mapchart 0.3.0

Vector map chart for Flutter. Highly customizable. Compatible with GeoJSON. Pure Flutter.

Map Chart

• Displays GeoJSON geometries
• Multi resolution with geometry simplification
• Highly customizable
• Interactable
• Pure Flutter (no WebView/JavaScript)

Get started

A simplified GeoJSON will be used in the examples to demonstrate the different possibilities of themes. This GeoJSON has only 4 features with the following properties:

Id	Name	Satellites	Distance
venus	Venus		108200000
earth	Earth	Moon	149600000
mars	Mars	Phobos, Deimos	227900000
mercury	Mercury		57910000

To view the full content, use this link.

The following examples will assume that GeoJSON has already been loaded into a String.

Reading GeoJSON from String

    MapChartDataSource dataSource =
        await MapChartDataSource.geoJSON(geojson: geojson);

Creating the Widget

    MapChart map = MapChart(dataSource: dataSource);

Changing the default colors

    MapChart map = MapChart(
        dataSource: dataSource,
        theme: MapChartTheme(
            color: Colors.yellow,
            contourColor: Colors.red,
            hoverColor: Colors.orange));

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

    MapChartDataSource dataSource =
        await MapChartDataSource.geoJSON(geojson: geojson, valueKeys: ['Id']);

Setting the colors for the property values

    MapChartTheme theme =
        MapChartTheme.value(contourColor: Colors.white, key: 'Id', colors: {
      'earth': Colors.green,
      'mars': Colors.red,
      'venus': Colors.orange
    }, hoverColors: {
      'earth': Colors.green[900]!,
      'mars': Colors.red[900]!,
      'venus': Colors.orange[900]!
    });

    MapChart map = MapChart(dataSource: dataSource, theme: theme);

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

    MapChartDataSource dataSource = await MapChartDataSource.geoJSON(
        geojson: geojson, valueKeys: ['Distance']);

Setting the rules

    MapChartTheme theme = MapChartTheme.rule(
        contourColor: Colors.white,
        hoverColor: Colors.grey[700]!,
        colorRules: [
          (feature) {
            return feature.getValue('Distance') < 100000000
                ? Colors.green
                : null;
          },
          (feature) {
            return feature.getValue('Distance') < 200000000
                ? Colors.blue
                : null;
          }
        ]);

    MapChart map = MapChart(dataSource: dataSource, theme: theme);

Contour

Thickness

    MapChart map = MapChart(
        dataSource: dataSource, theme: MapChartTheme(contourThickness: 3));

Hover contour color

    MapChart map = MapChart(
        dataSource: dataSource,
        theme: MapChartTheme(hoverContourColor: Colors.red));

Hover

Listener

    MapChart map = MapChart(
        dataSource: dataSource,
        theme: MapChartTheme(hoverColor: Colors.grey[700]),
        hoverListener: (MapFeature? feature) {
          if (feature != null) {
            int id = feature.id;
            print('Hover - Feature id: $id');
          }
        });

Rule

Enabling hover by property value

    MapChartDataSource dataSource =
        await MapChartDataSource.geoJSON(geojson: geojson, valueKeys: ['Id']);

    // coloring only the 'earth' feature
    MapChartTheme theme = MapChartTheme.value(
        key: 'Id',
        colors: {'earth': Colors.green},
        hoverColor: Colors.green[900]!);

    // enabling hover only for the 'earth' feature
    MapChart map = MapChart(
      dataSource: dataSource,
      theme: theme,
      hoverRule: (feature) {
        return feature.getValue('Id') == 'earth';
      },
    );

Click listener

    MapChart map = MapChart(
        dataSource: dataSource,
        theme: MapChartTheme(hoverColor: Colors.grey[800]!),
        clickListener: (feature) {
          print(feature.id);
        });

Agenda for the next few days

• More theming features.
• Legend.
• Release the final version (1.0.0). The API may have some small changes.