Controllers & Cameras

flutter_map makes use of InheritedModel to share 3 'aspects' with its built children:

• MapController: use to programatically control the map camera & access some helper functionality - control camera

• MapCamera: use to read the current state/position of the map camera & access some helper functionality that depends on the camera (such as latlngToPoint) - read camera

Accessing Aspects Within Descendants

All 3 aspects can be retrieved from within the context of a FlutterMap, which all built descendants should have access to. This usually means from within a layer: anywhere where there is at least one 'visible' builder method between the FlutterMap and the invocation.

Use the static of (or null-safe maybeOf) method to access the inherited aspect. For example, to access the MapCamera:

final inheritedCamera = MapCamera.of(context);

This will attach the widget to the state of the map, causing it to rebuild whenever the depended-on aspects change. See #id-2.-hooking-into-inherited-state for more information.

children: [
    Builder(
        builder: (context) {
            if (MapCamera.of(context).zoom < 13) return SizedBox.shrink();
            return TileLayer();
        },
    ),
],

Accessing Aspects Elsewhere

MapCamera

To access the MapCamera outside of a FlutterMap descendant, first setup an external MapController, as guided below.

Then use the camera getter on the MapController instance.

MapController

For more information about correctly setting up an external(ly accessible) MapController, see:

MapOptions