Demo application - https://whimsical-moxie-6e43a0.netlify.app/

grommet-leaflet

A map for Grommet and React using LeafletJS.

Contents

• Installation
• Getting started
• Component docs
  • Map
  • Marker
  • MarkerCluster
  • Controls
  • Pin
  • Cluster
  • Popup
• Theming

Accessibility notice: Map should be a supplementary data visualization. A table or list view should also be provided for a more comprehensive, accessible experience for users that navigate with keyboard or rely on assistive technologies.

Installation

Using npm:

npm install grommet-leaflet

Using yarn:

yarn add grommet-leaflet

Using pnpm:

pnpm add grommet-leaflet

Getting started

The getting started guide shows how to add grommet-leaflet to an existing Grommet application and provides orientation for its fundamental concepts. For more detailed information on the components and ability to customize, see the Component docs.

If you do not have an existing Grommet application, you can follow the Grommet installation instructions to create one, then continue on from this point.

Go to Getting Started.

Component Docs

Map

Map component is responsible for creating the Leaflet Map instance.

Map supports all Leaflet Map and React Leaflet MapContainer properties.

In addition, it also supports the following props:

Prop	Type	Default value	Required	Notes
tileLayer	object	undefined	true	{     url: string in the form of 'https://{s}.somedomain.com/blabla/{z}/{x}/{y}{r}.png',     attribution?: string e.g. &copy; <a href="https://openstreetmap.org">OpenStreetMap</a> contributors }
theme	object			See theme structure

Marker

A customizable Leaflet marker for an individual location.

Marker supports all Leaflet Marker properties.

In addition, it also supports the following props:

Prop	Type	Default value
icon	Element	undefined
popup	Element	undefined

Customizing the marker

Marker will render whatever is passed to its icon prop. By default, grommet-leaflet will render this as Pin. However, this can be customized by passing a Pin with a specific kind defined by the theme or a custom element.

Default marker

<Marker position={{ lat: 40.532, lng: -105.18 }} />

Theme defined marker

<Marker position={{ lat: 40.532, lng: -105.18 }} icon={<Pin kind="critical" />} />

Custom marker

<Marker position={{ lat: 40.532, lng: -105.18 }} icon={<MyCustomPin />} />

Adding a popup to the marker

A popup is a container in which to present addtional information about a location. A popup appears when a marker is clicked.

To add a popup, pass an element as a child to the marker. For ease and consistency, Marker will automatically wrap your element in the required Leaflet Popup component and a themed Popup container. The grommet-leaflet Popup styling is defined in theme.popup.

<Marker position={{ lat: 40.532, lng: -105.18 }} popup={<MyCustomPopup />} />

MarkerCluster

A custom Leaflet marker cluster for a cluster of multiple locations. MarkerCluster supports all Leaflet.markercluster properties.

In addition, it also supports the following props:

Prop	Type	Default value
icon	({ cluster }) => Element	({ cluster }) => <Cluster cluster={cluster} />
popup	({ cluster }) => Element | null | false | undefined	undefined

For large datasets, it can be beneficial to apply chunkedLoading to MarkerCluster. See leaflet.markercluster docs for additional details.

Customizing the cluster

MarkerCluster will render whatever is passed to its icon prop. By default, grommet-leaflet will render this as <Cluster />. However, this can be customized by passing a Cluster with property overrides (see Cluster for details) or a custom element all together.

<MarkerCluster
   icon={({ cluster }) => {
      const kind = myKindLogic(cluster);
      const size = mySizeLogic(cluster);
      return <Cluster kind={kind} size={size} />
   }}
/>

OR

<MarkerCluster
   icon={({ cluster }) => <MyCluster cluster={cluster} />}
/>

Pin

Pin is used to render an individual location and is passed to the icon prop on Marker.

Pin supports the following props:

Prop	Type	Default value	Notes
kind	string	default	kind can be any key in marker. See theme structure for details.

Pin theming

Pin styles can be customized in a Map theme in theme.pin.

Cluster

Cluster is used to render a cluster of locations and is passed to the icon prop on MarkerCluster. Cluster will render the number of markers contained in the cluster and an icon associated with the marker kind if an icon for that kind has been specified in the theme. Cluster can accept any Box props.

Cluster supports the following props:

Prop	Type	Default value	Notes
kind	string	default	kind can be any key in cluster. See theme structure for details.
size	string	medium	size can be any key in cluster.size. See theme structure for details.

Cluster theming

Cluster styles can be customized in a Map theme in theme.cluster.

Popup

Popup provides additional details about a cluster of locations or an individual location. It appears when Marker or MarkerCluster has popup defined and is clicked.

Popup servers as a Box that wraps around whatever is passed to popup prop on Marker or MarkerCluster.

The default styling for Popup is defined in base.js.

Popup theming

Popup styles can be customized in a Map theme in theme.popup.

Theme object	Type	Notes
popup	object	Any Box props

Controls

Controls provides zoom in, zoom out, and center on data controls for the map.

Controls supports the following props:

Prop	Type	Notes
locations	array or GeoJSON object	array should be an array of arrays of lat, lng pairs (e.g. [[0, 0], [10, -10]]). If a geojson object is passed it should have coordinates defined within features[index].geometry.coordinates.

Theming

Theme structure

The default styling for grommet-leaflet is defined in base.js.

In the theme structure below, [kind] can be any string and there can be any number of kinds defined for pin or cluster. Additionally, [size] can be any string and there can be any number of sizes defined in cluster.size.

{
   cluster: {
      default: {
         container: { // any Grommet Box props },
         icon: Element, commonly an icon from grommet-icons,
      },
      [kind]: {
         container: { // any Grommet Box props },
         icon: Element, commonly an icon from grommet-icons,
      },
      size: {
         small: {
            container: { // any Grommet Box props },
            label: { // any Grommet Text props },
         },
         medium: {
            container: { // any Grommet Box props },
            label: { // any Grommet Text props },
         },
         large: {
            container: { // any Grommet Box props },
            label: { // any Grommet Text props },
         },
         [size]: {
            container: { // any Grommet Box props },
            label: { // any Grommet Text props },
         },
      }
   },
   pin: {
      default: {
         container: { // any Grommet Box props },
         icon: Element, commonly an icon from grommet-icons
      },
      [kind]: {
         container: { // any Grommet Box props },
         icon: Element, commonly an icon from grommet-icons
      },
   },
   popup: { // any Grommet Box props }
}

Example custom theme

const myTheme = {
   cluster: {
      size: {
         large: {
            container: { border: { color: 'blue', size: 'medium' } },
            label: { size: 'xlarge', weight: 'bold' },
         },
      }
   },
   pin: {
      retail: {
         container: { background: 'blue' },
         icon: <Shop />
      },
   },
}

To use the retail Pin kind, your code could look like:

<Map theme={myTheme} ...>
   <Marker icon={<Pin kind="retail" ... />}
</Map>

To use the large Cluster size, your code could look like:

<Map theme={myTheme} ...>
   <MarkerCluster icon={() => <Cluster size="large" ... />}>
      ...
   </MarkerCluster>
</Map>