public class ChartCustomIndicator :
    ChartIndicatorBase

Public Class ChartCustomIndicator
    Inherits ChartIndicatorBase

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Windows.Forms;
using DevExpress.DashboardCommon;
using DevExpress.DashboardCommon.ViewerData;

namespace WinForm {
    public partial class FormDesigner : Form {
        public FormDesigner() {
            try {
                IndicatorFactory.Register<MovingIndicator>("Moving average");
            } catch(Exception e) {
                MessageBox.Show(e.Message);
            }
            InitializeComponent();
            var dashboard = new Dashboard1();
            ChartDashboardItem chartItem = dashboard.Items.First(x => x.ComponentName == "chartDashboardItem1") as ChartDashboardItem;
            MovingIndicator trendLine = new MovingIndicator() {
                Name = "MovingLine1",
                Value = "DataItem1",
                ValueLevel = DevExpress.XtraCharts.ValueLevel.Value,
                Color = Color.Orange,
                LegendText = "Moving Average"
            };
            chartItem.Indicators.Add(trendLine);
            dashboardDesigner.Dashboard = dashboard;
            dashboardDesigner.CreateRibbon();
            dashboardDesigner.CreateCustomItemBars();
        }
    }

    public class MovingIndicator : ChartCustomIndicator {
        protected override Dictionary<AxisPoint, object> Calculate(Dictionary<AxisPoint, decimal?> values) {
            var items = new Dictionary<AxisPoint, object>(values.Count);

            var sum = decimal.Zero;
            var count = 0;
            foreach(KeyValuePair<AxisPoint, decimal?> point in values) {
                if(count == 0) {
                    items.Add(point.Key, null);
                } else {
                    items.Add(point.Key, sum / count);
                }
                sum += point.Value ?? 0;
                count++;
            }

            return items;
        }
    }
}

Imports System
Imports System.Collections.Generic
Imports System.Drawing
Imports System.Linq
Imports System.Windows.Forms
Imports DevExpress.DashboardCommon
Imports DevExpress.DashboardCommon.ViewerData

Namespace WinForm
    Partial Public Class FormDesigner
        Inherits Form

        Public Sub New()
            Try
                IndicatorFactory.Register(Of MovingIndicator)("Moving average")
            Catch e As Exception
                MessageBox.Show(e.Message)
            End Try
            InitializeComponent()
            Dim dashboard = New Dashboard1()
            Dim chartItem As ChartDashboardItem = TryCast(dashboard.Items.First(Function(x) x.ComponentName = "chartDashboardItem1"), ChartDashboardItem)
            Dim trendLine As New MovingIndicator() With {
                .Name = "MovingLine1",
                .Value = "DataItem1",
                .ValueLevel = DevExpress.XtraCharts.ValueLevel.Value,
                .Color = Color.Orange,
                .LegendText = "Moving Average"
            }
            chartItem.Indicators.Add(trendLine)
            dashboardDesigner.Dashboard = dashboard
            dashboardDesigner.CreateRibbon()
            dashboardDesigner.CreateCustomItemBars()
        End Sub
    End Class

    Public Class MovingIndicator
        Inherits ChartCustomIndicator

        Protected Overrides Function Calculate(ByVal values As Dictionary(Of AxisPoint, Decimal?)) As Dictionary(Of AxisPoint, Object)
            Dim items = New Dictionary(Of AxisPoint, Object)(values.Count)

            Dim sum = Decimal.Zero
            Dim count = 0
            For Each point As KeyValuePair(Of AxisPoint, Decimal?) In values
                If count = 0 Then
                    items.Add(point.Key, Nothing)
                Else
                    items.Add(point.Key, sum / count)
                End If
                sum += If(point.Value, 0)
                count += 1
            Next point

            Return items
        End Function
    End Class
End Namespace