mapboxgl.accessToken = 'pk.eyJ1IjoiYWRtaW4wMDc5NiIsImEiOiJja2czYm5nbzgwOTRhMnBvNTExaXV5MTY5In0.DQmNyRgl7IzeqpAuiTI4uA';
var map = new mapboxgl.Map({
container: 'map',
style: 'mapbox://styles/mapbox/streets-v11',
center: [64,40],
zoom: 7
});
var distanceContainer = document.getElementById('distance');
// GeoJSON object to hold our measurement features
var geojson = {
'type': 'FeatureCollection',
'features': []
};
// Used to draw a line between points
var linestring = {
'type': 'Feature',
'geometry': {
'type': 'LineString',
'coordinates': []
}
};
map.on('load', function () {
map.addSource('geojson', {
'type': 'geojson',
'data': geojson
});
// Add styles to the map
map.addLayer({
id: 'measure-points',
type: 'circle',
source: 'geojson',
paint: {
'circle-radius': 5,
'circle-color': '#000'
},
filter: ['in', '$type', 'Point']
});
map.addLayer({
id: 'measure-lines',
type: 'line',
source: 'geojson',
layout: {
'line-cap': 'round',
'line-join': 'round'
},
paint: {
'line-color': '#000',
'line-width': 2.5
},
filter: ['in', '$type', 'LineString']
});
map.on('click', function (e) {
var features = map.queryRenderedFeatures(e.point, {
layers: ['measure-points']
});
// Remove the linestring from the group
// So we can redraw it based on the points collection
if (geojson.features.length > 1) geojson.features.pop();
// Clear the Distance container to populate it with a new value
distanceContainer.innerHTML = '';
// If a feature was clicked, remove it from the map
if (features.length) {
var id = features[0].properties.id;
geojson.features = geojson.features.filter(function (point) {
return point.properties.id !== id;
});
} else {
var point = {
'type': 'Feature',
'geometry': {
'type': 'Point',
'coordinates': [e.lngLat.lng, e.lngLat.lat]
},
'properties': {
'id': String(new Date().getTime())
}
};
geojson.features.push(point);
}
if (geojson.features.length > 1) {
linestring.geometry.coordinates = geojson.features.map(
function (point) {
return point.geometry.coordinates;
}
);
geojson.features.push(linestring);
// Populate the distanceContainer with total distance
var value = document.createElement('pre');
value.textContent =
'Total distance: ' +
turf.length(linestring).toLocaleString() +
'km';
distanceContainer.appendChild(value);
}
map.getSource('geojson').setData(geojson);
});
});
map.on('mousemove', function (e) {
var features = map.queryRenderedFeatures(e.point, {
layers: ['measure-points']
});
// UI indicator for clicking/hovering a point on the map
map.getCanvas().style.cursor = features.length
? 'pointer'
: 'crosshair';
});