smap_flutter 1.1.0

sMap for Flutter: maps from the sMap service in Flutter apps, with styles, labels in any language, clustered points, lines, areas and 3D buildings.

sMap for Flutter: smap_flutter

Maps from the sMap service for Flutter apps on Android and iOS.

• Five colour schemes: light, white, grayscale, dark, black
• Labels in any language (BCP-47 tags such as en, fr, zh-Hans); the device language by default
• Switching scheme or language keeps every layer you added
• Points at any scale: clustered (tap a cluster to zoom in), circles or your own icons, labels
• Lines (colour, width, dashes) and areas (flat or extruded in 3D)
• 3D buildings
• Draw order, visibility, replacing data, fitting the camera to a layer, tap handlers
• Reads from the nearest service node and moves to the next one when a node fails; keeps working while the service address is down (kept node list, optional seed nodes)
• Short-lived tokens refreshed automatically, or a map key that ships inside the app
• Standard style layers and sources (Style Specification v8) passed through as they are, placed in named basemap slots
• The basemap shown, hidden and recoloured by class (water, parks, roads by level, labels, …), and saved custom styles
• Files of other tools read on the device: KML, KMZ, GPX, encoded polylines, WKT, WKB, CSV, TopoJSON, GeoJSON; any layer written back as GeoJSON or KML
• External layers: raster XYZ, TileJSON, OGC WMS and WMTS, vector tiles and PMTiles, ArcGIS REST services
• One layer description shared with the other sMap SDKs: a map built on the web opens the same in the app

The map's attribution button stays visible: the map data licence requires it. Every map shows a small sMap badge in its bottom-right corner, just left of the attribution button.

Installation

From pub.dev:

dependencies:
  smap_flutter: ^1.1.0

Or straight from the repository:

dependencies:
  smap_flutter:
    git:
      url: https://github.com/Goodneo-Solutions/smap-sdk
      path: flutter
      ref: 1.1.0

Requirements: Flutter 3.41 or later, Android minSdk 24 (the Flutter default) with the INTERNET permission, iOS 15 or later.

A minimal map

import 'package:smap_flutter/smap_flutter.dart';

SMap(
  options: SMapOptions(
    getToken: () => myServer.mapToken(),   // see "Tokens"
    style: SMapStyle.light,
    center: const LatLng(43.6532, -79.3832),
    zoom: 11,
  ),
  onReady: (map) async {
    await map.addPoints(
      'stores',
      [const SMapPoint(43.65, -79.38, properties: {'name': 'Queen St'})],
      const SMapPointOptions(cluster: true, label: 'name'),
    );
    map.onTap('stores', (properties, position) => print(properties['name']));
  },
)

Layers may also be added before the map is ready (in onCreated); they are drawn as soon as it is.

Tokens

The service uses short-lived map tokens issued by your server. Give the map either:

• token: a token you already have, or
• getToken: a Future<String> Function() that fetches one. It is called at start when no token is given, and again two minutes before each token expires (a failed call is retried after 30 seconds).

A new token reloads the style with it; your layers are put back automatically. Never ship the secret that signs tokens inside an app: issue tokens from your server.

Controller

Call	What it does
ready	Future that completes once the first style has loaded
setStyle(style) / setLanguage(tag)	Switch scheme (SMapStyle, its name, or 'custom:<id>') or label language; layers are kept
setBuildings3D(on, color:, opacity:)	Buildings in 3D below your layers; tilts a flat map to 55°
addPoints(id, points, SMapPointOptions)	GeoJSON or a list of SMapPoint / {lat, lng, properties} maps
addLines(id, lines, SMapLineOptions)	GeoJSON or a list of SMapLine
addPolygons(id, polygons, SMapPolygonOptions)	GeoJSON or a list of SMapPolygon; extrude draws them in 3D
addImage(name, bytes)	Registers an image for the icon of points
setData(id, data) / setVisible(id, visible) / removeLayer(id)	Change a layer
layers()	Layer ids in draw order, bottom first
fitLayer(id, padding: 40, maxZoom: 15)	Show all of a layer's data
onTap(id, handler)	handler(properties, LatLng) for a tapped feature
flyTo(center, zoom:)	Move the camera
engine	The underlying map controller, for anything not wrapped

Draw order: a higher zIndex draws on top; equal values draw in the order added. A layer with a slot is drawn at that place in the basemap instead (see "Slots"); a layer without one draws on top, as before. Errors are raised as SMapException; errors with no caller (token refresh, style reloads) go to the widget's onError.

