LengthToPoint Class Reference

Computes the length along a LineString to the point on the line nearest a given point. More...

Collaboration diagram for LengthToPoint:

Public Member Functions
	LengthToPoint (LineString line, Coordinate inputPt)
double	getLength ()

Static Public Member Functions
static double	lengthAlongSegment (LineSegment seg, Coordinate pt)
static double	length (LineString line, Coordinate inputPt)
	Computes the length along a LineString to the point on the line nearest a given point. More...

Private Member Functions
void	computeLength (LineString line, Coordinate inputPt)
void	updateLength (LineSegment seg, Coordinate inputPt, double segStartLocationDistance)

Private Attributes
double	minDistanceToPoint
double	locationLength

Detailed Description

Computes the length along a LineString to the point on the line nearest a given point.

Constructor & Destructor Documentation

LengthToPoint()

LengthToPoint	(	LineString	line,
		Coordinate	inputPt
	)

References LengthToPoint.computeLength().

Referenced by LengthToPoint.length().

  {
    computeLength(line, inputPt);
  }

Member Function Documentation

computeLength()

void computeLength ( LineString  line, Coordinate  inputPt  )

private

References LengthToPoint.updateLength().

Referenced by LengthToPoint.LengthToPoint().

  {
    minDistanceToPoint = Double.MAX_VALUE;
    double baseLocationDistance = 0.0;
    Coordinate[] pts = line.getCoordinates();
    LineSegment seg = new LineSegment();
    for (int i = 0; i < pts.length - 1; i++) {
      seg.p0 = pts[i];
      seg.p1 = pts[i + 1];
      updateLength(seg, inputPt, baseLocationDistance);
      baseLocationDistance += seg.getLength();

    }
  }

getLength()

double getLength

(

)

References LengthToPoint.locationLength.

Referenced by LengthToPoint.length().

  {
    return locationLength;
  }

length()

static double length ( LineString  line, Coordinate  inputPt  )

static

Computes the length along a LineString to the point on the line nearest a given point.

References LengthToPoint.getLength(), and LengthToPoint.LengthToPoint().

  {
    LengthToPoint lp = new LengthToPoint(line, inputPt);
    return lp.getLength();
  }

lengthAlongSegment()

static double lengthAlongSegment ( LineSegment  seg, Coordinate  pt  )

static

  {
    double projFactor = seg.projectionFactor(pt);
    double len = 0.0;
    if (projFactor <= 0.0)
      len = 0.0;
    else if (projFactor <= 1.0)
      len = projFactor * seg.getLength();
    else
      len = seg.getLength();
    return len;
  }

updateLength()

void updateLength ( LineSegment  seg, Coordinate  inputPt, double  segStartLocationDistance  )

private

Referenced by LengthToPoint.computeLength().

  {
    double dist = seg.distance(inputPt);
    if (dist > minDistanceToPoint) return;
    minDistanceToPoint = dist;
    // found new minimum, so compute location distance of point
    double projFactor = seg.projectionFactor(inputPt);
    if (projFactor <= 0.0)
      locationLength = segStartLocationDistance;
    else if (projFactor <= 1.0)
      locationLength = segStartLocationDistance + projFactor * seg.getLength();
    else
      locationLength = segStartLocationDistance + seg.getLength();
  }

Member Data Documentation

locationLength

double locationLength

private

Referenced by LengthToPoint.getLength().

minDistanceToPoint

double minDistanceToPoint

private