如何将地图的当前视口作为几何体、边界框或wkt从OpenLayers中获取

How to get the current viewport of the map out of OpenLayers as geometry, bounding box or wkt?

本文关键字：边界 wkt 获取 OpenLayers 几何体 地图 视口      更新时间：2023-09-26

我试图在应该搜索这个主题的地方找到一些提示，但我什么都没找到——我花了很多时间在这上面。

我还试图从OpenLayers贴图中获取当前显示视口的当前坐标，以仅添加当前视口的当前边界框中的这些矢量。

对于OpenLayers 2:

Map.getExtent()

将返回Bounds，然后您可以使用该Bounds以多种方式获取纬度/经度坐标：http://dev.openlayers.org/apidocs/files/OpenLayers/BaseTypes/Bounds-js.html#OpenLayers.Bounds

理想情况下，您应该将矢量转换为几何体对象，并使用Bounds.contersectBounds（）根据Map.getExtent（）检查它们，以查看它们是否在当前视口中。

对于OpenLayers 3：

ol.Map.getView().calculateExtent(map.getSize())

将返回一个坐标数组，表示范围的边界框。

对于openlayers 5.3。

olmap.getView().calculateExtent(olmap.getSize());

openlayers 5.3的可运行代码如下：

（V6.5.0有相同的关于getView and getSize使用的API文档，上面的代码也应该使用它。）

// import modules
const Map = ol.Map;
const View = ol.View;
const TileLayer = ol.layer.Tile;
const VectorLayer = ol.layer.Vector;
const fromLonLat = ol.proj.fromLonLat;
const OSM = ol.source.OSM;
const VectorSource = ol.source.Vector;
const Overlay = ol.Overlay;
const Style = ol.style.Style;
const Fill = ol.style.Fill;
const Text = ol.style.Text;
// basic base layer: raster
var rasterLayer = new TileLayer({
  source: new OSM()
});
// create main map with a base map
var mapcenter = [100.5330981, 13.7364029];
var olmap = new Map({
  layers: [rasterLayer] /* more layers can be added here, or later steps */ ,
  target: document.getElementById("map1"),
  view: new View({
    center: fromLonLat(mapcenter),
    zoom: 17
  })
});
// add eng-chula marker
const engchula = [100.5330981, 13.7364029];
var marker1 = new Overlay({
  position: fromLonLat(engchula),
  positioning: "center-center",
  element: document.getElementById("marker1"),
  stopEvent: false
});
// 'Eng-chula' label
var engchula1 = new Overlay({
  position: fromLonLat(engchula),
  element: document.getElementById("engchula1")
});
// add overlay(s) to 'olmap'
olmap.addOverlay(marker1);
olmap.addOverlay(engchula1);
// Demo the use of .getSize()
var sizes = olmap.getSize(); //units:pixels; columns x rows
console.log("getSize (pixels): " + sizes); //2 numbers
// get `extent` through getView()
var extent = olmap.getView().calculateExtent(olmap.getSize());
console.log("Extent, LL_x: " + extent[0]); //left
console.log("Extent, LL_y: " + extent[1]); //bottom
console.log("Extent, UR_x: " + extent[2]); //right
console.log("Extent, UR_y: " + extent[3]); //top
/*
Status:ok
*/
#map1 {
  width: 70%;
  height: 500px;
}
#marker1 {
  width: 25px;
  height: 25px;
  border: 2px solid #088;
  border-radius: 10px;
  background-color: firebrick;
  opacity: 0.75;
}
<head>
  <link rel="stylesheet" href="https://openlayers.org/en/v5.3.0/css/ol.css" type="text/css">
  <link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css">
  <script src="https://cdn.rawgit.com/openlayers/openlayers.github.io/master/en/v5.3.0/build/ol.js"></script>
  <script src="https://code.jquery.com/jquery-2.2.3.min.js"></script>
</head>
<body>
  <H3>Openlayers v5.3.0 Web Map with Geojson Data</H3>
  <div id="map1" class="map"></div>
  <i>:</i>
  <p id="p1">Find &quot;<b>Eng_Chula</b>&quot;, then click it.</p>
  <div style="display: none;">
    <!-- Clickable label for Eng-Chula -->
    <a class="overlay" id="engchula1" target="_blank" href="https://www.eng.chula.ac.th/th/">Eng_Chula</a>
    <div id="marker1" title="Marker1"></div>
  </div>
</body>

基于这里的答案，但如果您希望结果在经纬度坐标中。

function getBounds() {
  const extent = olMap.getView().calculateExtent(olMap.getSize())
  return transformExtent(extent, 'EPSG:3857', 'EPSG:4326')
}
相关文章：