SignalSeries

Example.cs

        [Example("EndlessSignals")]
        public static PlotModel EndlessSignal()
        {
            var model = new PlotModel { Title = "Endless Signals" };

            var signals = new SignalSeries[3];

            for (int i = 0; i < signals.Length; i++)
            {
                signals[i] = new SignalSeries();
                signals[i].MarkerType = MarkerType.Diamond; // just to show where the datapoint are
                signals[i].PushValue(0, i);
                model.Series.Add(signals[i]);
            }

            System.Threading.Tasks.Task.Run(async () =>
            {
                var rnd = new Random();
                var sw = new System.Diagnostics.Stopwatch();
                sw.Start();

                while (true)
                {
                    await System.Threading.Tasks.Task.Delay(50);

                    lock (model.SyncRoot)
                    {
                        var t = sw.Elapsed.TotalSeconds;

                        for (int i = 0; i < signals.Length; i++)
                        {
                            var v = signals[i].Points.Last().Y;
                            if (rnd.NextDouble() < 0.1)
                                v = 0.5 - (v - i) + i;

                            // Updates the EndX value, and adds more points as necessary
                            signals[i].PushValue(t, v);

                            // or, if we just wanted to inform it of the time, and not any change in value:
                            signals[i].EndX = t;
                        }

                        model.InvalidatePlot(true);
                    }
                }
            });

            return model;
        }

SignalSeries.cs

using OxyPlot;
using OxyPlot.Series;
using System;
using System.Collections.Generic;

namespace ExampleLibrary
{
    // StairStepSeries might make more sense
    public class SignalSeries : LineSeries
    {
        /// <summary>
        /// Gets or sets the x-value to which the signal should be extended.
        /// </summary>
        public double EndX { get; set; }

        public SignalSeries()
        {
            this.EndX = double.NaN;
        }

        protected override void RenderLine(IRenderContext rc, IList<ScreenPoint> pointsToRender)
        {
            bool removeLast = false;

            if (pointsToRender.Count != 0 && !double.IsNaN(this.EndX))
            {
                // assumes left-to-right data and axis, should really check this.XAxis.IsReversed
                var sx = this.XAxis.Transform(EndX);
                var last = pointsToRender[pointsToRender.Count - 1];
                
                if (last.X < sx)
                {
                    pointsToRender.Add(new ScreenPoint(sx, last.Y));
                }
            }

            base.RenderLine(rc, pointsToRender);

            if (removeLast)
            {
                pointsToRender.RemoveAt(pointsToRender.Count - 1);
            }
        }

        protected override void UpdateMaxMin()
        {
            base.UpdateMaxMin();

            this.MaxX = Math.Max(this.MaxX, this.EndX);
        }

        /// <summary>
        /// Pushes a sample to the series.
        /// </summary>
        /// <param name="x"></param>
        /// <param name="y"></param>
        public void PushValue(double x, double y)
        {
            if (Points.Count != 0 && !double.IsNaN(EndX))
            {
                var lastPoint = Points[Points.Count - 1];
                if (lastPoint.Y != y)
                {
                    // if the value has changed, we may need to inject a value for the 'last' value
            
                    // really make any sense, but works for an example)
                    if (EndX > lastPoint.X)
                        Points.Add(new DataPoint(EndX, lastPoint.Y));
                    
                    Points.Add(new DataPoint(x, y));
                }
            }
            else
            {
                Points.Add(new DataPoint(x, y));
            }

            this.EndX = x;
        }
    }
}