tile2location static method

Tuple2<double, double> tile2location(
  1. int zoom,
  2. double x,
  3. double y
)

Convert tile zoom, x, y to latitude, longitude. cf. https://wiki.openstreetmap.org/wiki/Slippy_map_tilenames#ECMAScript_(JavaScript/ActionScript,_etc.)

Implementation

static Tuple2<double, double> tile2location(int zoom, double x, double y) {
  final scale = 1 << zoom;
  final lng = x / scale * 360 - 180;

  var n = pi - 2 * pi * y / scale;
  final lat = 180 / pi * atan(0.5 * (exp(n) - exp(-n)));

  return Tuple2(lat, lng);
}