The indicator shows moving average, calculated using the digital filter. In this example the Hann Window is used.

You can use the other filter coefficients, just modify them in OnInit():

   for(int k=0;k<Per;k++)
   {
      w[k]=0.5-0.5*MathCos(2.*pi*(k+1)/(Per+1));
      wsum+=w[k];
   }