Style layers and sources

Layers and sources written for the Style Specification v8 (copied from Mapbox Studio, Maputnik or a web map) are passed through unchanged:

await map.addSource('parcels', {'type': 'vector', 'url': 'https://example.com/parcels.json'});
await map.addStyleLayer({
  'id': 'parcels-fill',
  'type': 'fill',
  'source': 'parcels',
  'source-layer': 'parcels',
  'paint': {'fill-color': '#f97316', 'fill-opacity': 0.3},
}, slot: SMapSlot.labels);
await map.setPaint('parcels-fill', 'fill-opacity', 0.5);
await map.setFilter('parcels-fill', ['==', ['get', 'zone'], 'R1']);

Call	What it does
addSource(id, source) / removeSource(id)	A source (vector, raster, raster-dem, geojson, image)
addStyleLayer(layer, slot:, before:, zIndex:)	A layer, in slot or below before (a layer id), else on top in the order added; source may be inline
setPaint(layerId, name, value) / setLayout(…) / setFilter(layerId, filter)	Change a style layer, yours or the basemap's (the look of addPoints / addLines / addPolygons layers is set with their options)
getStyleLayer(layerId)	The layer as it stands now
sources()	The sources added so far
removeLayer(id)	Removes a layer of any kind (with the source an external-layer helper made for it), or a source

Style layers, sources and every change made with setPaint, setLayout and setFilter (to your layers and to the basemap's) are put back after every style, language or token change.

Slots

SMapSlot.bottom (over land and water, under everything else), roads (under the roads), labels (under the labels) and top. addPoints, addLines and addPolygons take slot (or before) in their options too; inside a slot a higher zIndex draws on top. A layer without a slot draws as before: on top, in the order added. The slots follow the basemap when its layers change; slots() says where each one begins.

Basemap

await map.setBasemap({
  'water': {'color': '#9cc0e6'},
  'roads': {'color': '#ffffff', 'width': 1.2},
  'roads.highway': {'color': '#fde68a'},
  'pois': {'visible': false},
  'labels': {'halo': '#000000'},
});

Classes: land, landcover, parks, landuse, airports, water, roads.paths, roads.minor, roads.major, roads.highway, buildings, rail, boundaries, labels.addresses, labels.water, labels.roads, labels.places, pois; roads and labels set every class below them (a class's own settings win). Each takes visible, color, casing (road edges), halo (labels), opacity (0–1) and width (a factor, 0.25–4). An unknown class or setting is refused with an SMapException that names it. setBasemap replaces the previous settings ({} clears them), basemap() reads them back, and they stay across style and language changes. The basemap option applies them from the first style on.

Saved custom styles from the Open Platform portal: SMapOptions(customStyle: 'custom:sms_…') or setStyle('custom:sms_…').

Files

final collection = formats.read(kmlText);              // format guessed; or format: 'gpx', name: 'trip.gpx'
await map.addData('trip', gpxText, lines: const SMapLineOptions(width: 5));
final kml = map.toKML('trip:lines');

Call	What it does
formats.read(input, format:, lat:, lng:, name:)	Text or bytes as a GeoJSON FeatureCollection: kml, kmz, gpx, polyline, polyline6, wkt, wkb, csv, topojson, geojson (from name's extension or the content when not given; polylines are never guessed; lat / lng name CSV columns)
formats.write(collection, format:)	geojson or kml text
addData(id, input, …)	Reads and draws: areas as id:areas, lines as id:lines, points as id; removeLayer(id) and toGeoJSON(id) take them together
toGeoJSON(layerId) / toKML(layerId)	A layer's data out again
convert(input, format:)	The service converts the file (up to 20 MB)

KML styles become simplestyle properties (marker-color, stroke, stroke-width, stroke-opacity, fill, fill-opacity). Simplestyle properties in any data are drawn when the layer gives no colour, width or opacity of its own, so files from geojson.io and similar tools look as they do there. marker-symbol is not drawn. Every SDK of the family reads a file into the same features.

