computeLine method

LineString computeLine(LinearLocation start, LinearLocation end)

Assumes input is valid (e.g. start <= end)

@param start @param end @return a linear geometry

Implementation

LineString computeLine(LinearLocation start, LinearLocation end) {
  List<Coordinate> coordinates = line.getCoordinates();
  CoordinateList newCoordinates = new CoordinateList();

  int startSegmentIndex = start.getSegmentIndex();
  if (start.getSegmentFraction() > 0.0) startSegmentIndex += 1;
  int lastSegmentIndex = end.getSegmentIndex();
  if (end.getSegmentFraction() == 1.0) lastSegmentIndex += 1;
  if (lastSegmentIndex >= coordinates.length)
    lastSegmentIndex = coordinates.length - 1;
  // not needed - LinearLocation values should always be correct
  //Assert.isTrue(end.getSegmentFraction() <= 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._backingList.length <= 0)
    newCoordinates.add(start.getCoordinate(line));

  List<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 = <Coordinate>[
      newCoordinateArray[0],
      newCoordinateArray[0]
    ];
  }
  return line.getFactory().createLineString(newCoordinateArray);
}