protected MapTile findCovering(int zoom,long i,long j){
  while (zoom > 0) {
    zoom--;
    i=i / 2;
    j=j / 2;
    MapTile candidate=findTile(zoom,i,j);
    if ((candidate != null) && (!candidate.loading())) {
      return candidate;
    }
  }
  return null;
}

protected MapTile findCovering ( int zoom , long i , long j ) { while ( zoom > 0 ) { zoom -- ; i = i / 2 ; j = j / 2 ; MapTile candidate = findTile ( zoom , i , j ) ; if ( ( candidate != null ) && ( ! candidate . loading ( ) ) ) { return candidate ; } } return null ; }
find the " nearest " lower - zoom tile that covers a specific tile . this is used to find out what tile we have to show while a new tile is still loading
