------------------+
//| Filling indicator buffers from the iStdDev indicator |
//+------------------------------------------------------------------+
bool FillArrayFromBuffer(double &std_buffer[], // indicator buffer of the Standard Deviation line
int std_shift, // shift of the Standard Deviation line
int ind_handle, // handle of the iStdDev indicator
int amount // number of copied values
)
{
//--- reset error code
ResetLastError();
//--- fill a part of the iStdDevBuffer array with values from the indicator buffer that has 0 index
if(CopyBuffer(ind_handle,0,-std_shift,amount,std_buffer)<0)
{
//--- if the copying fails, tell the error code
PrintFormat("Failed to copy data from the iStdDev indicator, error code %d",GetLastError());
//--- quit with zero result - it means that the indicator is considered as not calculated
return(false);
}
//--- everything is fine
return(true);
}
//+------------------------------------------------------------------+
//| Indicator deinitialization function |
//+------------------------------------------------------------------+
void OnDeinit(const int reason)
{
if(handle!=INVALID_HANDLE)
IndicatorRelease(handle);
//--- clear the chart after deleting the indicator
Comment("");
} |