protected override void OnRender(DrawingContext DC)
{
DC.DrawRectangle(BorderBrush, null, new Rect(0, 0, ActualWidth, ActualHeight));
Rect bounds = new Rect(
BorderThickness.Left,
BorderThickness.Top,
ActualWidth - (BorderThickness.Right + BorderThickness.Left),
ActualHeight - (BorderThickness.Top + BorderThickness.Bottom));
DC.PushClip(new RectangleGeometry(bounds));
DC.DrawRectangle(Background, null, bounds);
DrawTimeAxis(DC, bounds);
if (Signals.Empty())
{
DC.Pop();
return;
}
Signal stats = SelectedSignal;
Signal stabilize = stats;
if (stabilize == null)
{
stabilize = Signals.First();
}
double sampleRate = Signals.SampleRate;
double f0 = 0.0;
// Remembe the clock for when we analyzed the signal to keep the signals in sync even if new data gets added in the background.
long sync = stabilize.Clock;
lock (stabilize.Lock)
{
int Decimate = 1 << (int)Math.Floor(Math.Log(sampleRate / 22000, 2));
int BlockSize = 8192;
if (stabilize.Count >= BlockSize)
{
double[] data = stabilize.Skip(stabilize.Count - BlockSize).ToArray();
// Estimate the fundamental frequency of the signal.
double phase;
double f = Frequency.Estimate(data, Decimate, out phase);
// Convert phase from (-pi, pi] to (0, 1]
phase = ((phase + Math.PI) / (2 * Math.PI));
// Shift all the signals by the phase in samples to align the signal between frames.
if (f > 1.0)
{
sync -= (int)Math.Round(phase * BlockSize / f);
}
// Compute fundamental frequency in Hz.
f0 = sampleRate * f / BlockSize;
}
}
double mean = 0.0;
double peak = 0.0;
double rms = 0.0;
if (stats != null)
{
lock (stats.Lock)
{
// Compute statistics of the clock signal.
mean = stats.Sum() / stats.Count;
peak = stats.Max(i => Math.Abs(i - mean), 0.0);
rms = Math.Sqrt(stats.Sum(i => (i - mean) * (i - mean)) / stats.Count);
}
}
else
{
foreach (Signal i in signals)
{
lock (i.Lock) peak = Math.Max(peak, i.Max(j => Math.Abs(j), 0.0));
}
}
// Compute the target min/max
double bound = peak;
double gamma = 0.1;
double window = Math.Max(Math.Pow(2.0, Math.Ceiling(Math.Log(bound + 1e-9, 2.0))), 5e-3);
Vmax = Math.Max(TimeFilter(Vmax, window, gamma), Math.Abs(bound + (Vmean - mean)));
Vmean = TimeFilter(Vmean, mean, gamma);
if (Math.Abs(mean) * 1e2 < Vmax)
{
Vmean = 0.0;
}
DrawSignalAxis(DC, bounds);
foreach (Signal i in signals.Except(stabilize).Append(stabilize))
{
lock (i.Lock) DrawSignal(DC, bounds, i, (int)(sync - i.Clock));
}
if (stats != null)
{
DrawStatistics(DC, bounds, stats.Pen.Brush, peak, mean, rms, f0);
}
if (tracePoint.HasValue)
{
DrawTrace(DC, bounds, tracePoint.Value);
}
DC.Pop();
}
/// <summary>
/// Update the signal level of this channel.
/// </summary>
/// <param name="level"></param>
/// <param name="time"></param>
public void SampleSignalLevel(double level, double time)
{
double a = Frequency.DecayRate(time, 0.25);
signalLevel = Math.Max(level, level * a + signalLevel * (1 - a));
}