clustering_google_maps

Description:

clustering google maps

Clustering for Flutter Google Maps #

A Flutter package that recreate clustering technique in a Google Maps widget.






Developers Preview Status #
The package recreate the CLUSTERING technique in a Google Maps.
It's work with data recordered in a dababase SQLite. I use sqflite (DB TECHNIQUE)
It's work with a list of LatLngAndGeohash object. (MEMORY TECHNIQUE)
Usage #
To use this package, add clustering_google_maps as a dependency in your pubspec.yaml file.
For a better performance, at every zoom variation on the map, the package performs
a specific query on the SQLite database, but you can force update with updateMap() method.
Getting Started #
DB TECHNIQUE #
To work properly, you must have the data of the points saved in a SQLite database.
Latitude, longitude and the string of geohash. These three parameters are necessary for correct operation.
If you have not saved the GEOHASH, I suggest you install GEOHASH
plugin and save the value of Geohash in the points table of db.
For this solution you must use the db constructor of ClusteringHelper:
ClusteringHelper.forDB(...);
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MEMORY TECHNIQUE #
To work properly you must have a list of LatLngAndGeohash object. LatLngAndGeohash is a simple object with Location
and Geohash property, the last is generated automatically; you need only location of the point.
For this solution you must use the MEMORY constructor of ClusteringHelper:
ClusteringHelper.forMemory(...);
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Aggregation Setup #
Yuo can customize color, range count and zoom limit of aggregation.
See this class: AggregationSetup.
Future Implementations #

To further improve performance I am creating a way to perform sql queries only on the latlng bounding box displayed on the map.
I will insert custom marker with number of points.

Quick Example for both solution #
import 'package:example/app_db.dart';
import 'package:example/fake_point.dart';
import 'package:flutter/material.dart';
import 'package:google_maps_flutter/google_maps_flutter.dart';
import 'package:clustering_google_maps/clustering_google_maps.dart';

class HomeScreen extends StatefulWidget {
final List<LatLngAndGeohash> list;

HomeScreen({Key key, this.list}) : super(key: key);

@override
_HomeScreenState createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
ClusteringHelper clusteringHelper;
final CameraPosition initialCameraPosition =
CameraPosition(target: LatLng(0.000000, 0.000000), zoom: 0.0);

Set<Marker> markers = Set();

void _onMapCreated(GoogleMapController mapController) async {
print("onMapCreated");
clusteringHelper.mapController = mapController;
if (widget.list == null) {
clusteringHelper.database = await AppDatabase.get().getDb();
}
clusteringHelper.updateMap();
}

updateMarkers(Set<Marker> markers) {
setState(() {
this.markers = markers;
});
}

@override
void initState() {
if (widget.list != null) {
initMemoryClustering();
} else {
initDatabaseClustering();
}

super.initState();
}

// For db solution
initDatabaseClustering() {
clusteringHelper = ClusteringHelper.forDB(
dbGeohashColumn: FakePoint.dbGeohash,
dbLatColumn: FakePoint.dbLat,
dbLongColumn: FakePoint.dbLong,
dbTable: FakePoint.tblFakePoints,
updateMarkers: updateMarkers,
aggregationSetup: AggregationSetup(),
);
}

// For memory solution
initMemoryClustering() {
clusteringHelper = ClusteringHelper.forMemory(
list: widget.list,
updateMarkers: updateMarkers,
aggregationSetup: AggregationSetup(markerSize: 150),
);
}

@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Clustering Example"),
),
body: GoogleMap(
onMapCreated: _onMapCreated,
initialCameraPosition: initialCameraPosition,
markers: markers,
onCameraMove: (newPosition) =>
clusteringHelper.onCameraMove(newPosition, forceUpdate: false),
onCameraIdle: clusteringHelper.onMapIdle,
),
floatingActionButton: FloatingActionButton(
child:
widget.list == null ? Icon(Icons.content_cut) : Icon(Icons.update),
onPressed: () {
if (widget.list == null) {
//Test WHERE CLAUSE
clusteringHelper.whereClause = "WHERE ${FakePoint.dbLat} > 42.6";
}
//Force map update
clusteringHelper.updateMap();
},
),
);
}
}
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See the example directory for a complete sample app.