Trends and History Binding

The point table keeps recent successful samples. Since 0.6, that history can be pushed directly to WinForms or WPF for trend charts, alarm timelines, or recent-sample lists.

Callback Binding

BindHistory pushes the current history immediately, then pushes again whenever a successful sample enters history. Failed polls only update the current snapshot Error; they do not enter history.

points.BindHistory("temperature", this, history =>
{
    HistoryText.Text = string.Join(
        " -> ",
        history.TakeLast(8).Select(sample => $"{sample.Value} {sample.AlarmState}"));
});

Pass any WinForms Control or WPF FrameworkElement. Zeus marshals the callback to that UI thread.

Binding Source

var source = points.AsHistoryBindingSource("temperature", this);
TrendPanel.DataContext = source;

PointHistoryBindingSource exposes:

Property	Meaning
History	Successful samples, oldest to newest
Latest	Latest successful sample
Count / HasSamples	Sample count and availability
LatestValue / LatestUpdatedAt	Latest value and timestamp
LatestAlarmState / IsLatestAlarmed	Alarm state of the latest sample

Chart Controls

Zeus does not depend on a chart library. Convert PointSnapshot to the format your chart needs:

points.BindHistory("temperature", this, history =>
{
    chart.Series[0].Points.Clear();
    foreach (var sample in history)
    {
        if (sample.UpdatedAt is not null && sample.Value is not null)
        {
            chart.Series[0].Points.AddXY(sample.UpdatedAt.Value.LocalDateTime, sample.Value);
        }
    }
});

History Capacity

Default capacity is 128 successful samples per point. Register a custom PointTable to change it:

builder.Services.AddSingleton(sp => new PointTable(sp.GetRequiredService<DeviceRegistry>(), historyCapacity: 32));

Set capacity to 0 to keep no samples; BindHistory still pushes an empty history.

Next: WinForms Adapter or WPF Adapter.