Hover Tooltip

<!--
  示例：悬浮提示
  要点：Overlay 承载气泡 DOM，pointermove 中 forEachFeatureAtPixel 判断命中
  依赖：OpenLayers 10.3.1 · jsDelivr CDN
-->
<!DOCTYPE html>
<html lang="zh-CN">
<head>
<meta name="robots" content="noindex,follow">
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>悬浮提示</title>
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/ol@10.3.1/ol.css">
<style>
  html,body{height:100%;margin:0}
  body{display:flex;flex-direction:column;overflow:hidden;
       font:13px/1.6 -apple-system,"Segoe UI","PingFang SC",sans-serif}
  .bar{flex:0 0 auto;padding:8px 12px;background:#f6f7f9;border-bottom:1px solid #e3e6ea;
       font-size:12px;color:#58606e}
  #map{flex:1 1 auto;min-height:0;background:#eef0f3;position:relative}
  .tip{position:relative;background:#16181d;color:#fff;padding:6px 9px;border-radius:4px;
       font-size:12px;white-space:nowrap;
       box-shadow:0 2px 8px rgba(0,0,0,.25)}
  .tip::after{content:"";position:absolute;left:50%;bottom:-5px;margin-left:-5px;
              border:5px solid transparent;border-top-color:#16181d;border-bottom:0}
  .tip b{color:#9dc0ff}
</style>
</head>
<body>
<div class="bar">鼠标移到点符号上查看信息</div>
<div id="map">
  <div class="tip" id="tip" style="display:none"></div>
</div>
<script src="https://cdn.jsdelivr.net/npm/ol@10.3.1/dist/ol.js"></script>
<script>
(function () {
  'use strict';

  if (typeof ol === 'undefined') {
    document.getElementById('map').innerHTML =
      '<div style="padding:20px;color:#b42318">OpenLayers 加载失败，请检查能否访问 cdn.jsdelivr.net</div>';
    return;
  }

  var fromLonLat = ol.proj.fromLonLat;

  var data = [
    [116.3912, 39.9074, '天安门', '广场'],
    [116.4106, 39.9147, '王府井', '商圈'],
    [116.3800, 39.9005, '西单', '商圈'],
    [116.3966, 39.9182, '景山', '公园'],
    [116.4128, 39.9049, '崇文门', '地铁站']
  ];

  var features = data.map(function (p) {
    return new ol.Feature({
      geometry: new ol.geom.Point(fromLonLat([p[0], p[1]])),
      name: p[2],
      kind: p[3]
    });
  });

  var layer = new ol.layer.Vector({
    source: new ol.source.Vector({ features: features }),
    style: new ol.style.Style({
      image: new ol.style.Circle({
        radius: 7,
        fill: new ol.style.Fill({ color: '#1f5fd0' }),
        stroke: new ol.style.Stroke({ color: '#ffffff', width: 2 })
      })
    })
  });

  var tipEl = document.getElementById('tip');

  var tipOverlay = new ol.Overlay({
    element: tipEl,
    positioning: 'bottom-center',
    stopEvent: false,
    offset: [0, -10]
  });

  var map = new ol.Map({
    target: 'map',
    layers: [new ol.layer.Tile({ source: new ol.source.XYZ({url: 'https://server.arcgisonline.com/ArcGIS/rest/services/World_Street_Map/MapServer/tile/{z}/{y}/{x}', attributions: 'Tiles © Esri'}) }), layer],
    overlays: [tipOverlay],
    view: new ol.View({
      center: fromLonLat([116.397, 39.911]),
      zoom: 14
    }),
    controls: ol.control.defaults.defaults({ attribution: false })
  });

  var hit = null;

  map.on('pointermove', function (evt) {
    if (evt.dragging) {
      return;
    }

    var feature = map.forEachFeatureAtPixel(evt.pixel, function (f) {
      return f;
    }, { hitTolerance: 6 });

    if (feature === hit) {
      return;
    }
    hit = feature;

    if (feature) {
      tipEl.style.display = 'block';
      tipEl.innerHTML = '<b>' + feature.get('name') + '</b> · ' + feature.get('kind');
      tipOverlay.setPosition(feature.getGeometry().getCoordinates());
      map.getTargetElement().style.cursor = 'pointer';
    } else {
      tipEl.style.display = 'none';
      tipOverlay.setPosition(undefined);
      map.getTargetElement().style.cursor = '';
    }
  });
})();
</script>
</body>
</html>