flutter_simple_map 0.1.0

Create beautiful maps in flutter with GeoJson using a declarative api, highly customizable, pure Flutter.

Flutter Geo Map

• Compatible with GeoJSON
• Multi resolution with geometry simplification
• Highly customizable
• High performance
• Interactable
• Pure Flutter (no WebView/JavaScript)

GeoJson

GeoJSON is a JSON-based open standard format designed to represent geographical features, alongside non-spatial attributes (properties). Geographic shapes would usually be represented as features in geojson. Each feature has a type, geometry, and properties attribute. properties is an object that can contain any kind of data that can be represented in JSON format. This can be time-series population data, GDP, or any other kind of data that relates to a given geography.

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [10.6, 47.9],
            [5.8, 47.9],
            [5.8, 45.8],
            [10.6, 45.8],
            [10.6, 47.9]
          ]
        ]
      },
      "properties": {
        "firstProperty": "Something",
        "secondProperty": "Something else"
      }
    },
    { "type": "Feature", "geometry": {...}, "properties": {...} },
    { "type": "Feature", "geometry": {...}, "properties": {...} }
  ]
}

Reading GeoJSON from String

Reading the geometries only.

  MapDataSource polygons = await MapDataSource.geoJson(geoJson: geoJson);

Reading GeoJSON properties

The keys argument defines which properties must be loaded. The parseToNumber argument defines which properties will have numeric values in quotes parsed to numbers. The labelKey defines which property will be used to display its values as feature labels. The filterKey & filterValue defines which property key will be used to filter json match value

  MapDataSource polygons = await MapDataSource.geoJson(
      geoJson: geoJson,
      keys: ['Seq', 'Rnd'],
      parseToNumber: ['Rnd'],
      labelKey: 'Rnd',
      filterKet: 'Seq',
      filterValue '01');

Creating the Widget

  SimpleMapController _controller = SimpleMapController();

  MapDataSource polygons = await MapDataSource.geoJson(geoJson: geoJson);
  MapLayer layer = MapLayer(dataSource: polygons);
  _controller.addLayer(layer);

  SimpleMap map = SimpleMap(controller: _controller);

Theme

  MapLayer layer = MapLayer(
      dataSource: polygons,
      theme: MapTheme(color: Colors.yellow, contourColor: Colors.red));

Label visibility

  MapDataSource polygons =
      await MapDataSource.geoJson(geoJson: geoJson, labelKey: 'Name');

  MapLayer layer = MapLayer(
      dataSource: polygons,
      theme: MapTheme(labelVisibility: (feature) => true));

Filter label name to visible

  MapLayer layer = MapLayer(
      dataSource: polygons,
      theme: MapTheme(labelVisibility: (feature) => feature.label == 'Darwin'));

Label style

  MapLayer layer = MapLayer(
      dataSource: polygons,
      theme: MapTheme(
          labelVisibility: (feature) => true,
          labelStyleBuilder: (feature, featureColor, labelColor) {
            if (feature.label == 'Darwin') {
              return TextStyle(
                color: labelColor,
                fontWeight: FontWeight.bold,
                fontSize: 11,
              );
            }
            return TextStyle(
              color: labelColor,
              fontSize: 11,
            );
          }));

Color by property value

Sets a color for each property value in GeoJSON. If a color is not set, the default color is used.

Mapping the property key:

  MapDataSource polygons = await MapDataSource.geoJson(
      geoJson: geoJson, keys: ['Seq'], labelKey: 'Seq');

Setting the colors for the property values:

  MapLayer layer = MapLayer(
      dataSource: polygons,
      theme: MapValueTheme(
          contourColor: Colors.white,
          labelVisibility: (feature) => true,
          key: 'Seq',
          colors: {
            2: Colors.green,
            4: Colors.red,
            6: Colors.orange,
            8: Colors.blue
          }));

Color by rule

The feature color is obtained from the first rule that returns a non-null color. If all rules return a null color, the default color is used.

Mapping the property key:

  MapDataSource polygons =
      await MapDataSource.geoJson(geoJson: geoJson, keys: ['Name', 'Seq']);

Setting the rules:

  MapLayer layer = MapLayer(
      dataSource: polygons,
      theme: MapRuleTheme(contourColor: Colors.white, colorRules: [
        (feature) {
          String? value = feature.getValue('Name');
          return value == 'Faraday' ? Colors.red : null;
        },
        (feature) {
          double? value = feature.getDoubleValue('Seq');
          return value != null && value < 3 ? Colors.green : null;
        },
        (feature) {
          double? value = feature.getDoubleValue('Seq');
          return value != null && value > 9 ? Colors.blue : null;
        }
      ]));

Gradient

The gradient is created given the colors and limit values of the chosen property. The property must have numeric values.

Auto min/max values

Uses the min and max values read from data source.

