Polygon Layer

You can add polygons to maps to display shapes made out of points to users using PolygonLayer().

FlutterMap(
    options: MapOptions(),
    children: [
        PolygonLayer(
            polygonCulling: false,
            polygons: [
                Polygon(
                  points: [LatLng(30, 40), LatLng(20, 50), LatLng(25, 45),],
                  color: Colors.blue,
                ),
            ],
        ),
    ],
),

Due to the nature of the Earth being a sphere, drawing lines perfectly requires large amounts of difficult maths that may not behave correctly when given certain edge-cases.

Avoid creating large polygons, or polygons that cross the edges of the map, as this may create undesired results.

Excessive use of polygons or use of complex polygons will create performance issues and lag/'jank' as the user interacts with the map. See for more information.

To improve performance, try enabling polygonCulling. This will prevent the calculation and rendering of polygons outside of the current viewport, however this may not work as expected in all situations.

Polygons (polygons)

As you can see PolygonLayerOptions() accepts list of Polygons. Each determines the shape of a polygon by defining the LatLng of each corner. 'flutter_map' will then draw a line between each coordinate, and fill it.

Property	Type	Defaults	Description
points	List<LatLng>	required	The coordinates of each vertex
holePointsList	List<List<LatLng>>?		The coordinates of each vertex to 'cut-out' from the shape
color	Color	Color(0xFF00FF00)	Fill color
borderStrokeWidth	double	0.0	Width of the border
borderColor	Color	Color(0xFFFFFF00)	Color of the border
disableHolesBorder	bool	false	Whether to apply the border at the edge of 'cut-outs'
isDotted	bool	false	Whether to make the border dotted/dashed instead of solid
label	String?		Text to display as label in center of polygon
labelStyle	TextStyle	TextStyle()	Custom styling to apply to the label
labelPlacement	PolygonLabelPlacement	PolygonLabelPlacement.polylabel	Where to place the label in the polygon

More Polygon Operations

'flutter_map' doesn't provide any public methods to manipulate polygons, as these would be deemed out of scope.

However, some useful methods can be found in libraries such as 'latlong2' and 'poly_bool_dart'. These can be applied to the input of Polygon's points argument, and the map will do it's best to try to render them. However, more complex polygons - such as those with holes - may be painted inaccurately, and may therefore require manual adjustment (of holePointsList, for example).