draw_filling_v1

//+------------------------------------------------------------------+
//|                                                 DRAW_FILLING.mq5 |
//|                        Copyright 2011, MetaQuotes Software Corp. |
//|                                              http://www.mql5.com |
//+------------------------------------------------------------------+
#property copyright "Copyright 2011, MetaQuotes Software Corp."
#property link      "http://www.mql5.com"
#property version   "1.00"

#property description "An indicator to demonstrate DRAW_FILLING"
#property description "It draws a channel between two MAs in a separate window"
#property description "The fill color is changed randomly"
#property description "after every N ticks"

#property indicator_separate_window
#property indicator_buffers 2
#property indicator_plots   1
//--- plot Intersection
#property indicator_label1  "Intersection"
#property indicator_type1   DRAW_FILLING
#property indicator_color1  clrRed,clrBlue
#property indicator_style1  STYLE_SOLID
#property indicator_width1  1
//--- input parameters
input int      Fast=13;          // The period of a fast MA
input int      Slow=21;          // The period of a slow MA
input int      shift=1;          // A shift of MAs towards the future (positive)
input int      N=5;              // Number of ticks to change 
//--- indicator buffers
double         IntersectionBuffer1[];
double         IntersectionBuffer2[];
int fast_handle;
int slow_handle;
//--- an array to store colors
color colors[]={clrRed,clrBlue,clrGreen,clrAquamarine,clrBlanchedAlmond,clrBrown,clrCoral,clrDarkSlateGray};
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int OnInit()
  {
//--- indicator buffers mapping
   SetIndexBuffer(0,IntersectionBuffer1,INDICATOR_DATA);
   SetIndexBuffer(1,IntersectionBuffer2,INDICATOR_DATA);
//---
   PlotIndexSetInteger(0,PLOT_SHIFT,shift);
//---
   fast_handle=iMA(_Symbol,_Period,Fast,0,MODE_SMA,PRICE_CLOSE);
   slow_handle=iMA(_Symbol,_Period,Slow,0,MODE_SMA,PRICE_CLOSE);
//---
   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[])
  {
   static int ticks=0;
//--- Calculate ticks to change the style, color and width of the line
   ticks++;
//--- If a sufficient number of ticks has been accumulated
   if(ticks>=N)
     {
      //--- change the line properties
      ChangeLineAppearance();
      //--- Reset the counter of ticks to zero
      ticks=0;
     }

//--- Make the first calculation of the indicator, or data has changed and requires a complete recalculation
   if(prev_calculated==0)
     {
      //--- Copy all the values of the indicators to the appropriate buffers
      int copied1=CopyBuffer(fast_handle,0,0,rates_total,IntersectionBuffer1);
      int copied2=CopyBuffer(slow_handle,0,0,rates_total,IntersectionBuffer2);
     }
   else // Fill only those data that are updated
     {
      //--- Get the difference in bars between the current and previous start of OnCalculate()
      int to_copy=rates_total-prev_calculated;
      //--- If there is no difference, we still copy one value - on the zero bar
      if(to_copy==0) to_copy=1;
      //--- copy to_copy values to the very end of indicator buffers
      int copied1=CopyBuffer(fast_handle,0,0,to_copy,IntersectionBuffer1);
      int copied2=CopyBuffer(slow_handle,0,0,to_copy,IntersectionBuffer2);
     }
//--- return value of prev_calculated for next call
   return(rates_total);
  }
//+------------------------------------------------------------------+
//| Change the colors of the channel filling                                    |
//+------------------------------------------------------------------+
void ChangeLineAppearance()
  {
//--- A string for the formation of information about the line properties
   string comm="";
//--- A block for changing the color of the line
   int number=MathRand(); // Get a random number
//--- The divisor is equal to the size of the colors[] array
   int size=ArraySize(colors);

//--- Get the index to select a new color as the remainder of integer division
   int color_index1=number%size;
//--- Set the first color as the PLOT_LINE_COLOR property
   PlotIndexSetInteger(0,PLOT_LINE_COLOR,0,colors[color_index1]);
//--- Write the first color
   comm=comm+"\r\nColor1 "+(string)colors[color_index1];

//--- Get the index to select a new color as the remainder of integer division
   number=MathRand(); // Get a random number
   int color_index2=number%size;
//--- Set the second color as the PLOT_LINE_COLOR property
   PlotIndexSetInteger(0,PLOT_LINE_COLOR,1,colors[color_index2]);
//--- Write the second color
   comm=comm+"\r\nColor2 "+(string)colors[color_index2];
//--- Show the information on the chart using a comment
   Comment(comm);
  }
//+------------------------------------------------------------------+