Lines in Flutter Maps (SfMaps)

5 May 202124 minutes to read

Line layer is a sublayer that renders a group of MapLine on MapShapeLayer and MapTileLayer. This section helps to learn about how to add the lines and customize them.

Adding lines

The lines is a collection of MapLine. Every single MapLine connects two location coordinates through a straight line. The start coordinate is set to MapLine.from property and the end coordinate is set to MapLine.to property.

NOTE

It is applicable for both the tile layer and shape layer.

In the shape layer

late MapShapeSource dataSource;
late List<DataModel> data;

@override
void initState() {
  data = <DataModel>[
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(56.1304, -106.3468)),
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(-9.1900, -75.0152)),
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(61.5240, 105.3188)),
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(-25.2744, 133.7751)),
  ];

  dataSource = MapShapeSource.asset(
    'assets/world_map.json',
    shapeDataField: 'continent',
  );
  super.initState();
}

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: Padding(
      padding: EdgeInsets.all(10),
      child: SfMaps(layers: [
        MapShapeLayer(
          source: dataSource,
          sublayers: [
            MapLineLayer(
              lines: List<MapLine>.generate(data.length, (int index) {
                return MapLine(
                  from: data[index].from,
                  to: data[index].to,
                );
              }).toSet(),
            ),
          ],
        ),
      ]),
    ),
  );
}

class DataModel {
  DataModel(this.from, this.to);

  final MapLatLng from;
  final MapLatLng to;
}

In the tile layer

late List<DataModel> data;

@override
void initState() {
  data = <DataModel>[
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(56.1304, -106.3468)),
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(-9.1900, -75.0152)),
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(61.5240, 105.3188)),
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(-25.2744, 133.7751)),
  ];
  super.initState();
}

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: Padding(
      padding: EdgeInsets.all(10),
      child: SfMaps(layers: [
        MapTileLayer(
          urlTemplate: 'https://tile.openstreetmap.org/{z}/{x}/{y}.png',
          sublayers: [
            MapLineLayer(
              lines: List<MapLine>.generate(data.length, (int index) {
                return MapLine(
                  from: data[index].from,
                  to: data[index].to,
                );
              }).toSet(),
            ),
          ],
        ),
      ]),
    ),
  );
}

class DataModel {
  DataModel(this.from, this.to);

  final MapLatLng from;
  final MapLatLng to;
}

Default line shape

Color

You can apply the same color for all MapLine in the lines collection using the MapLineLayer.color property. Alternatively, you can apply different colors to each MapLine in the lines collection using the individual MapLine.color property.

late MapShapeSource dataSource;
late List<DataModel> data;

@override
void initState() {
  data = <DataModel>[
     DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(56.1304, -106.3468), Colors.redAccent),
     DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(-9.1900, -75.0152), Colors.deepPurpleAccent),
     DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(61.5240, 105.3188), Colors.blueAccent),
     DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(-25.2744, 133.7751), Colors.teal),
  ];

  dataSource = MapShapeSource.asset(
    'assets/world_map.json',
    shapeDataField: 'continent',
  );
  super.initState();
}

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: Padding(
      padding: EdgeInsets.all(10),
      child: SfMaps(layers: [
        MapShapeLayer(
          source: dataSource,
          sublayers: [
            MapLineLayer(
              lines: List<MapLine>.generate(data.length, (int index) {
                return MapLine(
                  from: data[index].from,
                  to: data[index].to,
                  color: data[index].color,
                );
              }).toSet(),
            ),
          ],
        ),
      ]),
    ),
  );
}

class DataModel {
  DataModel(this.from, this.to, this.color);

  final MapLatLng from;
  final MapLatLng to;
  final Color color;
}

Line shape color

Width

You can apply the same width for all MapLine in the lines collection using the MapLineLayer.width property. Alternatively, you can apply different width to each MapLine in the lines collection using the individual MapLine.width property. The default value of the MapLineLayer.width property is 2.

late MapShapeSource dataSource;
late List<DataModel> data;

@override
void initState() {
  data = <DataModel>[
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(56.1304, -106.3468), 2),
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(-9.1900, -75.0152), 4),
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(61.5240, 105.3188), 5),
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(-25.2744, 133.7751), 6),
  ];

  dataSource = MapShapeSource.asset(
    'assets/world_map.json',
    shapeDataField: 'continent',
  );
  super.initState();
}

