npm package: @jetblack/map-geojson
Description: A geojson layer for @jetblack/map
Author: Rob Blackbourn
Latest version: 2.0.0

# @jetblack/map-geojson

A GeoJSON layer for @jetblack/map.

## Example

Here is an example which demonstrates some different geojson features.

```ts
import React, { SVGProps, useRef } from 'react'

import { Feature, FeatureCollection } from 'geojson'

import { Coordinate, Map, osmTileProvider, useDrag, useZoom } from '@jetblack/map'

import { GeoJSONLayer } from '../../../dist'

const GREENWICH_OBSERVATORY: Coordinate = {
  latitude: 51.47684676353231,
  longitude: -0.0005261695762532147,
}

export default function App() {
  const data: FeatureCollection = {
    type: 'FeatureCollection',
    features: [
      {
        type: 'Feature',
        geometry: {
          type: 'Point',
          coordinates: [-0.0005261695762532147, 51.47684676353231],
        },
        properties: { name: 'Greenwich Observatory' },
      },
      {
        type: 'Feature',
        geometry: {
          type: 'MultiPoint',
          coordinates: [
            [2.3742684290761105, 48.86380120851702],
            [-1.5517871865064765, 47.246730628236755],
            [1.4460149695779017, 43.606797136829464],
            [3.8655608722043815, 43.59577745327528],
            [5.341636045504812, 43.30855735318184],
            [4.839466141186111, 45.77013358229793],
          ],
        },
        properties: { name: 'French Cities' },
      },
      {
        type: 'Feature',
        geometry: {
          type: 'LineString',
          coordinates: [
            [-2.5826946698502713, 51.46359918153936],
            [-1.8773290720606506, 52.48054446053743],
            [-2.237515760293648, 53.48344634623912],
          ],
        },
        properties: {
          name: 'Bristol-Birmingham-Manchester',
        },
      },
      {
        type: 'Feature',
        geometry: {
          type: 'MultiLineString',
          coordinates: [
            [
              [-1.9866601334551377, 50.71284269506134],
              [-1.8210675694654823, 50.64988780301567],
              [-1.6223564926778955, 49.63967630461819],
            ],
            [
              [1.3185676135378612, 51.132464268639396],
              [1.8451519670249663, 50.95964640369708],
            ],
          ],
        },
        properties: {
          name: 'Channel Ferry Routes',
        },
      },
      {
        type: 'Feature',
        geometry: {
          type: 'Polygon',
          coordinates: [
            [
              [-2.725202984442157, 49.59676280493421],
              [-2.410577112861812, 49.60105585469554],
              [-1.8674335029757423, 49.25857832678847],
              [-1.9667890413695357, 49.07668096925981],
              [-2.357587492385122, 49.05498200171354],
              [-2.7980637125976053, 49.392407428298945],
            ],
          ],
        },
        properties: {
          name: 'Channel Islands',
        },
      },
    ],
  }

  const ref = useRef<HTMLDivElement>(null)

  const [zoom, setZoom] = useZoom({ ref, defaultZoom: 6 })
  const [center, setCenter] = useDrag({
    ref,
    zoom,
    defaultCenter: GREENWICH_OBSERVATORY,
    tileSize: osmTileProvider.tileSize,
  })

  const handleRequestFeatureStyle = (feature: Feature): SVGProps<SVGSVGElement> | null => {
    if (feature?.properties?.name === 'French Cities') {
      return {
        fill: '#93c0d099',
        strokeWidth: '2',
        stroke: 'red',
        r: '15',
      }
    } else if (feature?.properties?.name === 'Bristol-Birmingham-Manchester') {
      return {
        fill: 'none',
        strokeWidth: '2',
        stroke: 'blue',
      }
    } else {
      return null
    }
  }

  return (
    <Map
      ref={ref}
      center={center}
      zoom={zoom}
      tileProvider={osmTileProvider}
      width={600}
      height={400}
    >
      <GeoJSONLayer data={data} requestFeatureStyle={handleRequestFeatureStyle} />
    </Map>
  )
}
```