External layers

Call	What it does
addRasterLayer(id, tiles: | url:, tileSize:, attribution:, opacity:, slot:, …)	Raster {z}/{x}/{y} tiles or a TileJSON
addWmsLayer(id, url:, layers:, styles:, format:, transparent:, version:, params:, …)	OGC WMS, one image per tile
addWmtsLayer(id, url: | capabilities:, layer:, tileMatrixSet:, style:, format:, encoding:, …)	OGC WMTS from its capabilities or a REST template
addVectorTiles(id, tiles: | url: | pmtiles:, layers:, attribution:, …)	Vector tiles or a PMTiles archive, drawn by your style layers
addArcGisLayer(id, url:, layers:, attribution:, …)	ArcGIS MapServer, ImageServer or VectorTileServer
rasterUrl(style, lang:, retina:)	The service's own raster tiles as a template (with your map key), for other tools

Each helper adds a source and a style layer, both under id (vector tiles: the source under id, your layers under their own ids), so setPaint, getStyleLayer and removeLayer work on them as on any style layer. Each source's attribution is shown with the map data credit. WMTS layers are drawn when their tile matrix set is the Web Mercator grid with matrices named by zoom level (3, or EPSG:3857:3); other sets are refused. Labels of ArcGIS vector styles are drawn only in fonts the map service has, and their icons are left out. Google and Bing tiles are refused.

Layer description

map.toJSON() describes the basemap (style, language, settings), the sources and every layer (with its data, options, slot, order and visibility); map.loadLayers(json) adds them to another map. The other sMap SDKs read and write the same description, so a map built on the web opens the same in the app; options this SDK does not draw are kept and written back.

Map keys

A map key (smk_…) can ship inside the app instead of a token from your server. Create one in the developer center and list your app on its allowlist:

• Android: the package name and the SHA-256 of each signing certificate (debug, release, and the store's app signing key when the store re-signs the app). Print it with keytool -list -v -keystore ~/.android/debug.keystore -alias androiddebugkey -storepass android | grep SHA256, or apksigner verify --print-certs app-release.apk | grep SHA-256 for a built app.
• iOS: the bundle id.

SMap(options: const SMapOptions(apiKey: 'smk_…'))

The package reads the app's identity from the platform (package name and signing certificate on Android, bundle id on iOS) and sends it, with the key, on every request to the map service's nodes and to no other host; the app cannot set it itself. With a token too, both are sent and the token is checked first.

The map's tile requests go through one HTTP layer shared by every map in the app, which this package sets when it starts. An app that sets its own HTTP client or request headers for the map afterwards (including the global header functions of the map engine package) replaces it, and the map's tile requests no longer carry the app identity.

Options

Option	Default	What it does
baseUrl	https://tile.srsr.ca	The service address; its node list is asked for first
nodes	none	Node URLs known in advance; their node list is asked for when baseUrl does not answer, so a first start works while it is down
token / getToken	none	See "Tokens"
apiKey	none	A map key, see "Map keys"
style	SMapStyle.light	Colour scheme
language	device language	Label language
nearest	true	Read from the nearest node (the measured order is remembered for an hour)
center, zoom, bearing, pitch	0, 0, 1, 0, 0	Initial camera

The last node list received is kept for 30 days. When no node answers for its list (baseUrl, then every other known node in turn), the kept list and nodes are measured instead, so the map keeps working while the service address is down. An order found that way is used for the current run only and is not remembered; the next start asks for the node list again.

Example

example/ is a one-screen demo: scheme and language switchers, 2,000 clustered points, a line, an extruded block and a 3D buildings switch.

cd example
flutter run --dart-define=SMAP_TOKEN=sm1.…   # or --dart-define=SMAP_API_KEY=smk_…