// functions for supporting target selection
private void PrepareLocalTargets()
{
// set local region center as current average gaze position
PointF center = this.fixationDetector.AveragedGazePosition;
// collect local targets within in region, ordered by Y coordinates
var selectedTargets = targets
.Where(t => center.DistanceFrom(t.Position) < settings.LocalSelectionRegionRadius)
.OrderBy(t => t.Position.Y);
// find the closest target and its index
var(minTarget, minIndex, _) = selectedTargets
.Select((t, i) => (t, i, d: center.DistanceFrom(t.Position)))
.Aggregate((min, next) => min.d < next.d ? min : next);
this.localSelectionRegionCenter = center;
this.localTargets = selectedTargets.ToList();
this.localSelectionIndex = minIndex;
this.currentTarget = minTarget;
this.mouseDisplacement = new Point(0, 0);
}