google-s2 improve

ImproveS2.scala

import com.google.common.geometry.{MutableInteger, S2CellId}

/**
  * Created by fuyun on 2017/7/25.
  */
object ImproveS2 {
  val level = 17
  // at level 17
  def cellIj(cell: S2CellId): (Int, Int) = {
    val i = new MutableInteger(0)
    val j = new MutableInteger(0)
    val face = cell.toFaceIJOrientation(i, j, null)
    val shift = 30 - level
    (i.intValue() >> shift, (j.intValue() >> shift) + ((face - 1) << level))
  }
  def fromIj(i: Int, j: Int): S2CellId = {
    val shift = 30 - level
    val face = (j >> level) + 1
    S2CellId.fromFaceIJ(face, i << shift, (j << shift) << 1 >> 1).parent(level)
  }

  def id2QuadKey(cellId: S2CellId): String = {
    val buf = new Array[Char](cellId.level() + 2)
    buf(0) = (cellId.face() + '0').toChar
    buf(1) = '/'
    val mask = 0x03
    val id = cellId.id()
    for (i <- 1 to cellId.level()) {
      buf(i + 1) = (((id >>> (64 - (i * 2 + 3))) & mask) + '0').toChar
    }
    new String(buf)
  }
}