DocumentationSections
MQL5 ReferenceCustom IndicatorsIndicator Styles in ExamplesDRAW_LINE 

DRAW_LINE

DRAW_LINE draws a line of the specified color by the values of the indicator buffer. The width, style and color of the line can be set using the compiler directives and dynamically using the PlotIndexSetInteger() function. Dynamic changes of the plotting properties allows "to enliven" indicators, so that their appearance changes depending on the current situation.

The number of buffers required for plotting DRAW_LINE is 1.

An example of the indicator that draws a line using Close prices of bars. The line color, width and style change randomly every N=5 ticks.

An example of DRAW_LINE

Note that initially for plot1 with DRAW_LINE 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_LINE.mq5 |
//|                        Copyright 2011, MetaQuotes Software Corp. |
//|                                              https://www.mql5.com |
//+------------------------------------------------------------------+
#property copyright "Copyright 2000-2024, MetaQuotes Ltd."
#property link      "https://www.mql5.com"
#property version   "1.00"
 
#property description "An indicator to demonstrate DRAW_LINE"
#property description "It draws a line of a specified color at Close prices"
#property description "Color, width and style of lines is changed randomly"
#property description "after every N ticks"
 
#property indicator_chart_window
#property indicator_buffers 1
#property indicator_plots   1
//--- Line properties are set using the compiler directives
#property indicator_label1  "Line"      // Name of a plot for the Data Window
#property indicator_type1   DRAW_LINE   // Type of plotting is line
#property indicator_color1  clrRed      // Line color
#property indicator_style1  STYLE_SOLID // Line style
#property indicator_width1  1           // Line Width
//--- input parameter
input int      N=5;         // Number of ticks to change 
//--- An indicator buffer for the plot
double         LineBuffer[];
//--- An array to store colors
color colors[]={clrRed,clrBlue,clrGreen};
//--- An array to store the line styles
ENUM_LINE_STYLE styles[]={STYLE_SOLID,STYLE_DASH,STYLE_DOT,STYLE_DASHDOT,STYLE_DASHDOTDOT};
//+------------------------------------------------------------------+
//| Custom indicator initialization function                         |
//+------------------------------------------------------------------+
int OnInit()
  {
//--- Binding an array and an indicator buffer
   SetIndexBuffer(0,LineBuffer,INDICATOR_DATA);
//--- Initializing the generator of pseudo-random numbers
   MathSrand(GetTickCount());
//---
   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 critical number of ticks has been accumulated
   if(ticks>=N)
     {
      //--- Change the line properties
      ChangeLineAppearance();
      //--- Reset the counter of ticks to zero
      ticks=0;
     }
 
//--- Block for calculating indicator values
   for(int i=0;i<rates_total;i++)
     {
      LineBuffer[i]=close[i];
     }
 
//--- Return the prev_calculated value for the next call of the function
   return(rates_total);
  }
//+------------------------------------------------------------------+
//| Changes the appearance of the drawn line in the indicator        |
//+------------------------------------------------------------------+
void ChangeLineAppearance()
  {
//--- A string for the formation of information about the line properties
   string comm="";
//--- A block for changing the color of the line
//--- Get a random number
   int number=MathRand();
//--- 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
   PlotIndexSetInteger(0,PLOT_LINE_COLOR,colors[color_index]);
//--- Write the line color
   comm=comm+(string)colors[color_index];
 
//--- A block for changing the width of the line
   number=MathRand();
//--- Get the width of the remainder of integer division
   int width=number%5; // The width is set from 0 to 4
//--- Set the color as the PLOT_LINE_WIDTH property
   PlotIndexSetInteger(0,PLOT_LINE_WIDTH,width);
//--- Write the line width
   comm=comm+", Width="+IntegerToString(width);
 
//--- A block for changing the style of the line
   number=MathRand();
//--- The divisor is equal to the size of the styles array
   size=ArraySize(styles);
//--- Get the index to select a new style as the remainder of integer division
   int style_index=number%size;
//--- Set the color as the PLOT_LINE_COLOR property
   PlotIndexSetInteger(0,PLOT_LINE_STYLE,styles[style_index]);
//--- Write the line style
   comm=EnumToString(styles[style_index])+", "+comm;
//--- Show the information on the chart using a comment
   Comment(comm);
  }