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The DRAW_HISTOGRAM2 style draws a histogram of a specified color — vertical segments using the values of two indicator buffers. The width, color and style of the segments can be specified like for the DRAW_LINE style - using compiler directives or dynamically using the PlotIndexSetInteger() function. Dynamic changes of the plotting properties allows changing the look of the histogram based on the current situation.

The DRAW_HISTOGRAM2 style can be used in a separate subwindow of a chart and in its main window. For empty values nothing is drawn, all the values in the indicator buffers need to be set explicitly. Buffers are not initialized with a zero value.

The number of buffers required for plotting DRAW_HISTOGRAM2 is 2.

An example of the indicator that plots a vertical segment of the specified color and width between the Open and Close prices of each bar. The color, width and style of all histogram columns change randomly each N ticks. During the start of the indicator, in the OnInit() function, the number of the day of week for which the histogram will not be drawn - invisible_day - is set randomly. For this purpose an empty value is set PLOT_EMPTY_VALUE=0:

//--- Set an empty value

An example of DRAW_HISTOGRAM2

Note that initially for plot1 with DRAW_HISTOGRAM2 the properties are set using the compiler directive #property, and then in the OnCalculate() function these three properties are set randomly. The N parameter is set in external parameters of the indicator for the possibility of manual configuration (the Parameters tab in the indicator's Properties window).

//|                                              DRAW_HISTOGRAM2.mq5 |
//|                        Copyright 2011, MetaQuotes Software Corp. |
//|                                     |
#property copyright "Copyright 2011, MetaQuotes Software Corp."
#property link      ""
#property version   "1.00"
#property description "An indicator to demonstrate DRAW_HISTOGRAM2"
#property description "It draws a segment between Open and Close on each bar"
#property description "The color, width and style are changed randomly"
#property description "after every N ticks"
#property indicator_chart_window
#property indicator_buffers 2
#property indicator_plots   1
//--- plot Histogram_2
#property indicator_label1  "Histogram_2"
#property indicator_type1   DRAW_HISTOGRAM2
#property indicator_color1  clrRed
#property indicator_style1  STYLE_SOLID
#property indicator_width1  1
//--- input parameters
input int      N=5;              // The number of ticks to change the histogram
//--- indicator buffers
double         Histogram_2Buffer1[];
double         Histogram_2Buffer2[];
//--- The day of the week for which the indicator is not plotted
int invisible_day;
//--- An array to store colors
color colors[]={clrRed,clrBlue,clrGreen};
//--- An array to store the line styles
//| Custom indicator initialization function                         |
int OnInit()
//--- indicator buffers mapping
//--- Set an empty value
//--- Get a random number from 0 to 5
//| 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
//--- If a critical number of ticks has been accumulated
      //--- Change the line properties
      //--- Reset the counter of ticks to zero
//--- Calculate the indicator values
   int start=0;
//--- To get the day of week by the open price of each bar
   MqlDateTime dt;
//--- If already calculated during the previous starts of OnCalculate
   if(prev_calculated>0) start=prev_calculated-1; // set the beginning of the calculation with the last but one bar
//--- Fill in the indicator buffer with values
   for(int i=start;i<rates_total;i++)
//--- Return the prev_calculated value for the next call of the function
//| Changes the appearance of lines in the indicator                 |
void ChangeLineAppearance()
//--- A string for the formation of information about the line properties
   string comm="";
//--- A block of line color change
   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_index=number%size;
//--- Set the color as the PLOT_LINE_COLOR property
//--- Write the line color
//--- A block for changing the width of the line
//--- Get the width of the remainder of integer division
   int width=number%5;   // The width is set from 0 to 4
//--- Set the line width
//--- Write the line width
//--- A block for changing the style of the line
//--- The divisor is equal to the size of the styles array
//--- Get the index to select a new style as the remainder of integer division
   int style_index=number%size;
//--- Set the line style
//--- Write the line style
//--- Add information about the day that is omitted in calculations
   comm="\r\nNot plotted day - "+EnumToString((ENUM_DAY_OF_WEEK)invisible_day)+comm;
//--- Show the information on the chart using a comment


Updated: 2015.12.03