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@mpmckenna8
Last active February 12, 2019 15:27
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mapbox-gl.js drag a point and have a line that connects it to another point move

A pretty contrived example to try to help someone to show how to drag circles and have a line move with it. You can drag the light blue circle around and the line connecting it to the red point moves with it.

<!DOCTYPE html>
<html>
<head>
<meta charset='utf-8' />
<title>Create a draggable point</title>
<meta name='viewport' content='initial-scale=1,maximum-scale=1,user-scalable=no' />
<script src='https://api.tiles.mapbox.com/mapbox-gl-js/v0.53.0/mapbox-gl.js'></script>
<link href='https://api.tiles.mapbox.com/mapbox-gl-js/v0.53.0/mapbox-gl.css' rel='stylesheet' />
<style>
body { margin:0; padding:0; }
#map { position:absolute; top:0; bottom:0; width:100%; }
</style>
</head>
<body>
<style>
.coordinates {
background: rgba(0,0,0,0.5);
color: #fff;
position: absolute;
bottom: 10px;
left: 10px;
padding:5px 10px;
margin: 0;
font-size: 11px;
line-height: 18px;
border-radius: 3px;
display: none;
}
</style>
<div id='map'></div>
<pre id='coordinates' class='coordinates'></pre>
<script src='./map.js'>
</script>
</body>
</html>
mapboxgl.accessToken = 'pk.eyJ1IjoibXBtY2tlbm5hOCIsImEiOiJfYWx3RlJZIn0.v-vrWv_t1ytntvWpeePhgQ';
var coordinates = document.getElementById('coordinates');
var map = new mapboxgl.Map({
container: 'map',
style: 'mapbox://styles/mapbox/streets-v9',
center: [0, 0],
zoom: 2
});
var canvas = map.getCanvasContainer();
var geojson = {
"type": "FeatureCollection",
"features": [{
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [0, 0]
}
}]
};
var parent = {
"type": "FeatureCollection",
"features": [{
"type": "Feature",
"geometry": {
"type": "Point",
"coordinates": [13, 4]
}
}]
};
var liner = {
"type": "FeatureCollection",
"features": [{
"type": "Feature",
"geometry": {
"type": "LineString",
"coordinates": [
parent.features[0].geometry.coordinates, geojson.features[0].geometry.coordinates
]
}
}]
};
function onMove(e) {
var coords = e.lngLat;
// Set a UI indicator for dragging.
canvas.style.cursor = 'grabbing';
// Update the Point feature in `geojson` coordinates
// and call setData to the source layer `point` on it.
geojson.features[0].geometry.coordinates = [coords.lng, coords.lat];
liner.features[0].geometry.coordinates[1] = [coords.lng, coords.lat];
map.getSource('point').setData(geojson);
map.getSource('liner').setData(liner);
}
function onUp(e) {
var coords = e.lngLat;
// Print the coordinates of where the point had
// finished being dragged to on the map.
coordinates.style.display = 'block';
coordinates.innerHTML = 'Longitude: ' + coords.lng + '<br />Latitude: ' + coords.lat;
canvas.style.cursor = '';
// Unbind mouse/touch events
map.off('mousemove', onMove);
map.off('touchmove', onMove);
}
map.on('load', function() {
// Add a single point to the map
map.addSource('point', {
"type": "geojson",
"data": geojson
});
map.addSource('parent', {
"type": "geojson",
"data": parent
});
map.addLayer({
"id": "point",
"type": "circle",
"source": "point",
"paint": {
"circle-radius": 10,
"circle-color": "#3887be"
}
});
map.addLayer({
"id": "parent",
"type": "circle",
"source": "parent",
"paint": {
"circle-radius": 30,
"circle-color": "#e887be"
}
});
map.addLayer({
'id': 'liner',
'type': 'line',
'source': {
'type': 'geojson',
'data': liner
},
'layout': {
'line-cap': 'round',
'line-join': 'round'
},
'paint': {
'line-color': '#ed6498',
'line-width': 5,
'line-opacity': .8
}
});
// When the cursor enters a feature in the point layer, prepare for dragging.
map.on('mouseenter', 'point', function() {
map.setPaintProperty('point', 'circle-color', '#3bb2d0');
canvas.style.cursor = 'move';
});
map.on('mouseleave', 'point', function() {
map.setPaintProperty('point', 'circle-color', '#3887be');
canvas.style.cursor = '';
});
map.on('mousedown', 'point', function(e) {
// Prevent the default map drag behavior.
e.preventDefault();
canvas.style.cursor = 'grab';
map.on('mousemove', onMove);
map.once('mouseup', onUp);
});
map.on('touchstart', 'point', function(e) {
if (e.points.length !== 1) return;
// Prevent the default map drag behavior.
e.preventDefault();
map.on('touchmove', onMove);
map.once('touchend', onUp);
});
});
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