public void addPosition(TimeSpan time, Offset position)
{
_index += 1;
if (_index == _historySize)
{
_index = 0;
}
_samples[_index] = new _PointAtTime(position, time);
}
public VelocityEstimate getVelocityEstimate()
{
List <float> x = new List <float>();
List <float> y = new List <float>();
List <float> w = new List <float>();
List <float> time = new List <float>();
int sampleCount = 0;
int index = _index;
_PointAtTime newestSample = _samples[index];
if (newestSample == null)
{
return(null);
}
_PointAtTime previousSample = newestSample;
_PointAtTime oldestSample = newestSample;
do
{
_PointAtTime sample = _samples[index];
if (sample == null)
{
break;
}
float age = (float)(newestSample.time - sample.time).TotalMilliseconds;
float delta = Mathf.Abs((float)(sample.time - previousSample.time).TotalMilliseconds);
previousSample = sample;
if (age > _horizonMilliseconds ||
delta > _assumePointerMoveStoppedMilliseconds)
{
break;
}
oldestSample = sample;
Offset position = sample.point;
x.Add(position.dx);
y.Add(position.dy);
w.Add(1.0f);
time.Add(-age);
index = (index == 0 ? _historySize : index) - 1;
sampleCount += 1;
} while (sampleCount < _historySize);
if (sampleCount >= _minSampleSize)
{
LeastSquaresSolver xSolver = new LeastSquaresSolver(time, x, w);
PolynomialFit xFit = xSolver.solve(2);
if (xFit != null)
{
LeastSquaresSolver ySolver = new LeastSquaresSolver(time, y, w);
PolynomialFit yFit = ySolver.solve(2);
if (yFit != null)
{
return(new VelocityEstimate(
pixelsPerSecond: new Offset(xFit.coefficients[1] * 1000, yFit.coefficients[1] * 1000),
confidence: xFit.confidence *yFit.confidence,
duration: newestSample.time - oldestSample.time,
offset: newestSample.point - oldestSample.point
));
}
}
}
return(new VelocityEstimate(
pixelsPerSecond: Offset.zero,
confidence: 1.0f,
duration: newestSample.time - oldestSample.time,
offset: newestSample.point - oldestSample.point
));
}