我想查看一个图形层中所有与鼠标的x,y相匹配的特征。hitTest()方法对最上面的一个点有效。
mapView.on("pointer-move", function(event) { // HANDLE HOVER
let screenPoint={ x: event.x, y: event.y };
mapView.hitTest(screenPoint).then(function(response) {
if (response.results.length) {
DO SOMETHING...
}
});
但是，当我放大时，这些点会重叠成一个。我怎么知道还有其他的点，并能访问它们？
Google Earth曾经有一个功能可以自动将它们显示在一个圆圈中。如果arcGis也有这个功能，那就太好了，但我还是想硬着头皮做。
在新版本的API中，4.x，通常是一个 "指针移动 "的方法。GraphicLayer 的目的（处理客户端功能）成为了 FeatureLayer 或其他层，如 GeoJSONLayer 或 CSVLayer.
现在，建议使用 FeatureLayer,
在处理客户端图形时，通常首选使用其源属性构建一个FeatureLayer，因为FeatureLayer比GraphicsLayer具有更多的功能，包括渲染、查询和标记。
ArcGIS JavaScript API - GraphicLayer
在可视化方面，你可以用聚类对 FeatureLayer.
看一下我给你做的这个例子，是基于 ArcGIS JavaScript示例 - 点聚类.
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8" />
<meta
name="viewport"
content="initial-scale=1,maximum-scale=1,user-scalable=no"
/>
<title>FeatureLayer Cluster - 4.15</title>
<style>
html,
body,
#viewDiv {
padding: 0;
margin: 0;
height: 100%;
width: 100%;
}
</style>
<link
rel="stylesheet"
href="https://js.arcgis.com/4.15/esri/themes/light/main.css"
/>
<script src="https://js.arcgis.com/4.15/"></script>
<script>
require([
"esri/Map",
"esri/views/MapView",
"esri/layers/FeatureLayer",
"esri/Graphic",
"esri/geometry/Point",
"esri/widgets/Legend",
"esri/widgets/Expand"
], function(
Map,
MapView,
FeatureLayer,
Graphic,
Point,
Legend,
Expand
) {
function getRandomNumber(min, ref) {
return Math.random() * ref + min;
}
function getGraphics() {
const graphics = [];
let location = null;
// generate random points features
let oid = 0;
for (let i = 0; i <= getRandomNumber(20, 50); i++) {
location = new Point({
latitude: getRandomNumber(10, 50),
longitude: -getRandomNumber(50, 50)
});
for (let j = 0; j <= getRandomNumber(0, 50); j++) {
graphics.push(
new Graphic({
geometry: location,
attributes: {
OBJECTID: oid,
name: `${i}-${j}`
}
})
);
oid++;
}
}
return graphics;
}
const graphics = getGraphics();
function popupTemplateContent(feature) {
const location = feature.graphic.geometry;
return `lat:${location.latitude.toFixed(2)} lon:${location.longitude.toFixed(2)}`;
}
const clusterConfig = {
type: "cluster",
clusterRadius: "100px",
popupTemplate: {
content: "{cluster_count} features."
}
};
function createLayer() {
return new FeatureLayer({
source: graphics,
objectIdField: "OBJECTID",
fields: [
{
name: "OBJECTID",
type: "oid"
},
{
name: "name",
type: "string"
}
],
featureReduction: clusterConfig,
popupTemplate: {
title: '{name}',
content: popupTemplateContent
},
renderer: {
type: "simple",
field: "mag",
symbol: {
type: "simple-marker",
size: 4,
color: "#fc3232",
outline: {
color: [50, 50, 50]
}
}
}
});
}
const layer = createLayer();
const view = new MapView({
map: new Map({
basemap: "gray-vector"
}),
container: "viewDiv",
zoom: 2,
center: [-75, 35]
});
view
.when()
.then(addLayerToView)
.catch(function(e) {
console.error("Creating FeatureLayer failed", e);
});
function addLayerToView() {
view.map.add(layer);
}
const legend = new Legend({
view: view,
container: "legendDiv"
});
const infoDiv = document.getElementById("infoDiv");
view.ui.add(
new Expand({
view: view,
content: infoDiv,
expandIconClass: "esri-icon-layer-list",
expanded: true
}),
"top-left"
);
const toggleButton = document.getElementById("cluster");
toggleButton.addEventListener("click", function() {
const fr = layer.featureReduction;
layer.featureReduction =
fr && fr.type === "cluster" ? null : clusterConfig;
toggleButton.innerText =
toggleButton.innerText === "Enable Clustering"
? "Disable Clustering"
: "Enable Clustering";
});
});
</script>
</head>
<body>
<div id="viewDiv"></div>
<div id="infoDiv" class="esri-widget">
<button id="cluster" class="esri-button">Disable Clustering</button>
<div id="legendDiv"></div>
</div>
</body>
</html>在这个例子中，当你选择聚类是否开启时，它将显示有多少个特征，如果聚类关闭，你将得到所有的特征。