module HSlippyMap (
Tile,
tileFromLatLong,
tileFromXY
) where
type Lat = Float
type Long = Float
type X = Integer
type Y = Integer
type ZLevel = Integer
data Tile = Tile {
lat :: Lat,
long :: Long,
x :: X,
y :: Y,
z :: ZLevel }
instance Show Tile where
show (Tile lat long x y z) = "http://tile.openstreetmap.org/" ++ show z ++ "/" ++ show x ++ "/" ++ show y ++ ".png"
tileFromLatLong :: Lat -> Long -> ZLevel -> Tile
tileFromLatLong lat lon z = Tile lat lon x y z
where
x = long2tilex lon z
y = lat2tiley lat z
tileFromXY :: X -> Y -> ZLevel -> Tile
tileFromXY x y z = Tile lat lon x y z
where
lat = tilex2long x z
lon = tiley2lat y z
long2tilex lon z = floor((lon + 180) / 360 * (2** fromInteger(z)::Long))
lat2tiley lat z = floor((1.0 log( tan(lat * pi/180.0) + 1.0 / cos(lat * pi/180.0)) / pi) / 2.0 * (2 ** fromInteger(z)::Long))
tilex2long x z = (fromInteger(x)::Long) / (2.0 ** fromInteger(z)::Long) * 360.0 180
tiley2lat y z = 180.0 / pi * atan(0.5 * (exp(n) exp(n)))
where
n = pi 2.0 * pi * (fromInteger(y)::Long) / (2.0 ** fromInteger(z)::Long)