@mapgis/vector-tile
v17.2.0
Published
Parses vector tiles
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vector-tile
This library reads Mapbox Vector Tiles and allows access to the layers and features.
Example
var VectorTile = require('@mapbox/vector-tile').VectorTile;
var Protobuf = require('pbf');
var tile = new VectorTile(new Protobuf(data));
// Contains a map of all layers
tile.layers;
var landuse = tile.layers.landuse;
// Amount of features in this layer
landuse.length;
// Returns the first feature
landuse.feature(0);
Vector tiles contained in serialtiles-spec are gzip-encoded, so a complete example of parsing them with the native zlib module would be:
var VectorTile = require('vector-tile').VectorTile;
var Protobuf = require('pbf');
var zlib = require('zlib');
zlib.gunzip(data, function(err, buffer) {
var tile = new VectorTile(new Protobuf(buffer));
});
Depends
- Node.js v0.10.x or v0.8.x
Install
To install:
npm install @mapbox/vector-tile
API Reference
VectorTile
An object that parses vector tile data and makes it readable.
Constructor
- new VectorTile(protobuf[, end]) —
parses the vector tile data contained in the given Protobuf object,
saving resulting layers in the created object as a
layers
property. Optionally accepts end index.
Properties
- layers (Object) — an object containing parsed layers in the form of
{<name>: <layer>, ...}
, where each layer is aVectorTileLayer
object.
VectorTileLayer
An object that contains the data for a single vector tile layer.
Properties
- version (
Number
, default:1
) - name (
String)
— layer name - extent (
Number
, default:4096
) — tile extent size - length (
Number
) — number of features in the layer
Methods
- feature(i) — get a feature (
VectorTileFeature
) by the given index from the layer.
VectorTileFeature
An object that contains the data for a single feature.
Properties
- type (
Number
) — type of the feature (also seeVectorTileFeature.types
) - extent (
Number
) — feature extent size - id (
Number
) — feature identifier, if present - properties (
Object
) — object literal with feature properties
Methods
- loadGeometry() — parses feature geometry and returns an array of
Point arrays (with each point having
x
andy
properties) - bbox() — calculates and returns the bounding box of the feature in the form
[x1, y1, x2, y2]
- toGeoJSON(x, y, z) — returns a GeoJSON representation of the feature. (
x
,y
, andz
refer to the containing tile's index.)