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<!DOCTYPE html>
<html>
<head>
<title>Display cluster area with Convex Hull - Azure Maps Web SDK Samples</title>
<meta charset="utf-8" />
<meta http-equiv="x-ua-compatible" content="IE=Edge" />
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no" />
<meta name="description" content="This sample shows how to display the area of the points contained within a cluster by calculating a convex hull. " />
<meta name="keywords" content="map, gis, API, SDK, markers, pins, pushpins, symbols, layer, clustering, superclusterer, convex hull, spatial math" />
<meta name="author" content="Microsoft Azure Maps" />
<!-- Add references to the Azure Maps Map control JavaScript and CSS files. -->
<link rel="stylesheet" href="https://atlas.microsoft.com/sdk/javascript/mapcontrol/2/atlas.min.css" type="text/css" />
<script src="https://atlas.microsoft.com/sdk/javascript/mapcontrol/2/atlas.min.js"></script>
<script type='text/javascript'>
var map, datasource, polygonDatasource;
//GeoJSON feed of all earthquakes from the past 30 days. Sourced from the USGS.
var earthquakeFeed = "https://earthquake.usgs.gov/earthquakes/feed/v1.0/summary/all_month.geojson";
//Find more earthquake data feeds here: https://earthquake.usgs.gov/earthquakes/feed/v1.0/geojson.php
function GetMap() {
//Initialize a map instance.
map = new atlas.Map('myMap', {
center: [-97, 39],
zoom: 3,
style: 'grayscale_dark',
view: 'Auto',
//Add your Azure Maps subscription key to the map SDK. Get an Azure Maps key at https://azure.com/maps
authOptions: {
authType: 'subscriptionKey',
subscriptionKey: '<Your Azure Maps Key>'
}
});
//Wait until the map resources are ready.
map.events.add('ready', function () {
//Create a data source for the point data.
datasource = new atlas.source.DataSource(null, {
//Tell the data source to cluster point data.
cluster: true
});
//Create a data source for the convex hull polygon. Since this will be updated frequently it is more efficient to seperate this into its own data source.
polygonDatasource = new atlas.source.DataSource();
//Add the data sources to the map.
map.sources.add([polygonDatasource, datasource]);
//Create a symbol layer to render the clusters.
var clusterLayer = new atlas.layer.SymbolLayer(datasource, null, {
iconOptions: {
image: 'marker-red'
},
textOptions: {
textField: ['get', 'point_count_abbreviated'],
offset: [0, -1.2],
color: "#ffffff",
size: 14
},
filter: ['has', 'point_count'] //Filter individual points from this layer.
});
//Add a mouse over event to calculate and display the cluster area using a convex hull.
map.events.add('mouseover', clusterLayer, displayClusterArea);
//Add a mouse leave event to remove the convex hull from the map.
map.events.add('mouseleave', clusterLayer, function () {
polygonDatasource.clear();
});
//Add a polygon layer and a line layer to display the convex hull.
//Add two symbol layers to the map, one for clusters, one for individual points.
map.layers.add([
//Create a polygon layer to display the area of the convex hull.
new atlas.layer.PolygonLayer(polygonDatasource),
//Create a line layer to display the outline of the convex hull.
new atlas.layer.LineLayer(polygonDatasource),
clusterLayer,
//Create a layer to render the individual locations.
new atlas.layer.SymbolLayer(datasource, null, {
filter: ['!', ['has', 'point_count']] //Filter out clustered points from this layer.
})
]);
//Retrieve a GeoJSON data set and add it to the data source.
datasource.importDataFromUrl(earthquakeFeed);
});
}
function displayClusterArea(e) {
if (e && e.shapes && e.shapes.length > 0 && e.shapes[0].properties.cluster) {
//Get the clustered point from the event.
var cluster = e.shapes[0];
//Get all points in the cluster. Set the offset to 0 and the limit to Infinity to return all points.
datasource.getClusterLeaves(cluster.properties.cluster_id, Infinity, 0).then(function (points) {
if (points.length === 2) {
//When only two points in a cluster. Render a line.
polygonDatasource.setShapes(new atlas.data.LineString(getPositions(points)));
} else {
var hullPolygon = atlas.math.getConvexHull(getPositions(points));
//Overwrite all data in the polygon data source with the newly calculated convex hull polygon.
polygonDatasource.setShapes(hullPolygon);
}
});
}
}
//TODO: update this when atlas.Shapes is supported by atlas.math.getPositions and update codepen
function getPositions(shapes) {
var pos = [];
if (shapes) {
for (var i = 0; i < shapes.length; i++) {
if (shapes[i] instanceof atlas.Shape) {
pos.push(shapes[i].getCoordinates());
} else {
pos.push(atlas.math.getPosition(shapes[i]));
}
}
}
return pos;
}
</script>
</head>
<body onload="GetMap()">
<div id="myMap" style="position:relative;width:100%;min-width:290px;height:600px;"></div>
<fieldset style="width:calc(100% - 30px);min-width:290px;margin-top:10px;">
<legend>Display cluster area with Convex Hull</legend>
This sample shows how to display the area of the points contained within a cluster by calculating a convex hull.
</fieldset>
</body>
</html>
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