noruka-google-vector-tiles/lib/vectortiles/VectorTileLayer.js

A vector map tiler for google map

import { VectorTileFeature } from './VectorTileFeature'

function VectorTileLayer (buffer, end) {
    // Public
    this.version = 1;
    this.name = null;
    this.extent = 4096;
    this.length = 0;

    // Private
    this._buffer = buffer;
    this._keys = [];
    this._values = [];
    this._features = [];

    var val, tag;

    end = end || buffer.length;

    while (buffer.pos < end) {
        val = buffer.readVarint();
        tag = val >> 3;

        if (tag === 15) {
            this.version = buffer.readVarint();
        } else if (tag === 1) {
            this.name = buffer.readString();
        } else if (tag === 5) {
            this.extent = buffer.readVarint();
        } else if (tag === 2) {
            this.length++;
            this._features.push(buffer.pos);
            buffer.skip(val);
        } else if (tag === 3) {
            this._keys.push(buffer.readString());
        } else if (tag === 4) {
            this._values.push(this.readFeatureValue());
        } else {
            buffer.skip(val);
        }
    }
}

VectorTileLayer.prototype.readFeatureValue = function () {
    var buffer = this._buffer,
        value = null,
        bytes = buffer.readVarint(),
        end = buffer.pos + bytes,
        val, tag;

    while (buffer.pos < end) {
        val = buffer.readVarint();
        tag = val >> 3;

        if (tag == 1) {
            value = buffer.readString();
        } else if (tag == 2) {
            //throw new Error('read float');
            value = buffer.readFloat();
        } else if (tag == 3) {
            value = buffer.readDouble();
        } else if (tag == 4) {
            value = buffer.readVarint();
        } else if (tag == 5) {
            //throw new Error('read uint');
            value = buffer.readVarint();
        } else if (tag == 6) {
            value = buffer.readSVarint();
        } else if (tag == 7) {
            value = Boolean(buffer.readVarint());
        } else {
            buffer.skip(val);
        }
    }

    return value;
};

// return feature `i` from this layer as a `VectorTileFeature`
VectorTileLayer.prototype.feature = function (i) {
    if (i < 0 || i >= this._features.length) throw new Error('feature index out of bounds');

    this._buffer.pos = this._features[i];
    var end = this._buffer.readVarint() + this._buffer.pos;

    return new VectorTileFeature(this._buffer, end, this.extent, this._keys, this._values);
};

export { VectorTileLayer }