2020-02-25 08:04:09 -08:00

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# Marker Control
![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 {Component} from 'react';
import ReactMapGL, {Marker} from 'react-map-gl';
class Map extends Component {
render() {
return (
<ReactMapGL latitude={37.78} longitude={-122.41} zoom={8}>
<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 {PureComponent} from 'react';
import ReactMapGL, {Marker} from 'react-map-gl';
const CITIES = [...];
// PureComponent ensures that the markers are only rerendered when data changes
class Markers extends PureComponent {
render() {
const {data} = this.props;
return data.map(
city => <Marker key={city.name} longitude={city.longitude} latitude={city.latitude} ><img src="pin.png" /></Marker>
)
}
}
class Map extends PureComponent {
state = {
viewport: {
latitude: 37.78,
longitude: -122.41,
zoom: 8
}
};
render() {
return (
<ReactMapGL {...this.state.viewport} onViewportChange={viewport => this.setState({viewport})}>
<Markers data={CITIES} />
</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]`.
##### `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. Automatically true if `draggable` is `true`.
##### `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.
## 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/uber/react-map-gl/tree/5.2-release/src/components/marker.js)