JTS custom CoordinateSequence example

gistfile1.scala

import com.vividsolutions.jts.geom._
import com.vividsolutions.jts.geom.impl.PackedCoordinateSequence
import com.vividsolutions.jts.geom.util.GeometryTransformer

/**
 * A custom CoordSequence based on byte arrays for compactness and speed
 * Just 2 dimensions for now.
 *
 * It's an example of creating a custom CoordinateSequence.
 * NOTE: This is much more memory efficient, but slower because of deserialization cost.
 * To achieve both speed and memory efficiency, the JTS libraries need to be modified to stop
 * relying on Coordinate[]'s and more of the other methods.
 */
class ByteArrayCoordSequence(coords: Array[Coordinate]) extends XYReadOnlyCoordSequence {
  val xArray: Array[Double] = coords.map(_.x)
  val yArray: Array[Double] = coords.map(_.y)

  def getCoordinate(i: Int): Coordinate =
    new Coordinate(xArray(i), yArray(i))

  // A mutable method to set the coordinate instance
  def getCoordinate(i: Int, coord: Coordinate): Unit = {
    coord.x = xArray(i)
    coord.y = yArray(i)
  }

  def getX(i: Int): Double = xArray(i)
  def getY(i: Int): Double = yArray(i)

  def size(): Int = xArray.size

  def expandEnvelope(env: Envelope): Envelope = {
    env.expandToInclude(xArray.min, yArray.min)
    env.expandToInclude(xArray.max, yArray.max)
    env
  }
}

trait XYReadOnlyCoordSequence extends CoordinateSequence {
  def getCoordinate(i: Int): Coordinate
  def getCoordinate(i: Int, coord: Coordinate): Unit
  def getX(i: Int): Double
  def getY(i: Int): Double
  def size(): Int

  def getDimension(): Int = 2

  def getCoordinateCopy(i: Int): Coordinate = getCoordinate(i)

  def getOrdinate(index: Int, ordinateIndex: Int): Double = {
    require(ordinateIndex < 2, "only 2 dimensions!")
    ordinateIndex match {
      case 0 =>  getX(index)
      case 1 =>  getY(index)
    }
  }

  def setOrdinate(index: Int, ordinateIndex: Int, value: Double) = ???

  def toCoordinateArray(): Array[Coordinate] =
    (0 until size()).map(getCoordinate).toArray
}

object GeometryConverter {
  // To easily transform another geometry to use our custom CoordinateSequence, do transformer.transform(geo)
  val transformer = new GeometryTransformer {
    override def transformCoordinates(coordSeq: CoordinateSequence, parent: Geometry): CoordinateSequence = {
      new ByteArrayCoordSequence(coordSeq.toCoordinateArray)
    }
  }
}