# Marker

![Since v3.0](https://img.shields.io/badge/since-v3.0-green)

This is a React equivalent of Mapbox's
[Marker Control](https://www.mapbox.com/mapbox-gl-js/api/#marker), which can
be used to render custom icons at specific locations on the map.

```js
import * as React from 'react';
import ReactMapGL, {Marker} from 'react-map-gl';

function App() {
  const [viewport, setViewport] = React.useState({
    longitude: -122.45,
    latitude: 37.78,
    zoom: 14
  });
  return (
    <ReactMapGL {...viewport} width="100vw" height="100vh" onViewportChange={setViewport}>
      <Marker latitude={37.78} longitude={-122.41} offsetLeft={-20} offsetTop={-10}>
        <div>You are here</div>
      </Marker>
    </ReactMapGL>
  );
}
```

Performance notes: if a large number of markers are needed, it's generally favorable to cache the `<Marker>` nodes, so that we don't rerender them when the viewport changes.

```js
import * as React from 'react';
import ReactMapGL, {Marker} from 'react-map-gl';

function App(props) {
  const [viewport, setViewport] = React.useState({
    longitude: -122.45,
    latitude: 37.78,
    zoom: 14
  });

  // Only rerender markers if props.data has changed
  const markers = React.useMemo(() => data.map(
    city => (
      <Marker key={city.name} longitude={city.longitude} latitude={city.latitude} >
        <img src="pin.png" />
      </Marker>
    )
  ), [props.data]);

  return (
    <ReactMapGL {...viewport} width="100vw" height="100vh" onViewportChange={setViewport}>
      {markers}
    </ReactMapGL>
  );
}
```


## Properties

##### `latitude` (Number, required)
Latitude of the marker.

##### `longitude` (Number, required)
Longitude of the marker.

##### `offsetLeft` (Number)

- default: `0`

Offset of the marker from the left in pixels, negative number indicates left.

##### `offsetTop` (Number)

- default: `0`

Offset of the marker from the top in pixels, negative number indicates up.

##### `draggable` (Boolean)

- default: `false`

Allows this marker component to be dragged around the map. (Use `onDragEnd` to capture the final position and update `longitude` and `latitude`).

##### `onDragStart` (Function)

Called when a draggable marker starts being dragged.

Parameters:

- `event` - The pointer event.
  + `event.lngLat` - The geo coordinates where the drag started, as `[lng, lat]`.

##### `onDrag` (Function)

Continuously called while a draggable marker is being dragged.

Parameters:

- `event` - The pointer event.
  + `event.lngLat` - The geo coordinates of the drag event, as `[lng, lat]`.

##### `onDragEnd` (Function)

Called when a draggable marker is released at its final position. This is usually a good time to capture `event.lngLat` and update the marker's `longitude` and `latitude` props.

Parameters:

- `event` - The pointer event.
  + `event.lngLat` - The geo coordinates where the drag ended, as `[lng, lat]`.

##### `className` (String)

Assign a custom class name to the container of this control.

##### `captureScroll` (Boolean)

- default: `false`

Stop propagation of mouse wheel event to the map component. Can be used to stop map from zooming when this component is scrolled.

##### `captureDrag` (Boolean)

- default: `true`

Stop propagation of dragstart event to the map component. Can be used to stop map from panning when this component is dragged.

##### `captureClick` (Boolean)

- default: `true`

Stop propagation of click event to the map component. Can be used to stop map from calling the `onClick` callback when this component is clicked.

##### `captureDoubleClick` (Boolean)

- default: `true`

Stop propagation of dblclick event to the map component. Can be used to stop map from zooming when this component is double clicked.

##### `capturePointerMove` (Boolean)

- default: `false`

Stop propagation of pointermove event to the map component. Can be used to stop map from calling the `onMouseMove` or `onTouchMove` callback when this component is hovered.

##### `style` (object)

- default: `undefined`

Optional extra style object to be applied to the marker. Can be used to add properties like `zIndex` to the marker as inline style.

## Styling

Like its Mapbox counterpart, this control relies on the mapbox-gl stylesheet to work properly. Make sure to add the stylesheet to your page.

## Source

[marker.js](https://github.com/visgl/react-map-gl/tree/6.1-release/src/components/marker.js)