Calculate map tiles for given map extent and zoom level. Considering map extent coordinates are in sperical (web) mercator projection.
npm install web-mercator-tiles
var webMercatorTiles = require('web-mercator-tiles');
function: webMercatorTiles(extent,zoom)
parameters:
extent: map extent of window or div in spherical mercator projeection (meters)
{
left: coordinate in meter,
right: coordinate in meter,
bottom: coordinate in meter,
top: coordinate in meter
}
zoom: zoom level as integer
output: array of tiles object, where tile object is
{
X: tile number in x direction
Y: tile number in y direction
Z: tile number for zoom
top: top of tile image position in window as pixel
left: left of tile image position in window as pixel
}
TileExtent, a static funtion to get tile extent in web mercator coordinates
param: {z: zoom leve, x: x tile no, y: y tile no}
var webMercatorTiles = require('web-mercator-tiles'),
mapExtent = {
left:-7929831.7499857,
bottom:5227055.1160079,
right:-7910263.8707475,
top:5236839.0556271
},
zoom = 12;
tiles = webMercatorTiles(mapExtent,zoom);
// tiles are
/*
[ { X: 1237, Y: 1512, Z: 12, top: -192, left: -129 },
{ X: 1237, Y: 1513, Z: 12, top: 64, left: -129 },
{ X: 1238, Y: 1512, Z: 12, top: -192, left: 127 },
{ X: 1238, Y: 1513, Z: 12, top: 64, left: 127 },
{ X: 1239, Y: 1512, Z: 12, top: -192, left: 383 },
{ X: 1239, Y: 1513, Z: 12, top: 64, left: 383 } ]
*/
// Tile Extent
var tile = {z:12, x: 2953, y: 1697}
var extent = webMercatorTiles.TileExtent(tile)
// extent is
/*
{
left: 8844681.416934315,
right: 8854465.356554817,
bottom: 3434162.806796398,
top: 3443946.746416901,
res: 38.21851414258813
}
*/Check map-the-tiles for projections other than spherical mercator, and having spherical mecator as default projection.
Once you run
npm isntall
then for running test
npm run test
to create build
npm run build
This project is licensed under the terms of the MIT license.