Terminal slows down when using drawing type ZigZag - page 2

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Conor Mcnamara #:

I find it difficult to understand what you mean in saying "the connecting non horizontal lines"

Is it possible to see an actual chart screenshot of the undesired situation? 

I made this before with the zigzag drawing style:

not sure if that is what you were going for

It doesn't lag when using a specific bar lookback

hmm

run this , move the chart left and right (when and if you can)

#property indicator_buffers 2
#property indicator_plots 1
#property indicator_chart_window
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
double bufferA[],bufferB[];
int total_on_calc_entries=0;
int OnInit()
  {

  total_on_calc_entries=0;
  SetIndexBuffer(0,bufferA,INDICATOR_DATA);
  SetIndexBuffer(1,bufferB,INDICATOR_DATA);
  PlotIndexSetInteger(0,PLOT_DRAW_TYPE,DRAW_ZIGZAG);
  PlotIndexSetInteger(0,PLOT_LINE_COLOR,clrRed);
  PlotIndexSetDouble(0,PLOT_EMPTY_VALUE,0.0);
  ArrayFill(bufferA,0,ArraySize(bufferA),0.0);
  ArrayFill(bufferB,0,ArraySize(bufferB),0.0);
  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 totalcalcs=0;
  total_on_calc_entries++;
  for(int i=prev_calculated;i<rates_total;i++){
  totalcalcs++;
       bufferA[i]=high[i];
       bufferB[i]=high[i];

     } 
  Comment(IntegerToString(totalcalcs)+"\nOnCalc accessed "+IntegerToString(total_on_calc_entries));
//--- return value of prev_calculated for next call
   return(rates_total);
  }
//+------------------------------------------------------------------+
 

Tried now. I experienced only minor lag. But suddenly switching from M30 to D1 made it jitter a bit.

Ultimately I think you're correct here and Metaquotes need to take a look at this.

What Fernando said about the Comment function holds true as well and this can be a big part the perceived lag.
 
Conor Mcnamara #:

Tried now. I experienced only minor lag. But suddenly switching from M30 to D1 made it jitter a bit.

Ultimately I think you're correct here and Metaquotes need to take a look at this.

What Fernando said about the Comment function holds true as well and this can be a big part the perceived lag.

It also is faster if you limit the total initial calculation at first as you suggested

If you have no stickiness though its just my pc
 
There are other issues again if you use DRAW_COLOR_ZIGZAG, and weirdly enough, setting the color buffer on historic bars to EMPTY_VALUE sped it up.
 
Conor Mcnamara #:

Tried now. I experienced only minor lag. But suddenly switching from M30 to D1 made it jitter a bit.

Ultimately I think you're correct here and Metaquotes need to take a look at this.

What Fernando said about the Comment function holds true as well and this can be a big part the perceived lag.

if you change timeframe you have to empty the buffers too i think

 

I experience no lag at all with this optimization:

//+------------------------------------------------------------------+
//| 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 totalcalcs=0;
  total_on_calc_entries++;
  
  int start = (prev_calculated == 0) ? 1 : prev_calculated - 1;

  for(int i=start;i<rates_total;i++){
  totalcalcs++;
       bufferA[i]=high[i];
       bufferB[i]=high[i];

     } 
 // Comment(IntegerToString(totalcalcs)+"\nOnCalc accessed "+IntegerToString(total_on_calc_entries));
//--- return value of prev_calculated for next call
   return(rates_total);
  }
//+------------------------------------------------------------------+


I delete the chart where it lagged and open a new chart, because for some reason the previous processing lingers on it.

But yet, you will find some lag again if you really try to punish it by switching timeframes rapidly. It's not the same case for DRAW_LINE types.

 
Conor Mcnamara #:

I experience no lag at all with this optimization:


I delete the chart where it lagged and open a new chart, because for some reason the previous processing lingers on it.

But yet, you will find some lag again if you really try to punish it by switching timeframes rapidly. It's not the same case for DRAW_LINE types.

hmm its something on my pc then , its still sticky here.

I guess i'll limit the calculation and let the user opt in for more data

Thank you , it is not a bug if this is not lagging for you

 
Lorentzos Roussos #:

Thank you , it is not a bug if this is not lagging for you

It did lag again after a while if I use prev_calculated (reasons unknown), but did not lag after first loading the indicator

however no lag if I force the bar lookback:

int bar_recalculate = 200;

for(int i=rates_total-bar_recalculate-1;i<rates_total;i++){
   //code
}

even though I dislike doing this

 
Conor Mcnamara #:

It did lag again after a while if I use prev_calculated (reasons unknown), but did not lag after first loading the indicator

however no lag if I force the bar lookback:

even though I dislike doing this

hmm thanks for the info.

The users will likely care about past data initially and when they want to test, the rest of the time they care about the live aspect, so that 200 range may be good enough.

But there is a noticeable drop with DRAW_ZIGZAG if metaquotes cares even when it does not have to calculate (was lagging yesterday when market was closed and OnCalc only got accessed once) 

So their render function has some modification that slows it down probably.

 

I have considered about this possible issues some time ago. i think it will look for the past bars until find a non empty value to make the connection. if it does not find it quickly it will search until the first bar in the history.

I guess if you set a DRAW_BEGIN for the plot or reduce the number of bar on the chart in the terminal settings it may work correctly.

Another thing that you can do is replace it by DRAW_LINE and assign the value of each bar between the zigzag points by yourself.

If you are using vertical lines the problem is that to plot will need loop through all bars to find the correct direction of the vertical line because it alternates up or down and it depends on all past values. So the only solution in this case would be reduce number of bars in the terminal settings. This is why may have difference on redering it in M1 and D1 or higher timeframes, because on higher timeframes there less bars.

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