Module map_math 

Web Mercator projection + slippy tile math.

Tiles follow the OSM/Google/Bing convention: tile (0,0) at zoom 0 covers the whole world. At zoom z, the world is a 2^z x 2^z grid of 256x256 tiles.

Structs

LatLng

TileId

Viewport

Constants

MAX_ZOOM

MIN_ZOOM

TILE_SIZE

Functions

fit_bounds

Compute the bounding box of a set of pins, then return a (center, zoom) that fits all pins with a small padding margin. Returns a default map center + MIN_ZOOM if pins is empty.

lat_to_tile_y

Latitude to fractional tile Y at zoom z (Web Mercator). Clamps lat to [-85.0511, 85.0511] — the Mercator cutoff.

latlng_to_viewport_pixel

Project a LatLng to a pixel (x, y) within the viewport. Origin (0,0) is the top-left of the viewport.

lng_to_tile_x

Longitude to fractional tile X at zoom z.

tile_x_to_lng

tile_y_to_lat

viewport_center_tile

Given a viewport, return the (tile_x, tile_y) at the viewport’s center in fractional tile coordinates.

viewport_pixel_to_latlng

Inverse: a viewport pixel -> LatLng.

visible_tiles

Return every tile that intersects the viewport.