Expert Advisor Programming by Andrew R. Young

Custom Indicators and Scripts
We start by using the wizard to create our indicator file. Select New from the File menu or the toolbar
to open the wizard, and create a custom indicator. Fill out the indicator name, and add parameters if
you wish. On the final page, we added three indicator lines of the same color. Here is the result of
the wizard. We've left out the start() function for now:
//+------------------------------------------------------------------+
//| EMA Bollinger.mq4 |
//| Andrew Young |
//| http://www.easyexpertforex.com |
//+------------------------------------------------------------------+
#property copyright "Andrew Young"
#property link "http://www.easyexpertforex.com"
#property indicator_chart_window
#property indicator_buffers 3
#property indicator_color1 DeepSkyBlue
#property indicator_color2 DeepSkyBlue
#property indicator_color3 DeepSkyBlue
//---- buffers
double ExtMapBuffer1[];
double ExtMapBuffer2[];
double ExtMapBuffer3[];
//+------------------------------------------------------------------+
//| Custom indicator initialization function |
//+------------------------------------------------------------------+
int init()
{
//---- indicators
SetIndexStyle(0,DRAW_LINE);
SetIndexBuffer(0,ExtMapBuffer1);
SetIndexStyle(1,DRAW_LINE);
SetIndexBuffer(1,ExtMapBuffer2);
SetIndexStyle(2,DRAW_LINE);
SetIndexBuffer(2,ExtMapBuffer3);
//----
return(0);
}
Let's turn our attention to the elements listed in bold. The #property declarations set the parameters
for our indicator buffers. The indicator_chart_window property draws our indicator in the main
chart window. If we were creating an oscillator, and wanted to draw the indicator in a separate
window, we'd use the indicator_separate_window property instead.
The indicator_buffers property set the number of buffers for our indicator. In this case we are
using three buffers. The indicator_color properties set the color of all three lines to DeepSkyBlue.
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