/// <summary>
/// Assumes input is valid (e.g. start <= end)
/// </summary>
/// <param name="start">
/// </param>
/// <param name="end">
/// </param>
/// <returns>A linear geometry.</returns>
private LineString ComputeLine(LinearLocation start, LinearLocation end)
{
ICoordinateList coordinates = line.Coordinates;
CoordinateCollection newCoordinates = new CoordinateCollection();
int startSegmentIndex = start.SegmentIndex;
if (start.SegmentFraction > 0.0)
{
startSegmentIndex += 1;
}
int lastSegmentIndex = end.SegmentIndex;
if (end.SegmentFraction == 1.0)
{
lastSegmentIndex += 1;
}
if (lastSegmentIndex >= coordinates.Count)
{
lastSegmentIndex = coordinates.Count - 1;
}
// not needed - LinearLocation values should always be correct
//Assert.isTrue(end.getSegmentFraction() <= 1.0, "invalid segment fraction value");
if (!start.Vertex)
{
newCoordinates.Add(start.GetCoordinate(line));
}
for (int i = startSegmentIndex; i <= lastSegmentIndex; i++)
{
newCoordinates.Add(coordinates[i]);
}
if (!end.Vertex)
{
newCoordinates.Add(end.GetCoordinate(line));
}
// ensure there is at least one coordinate in the result
if (newCoordinates.Count <= 0)
{
newCoordinates.Add(start.GetCoordinate(line));
}
Coordinate[] newCoordinateArray = newCoordinates.ToArray();
// Ensure there is enough coordinates to build a valid line.
// Make a 2-point line with duplicate coordinates, if necessary.
// There will always be at least one coordinate in the coordList.
if (newCoordinateArray.Length <= 1)
{
newCoordinateArray = new Coordinate[] { newCoordinateArray[0],
newCoordinateArray[0] };
}
return(line.Factory.CreateLineString(newCoordinateArray));
}
/// <summary>
/// Assumes input is valid (e.g. start <= end)
/// </summary>
/// <param name="start">
/// </param>
/// <param name="end">
/// </param>
/// <returns> a linear geometry
/// </returns>
private Geometry ComputeLinear(LinearLocation start, LinearLocation end)
{
LinearGeometryBuilder builder = new LinearGeometryBuilder(line.Factory);
builder.FixInvalidLines = true;
if (!start.Vertex)
{
builder.Add(start.GetCoordinate(line));
}
for (LinearIterator it = new LinearIterator(line, start);
it.HasNext(); it.Next())
{
if (end.CompareLocationValues(it.ComponentIndex,
it.VertexIndex, 0.0) < 0)
{
break;
}
Coordinate pt = it.SegmentStart;
builder.Add(pt);
if (it.EndOfLine)
{
builder.EndLine();
}
}
if (!end.Vertex)
{
builder.Add(end.GetCoordinate(line));
}
return(builder.Geometry);
}
/// <summary>
/// Computes the <see cref="Coordinate"/> for the point on the line
/// at the given index.
/// </summary>
/// <param name="index">The index of the desired point.</param>
/// <returns>The Coordinate at the given index.</returns>
/// <remarks>
/// If the index is out of range the first or last point on the
/// line will be returned.
/// </remarks>
public virtual Coordinate ExtractPoint(double index)
{
LinearLocation loc = LengthLocationMap.GetLocation(
linearGeom, index);
return(loc.GetCoordinate(linearGeom));
}
/// <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>
/// <param name="length">the index of the desired point
/// </param>
/// <returns> the Coordinate at the given index
/// </returns>
public Coordinate ExtractPoint(LinearLocation index)
{
return(index.GetCoordinate(linearGeom));
}