/// <summary>
/// Finds the nearest point on the specified polyline.
/// </summary>
/// <param name="point">The point.</param>
/// <param name="points">The points.</param>
/// <returns>The nearest point.</returns>
public static ScreenPoint FindNearestPointOnPolyline(ScreenPoint point, IList <ScreenPoint> points)
{
double minimumDistance = double.MaxValue;
var nearestPoint = default(ScreenPoint);
for (int i = 0; i + 1 < points.Count; i++)
{
var p1 = points[i];
var p2 = points[i + 1];
if (ScreenPoint.IsUndefined(p1) || ScreenPoint.IsUndefined(p2))
{
continue;
}
// Find the nearest point on the line segment.
var nearestPointOnSegment = FindPointOnLine(point, p1, p2);
if (ScreenPoint.IsUndefined(nearestPointOnSegment))
{
continue;
}
double l2 = (point - nearestPointOnSegment).LengthSquared;
if (l2 < minimumDistance)
{
nearestPoint = nearestPointOnSegment;
minimumDistance = l2;
}
}
return(nearestPoint);
}
/// <summary>
/// Gets the point on the curve that is nearest the specified point.
/// </summary>
/// <param name="points">
/// The point list.
/// </param>
/// <param name="point">
/// The point.
/// </param>
/// <returns>
/// A tracker hit result if a point was found.
/// </returns>
protected TrackerHitResult GetNearestInterpolatedPointInternal(IList <IDataPoint> points, ScreenPoint point)
{
if (points == null)
{
return(null);
}
var spn = default(ScreenPoint);
var dpn = default(DataPoint);
double index = -1;
double minimumDistance = double.MaxValue;
for (int i = 0; i + 1 < points.Count; i++)
{
var p1 = points[i];
var p2 = points[i + 1];
if (!this.IsValidPoint(p1, this.XAxis, this.YAxis) || !this.IsValidPoint(p2, this.XAxis, this.YAxis))
{
continue;
}
var sp1 = this.Transform(p1);
var sp2 = this.Transform(p2);
// Find the nearest point on the line segment.
var spl = ScreenPointHelper.FindPointOnLine(point, sp1, sp2);
if (ScreenPoint.IsUndefined(spl))
{
// P1 && P2 coincident
continue;
}
double l2 = (point - spl).LengthSquared;
if (l2 < minimumDistance)
{
double u = (spl - sp1).Length / (sp2 - sp1).Length;
dpn = new DataPoint(p1.X + (u * (p2.X - p1.X)), p1.Y + (u * (p2.Y - p1.Y)));
spn = spl;
minimumDistance = l2;
index = i + u;
}
}
if (minimumDistance < double.MaxValue)
{
object item = this.GetItem((int)index);
return(new TrackerHitResult(this, dpn, spn, item)
{
Index = index
});
}
return(null);
}
