/// <summary>
///
/// </summary>
/// <param name="length"></param>
/// <returns></returns>
private LinearLocation GetLocationForward(double length)
{
if (length <= 0.0)
{
return(new LinearLocation());
}
double totalLength = 0.0;
var it = new LinearIterator(_linearGeom);
while (it.HasNext())
{
/**
* Special handling is required for the situation when the
* length references exactly to a component endpoint.
* In this case, the endpoint location of the current component
* is returned,
* rather than the startpoint location of the next component.
* This produces consistent behaviour with the project method.
*/
if (it.IsEndOfLine)
{
if (totalLength == length)
{
int compIndex = it.ComponentIndex;
int segIndex = it.VertexIndex;
return(new LinearLocation(compIndex, segIndex, 0.0));
}
}
else
{
var p0 = it.SegmentStart;
var p1 = it.SegmentEnd;
double segLen = p1.Distance(p0);
// length falls in this segment
if (totalLength + segLen > length)
{
double frac = (length - totalLength) / segLen;
int compIndex = it.ComponentIndex;
int segIndex = it.VertexIndex;
return(new LinearLocation(compIndex, segIndex, frac));
}
totalLength += segLen;
}
it.Next();
}
// length is longer than line - return end location
return(LinearLocation.GetEndLocation(_linearGeom));
}
/// <summary>
/// Computes the <see cref="LineString" /> for the interval
/// on the line between the given indices.
/// If the <paramref name="endIndex" /> lies before the <paramref name="startIndex" />,
/// the computed geometry is reversed.
/// </summary>
/// <param name="startIndex"></param>
/// <param name="endIndex"></param>
/// <returns></returns>
public IGeometry ExtractLine(double startIndex, double endIndex)
{
LocationIndexedLine lil = new LocationIndexedLine(_linearGeom);
double startIndex2 = ClampIndex(startIndex);
double endIndex2 = ClampIndex(endIndex);
// if extracted line is zero-length, resolve start lower as well to ensure they are equal
bool resolveStartLower = startIndex2 == endIndex2;
LinearLocation startLoc = LocationOf(startIndex2, resolveStartLower);
// LinearLocation endLoc = locationOf(endIndex2, true);
// LinearLocation startLoc = locationOf(startIndex2);
LinearLocation endLoc = LocationOf(endIndex2);
return(ExtractLineByLocation.Extract(_linearGeom, startLoc, endLoc));
}
private LinearLocation IndexOfFromStart(Coordinate inputPt, LinearLocation minIndex)
{
var minDistance = Double.MaxValue;
var minComponentIndex = 0;
var minSegmentIndex = 0;
var minFrac = -1.0;
var seg = new LineSegment();
for (var it = new LinearIterator(_linearGeom);
it.HasNext(); it.Next())
{
if (!it.IsEndOfLine)
{
seg.P0 = it.SegmentStart;
seg.P1 = it.SegmentEnd;
var segDistance = seg.Distance(inputPt);
var segFrac = seg.SegmentFraction(inputPt);
var candidateComponentIndex = it.ComponentIndex;
var candidateSegmentIndex = it.VertexIndex;
if (segDistance < minDistance)
{
// ensure after minLocation, if any
if (minIndex == null ||
minIndex.CompareLocationValues(candidateComponentIndex, candidateSegmentIndex, segFrac) < 0)
{
// otherwise, save this as new minimum
minComponentIndex = candidateComponentIndex;
minSegmentIndex = candidateSegmentIndex;
minFrac = segFrac;
minDistance = segDistance;
}
}
}
}
if (minDistance == Double.MaxValue)
{
// no minimum was found past minLocation, so return it
return(new LinearLocation(minIndex));
}
// otherwise, return computed location
var loc = new LinearLocation(minComponentIndex, minSegmentIndex, minFrac);
return(loc);
}
private LinearLocation ResolveHigher(LinearLocation loc)
{
if (!loc.IsEndpoint(_linearGeom))
{
return(loc);
}
int compIndex = loc.ComponentIndex;
// if last component can't resolve any higher
if (compIndex >= _linearGeom.NumGeometries - 1)
{
return(loc);
}
do
{
compIndex++;
} while (compIndex < _linearGeom.NumGeometries - 1 &&
_linearGeom.GetGeometryN(compIndex).Length == 0);
// resolve to next higher location
return(new LinearLocation(compIndex, 0, 0.0));
}
/// <summary>
///
/// </summary>
/// <param name="subLine"></param>
/// <returns></returns>
public virtual LinearLocation[] IndicesOf(IGeometry subLine)
{
var startPt = ((ILineString)subLine.GetGeometryN(0)).GetCoordinateN(0);
var lastLine = (ILineString)subLine.GetGeometryN(subLine.NumGeometries - 1);
var endPt = lastLine.GetCoordinateN(lastLine.NumPoints - 1);
var locPt = new LocationIndexOfPoint(_linearGeom);
var subLineLoc = new LinearLocation[2];
subLineLoc[0] = locPt.IndexOf(startPt);
// check for case where subline is zero length
if (subLine.Length == 0)
{
subLineLoc[1] = (LinearLocation)subLineLoc[0].Copy();
}
else
{
subLineLoc[1] = locPt.IndexOfAfter(endPt, subLineLoc[0]);
}
return(subLineLoc);
}
/// <summary>
/// Find the nearest <see cref="LinearLocation" /> along the linear <see cref="Geometry" />
/// to a given <see cref="Geometry" /> after the specified minimum <see cref="LinearLocation" />.
