Simple Moving Average

The smallest useful indicator: one series, two parameters.

Source: src/Basics/SimpleMovingAverage.cs · Calculated on: desktop or server

Start here. This example has every part an indicator needs and nothing else.

What it shows

• Register(): how the indicator is listed.
• Two parameters, a number and an enum.
• One series, declared with its attribute.
• The three most used calls: OnOpen, OnClose, OnEnd.

How it works

OnSet asks for the calls and sets the description shown on the chart:

public override void OnSet(bool setDefault, bool themeOverride)
{
    OnOpenCall = CallHandler.HistRT;
    OnCloseCall = CallHandler.HistRT;
    OnEndCall = CallHandler.HistRT;
    Description = $"SMA ({Length})";
}

OnOpen adds a hidden point for every new bar, so the point of index i is always the one of the bar i:

public override void OnOpen(bool isRt)
{
    VAn.AddPointToSeries(Average.BaseSeries, VAn.BarIndex, IsHidden: true);
}

OnClose keeps a running sum of the last Length closed bars, which makes every bar cost the same whatever the length:

public override void OnClose(bool isRt)
{
    int index = VAn.BarIndex;
    sum += GetSource(index);
    if (index >= Length)
        sum -= GetSource(index - Length);
    if (index >= Length - 1)
        SetPoint(index, sum / Length);
}

OnEnd updates the bar still open without touching the sum: the closed bars are already in it.

Things to notice

• OnLoad resets sum. Without it, changing a parameter would start the new calculation from the old total.
• The first Length - 1 points stay hidden: there are not enough bars for a value.

Try

• Add an exponential average as a second value of the enum.
• Add a parameter to shift the average by some bars.