vector_map_flutter

Vector Map

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

Usage

• About the examples
• Reading GeoJSON from String
• Reading GeoJSON properties
• Creating the Widget
• Theme
  • Label visibility
  • Label style
  • Color by property value
  • Color by rule
  • Gradient
• Highlight theme
• Contour thickness
• Cursor hover
  • Rule
  • Listener
• Layers
  • Overlay hover contour
• Marker
  • Circle
    • Fixed radius
    • Radius by mapping values
    • Radius by property values
    • Radius in proportion to property values
• Addons
  • Legend
    • Gradient legend
      • Setting min and max values
      • Highlight
      • Customization
• Click listener
• Mode
  • Auto fit
  • Pan and zoom
• Debugger
• Support this project

About the examples

Simplified GeoJSONs will be used in the examples to demonstrate package usage. The following examples will assume that GeoJSONs have already been loaded into Strings. The full code is at https://github.com/caduandrade/vector_map_flutter_demo.

polygons.json (link)

Name	Seq	Rnd	Gts
"Einstein"	1	"73"	15000
"Newton"	2	"92"	7500
"Galileu"	3	"10"	3000
"Darwin"	4		15000
"Pasteur"	5	"77"	17000
"Faraday"	6	"32"	17500
"Arquimedes"	7	"87"	25000
"Tesla"	8	"17"	12500
"Lavoisier"	9		4000
"Kepler"	10	"32"	18000
"Turing"	11	"93"	31400

points.json (link)

Name	AN
"Titanium"	22
"Niobium"	41
"Carbon"	6
"Neon"	10
"Silicon"	14
"Hydrogen"	1

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.

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

Creating the Widget

  VectorMapController _controller = VectorMapController();

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

  VectorMap map = VectorMap(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));

  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

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

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

Contour thickness

  VectorMapController _controller = VectorMapController(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
  VectorMap map = VectorMap(
      controller: _controller,
      hoverRule: (feature) {
        return feature.getValue('Seq') == 4;
      });

Cursor hover listener

  VectorMap map = VectorMap(
      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 = VectorMapController(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 = VectorMapController(layers: [layer1, layer2]);

Marker

Allows different displays for point geometry.

Circle marker

Default marker.

Fixed radius

Sets a fixed size radius.

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

  MapDataSource points = await MapDataSource.geoJson(
      geoJson: pointsGeoJson, keys: ['AN'], labelKey: 'AN');
  MapLayer pointsLayer = MapLayer(
      dataSource: points,
      theme: MapTheme(
          color: Colors.black,
          markerBuilder: CircleMakerBuilder.fixed(radius: 15)));
  _controller.addLayer(pointsLayer);

Radius by mapping values

Maps property values to radius values.

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

  MapDataSource points = await MapDataSource.geoJson(
      geoJson: pointsGeoJson, keys: ['AN'], labelKey: 'AN');
  MapLayer pointsLayer = MapLayer(
      dataSource: points,
      theme: MapTheme(
          color: Colors.black,
          labelVisibility: (feature) => true,
          markerBuilder: CircleMakerBuilder.map(
              key: 'AN', radiuses: {41: 25, 22: 20, 14: 10, 10: 10})));
  _controller.addLayer(pointsLayer);

Radius by property values

Uses the property values as radius values.

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

  MapDataSource points = await MapDataSource.geoJson(
      geoJson: pointsGeoJson, keys: ['AN'], labelKey: 'AN');
  MapLayer pointsLayer = MapLayer(
      dataSource: points,
      theme: MapTheme(
          color: Colors.black,
          labelVisibility: (feature) => true,
          markerBuilder: CircleMakerBuilder.property(key: 'AN')));
  _controller.addLayer(pointsLayer);

Radius in proportion to property values

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

  MapDataSource points = await MapDataSource.geoJson(
      geoJson: pointsGeoJson, keys: ['AN'], labelKey: 'AN');
  MapLayer pointsLayer = MapLayer(
      dataSource: points,
      theme: MapTheme(
          color: Colors.black,
          labelVisibility: (feature) => true,
          markerBuilder: CircleMakerBuilder.proportion(
              key: 'AN', minRadius: 8, maxRadius: 30)));
  _controller.addLayer(pointsLayer);

Addons

Allows adding components on the map.

Legend

Available customizations:

• padding
• margin
• decoration

Gradient legend

Legend for gradient themes.

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

  MapLayer layer = MapLayer(
      id: 1,
      dataSource: polygons,
      theme: MapGradientTheme(
          contourColor: Colors.white,
          labelVisibility: (feature) => true,
          key: 'Gts',
          colors: [Colors.blue, Colors.yellow, Colors.red]));
  _controller.addLayer(layer);

  _addons = [GradientLegend(layer: layer)];

  VectorMap map = VectorMap(
      controller: _controller,
      layersPadding: EdgeInsets.fromLTRB(8, 8, 56, 8),
      addons: _addons);

Gradient legend - Setting min and max values

  MapLayer layer = MapLayer(
      id: 1,
      dataSource: polygons,
      theme: MapGradientTheme(
          contourColor: Colors.white,
          labelVisibility: (feature) => true,
          key: 'Gts',
          min: 7500,
          max: 25000,
          colors: [Colors.blue, Colors.yellow, Colors.red]));

Gradient legend - Highlight

  MapLayer layer = MapLayer(
      id: 1,
      dataSource: polygons,
      theme: MapGradientTheme(
          contourColor: Colors.white,
          labelVisibility: (feature) => true,
          key: 'Gts',
          min: 7500,
          max: 25000,
          colors: [Colors.blue, Colors.yellow, Colors.red]),
      highlightTheme: MapHighlightTheme(color: Colors.brown[900]));

Gradient legend - Customization

Available customizations:

• gradient bar width
• gradient bar height
• gradient bar border
• values font size
• gap between bar and values

  MapLayer layer = MapLayer(
      id: 1,
      dataSource: polygons,
      theme: MapGradientTheme(
          contourColor: Colors.white,
          labelVisibility: (feature) => true,
          key: 'Gts',
          colors: [Colors.blue, Colors.yellow, Colors.red]));

  _addons = [
    GradientLegend(
        layer: layer,
        barBorder: Border.all(width: 2),
        barHeight: 50,
        barWidth: 30)
  ];

  VectorMap map = VectorMap(
      controller: _controller,
      layersPadding: EdgeInsets.fromLTRB(8, 8, 56, 8),
      addons: _addons);

Click listener

  VectorMap map = VectorMap(
      controller: _controller,
      clickListener: (feature) {
        print('feature id: ${feature.id}');
      });

Mode

Auto fit

This is the default mode

  VectorMapController _controller =
      VectorMapController(mode: VectorMapMode.autoFit);

Pan and zoom

  VectorMapController _controller =
      VectorMapController(mode: VectorMapMode.panAndZoom);

Debugger

Building a debugger

  MapDebugger debugger = MapDebugger();

Binding the debugger on the map

  _controller = VectorMapController(debugger: widget.debugger);

Building the debugger widget

  MapDebuggerWidget debuggerWidget = MapDebuggerWidget(debugger);

I'm working on

• More theming features
• More legends
  • More gradient legend customizations
• More addons
• Handle line type geometries
  • Click and mouse hover (need geometry buffer)
• Improve the performance of heavy geometries (over 500k points) on mobile devices
• Pan limits?
• Release the final version (1.0.0). The API may have some small changes.

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