AMA Histogram

ÿþ//+------------------------------------------------------------------+

//|                                                AMA Histogram.mq5 |

//|                              Copyright © 2018, Vladimir Karputov |

//|                                           http://wmua.ru/slesar/ |

//+------------------------------------------------------------------+

#property copyright "Copyright © 2018, Vladimir Karputov"

#property link      "http://wmua.ru/slesar/"

#property version   "1.001"

#property indicator_separate_window

#property indicator_buffers 2 

#property indicator_plots   1 

//--- plot iAMA 

#property indicator_label1  "iAMA" 

#property indicator_type1   DRAW_HISTOGRAM 

#property indicator_color1  clrBlueViolet 

#property indicator_style1  STYLE_SOLID 

#property indicator_width1  1 

//+------------------------------------------------------------------+ 

//| Enumeration of the methods of handle creation                    | 

//+------------------------------------------------------------------+ 

//--- input parameters 

input int                  ama_period=15;             // period of calculation 

input int                  fast_ma_period=2;          // period of fast MA 

input int                  slow_ma_period=30;         // period of slow MA 

input int                  ama_shift=0;               // horizontal shift 

input ENUM_APPLIED_PRICE   applied_price=PRICE_CLOSE; // type of price 

//--- indicator buffers

double         iAMABuffer[];

double         iAMABufferTemp[];

//--- variable for storing the handle of the iAMA 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 Adaptive Moving Average indicator 

int    bars_calculated=0;

//+------------------------------------------------------------------+ 

//| Custom indicator initialization function                         | 

//+------------------------------------------------------------------+ 

int OnInit()

  {

//--- indicator buffers mapping 

   SetIndexBuffer(0,iAMABuffer,INDICATOR_DATA);

   SetIndexBuffer(1,iAMABufferTemp,INDICATOR_CALCULATIONS);

//--- set shift 

   PlotIndexSetInteger(0,PLOT_SHIFT,ama_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 

   handle=iAMA(name,Period(),ama_period,fast_ma_period,slow_ma_period,ama_shift,applied_price);

//--- 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 iAMA 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 Adaptive Moving Average indicator is calculated for 

   short_name=StringFormat("AMA Histogram (%d,%d,%d)",ama_period,fast_ma_period,slow_ma_period);

   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 iAMA 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 iAMA 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 iAMABuffer array is greater than the number of values in the iAMA 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 arrays with values of the Adaptive Moving Average indicator 

//--- if FillArraysFromBuffer returns false, it means the information is nor ready yet, quit operation 

   if(!FillArrayFromBuffer(iAMABufferTemp,ama_shift,handle,values_to_copy))

      return(0);

//--- memorize the number of values in the Adaptive Moving Average indicator 

   bars_calculated=calculated;

   int limit=prev_calculated-1;

   if(limit<0)

      limit=0;

   for(int i=limit;i<rates_total;i++)

      iAMABuffer[i]=close[i]-iAMABufferTemp[i];

//--- return the prev_calculated value for the next call 

   return(rates_total);

  }

//+------------------------------------------------------------------+ 

//| Filling indicator buffer from the iAMA indicator                 | 

//+------------------------------------------------------------------+ 

bool FillArrayFromBuffer(double &ama_buffer[],  // indicator buffer of the AMA line 

                         int a_shift,           // shift of the AMA line 

                         int ind_handle,        // handle of the iAMA indicator 

                         int amount             // number of copied values 

                         )

  {

//--- reset error code 

   ResetLastError();

//--- fill a part of the iAMABuffer array with values from the indicator buffer that has 0 index 

   if(CopyBuffer(ind_handle,0,-a_shift,amount,ama_buffer)<0)

     {

      //--- if the copying fails, tell the error code 

      PrintFormat("Failed to copy data from the iAMA 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);

  }

//+------------------------------------------------------------------+