  MapDataSource polygons = await MapDataSource.geoJson(
      geoJson: geoJson, keys: ['Seq'], labelKey: 'Seq');

  MapLayer layer = MapLayer(
      dataSource: polygons,
      theme: MapGradientTheme(
          contourColor: Colors.white,
          labelVisibility: (feature) => true,
          key: 'Seq',
          colors: [Colors.blue, Colors.yellow, Colors.red]));

Setting min or max values manually

If the min value is set, all lower values will be displayed using the first gradient color. If the max value is set, all higher values will be displayed using the last gradient color.

  MapDataSource polygons = await MapDataSource.geoJson(
      geoJson: geoJson, keys: ['Seq'], labelKey: 'Seq');

  MapLayer layer = MapLayer(
      dataSource: polygons,
      theme: MapGradientTheme(
          contourColor: Colors.white,
          labelVisibility: (feature) => true,
          key: 'Seq',
          min: 3,
          max: 9,
          colors: [Colors.blue, Colors.yellow, Colors.red]));

Highlight theme

Used by addons and cursor hover to highlight layer features on the map.

Color

  MapLayer layer = MapLayer(
      dataSource: polygons,
      highlightTheme: MapHighlightTheme(color: Colors.green));

Contour color

  MapLayer layer = MapLayer(
      dataSource: polygons,
      highlightTheme: MapHighlightTheme(contourColor: Colors.red));

Label highlight

  MapDataSource polygons =
      await MapDataSource.geoJson(geoJson: geoJson, labelKey: 'Name');

  MapLayer layer = MapLayer(
      dataSource: polygons,
      highlightTheme: MapHighlightTheme(labelVisibility: (feature) => true));

Contour thickness

  SimpleMapController _controller = SimpleMapController(contourThickness: 3);

Cursor hover rule

Enabling hover by property value

  MapDataSource polygons =
      await MapDataSource.geoJson(geoJson: geoJson, keys: ['Seq']);

  // coloring only the 'Darwin' feature
  MapLayer layer = MapLayer(
      dataSource: polygons,
      theme: MapValueTheme(key: 'Seq', colors: {4: Colors.green}),
      highlightTheme: MapHighlightTheme(color: Colors.green[900]!));

  // enabling hover only for the 'Darwin' feature
  SimpleMap map = SimpleMap(
      controller: _controller,
      hoverRule: (feature) {
        return feature.getValue('Seq') == 4;
      });

Cursor hover listener

  SimpleMap map = SimpleMap(
      controller: _controller,
      hoverListener: (MapFeature? feature) {
        if (feature != null) {
          int id = feature.id;
        }
      });

Layers

  MapHighlightTheme highlightTheme = MapHighlightTheme(color: Colors.green);

  MapDataSource polygons =
      await MapDataSource.geoJson(geoJson: polygonsGeoJson);
  MapLayer polygonLayer =
      MapLayer(dataSource: polygons, highlightTheme: highlightTheme);
  _controller.addLayer(polygonLayer);

  MapDataSource points = await MapDataSource.geoJson(geoJson: pointsGeoJson);
  MapLayer pointsLayer = MapLayer(
      dataSource: points,
      theme: MapTheme(color: Colors.black),
      highlightTheme: highlightTheme);
  _controller.addLayer(pointsLayer);

Overlay hover contour

Allows you to draw the contour over all layers

  MapDataSource dataSource1 = MapDataSource.geometries([
    MapPolygon.coordinates([2, 3, 4, 5, 6, 3, 4, 1, 2, 3])
  ]);
  MapDataSource dataSource2 = MapDataSource.geometries([
    MapPolygon.coordinates([0, 2, 2, 4, 4, 2, 2, 0, 0, 2]),
    MapPolygon.coordinates([4, 2, 6, 4, 8, 2, 6, 0, 4, 2])
  ]);

Overlay disabled:

  MapHighlightTheme highlightTheme =
      MapHighlightTheme(color: Colors.black, contourColor: Colors.black);

  MapLayer layer1 = MapLayer(
      dataSource: dataSource1,
      theme: MapTheme(color: Colors.yellow, contourColor: Colors.black),
      highlightTheme: highlightTheme);
  MapLayer layer2 = MapLayer(
      dataSource: dataSource2,
      theme: MapTheme(color: Colors.green, contourColor: Colors.black),
      highlightTheme: highlightTheme);

  _controller = SimpleMapController(layers: [layer1, layer2]);

Overlay enabled:

  MapLayer layer1 = MapLayer(
      dataSource: dataSource1,
      theme: MapTheme(color: Colors.yellow, contourColor: Colors.black),
      highlightTheme: MapHighlightTheme(
          color: Colors.black,
          contourColor: Colors.black,
          overlayContour: true));
  MapLayer layer2 = MapLayer(
      dataSource: dataSource2,
      theme: MapTheme(color: Colors.green, contourColor: Colors.black),
      highlightTheme:
          MapHighlightTheme(color: Colors.black, contourColor: Colors.black));

  _controller = SimpleMapController(layers: [layer1, layer2]);