/// <summary>
/// Assumes input is valid
/// (e.g. <paramref name="start" /> minor or equals to <paramref name="end" />).
/// </summary>
/// <param name="start"></param>
/// <param name="end"></param>
/// <returns></returns>
private ILineString ComputeLine(LinearLocation start, LinearLocation end)
{
ICoordinate[] coordinates = line.Coordinates;
CoordinateList newCoordinates = new CoordinateList();
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.Length)
{
lastSegmentIndex = coordinates.Length - 1;
}
// not needed - LinearLocation values should always be correct
// Assert.IsTrue(end.SegmentFraction <= 1.0, "invalid segment fraction value");
if (!start.IsVertex)
{
newCoordinates.Add(start.GetCoordinate(line));
}
for (int i = startSegmentIndex; i <= lastSegmentIndex; i++)
{
newCoordinates.Add(coordinates[i]);
}
if (!end.IsVertex)
{
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.ToCoordinateArray();
/*
* 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. <paramref name="start" /> minor or equals to <paramref name="end" />).
/// </summary>
/// <param name="start"></param>
/// <param name="end"></param>
/// <returns></returns>
private IGeometry ComputeLinear(LinearLocation start, LinearLocation end)
{
LinearGeometryBuilder builder = new LinearGeometryBuilder(line.Factory);
builder.FixInvalidLines = true;
if (!start.IsVertex)
{
builder.Add(start.GetCoordinate(line));
}
LinearIterator it = new LinearIterator(line, start);
foreach (LinearIterator.LinearElement element in it)
{
int compare = end.CompareLocationValues(element.ComponentIndex, element.VertexIndex, 0.0);
if (compare < 0)
{
break;
}
ICoordinate pt = element.SegmentStart;
builder.Add(pt);
if (element.IsEndOfLine)
{
builder.EndLine();
}
}
if (!end.IsVertex)
{
builder.Add(end.GetCoordinate(line));
}
return(builder.GetGeometry());
}
/// <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="index">The index of the desired point.</param>
/// <returns>The <see cref="Coordinate" /> at the given index.</returns>
public virtual ICoordinate 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 <paramref name="index" /> is out of range,
/// the first or last point on the line will be returned.
/// </summary>
/// <param name="index">The index of the desired point.</param>
/// <returns>The <see cref="Coordinate" /> at the given index.</returns>
public virtual ICoordinate ExtractPoint(LinearLocation index)
{
return(index.GetCoordinate(linearGeom));
}