/// If possible the location returned will be strictly greater than the <paramref name="minIndex" />.
/// If this is not possible, the value returned will equal <paramref name="minIndex" />.
/// (An example where this is not possible is when <paramref name="minIndex" /> = [end of line] ).
/// </summary>
/// <param name="inputPt">The coordinate to locate.</param>
/// <param name="minIndex">The minimum location for the point location.</param>
/// <returns>The location of the nearest point.</returns>
public LinearLocation IndexOfAfter(Coordinate inputPt, LinearLocation minIndex)
{
if (minIndex == null)
{
return(IndexOf(inputPt));
}
// sanity check for minLocation at or past end of line
var endLoc = LinearLocation.GetEndLocation(_linearGeom);
if (endLoc.CompareTo(minIndex) <= 0)
{
return(endLoc);
}
var closestAfter = IndexOfFromStart(inputPt, minIndex);
/*
* Return the minDistanceLocation found.
* This will not be null, since it was initialized to minLocation
*/
Assert.IsTrue(closestAfter.CompareTo(minIndex) >= 0, "computed location is before specified minimum location");
return(closestAfter);
}
/// <summary>
/// Creates an iterator starting at a <see cref="LinearLocation" /> on a linear <see cref="Geometry" />.
/// </summary>
/// <param name="linearGeom">The linear geometry to iterate over.</param>
/// <param name="start">The location to start at.</param>
/// <exception cref="ArgumentException"> if <paramref name="linearGeom"/> is not <see cref="ILineal"/></exception>
public LinearIterator(IGeometry linearGeom, LinearLocation start) :
this(linearGeom, start.ComponentIndex, SegmentEndVertexIndex(start))
{
}
/// <summary>
/// Computes the <see cref="Coordinate" /> for the point
/// on the line at the given index.
/// If the index is out of range the first or last point on the
/// line will be returned.
/// </summary>
/// <remarks>
/// The Z-ordinate of the computed point will be interpolated from
/// the Z-ordinates of the line segment containing it, if they exist.
/// </remarks>
/// <param name="index">The index of the desired point.</param>
/// <returns>The <see cref="Coordinate" /> at the given index.</returns>
public Coordinate ExtractPoint(double index)
{
LinearLocation loc = LengthLocationMap.GetLocation(_linearGeom, index);
return(loc.GetCoordinate(_linearGeom));
}
/// <summary>
/// Computes the <see cref="LineString" /> for the interval
/// on the line between the given indices.
/// If the start location is after the end location,
/// the computed linear geometry has reverse orientation to the input line.
/// </summary>
/// <param name="startIndex">The index of the start of the interval.</param>
/// <param name="endIndex">The index of the end of the interval.</param>
/// <returns>The linear interval between the indices.</returns>
public Geometry ExtractLine(LinearLocation startIndex, LinearLocation endIndex)
{
return(ExtractLineByLocation.Extract(_linearGeom, startIndex, endIndex));
}
/// <summary>
/// Computes the <see cref="Coordinate"/> for the point
/// on the line at the given index, offset by the given distance.
/// If the index is out of range the first or last point on the
/// line will be returned.<para/>
/// The computed point is offset to the left of the line if the offset distance is
/// positive, to the right if negative.<para/>
/// The Z-ordinate of the computed point will be interpolated from
/// the Z-ordinates of the line segment containing it, if they exist.
