@galihrivanto/google-vector-tiles/lib/vectortiles/VectorTileFeature.js

A vector map tiler for google map

import { Point } from './Point'

function VectorTileFeature (buffer, end, extent, keys, values) {
    this.properties = {};

    // Public
    this.extent = extent;
    this.type = 0;

    // Private
    this._buffer = buffer;
    this._geometry = -1;

    end = end || buffer.length;

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

        if (tag == 1) {
            this._id = buffer.readVarint();
        } else if (tag == 2) {
            var tagLen = buffer.readVarint(),
                tagEnd = buffer.pos + tagLen;

            while (buffer.pos < tagEnd) {
                var key = keys[buffer.readVarint()];
                var value = values[buffer.readVarint()];
                this.properties[key] = value;
            }
        } else if (tag == 3) {
            this.type = buffer.readVarint();
        } else if (tag == 4) {
            this._geometry = buffer.pos;
            buffer.skip(val);
        } else {
            buffer.skip(val);
        }
    }
}

VectorTileFeature.types = ['Unknown', 'Point', 'LineString', 'Polygon'];

VectorTileFeature.prototype.loadGeometry = function () {
    var buffer = this._buffer;
    buffer.pos = this._geometry;

    var bytes = buffer.readVarint(),
        end = buffer.pos + bytes,
        cmd = 1,
        length = 0,
        x = 0,
        y = 0,
        lines = [],
        line;

    while (buffer.pos < end) {
        if (!length) {
            var cmd_length = buffer.readVarint();
            cmd = cmd_length & 0x7;
            length = cmd_length >> 3;
        }

        length--;

        if (cmd === 1 || cmd === 2) {
            x += buffer.readSVarint();
            y += buffer.readSVarint();

            if (cmd === 1) {
                // moveTo
                if (line) {
                    lines.push(line);
                }
                line = [];
            }

            line.push(new Point(x, y));
        } else if (cmd === 7) {
            // closePolygon
            line.push(line[0].clone());
        } else {
            throw new Error('unknown command ' + cmd);
        }
    }

    if (line) lines.push(line);

    return lines;
};

VectorTileFeature.prototype.bbox = function () {
    var buffer = this._buffer;
    buffer.pos = this._geometry;

    var bytes = buffer.readVarint(),
        end = buffer.pos + bytes,

        cmd = 1,
        length = 0,
        x = 0,
        y = 0,
        x1 = Infinity,
        x2 = -Infinity,
        y1 = Infinity,
        y2 = -Infinity;

    while (buffer.pos < end) {
        if (!length) {
            var cmd_length = buffer.readVarint();
            cmd = cmd_length & 0x7;
            length = cmd_length >> 3;
        }

        length--;

        if (cmd === 1 || cmd === 2) {
            x += buffer.readSVarint();
            y += buffer.readSVarint();
            if (x < x1) x1 = x;
            if (x > x2) x2 = x;
            if (y < y1) y1 = y;
            if (y > y2) y2 = y;
        } else if (cmd !== 7) {
            throw new Error('unknown command ' + cmd);
        }
    }

    return [x1, y1, x2, y2];
};

export { VectorTileFeature }