地理坐标加载 WFS

geographic 4 vector 72 WFS 3 tile 9 strategy 2 loading 8 server 5 maptiler 25

本示例演示使用瓦片策略加载 WFS.

本示例演示使用基于瓦片载入策略同 GeoServer WFS 中加载新图形要素。在 'ol/proj' 模块中调用 useGeographic 方法使地图视图使用地理坐标(即使地图视图投影不是地理坐标)。

main.js

import GeoJSON from 'ol/format/GeoJSON.js';
import Map from 'ol/Map.js';
import VectorSource from 'ol/source/Vector.js';
import View from 'ol/View.js';
import XYZ from 'ol/source/XYZ.js';
import {Stroke, Style} from 'ol/style.js';
import {Tile as TileLayer, Vector as VectorLayer} from 'ol/layer.js';
import {createXYZ} from 'ol/tilegrid.js';
import {tile} from 'ol/loadingstrategy.js';
import {useGeographic} from 'ol/proj.js';

useGeographic();

const vectorSource = new VectorSource({
  format: new GeoJSON(),
  url: function (extent) {
    return (
      'https://ahocevar.com/geoserver/wfs?service=WFS&' +
      'version=1.1.0&request=GetFeature&typename=osm:water_areas&' +
      'outputFormat=application/json&srsname=EPSG:4326&' +
      'bbox=' +
      extent.join(',') +
      ',EPSG:4326'
    );
  },
  strategy: tile(createXYZ({tileSize: 512})),
});

const vector = new VectorLayer({
  source: vectorSource,
  style: new Style({
    stroke: new Stroke({
      color: 'rgba(0, 0, 255, 1.0)',
      width: 2,
    }),
  }),
});

const key = 'Get your own API key at https://www.maptiler.com/cloud/';
const attributions =
  '<a href="https://www.maptiler.com/copyright/" target="_blank">&copy; MapTiler</a> ' +
  '<a href="https://www.openstreetmap.org/copyright" target="_blank">&copy; OpenStreetMap contributors</a>';

const raster = new TileLayer({
  source: new XYZ({
    attributions: attributions,
    url: 'https://api.maptiler.com/tiles/satellite/{z}/{x}/{y}.jpg?key=' + key,
    maxZoom: 20,
  }),
});

const map = new Map({
  layers: [raster, vector],
  target: document.getElementById('map'),
  view: new View({
    center: [-80.0298, 43.4578],
    maxZoom: 19,
    zoom: 12,
  }),
});

index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>WFS with geographic coordinates</title>
    <link rel="stylesheet" href="node_modules/ol/ol.css">
    <style>
      .map {
        width: 100%;
        height: 400px;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <!-- Pointer events polyfill for old browsers, see https://caniuse.com/#feat=pointer -->
    <script src="./resources/elm-pep.js"></script>
    <script type="module" src="main.js"></script>
  </body>
</html>

package.json

{
  "name": "vector-wfs-geographic",
  "dependencies": {
    "ol": "7.3.0"
  },
  "devDependencies": {
    "vite": "^3.2.3"
  },
  "scripts": {
    "start": "vite",
    "build": "vite build"
  }
}