/// </summary>
/// <param name="index">The index of the desired point</param>
/// <param name="offsetDistance">The distance the point is offset from the segment
/// (positive is to the left, negative is to the right)</param>
/// <returns>The Coordinate at the given index</returns>
public Coordinate ExtractPoint(LinearLocation index, double offsetDistance)
{
var indexLow = index.ToLowest(_linearGeom);
return(indexLow.GetSegment(_linearGeom).PointAlongOffset(indexLow.SegmentFraction, offsetDistance));
}
/// <summary>
/// Computes the <see cref="Coordinate" />for the point on the line at the given index.
/// If the <paramref name="index" /> is out of range,
/// the first or last point on the line will be returned.
/// </summary>
/// <remarks>
/// The Z-ordinate of the computed point will be interpolated from
/// the Z-ordinates of the line segment containing it, if they exist.
/// </remarks>
/// <param name="index">The index of the desired point.</param>
/// <returns>The <see cref="Coordinate" /> at the given index.</returns>
public Coordinate ExtractPoint(LinearLocation index)
{
return(index.GetCoordinate(_linearGeom));
}
/// <summary>
/// Finds the index for a point on the line which is greater than the given index.
/// If no such index exists, returns <paramref name="minIndex" />.
/// </summary>
/// <remarks>
/// <para>
/// This method can be used to determine all indexes for
/// a point which occurs more than once on a non-simple line.
/// It can also be used to disambiguate cases where the given point lies
/// slightly off the line and is equidistant from two different
/// points on the line.
/// </para>
/// <para>
/// The supplied point does not <i>necessarily</i> have to lie precisely
/// on the line, but if it is far from the line the accuracy and
/// performance of this function is not guaranteed.
/// Use <see cref="Project"/> to compute a guaranteed result for points
/// which may be far from the line.
/// </para>
/// </remarks>
/// <param name="pt">A point on the line</param>
/// <param name="minIndex">The value the returned index must be greater than</param>
/// <returns>The index of the point greater than the given minimum index</returns>
/// <seealso cref="Project(Coordinate)"/>
public LinearLocation IndexOfAfter(Coordinate pt, LinearLocation minIndex)
{
return(LocationIndexOfPoint.IndexOfAfter(_linearGeom, pt, minIndex));
}
public static LinearLocation IndexOfAfter(IGeometry linearGeom, Coordinate inputPt, LinearLocation minIndex)
{
var locater = new LocationIndexOfPoint(linearGeom);
return(locater.IndexOfAfter(inputPt, minIndex));
}
/// <summary>
/// Computes the length for a given <see cref="LinearLocation" />
/// on a linear <see cref="Geometry" />.
/// </summary>
/// <param name="linearGeom">The linear geometry to use.</param>
/// <param name="loc">The <see cref="LinearLocation" /> index of the location.</param>
/// <returns>The length for the <see cref="LinearLocation" />.</returns>
public static double GetLength(Geometry linearGeom, LinearLocation loc)
{
var locater = new LengthLocationMap(linearGeom);
return(locater.GetLength(loc));
}
/// <summary>
/// Tests whether an index is in the valid index range for the line.
/// </summary>
/// <param name="index">The index to test.</param>
/// <returns><c>true</c> if the index is in the valid range.</returns>
public bool IsValidIndex(LinearLocation index)
{
return(index.IsValid(_linearGeom));
}
/// <summary>
/// Computes the subline of a <see cref="ILineString" /> between
/// two <see cref="LinearLocation"/>s on the line.
/// If the start location is after the end location,
/// the computed geometry is reversed.
/// </summary>
/// <param name="line">The line to use as the baseline.</param>
/// <param name="start">The start location.</param>
/// <param name="end">The end location.</param>
/// <returns>The extracted subline.</returns>
public static IGeometry Extract(IGeometry line, LinearLocation start, LinearLocation end)
{
var ls = new ExtractLineByLocation(line);
return(ls.Extract(start, end));
}
///<summary>
/// Computes the <see cref="Coordinate"/> for the point on the line at the given index, offset by the given distance.
///</summary>
/// <remarks>
/// If the index is out of range the first or last point on the line will be returned.
/// The computed point is offset to the left of the line if the offset distance is
/// positive, to the right if negative.
/// The Z-ordinate of the computed point will be interpolated from the Z-ordinates of the line segment containing it, if they exist.
/// </remarks>
/// <param name="index">The index of the desired point</param>
/// <param name="offsetDistance">The distance the point is offset from the segment (positive is to the left, negative is to the right)</param>
/// <returns>The Coordinate at the given index</returns>
public Coordinate ExtractPoint(double index, double offsetDistance)
{
LinearLocation loc = LengthLocationMap.GetLocation(_linearGeom, index);
return(loc.GetSegment(_linearGeom).PointAlongOffset(loc.SegmentFraction, offsetDistance));
}