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: Padding(
      padding: EdgeInsets.all(10),
      child: SfMaps(layers: [
        MapShapeLayer(
          source: dataSource,
          sublayers: [
            MapLineLayer(
              lines: List<MapLine>.generate(data.length, (int index) {
                return MapLine(
                  from: data[index].from,
                  to: data[index].to,
                  width: data[index].width,
                );
              }).toSet(),
            ),
          ],
        ),
      ]),
    ),
  );
}

class DataModel {
  DataModel(this.from, this.to, this.width);

  final MapLatLng from;
  final MapLatLng to;
  final double width;
}

Line shape width

Dash array

You can apply dash support for the line using the MapLine.dashArray property.

A sequence of dash and gap will be rendered based on the values in this list. Once all values of the list is rendered, it will be repeated again till the end of the line.

late MapShapeSource dataSource;
late List<DataModel> data;

@override
void initState() {
  data = <DataModel>[
     DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(56.1304, -106.3468)),
     DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(-9.1900, -75.0152)),
     DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(61.5240, 105.3188)),
     DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(-25.2744, 133.7751)),
  ];

  dataSource = MapShapeSource.asset(
    'assets/world_map.json',
    shapeDataField: 'continent',
  );
  super.initState();
}

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: Padding(
      padding: EdgeInsets.all(10),
      child: SfMaps(layers: [
        MapShapeLayer(
          source: dataSource,
          sublayers: [
            MapLineLayer(
              lines: List<MapLine>.generate(data.length, (int index) {
                return MapLine(
                  from: data[index].from,
                  to: data[index].to,
                  dashArray: [8, 4, 2, 4],
                );
              }).toSet(),
              color: Colors.blue,
            ),
          ],
        ),
      ]),
    ),
  );
}

class DataModel {
  DataModel(this.from, this.to);

  final MapLatLng from;
  final MapLatLng to;
}

Line shape dash array

Animation

You can apply animation for the MapLine using the MapLineLayer.animation property and able to customize the animation flow, curve and duration.

By default, there will not be any animation.

late MapShapeSource dataSource;
late List<DataModel> data;
late AnimationController animationController;
late Animation animation;

@override
void initState() {
  data = <DataModel>[
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(56.1304, -106.3468)),
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(-9.1900, -75.0152)),
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(61.5240, 105.3188)),
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(-25.2744, 133.7751)),
  ];

  dataSource = MapShapeSource.asset(
    'assets/world_map.json',
    shapeDataField: 'continent',
  );

  animationController = AnimationController(
    duration: Duration(seconds: 3),
    vsync: this,
  );
  animation = CurvedAnimation(
    parent: animationController,
    curve: Curves.easeInOut,
  );
  animationController.forward(from: 0);
  super.initState();
}

@override
void dispose() {
  animationController?.dispose();
  super.dispose();
}

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: Padding(
      padding: EdgeInsets.all(10),
      child: SfMaps(layers: [
        MapShapeLayer(
          source: dataSource,
          sublayers: [
            MapLineLayer(
              lines: List<MapLine>.generate(data.length, (int index) {
                return MapLine(
                  from: data[index].from,
                  to: data[index].to,
                );
              }).toSet(),
              color: Colors.blue,
              animation: animation,
            ),
          ],
        ),
      ]),
    ),
  );
}

class DataModel {
  DataModel(this.from, this.to);

  final MapLatLng from;
  final MapLatLng to;
}

Line shape animation

Tap

You can use the onTap callback to get a notification if the particular MapLine is tapped. You can also customize the tapped MapLine based on the index passed in the callback as shown in the below code snippet.

late MapShapeSource dataSource;
late List<DataModel> data;
late int selectedIndex;

