wclwksn/vector-tile-js

Parses vector tiles with JavaScript

This repository is a fork of mapbox/vector-tile-js, adding support for CGCS2000.

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 a VectorTileLayer 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 see VectorTileFeature.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 and y 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, and z refer to the containing tile's index.)