Indicator redraw won't work !!

[i.Andy]

Hi all ,

Im a new bit for MT5, and now I face a problem about the indicator redraw ...

I have a moving average and arrow in the chart, first run everything looks just fine（see attach #1）

but after cpuple minutes , the indicator redraw seems go wrong (see attach #2) 

here is my code 

//+------------------------------------------------------------------+
//|                                                    myReg v02.mq5 |
//+------------------------------------------------------------------+
#property indicator_chart_window
#property indicator_buffers 3
#property indicator_plots   3

//--- plot ShortAverage
#property indicator_label1  "ShortAverage"
#property indicator_type1   DRAW_LINE
#property indicator_color1  clrOrange
#property indicator_style1  STYLE_DOT
#property indicator_width1  1

//--- 
#property indicator_label2  "Up Arrows" 
#property indicator_type2   DRAW_ARROW 
#property indicator_color2  clrRed
#property indicator_width2  2

#property indicator_label3  "Down Arrows" 
#property indicator_type3   DRAW_ARROW 
#property indicator_color3  clrGreenYellow
#property indicator_width3  2

//--- input parameters
input int      ShortAvg=5;

//--- indicator buffers
double   ShortAverageBuffer[];
double   ColorUpArrowBuffer[];
double   ColorDownArrowBuffer[];
int      MA_handle;
ushort   UpCode=234;
ushort   DownCode=233;
double   offset=0.0003;
string   short_name;
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int OnInit()
  {
//--- indicator buffers mapping
   SetIndexBuffer(0,ShortAverageBuffer,INDICATOR_DATA);
   SetIndexBuffer(1,ColorUpArrowBuffer,INDICATOR_DATA);
   SetIndexBuffer(2,ColorDownArrowBuffer,INDICATOR_DATA);

   ResetLastError();

   MA_handle=iCustom(NULL,0,"Examples\\Custom Moving Average",
                     ShortAvg,
                     0,
                     MODE_LWMA,
                     PRICE_MEDIAN  // using the close prices 
                     );
   Print("MA_handle = ",MA_handle,"  error = ",GetLastError());

   PlotIndexSetInteger(5,PLOT_ARROW,UpCode);
   PlotIndexSetInteger(5,PLOT_ARROW_SHIFT,0);
   PlotIndexSetDouble(5,PLOT_EMPTY_VALUE,0);

   PlotIndexSetInteger(6,PLOT_ARROW,DownCode);
   PlotIndexSetInteger(6,PLOT_ARROW_SHIFT,0);
   PlotIndexSetDouble(6,PLOT_EMPTY_VALUE,0);

// short_name=StringFormat("iMA(%s/%s, %d, %d, %s, %s)",name,EnumToString(period),ma_period,ma_shift,EnumToString(ma_method),EnumToString(applied_price));
   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[])
  {
   int values_to_copy;
   int calculated=BarsCalculated(MA_handle);
   int bars_calculated=0;
   if(prev_calculated==0 || calculated!=BarsCalculated(MA_handle) || rates_total>prev_calculated+1)
     {
      if(calculated>rates_total) values_to_copy=rates_total;
      else                       values_to_copy=calculated;
     }
   else
     {
      values_to_copy=(rates_total-prev_calculated)+1;
     }

   int copy=CopyBuffer(MA_handle,0,0,rates_total,ShortAverageBuffer);
   Print("copy = ",copy,"    rates_total = ",rates_total);
   if(copy<=0)
     {
      Print("An attempt to get the values if Custom Moving Average has failed");
      return(false);
     }

// ----------------------------

   for(int i=1;i<rates_total;i++)
     {
      ColorDownArrowBuffer[i]=0;
      ColorUpArrowBuffer[i]=0;
      //--- check the condition
      if(ShortAverageBuffer[i+3]<ShortAverageBuffer[i+2] && 
         ShortAverageBuffer[i+2]<ShortAverageBuffer[i+1] && 
         ShortAverageBuffer[i+1]>ShortAverageBuffer[i])
         ColorDownArrowBuffer[i]=high[i]+high[i]*offset;
      else
         ColorDownArrowBuffer[i]=0;

      if(ShortAverageBuffer[i+3]>ShortAverageBuffer[i+2] && 
         ShortAverageBuffer[i+2]>ShortAverageBuffer[i+1] && 
         ShortAverageBuffer[i+1]<ShortAverageBuffer[i])
         ColorUpArrowBuffer[i]=low[i]-low[i]*offset;
      else
         ColorUpArrowBuffer[i]=0;

     }

   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 Moving Average indicator 
   bars_calculated=calculated;
   return(rates_total);
  }
//+------------------------------------------------------------------+

Any help ? 

Thank you in advance ! :D

[kypa]

int rates_zero=(int)MathMax(1,prev_calculated-1);
for(int i=rates_zero; i<rates_total; i++)

You also need an extra variable instead of rates_total for the arrow buffers. Two 'for' functions, =0 to <rates_total for MA and =1 to <rates_total-2 for arrows.

P.S. You also don't need 'offset', you can set the arrow value equal to high/low and offset it in pixels like with Fractals indicator with +-PLOT_ARROW_SHIFT. It''s one of the new things in MT5 which isn't available in MT4.

[i.Andy]

kypa:

You also need an extra variable instead of rates_total for the arrow buffers. Two 'for' functions, =0 to <rates_total for MA and =1 to <rates_total-2 for arrows.

P.S. You also don't need 'offset', you can set the arrow value equal to high/low and offset it in pixels like with Fractals indicator with +-PLOT_ARROW_SHIFT. It''s one of the new things in MT5 which isn't available in MT4.

Thank you for your reply, I'll try it later ! :D

[i.Andy]

kypa:

You also need an extra variable instead of rates_total for the arrow buffers. Two 'for' functions, =0 to <rates_total for MA and =1 to <rates_total-2 for arrows.

Still can't figurt it out , would you please tell me more detail , and any article to learn all the concept  of  "OnCalculate" ?

Many many thanks !!

[William Roeder]

i.Andy: descript all the concept  of  "OnCalculate" ?

See How to do your lookbacks correctly.

@Alain Verleyen It was the wrong link.

[Alain Verleyen]

whroeder1:

See Detailed explanation of iCustom - MQL4 and MetaTrader 4 - MQL4 programming forum

Please stop confuse people. iCustom has nothing to do here,  and it's an mql5 topic. I removed the link.

[kypa]

This link might help:

https://www.mql5.com/en/docs/basis/function/events

You need to recalculate only the last bars' values that change with new ticks. And the last bar is rates_total-1, you can't have buffer[rates_total-1+3] (that's why the MA goes to the sky on your second screenshot).

Look at the values_to_copy calculation, understand those and you'll know what to write for your buffers.

[i.Andy]

Its good to have you guys' help,  Thank you all .

Now I figure out the PLOT_ARROW_SHIFT, and  I study hard every article for coding what I need since last weekend , but  unluckily it still now work . 

@kypa can you tell me more about this ? ( what a dumb am I ... 

kypa:

You also need an extra variable instead of rates_total for the arrow buffers. Two 'for' functions, =0 to <rates_total for MA and =1 to <rates_total-2 for arrows.

Thanks again !!  :D