@override
void initState() {
  data = <DataModel>[
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(56.1304, -106.3468)),
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(-9.1900, -75.0152)),
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(61.5240, 105.3188)),
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(-25.2744, 133.7751)),
  ];

  dataSource = MapShapeSource.asset(
    'assets/world_map.json',
    shapeDataField: 'continent',
  );

  selectedIndex = -1;
  super.initState();
}

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: Padding(
      padding: EdgeInsets.all(10),
      child: SfMaps(layers: [
        MapShapeLayer(
          source: dataSource,
          sublayers: [
            MapLineLayer(
              lines: List<MapLine>.generate(data.length, (int index) {
                return MapLine(
                    from: data[index].from,
                    to: data[index].to,
                    color: selectedIndex == index ? Colors.pink : Colors.blue,
                    onTap: () {
                      setState(() {
                        selectedIndex = index;
                      });
                    });
              }).toSet(),
            ),
          ],
        ),
      ]),
    ),
  );
}

class DataModel {
  DataModel(this.from, this.to);

  final MapLatLng from;
  final MapLatLng to;
}

Line shape onTap

Tooltip

You can show additional information about the line drawn using the tooltipBuilder property.

late MapShapeSource dataSource;
late List<DataModel> data;
late Random random;

@override
void initState() {
  data = <DataModel>[
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(56.1304, -106.3468)),
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(-9.1900, -75.0152)),
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(61.5240, 105.3188)),
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(-25.2744, 133.7751)),
  ];

  dataSource = MapShapeSource.asset(
    'assets/world_map.json',
    shapeDataField: 'continent',
  );

  random = Random();
  super.initState();
}

@override
Widget build(BuildContext context) {
 final ThemeData themeData = Theme.of(context);
    final TextStyle textStyle = themeData.textTheme.caption!
        .copyWith(color: themeData.colorScheme.surface);
  return Scaffold(
    body: Padding(
      padding: EdgeInsets.all(10),
      child: SfMaps(layers: [
        MapShapeLayer(
          source: dataSource,
          sublayers: [
            MapLineLayer(
              lines: List<MapLine>.generate(data.length, (int index) {
                return MapLine(
                  from: data[index].from,
                  to: data[index].to,
                );
              }).toSet(),
              tooltipBuilder: (BuildContext context, int index) {
                return Container(
                  padding: EdgeInsets.only(left: 5, top: 5),
                  height: 40,
                  width: 100,
                  child: Column(
                    children: [
                      Row(
                        children: [
                          Text('Flight   : ', style: textStyle),
                          Text('Air India', style: textStyle),
                        ],
                      ),
                      Row(
                        children: [
                          Text('Depart : ', style: textStyle),
                          Text(random.nextInt(12).toString() + 'AM', style: textStyle),
                        ],
                      ),
                    ],
                  ),
                );
              },
            ),
          ],
        ),
      ]),
    ),
  );
}

class DataModel {
  DataModel(this.from, this.to);

  final MapLatLng from;
  final MapLatLng to;
}

Line shape tooltip

Tooltip customization

You can customize the appearance of the tooltip.

late MapShapeSource dataSource;
late List<DataModel> data;
late Random random;

@override
void initState() {
  data = <DataModel>[
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(56.1304, -106.3468)),
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(-9.1900, -75.0152)),
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(61.5240, 105.3188)),
    DataModel(MapLatLng(28.7041, 77.1025), MapLatLng(-25.2744, 133.7751)),
  ];

  dataSource = MapShapeSource.asset(
    'assets/world_map.json',
    shapeDataField: 'continent',
  );

  random = Random();
  super.initState();
}

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: Padding(
      padding: EdgeInsets.all(10),
      child: SfMaps(layers: [
        MapShapeLayer(
          source: dataSource,
          tooltipSettings: const MapTooltipSettings(
            color: Colors.white,
            strokeWidth: 2,
            strokeColor: Colors.black,
          ),
          sublayers: [
            MapLineLayer(
              lines: List<MapLine>.generate(data.length, (int index) {
                return MapLine(
                  from: data[index].from,
                  to: data[index].to,
                );
              }).toSet(),
              tooltipBuilder: (BuildContext context, int index) {
                return Container(
                  padding: EdgeInsets.only(left: 5, top: 5),
                  height: 40,
                  width: 100,
                  child: Column(
                    children: [
                      Row(
                        children: [
                          Text('Flight   : '),
                          Text('Air India'),
                        ],
                      ),
                      Row(
                        children: [
                          Text('Depart : '),
                          Text(random.nextInt(12).toString() + 'AM'),
                        ],
                      ),
                    ],
                  ),
                );
              },
            ),
          ],
        ),
      ]),
    ),
  );
}

class DataModel {
  DataModel(this.from, this.to);

  final MapLatLng from;
  final MapLatLng to;
}

Line shape tooltip customization